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Journal Cover Ecology
  [SJR: 3.995]   [H-I: 220]   [345 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 0012-9658 - ISSN (Online) 1939-9170
   Published by John Wiley and Sons Homepage  [1592 journals]
  • Moisture availability limits subalpine tree establishment
    • Authors: Robert A. Andrus; Brian J. Harvey, Kyle C. Rodman, Sarah J. Hart, Thomas T. Veblen
      Abstract: In the absence of broad-scale disturbance, many temperate coniferous forests experience successful seedling establishment only when abundant seed production coincides with favorable climate. Identifying the frequency of past establishment events and the climate conditions favorable for seedling establishment is essential to understanding how climate warming could affect the frequency of future tree establishment events and therefore future forest composition or even persistence of a forest cover. In the southern Rocky Mountains, USA, research on the sensitivity of establishment of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa)—two widely distributed, co-occurring conifers in North America—to climate variability has focused on the alpine treeline ecotone, leaving uncertainty about the sensitivity of these species across much of their elevation distribution. We compared annual germination dates for>450 Engelmann spruce and>500 subalpine fir seedlings collected across a complex topographic-moisture gradient to climate variability in the Colorado Front Range. We found that Engelmann spruce and subalpine fir established episodically with strong synchrony in establishment events across the study area. Broad-scale establishment events occurred in years of high soil moisture availability, which were characterized by above-average snowpack and/or cool and wet summer climatic conditions. In the recent half of the study period (1975–2010), a decrease in the number of fir and spruce establishment events across their distribution coincided with declining snowpack and a multi-decadal trend of rising summer temperature and increasing moisture deficits. Counter to expected and observed increases in tree establishment with climate warming in maritime subalpine forests, our results show that recruitment declines will likely occur across the core of moisture-limited subalpine tree ranges as warming drives increased moisture deficits.
      PubDate: 2018-02-22T10:11:01.82768-05:0
      DOI: 10.1002/ecy.2134
       
  • Inferring species interactions through joint mark–recapture analysis
    • Authors: Charles B. Yackulic; Josh Korman, Michael D. Yard, Maria Dzul
      Abstract: Introduced species are frequently implicated in declines of native species. In many cases, however, evidence linking introduced species to native declines is weak. Failure to make strong inferences regarding the role of introduced species can hamper attempts to predict population viability and delay effective management responses. For many species, mark–recapture analysis is the more rigorous form of demographic analysis. However, to our knowledge, there are no mark–recapture models that allow for joint modeling of interacting species. Here, we introduce a two-species mark–recapture population model in which the vital rates (and capture probabilities) of one species are allowed to vary in response to the abundance of the other species. We use a simulation study to explore bias and choose an approach to model selection. We then use the model to investigate species interactions between endangered humpback chub (Gila cypha) and introduced rainbow trout (Oncorhynchus mykiss) in the Colorado River between 2009 and 2016. In particular, we test hypotheses about how two environmental factors (turbidity and temperature), intraspecific density dependence, and rainbow trout abundance are related to survival, growth, and capture of juvenile humpback chub. We also project the long-term effects of different rainbow trout abundances on adult humpback chub abundances. Our simulation study suggests this approach has minimal bias under potentially challenging circumstances (i.e., low capture probabilities) that characterized our application and that model selection using indicator variables could reliably identify the true generating model even when process error was high. When the model was applied to rainbow trout and humpback chub, we identified negative relationships between rainbow trout abundance and the survival, growth, and capture probability of juvenile humpback chub. Effects on interspecific interactions on survival and capture probability were strongly supported, whereas support for the growth effect was weaker. Environmental factors were also identified to be important and in many cases stronger than interspecific interactions, and there was still substantial unexplained variation in growth and survival rates. The general approach presented here for combining mark–recapture data for two species is applicable in many other systems and could be modified to model abundance of the invader via other modeling approaches.
      PubDate: 2018-02-21T11:30:44.989568-05:
      DOI: 10.1002/ecy.2166
       
  • Species associations overwhelm abiotic conditions to dictate the structure
           and function of wood-decay fungal communities
    • Authors: Daniel S. Maynard; Kristofer R. Covey, Thomas W. Crowther, Noah W. Sokol, Eric W. Morrison, Serita D. Frey, Linda T. A. van Diepen, Mark A. Bradford
      Abstract: Environmental conditions exert strong controls on the activity of saprotrophic microbes, yet abiotic factors often fail to adequately predict wood decomposition rates across broad spatial scales. Given that species interactions can have significant positive and negative effects on wood-decay fungal activity, one possibility is that biotic processes serve as the primary controls on community function, with abiotic controls emerging only after species associations are accounted for. Here we explore this hypothesis in a factorial field warming- and nitrogen-addition experiment by examining relationships among wood decomposition rates, fungal activity, and fungal community structure. We show that functional outcomes and community structure are largely unrelated to abiotic conditions, with microsite and plot-level abiotic variables explaining at most 19% of the total variability in decomposition and fungal activity, and 2% of the variability in richness and evenness. In contrast, taxonomic richness, evenness, and species associations (i.e., co-occurrence patterns) exhibited strong relationships with community function, accounting for 52% of the variation in decomposition rates and 73% in fungal activity. A greater proportion of positive vs. negative species associations in a community was linked to strong declines in decomposition rates and richness. Evenness emerged as a key mediator between richness and function, with highly even communities exhibiting a positive richness–function relationship and uneven communities exhibiting a negative or null response. These results suggest that community-assembly processes and species interactions are important controls on the function of wood-decay fungal communities, ultimately overwhelming substantial differences in abiotic conditions.
      PubDate: 2018-02-21T11:30:40.692377-05:
      DOI: 10.1002/ecy.2165
       
  • It takes a few to tango: Changing climate and fire regimes can cause
           regeneration failure of two subalpine conifers
    • Authors: Winslow D. Hansen; Kristin H. Braziunas, Werner Rammer, Rupert Seidl, Monica G. Turner
      Abstract: Environmental change is accelerating in the 21st century, but how multiple drivers may interact to alter forest resilience remains uncertain. In forests affected by large high-severity disturbances, tree regeneration is a resilience linchpin that shapes successional trajectories for decades. We modeled stands of two widespread western US conifers, Douglas-fir (Pseudotsuga menziesii var. glauca) and lodgepole pine (Pinus contorta var. latifolia), in Yellowstone National Park (Wyoming, USA) to ask: (1) What combinations of distance to seed source, fire return interval and warming-drying conditions cause postfire tree-regeneration failure' (2) If postfire tree regeneration was successful, how does early tree density differ under future climate relative to historical climate' We conducted a stand-level (1 ha) factorial simulation experiment using the individual-based forest process model iLand to identify combinations of fire return interval (11 to 100 years), distance to seed source (50 to 1000 m), and climate (historical, mid-21st century, late-21st century) where trees failed to regenerate by 30-years postfire. If regeneration was successful, we compared stand densities between climate periods. Simulated postfire regeneration were surprisingly resilient to changing climate and fire drivers. Douglas-fir regeneration failed more frequently (55%) than lodgepole pine (28% and 16% for non-serotinous and serotinous stands, respectively). Distance to seed source was an important driver of regeneration failure for Douglas-fir and non-serotinous lodgepole pine; regeneration never failed when stands were 50 m from a seed source and nearly always failed when stands were 1 km away. Regeneration of serotinous lodgepole pine only failed when fire return intervals were ≤ 20 years and stands were far (1 km) from a seed source. Warming climate increased regeneration success for Douglas-fir but did not affect lodgepole pine. If regeneration was successful, postfire density varied with climate. Douglas-fir and serotinous lodgepole pine regeneration density both increased under 21st-century climate but in response to different climate variables (growing season length vs cold limitation). Results suggest that given a warmer future with larger and more frequent fires, a greater number of stands that fail to regenerate after fires combined with increasing density in stands where regeneration is successful could produce a more coarse-grained forest landscape.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-21T04:40:27.956036-05:
      DOI: 10.1002/ecy.2181
       
  • Dual guild herbivory disrupts predator-prey interactions in the field
    • Authors: Carmen K. Blubaugh; Jacob S. Asplund, Sanford D. Eigenbrode, Matthew J. Morra, Christopher R. Philips, Inna E. Popova, John P. Reganold, William E. Snyder
      Abstract: Plant defenses often mediate whether competing chewing and sucking herbivores indirectly benefit or harm one another. Dual guild herbivory also can muddle plant signals used by specialist natural enemies to locate prey, further complicating the net impact of herbivore-herbivore interactions in naturally diverse settings. While dual guild herbivore communities are common in nature, their community trilevel consequences are unclear, as chemically mediated tri-trophic interactions are rarely evaluated in field environments. Combining observational and experimental approaches in the open field, we test a prediction that chewing herbivores interfere with top-down suppression of phloem feeders on Brassica oleracea across broad landscapes. In a two-year survey of 52 working farm sites, we found that parasitoid and aphid densities on broccoli plants positively correlated at farms where aphids and caterpillars rarely co-occurred, but this relationship disappeared at farms where caterpillars commonly co-occurred. In a follow-up experiment, we compared single and dual guild herbivore communities at four local farm sites and found that caterpillars (P. rapae) caused a 30% reduction in aphid parasitism (primarily by Diaeretiella rapae), and increased aphid colony (Brevicoryne brassicae) growth at some sites. Notably, in the absence of predators, caterpillars indirectly suppressed, rather than enhanced, aphid growth. Amid considerable ecological noise, our study reveals a pattern of apparent commensalism: herbivore-herbivore facilitation via relaxed top-down suppression. This work suggests that enemy-mediated apparent commensalism may override constraints to growth induced by competing herbivores in field environments, and emphasizes the value of placing chemically-mediated interactions within their broader environmental and community contexts.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-21T04:40:21.318-05:00
      DOI: 10.1002/ecy.2192
       
  • Plant responses to fertilization experiments in lowland, species-rich,
           tropical forests
    • Authors: S. Joseph Wright; Benjamin L. Turner, Joseph B. Yavitt, Kyle E. Harms, Michael Kaspari, Edmund V. J. Tanner, Jelena Bujan, Eric A. Griffin, Jordan R. Mayor, Sarah C. Pasquini, Merlin Sheldrake, Milton N. Garcia
      Abstract: We present a meta-analysis of plant responses to fertilization experiments conducted in lowland, species-rich, tropical forests. We also update a key result and present the first species-level analyses of tree growth rates for a 15-year factorial nitrogen (N), phosphorus (P) and potassium (K) experiment conducted in central Panama. The update concerns community-level tree growth rates, which responded significantly to the addition of N and K together after 10 years of fertilization (Wright et al. 2011) but not after 15 years (this study). Our experimental soils are infertile for the region, and species whose regional distributions are strongly associated with low soil P availability dominate the local tree flora. Under these circumstances, we expect muted responses to fertilization, and we predicted species associated with low-P soils would respond most slowly. The data did not support this prediction – species-level tree growth responses to P addition were unrelated to species-level soil P associations. The meta-analysis demonstrated that nutrient limitation is widespread in lowland tropical forests and evaluated two directional hypotheses concerning plant responses to N addition and to P addition. The meta-analysis supported the hypothesis that tree (or biomass) growth rate responses to fertilization are weaker in old growth forests and stronger in secondary forests, where rapid biomass accumulation provides a nutrient sink. The meta-analysis found no support for the long-standing hypothesis that plant responses are stronger for P addition and weaker for N addition. We do not advocate discarding the latter hypothesis. There are only 14 fertilization experiments from lowland, species-rich, tropical forests, 13 of the 14 experiments added nutrients for five or fewer years, and responses vary widely among experiments. Potential fertilization responses should be muted when the species present are well adapted to nutrient-poor soils, as is the case in our experiment, and when pest pressure increases with fertilization, as it does in our experiment. The statistical power and especially the duration of fertilization experiments conducted in old growth, tropical forests might be insufficient to detect the slow, modest growth responses that are to be expected.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-20T03:41:04.13137-05:0
      DOI: 10.1002/ecy.2193
       
  • Estimating dispersal in spatiotemporally variable environments using
           multievent capture–recapture modeling
    • Authors: Hugo Cayuela; Roger Pradel, Pierre Joly, Eric Bonnaire, Aurélien Besnard
      Abstract: Dispersal is a key process in ecological and evolutionary dynamics. Spatiotemporal variation in habitat availability and characteristics has been suggested to be the main cause involved in dispersal evolution and has a strong influence on metapopulation dynamics. In recent decades, the study of dispersal has led to the development of capture–recapture (CR) models that allow movement between sites to be quantified, while handling imperfect detection. For studies involving numerous recapture sites, Lagrange et al. (2014) proposed a multievent CR model that allows dispersal to be estimated while omitting site identity by distinguishing between individuals that stay and individuals that move. More recently, Cayuela et al. (2017) extended this model to allow survival and dispersal probabilities to differ for the different types of habitat represented by several sites within a study area. Yet in both of these modeling systems, the state of sites is assumed to be static over time, which is not a realistic assumption in dynamic landscapes. For that purpose, we generalized the multievent CR model proposed by Cayuela et al. (2017) to allow the estimation of dispersal, survival and recapture probabilities when a site may appear or disappear over time (MODEL 1) or when the characteristics of a site fluctuate over space and time (MODEL 2). This paper first presents these two new modeling systems, and then provides an illustration of their efficacy and usefulness by applying them to simulated CR data and data collected on two metapopulations of amphibians. MODEL 1 was tested using CR data recorded on a metapopulation of yellow-bellied toads (Bombina variegata). In this first empirical case, we examined whether the drying-out dynamics of ponds and the past dispersal status of an individual might affect dispersal behavior. Our study revealed that the probability of facultative dispersal (i.e. from a pond group that remained available/flooded) fluctuated between years and was higher in individuals that had previously dispersed. MODEL 2 was tested using CR data collected on a metapopulation of great crested newts (Triturus cristatus). In this second empirical example, we investigated whether the density of alpine newts (Ichthyosaura alpestris), a potential competitor, might affect the dispersal and survival of the crested newt. Our study revealed that the departure rate was lower in ponds with a high density of heterospecifics than in ponds with a low density of heterospecifics at both inter-annual and intra-annual scales. Moreover, annual survival was slightly higher in ponds with a high density of heterospecifics. Overall, our findings indicate that these multievent CR models provide a highly flexible means of modeling dispersal in dynamic landscapes.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-20T03:20:35.540248-05:
      DOI: 10.1002/ecy.2195
       
  • Increasing connectivity between metapopulation ecology and landscape
           ecology
    • Authors: Paige E. Howell; Erin Muths, Blake R. Hossack, Brent H. Sigafus, Richard B. Chandler
      Abstract: Metapopulation ecology and landscape ecology aim to understand how spatial structure influences ecological processes, yet these disciplines address the problem using fundamentally different modeling approaches. Metapopulation models describe how the spatial distribution of patches affects colonization and extinction, but often do not account for the heterogeneity in the landscape between patches. Models in landscape ecology use detailed descriptions of landscape structure, but often without considering colonization and extinction dynamics. We present a novel spatially-explicit modeling framework for narrowing the divide between these disciplines to advance understanding of the effects of landscape structure on metapopulation dynamics. Unlike previous efforts, this framework allows for statistical inference on landscape resistance to colonization using empirical data. We demonstrate the approach using 11 years of data on a threatened amphibian in a desert ecosystem. Occupancy data for Lithobates chiricahuensis (Chiricahua leopard frog) were collected on the Buenos Aires National Wildlife Refuge (BANWR), Arizona, USA from 2007-2017 following a reintroduction in 2003. Results indicated that colonization dynamics were influenced by both patch characteristics and landscape structure. Landscape resistance increased with increasing elevation and distance to the nearest streambed. Colonization rate was also influenced by patch quality, with semi-permanent and permanent ponds contributing substantially more to the colonization of neighboring ponds relative to intermittent ponds. Ponds that only hold water intermittently also had the highest extinction rate. Our modeling framework can be widely applied to understand metapopulation dynamics in complex landscapes, particularly in systems in which the environment between habitat patches influences the colonization process.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-17T03:50:23.07682-05:0
      DOI: 10.1002/ecy.2189
       
  • Competition for nutrients and light: testing advances in resource
           competition with a natural phytoplankton community
    • Authors: Amanda Burson; Maayke Stomp, Emma Greenwell, Julia Grosse, Jef Huisman
      Abstract: A key challenge in ecology is to understand how nutrients and light affect the biodiversity and community structure of phytoplankton and plant communities. According to resource competition models, ratios of limiting nutrients are major determinants of the species composition. At high nutrient levels, however, species interactions may shift to competition for light, which might make nutrient ratios less relevant. The “nutrient-load hypothesis” merges these two perspectives, by extending the classic model of competition for two nutrients to include competition for light. Here, we test five key predictions of the nutrient-load hypothesis using multispecies competition experiments. A marine phytoplankton community sampled from the North Sea was inoculated in laboratory chemostats provided with different nitrogen (N) and phosphorus (P) loads, to induce either single resource limitation or co-limitation of N, P and light. Four of the five predictions were validated by the experiments. In particular, different resource limitations favored the dominance of different species. Increasing nutrient loads caused changes in phytoplankton species composition, even if the N:P ratio of the nutrient loads remained constant, by shifting the species interactions from competition for nutrients to competition for light. In all treatments, small species became dominant whereas larger species were competitively excluded, supporting the common view that small cell size provides a competitive advantage under resource-limited conditions. Contrary to expectation, all treatments led to coexistence of diatoms, cyanobacteria and green algae, resulting in a higher diversity of species than predicted by theory. Because the coexisting species comprised three phyla with different photosynthetic pigments, we speculate that niche differentiation in the light spectrum might play a role. Our results show that mechanistic resource competition models that integrate nutrient-based and light-based approaches provide an important step forward to understand and predict how changing nutrient loads affect community composition.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-17T02:45:53.616049-05:
      DOI: 10.1002/ecy.2187
       
  • Using niche breadth theory to explain generalization in mutualisms
    • Authors: Rebecca T. Batstone; Kelly A. Carscadden, Michelle E. Afkhami, Megan E. Frederickson
      Abstract: For a mutualism to remain evolutionarily stable, theory predicts that mutualists should limit their associations to high-quality partners. However, most mutualists either simultaneously or sequentially associate with multiple partners that confer the same type of reward. By viewing mutualisms through the lens of niche breadth evolution, we outline how the environment shapes partner availability and relative quality, and ultimately a focal mutualist's partner breadth. We argue that mutualists that associate with multiple partners may have a selective advantage compared to specialists for many reasons, including sampling, complementarity, and portfolio effects, as well as the possibility that broad partner breadth increases breadth along other niche axes. Furthermore, selection for narrow partner breadth is unlikely to be strong when the environment erodes variation in partner quality, reduces the costs of interacting with low-quality partners, spatially structures partner communities, or decreases the strength of mutualism. Thus, we should not be surprised that most mutualists have broad partner breadth, even if it allows for ineffective partners to persist.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-17T02:45:51.533132-05:
      DOI: 10.1002/ecy.2188
       
  • Individual heterogeneity and early life conditions shape growth in a
           freshwater top-predator
    • Authors: Chloé R. Nater; Atle Rustadbakken, Torbjørn Ergon, Øystein Langangen, S. Jannicke Moe, Yngvild Vindenes, L. Asbjørn Vøllestad, Per Aass
      Abstract: Body size can have profound impacts on survival, movement, and reproductive schedules shaping individual fitness, making growth a central process in ecological and evolutionary dynamics. Realized growth is the result of a complex interplay between life history schedules, individual variation, and environmental influences. Integrating all of these aspects into growth models is methodologically difficult, depends on the availability of repeated measurements of identifiable individuals, and consequently represents a major challenge in particular for natural populations. Using a unique 30-year time series of individual length measurements inferred from scale year rings of wild brown trout, we develop a Bayesian hierarchical model to estimate individual growth trajectories in temporally and spatially varying environments. We reveal a gradual decrease in average juvenile growth, which has carried over to adult life and contributed to decreasing sizes observed at the population level. Commonly studied environmental drivers like temperature and water flow did not explain much of this trend and overall persistent and among-year individual variation dwarfed temporal variation in growth patterns. Our model and results are relevant to a wide range of questions in ecology and evolution requiring a detailed understanding of growth patterns, including conservation and management of many size-structured populations.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-13T14:35:34.197854-05:
      DOI: 10.1002/ecy.2178
       
  • Landscapes of facilitation: how self-organized patchiness of aquatic
           macrophytes promotes diversity in streams
    • Authors: Loreta Cornacchia; Johan van de Koppel, Daphne van der Wal, Geraldene Wharton, Sara Puijalon, Tjeerd J. Bouma
      Abstract: Spatial heterogeneity plays a crucial role in the coexistence of species. Despite recognition of the importance of self-organization in creating environmental heterogeneity in otherwise uniform landscapes, the effects of such self-organized pattern formation in promoting coexistence through facilitation are still unknown. In this study, we investigated the effects of pattern formation on species interactions and community spatial structure in ecosystems with limited underlying environmental heterogeneity, using self-organized patchiness of the aquatic macrophyte Callitriche platycarpa in streams as a model system. Our theoretical model predicted that pattern formation in aquatic vegetation – due to feedback interactions between plant growth, water flow and sedimentation processes – could promote species coexistence, by creating heterogeneous flow conditions inside and around the plant patches. The spatial plant patterns predicted by our model agreed with field observations at the reach scale in naturally vegetated rivers, where we found a significant spatial aggregation of two macrophyte species around C. platycarpa. Field transplantation experiments showed that C. platycarpa had a positive effect on the growth of both beneficiary species, and the intensity of this facilitative effect was correlated with the heterogeneous hydrodynamic conditions created within and around C. platycarpa patches. Our results emphasize the importance of self-organized patchiness in promoting species coexistence by creating a landscape of facilitation, where new niches and facilitative effects arise in different locations. Understanding the interplay between competition and facilitation is therefore essential for successful management of biodiversity in many ecosystems.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-13T08:55:23.932178-05:
      DOI: 10.1002/ecy.2177
       
  • Leaf N resorption efficiency and litter N mineralization rate have a
           genotypic trade-off in a silver birch population
    • Authors: Juha Mikola; Tarja Silfver, Ulla Paaso, Boy J M H Possen, Matti Rousi
      Abstract: Plants enhance N use efficiency by resorbing N from senescing leaves. This can affect litter N mineralization rate due to the C:N-ratio requirements of microbial growth. We examined genotypic links between leaf N resorption and litter mineralization by collecting leaves and litter from 19 Betula pendula genotypes and following the N release of litter patches on forest ground. We found significant genotypic variation for N resorption efficiency, litter N concentration, cumulative three-year patch N-input and litter N release with high broad-sense heritabilities (H2 = 0.28–0.65). The genotype means of N resorption efficiency varied from 46% to 65% and correlated negatively with the genotype means of litter N concentration, cumulative patch N-input and litter N release. NH4+ yield under patches had a positive genotypic correlation with the cumulative patch N-input. During the first year of litter decomposition, genotypes varied from N immobilization (max 2.71 mg g−1 dry litter) to N release (max 1.41 mg g−1 dry litter), creating a genotypic trade-off between the N conserved by resorption and the N available for root uptake during the growing season. We speculate that this trade-off is one likely reason for the remarkably wide genotypic range of N resorption efficiencies in our birch population.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-07T05:50:51.48375-05:0
      DOI: 10.1002/ecy.2176
       
  • Propagules are not all equal: traits of vegetative fragments and
           disturbance regulate invasion success
    • Authors: Marc Uyà; Fabio Bulleri, Paul E. Gribben
      Abstract: Invasion success is regulated by multiple factors. While the roles of disturbance and propagule pressure in regulating the establishment of non-native species are widely acknowledged, that of propagule morphology (a proxy for quality) is poorly known. By means of a multi-factorial field experiment, we tested how the number (5 versus 10) and quality (intact, without fronds or without rhizoids) of fragments of the clonal invasive seaweed, Caulerpa cylindracea, influenced its ability to establish in patches of the native seagrass, Posidonia oceanica, exposed to different intensities of disturbance (0, 50 or 100% reduction in canopy cover). We hypothesized that the ability of fragments to establish would be greater for intact fragments (high quality) and reduced more by frond removal (low quality) than rhizoid removal (intermediate quality). At low propagule pressure or quality, fragment establishment was predicted to increase with increasing disturbance, whereas, at high propagule pressure or quality, it was predicted to be high regardless of disturbance intensity. Disturbance intensity, fragment number and quality had independent effects on C. cylindracea establishment success. Disturbance always facilitated fragment establishment. However, fragments retaining fronds, either intact or deprived of rhizoids, had higher establishment success than fragments deprived of fronds. Increasing propagule number had weak effects on the cover of C. cylindracea. Our results demonstrate that propagule traits enabling the acquisition of resources made available by disturbance can be more important than propagule number in determining the establishment and spread of clonal non-native plants. More generally, our study suggests that propagule quality is a key, yet underexplored, determinant of invasion success.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-02T08:45:34.644669-05:
      DOI: 10.1002/ecy.2168
       
  • MADA: Malagasy Animal trait Data Archive
    • Authors: Onja H. Razafindratsima; Yasmin Yacoby, Daniel S. Park
      Abstract: Species are characterized by their behavioral, physiological and ecological attributes, which determine their role in ecosystems. In turn, ecosystems and their functions are defined by the species that inhabit them. Thus, evaluating the functional diversity and distributions of species is of utmost importance to studies of biogeography, community ecology, macroevolution, and conservation. The functional diversity of species are determined by traits such as diet, foraging strata, trophic level, activity cycle, litter size, generation length, habitat breadth and body mass. While there has been a recent growth of information regarding the vertebrate taxa of Madagascar, this information is not always easy to access (non-digitized), and is often fragmented by taxon, location, trait, or combinations thereof. Here, we present the Malagasy Animal trait Data Archive (MADA), a compilation of these and other functional traits, representing the ecological and geographical diversity of all 214 extant mammal and 242 bird species of Madagascar. Data were collected from extensive literature reviews. This Archive is currently limited by select cases of missing data, errors, and uncertainty in the literature; however, it represents the most comprehensive collection of functional trait data of Malagasy mammals and birds to date. The structure of the database allows for different levels of information (and specificity) in each entry and organization by taxon, range, bioclimate and trait. MADA will be continuously updated as new data become available. Potential uses of MADA include ecological research on the trait or trophic structure of communities, inquiries regarding the mechanisms of community assembly, comparative studies of functionally (dis)similar species, and conservation efforts concerned with the loss of ecosystem function. Madagascar is simultaneously home to one of the most exclusive, diverse, and endangered faunas of the world, making MADA a uniquely valuable resource for biodiversity science and conservation. No copyright restrictions are associated with this dataset. We would appreciate that researchers cite this paper if using all or part of the datasets.This article is protected by copyright. All rights reserved.
      PubDate: 2018-02-02T08:45:22.919346-05:
      DOI: 10.1002/ecy.2167
       
  • Fundamental contradictions among observational and experimental estimates
           of non-trophic species interactions
    • Authors: Allison K. Barner; Kyle E. Coblentz, Sally D. Hacker, Bruce A. Menge
      Abstract: The difficulty of experimentally quantifying non-trophic species interactions has long troubled ecologists. Increasingly, a new application of the classic “checkerboard distribution” approach is used to infer interactions by examining the pairwise frequency at which species are found to spatially co-occur. However, the link between spatial associations, as estimated from observational co-occurrence, and species interactions has not been tested. Here we used nine common statistical methods to estimate associations from surveys of rocky intertidal communities in the Northeast Pacific Ocean. We compared those inferred associations with a new data set of experimentally determined net and direct species interactions. Although association methods generated networks with aggregate structure similar to previously published interaction networks, each method detected a different set of species associations from the same data set. Moreover, although association methods generally performed better than a random model, associations rarely matched empirical net or direct species interactions, with high rates of false positives and true positives, and many false negatives. Our findings cast doubt on studies that equate species co-occurrences to species interactions and highlight a persistent, unanswered question: how do we interpret spatial patterns in communities' We suggest future research directions to unify the observational and experimental study of species interactions, and discuss the need for community standards and best practices in association analysis.
      PubDate: 2018-01-31T12:00:41.357948-05:
      DOI: 10.1002/ecy.2133
       
  • On the ecological significance of pollen color: a case study in American
           trout lily (Erythronium americanum)
    • Authors: Emily J. Austen; Shang-Yao Lin, Jessica R. K. Forrest
      Abstract: Evolutionary ecologists seek to explain the processes that maintain variation within populations. In plants, petal color variation can affect pollinator visitation, environmental tolerance, and herbivore deterrence. Variation in sexual organs may similarly affect plant performance. Within-population variation in pollen color, as occurs in the eastern North American spring ephemeral Erythronium americanum, provides an excellent opportunity to investigate the maintenance of variation in this trait. Although the red/yellow pollen-color polymorphism of E. americanum is widely recognized, it has been poorly documented. Our goals were thus (1) to determine the geographic distribution of the color morphs, and (2) to test the effects of pollen color on components of pollen performance. Data provided by citizen scientists indicated that populations range from monomorphic red, to polymorphic, to monomorphic yellow, but there was no detectable geographic pattern in morph distribution, suggesting morph occurrence cannot be explained by a broad-scale ecological cline. In field experiments, we found no effect of pollen color on the probability of predation by the pollen-feeding beetle Asclera ruficollis, on the ability of pollen to tolerate UV-B radiation, or on siring success (as measured by the fruit set of hand-pollinated flowers). Pollinators, however, exhibited site-specific pollen-color preferences, suggesting they may act as agents of selection on this trait, and, depending on the constancy of their preferences, could contribute to the maintenance of variation. Collectively, our results eliminate some hypothesized ecological effects of pollen color in E. americanum, and identify effects of pollen color on pollinator attraction as a promising direction for future investigation.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-30T05:05:37.40009-05:0
      DOI: 10.1002/ecy.2164
       
  • Time-lagged effects of weather on plant demography: drought and Astragalus
           scaphoides
    • Authors: Brigitte Tenhumberg; Elizabeth E. Crone, Satu Ramula, Andrew J. Tyre
      Abstract: Temperature and precipitation determine the conditions where plant species can occur. Despite their significance, to date, surprisingly few demographic field studies have considered the effects of abiotic drivers. This is problematic because anticipating the effect of global climate change on plant population viability requires understanding how weather variables affect population dynamics. One possible reason for omitting the effect of weather variables in demographic studies is the difficulty in detecting tight associations between vital rates and environmental drivers. In this paper, we applied Functional Linear Models (FLMs) to long-term demographic data of the perennial wildflower, Astragalus scaphoides, and explored sensitivity of the results to reduced amounts of data. We compared models of the effect of average temperature, total precipitation, or an integrated measure of drought intensity (Standardized Precipitation Evapotranspiration Index, SPEI), on plant vital rates. We found that transitions to flowering and recruitment in year t were highest if winter/spring of year t was wet (positive effect of SPEI). Counterintuitively, if the preceding spring of year t-1 was wet, flowering probabilities were decreased (negative effect of SPEI). Survival of vegetative plants from t-1 to t was also negatively affected by wet weather in the spring of year t-1, and for large plants, even wet weather in the spring of t-2 had a negative effect. We assessed the integrated effect of all vital rates on life history performance by fitting FLMs to the asymptotic growth rate, log(λt) log(λt) was highest if dry conditions in year t-1 were followed by wet conditions in the year t. Overall, the positive effects of wet years exceed their negative effects, suggesting that increasing frequency of drought conditions would reduce population viability of A. scaphoides. The drought signal weakened when reducing the number of monitoring years. Substituting space for time did not recover the weather signal, probably because the weather variables varied little between sites. We detected the SPEI signal when the analysis included data from two sites monitored over 20 years (2x20 observations), but not when analyzing data from four sites monitored over 10 years (4x10 observations).This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-30T05:00:29.038156-05:
      DOI: 10.1002/ecy.2163
       
  • Environmental filtering and phylogenetic clustering correlate with the
           distribution patterns of cryptic protist species
    • Authors: David Singer; Anush Kosakyan, Christophe V.W. Seppey, Amandine Pillonel, Leonardo D. Fernández, Diego Fontaneto, Edward A.D. Mitchell, Enrique Lara
      Abstract: The community composition of any group of organisms should theoretically be determined by a combination of assembly processes including resource partitioning, competition, environmental filtering, and phylogenetic legacy. Environmental DNA studies have revealed a huge diversity of protists in all environments, raising questions about the ecological significance of such diversity and the degree to which they obey to the same rules as macroscopic organisms. The fast-growing cultivable protist species on which hypotheses are usually experimentally tested represent only a minority of the protist diversity. Addressing these questions for the lesser known majority can only be inferred through observational studies.We conducted an environmental DNA survey of the genus Nebela, a group of closely related testate (shelled) amoeba species, in different habitats within Sphagnum-dominated peatlands. Identification based on the mitochondrial cytochrome c oxidase 1 gene, allowed species-level resolution as well as phylogenetic reconstruction.Community composition varied strongly across habitats and associated environmental gradients. Species showed little overlap in their realized niche, suggesting resource partitioning, and a strong influence of environmental filtering driving community composition. Furthermore, phylogenetic clustering was observed in the most nitrogen-poor samples, supporting phylogenetic inheritance of adaptations in the group of N. guttata.This study showed that the studied free-living unicellular eukaryotes follow to community assembly rules similar to those known to determine plant and animal communities; the same may be true for much of the huge functional and taxonomic diversity of protists.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-29T02:44:05.23027-05:0
      DOI: 10.1002/ecy.2161
       
  • Community divergence and convergence along experimental gradients of
           stress and disturbance
    • Authors: Yuanzhi Li; Bill Shipley
      Abstract: We created 24 mesocosms containing mixtures of herbaceous species arranged along experimentally maintained gradients of stress (external abiotic constraints limiting biomass production) and disturbance (events causing partial or total live biomass destruction) in order to determine the degree to which community assembly is deterministic or historically contingent during succession. In this seven-year experiment, we found taxonomic divergence and functional convergence during the last three years. Although communities became more functionally dissimilar as the difference in the level of stress increased, they were equally taxonomically different irrespective of the amount of difference between them in terms of stress and disturbance. In addition, comparing communities experiencing the same conditions, taxonomic community structure was more dissimilar as the levels of stress and disturbance decreased. Therefore, community assembly was largely deterministic from a functional perspective but more historically contingent from a taxonomic perspective, and the relative importance of taxonomic historical contingency decreased as the levels of stress and disturbance frequency increased.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-27T11:50:22.95583-05:0
      DOI: 10.1002/ecy.2162
       
  • Nest webs beyond woodpeckers: the ecological role of other nest builders
    • Authors: Kaspar Delhey
      PubDate: 2018-01-26T10:30:32.973399-05:
      DOI: 10.1002/ecy.2108
       
  • Predator identity more than predator richness structures aquatic microbial
           assemblages in Sarracenia purpurea leaves
    • Authors: Erin J. Canter; Catalina Cuellar-Gempeler, Abigail I. Pastore, Thomas E. Miller, Olivia U. Mason
      Abstract: The importance of predators in influencing community structure is a well-studied area of ecology. However, few studies test ecological hypotheses of predation in multi-predator microbial communities. The phytotelmic community found within the water-filled leaves of the pitcher plant, Sarracenia purpurea, exhibits a simple trophic structure that includes multiple protozoan predators and microbial prey. Using this system, we sought to determine whether different predators target distinct microorganisms, how interactions among protozoans affect resource (microorganism) use, and how predator diversity affects prey community diversity. In particular, we endeavored to determine if protozoa followed known ecological patterns such as keystone predation or generalist predation. For these experiments, replicate inquiline microbial communities were maintained for seven days with five protozoan species. Microbial community structure was determined by 16S rRNA gene amplicon sequencing (iTag) and analysis. Compared to the control (no protozoa), two ciliates followed patterns of keystone predation by increasing microbial evenness. In pairwise competition treatments with a generalist flagellate, prey communities resembled the microbial communities of the respective keystone predator in monoculture. The relative abundance of the most common bacterial Operational Taxonomic Unit (OTU) in our system decreased compared to the control in the presence of these ciliates. This OTU was 98% similar to a known chitin degrader and nitrate reducer, important functions for the microbial community and the plant host. Collectively, the data demonstrated that predator identity had a greater effect on prey diversity and composition than overall predator diversity.
      PubDate: 2018-01-25T14:30:24.101099-05:
      DOI: 10.1002/ecy.2128
       
  • Pyrosome consumption by benthic organisms during blooms in the northeast
           Pacific and Gulf of Mexico
    • Authors: Stephanie K. Archer; Amanda S. Kahn, Sally P. Leys, Tammy Norgard, Fanny Girard, Cherisse Du Preez, Anya Dunham
      PubDate: 2018-01-25T10:32:59.801792-05:
      DOI: 10.1002/ecy.2097
       
  • Monitoring dynamic spatio-temporal ecological processes optimally
    • Authors: Perry J. Williams; Mevin B. Hooten, Jamie N. Womble, George G. Esslinger, Michael R. Bower
      Abstract: Population dynamics vary in space and time. Survey designs that ignore these dynamics may be inefficient and fail to capture essential spatio-temporal variability of a process. Alternatively, dynamic survey designs explicitly incorporate knowledge of ecological processes, the associated uncertainty in those processes, and can be optimized with respect to monitoring objectives. We describe a cohesive framework for monitoring a spreading population that explicitly links animal movement models with survey design and monitoring objectives. We apply the framework to develop an optimal survey design for sea otters in Glacier Bay. Sea otters were first detected in Glacier Bay in 1988 and have since increased in both abundance and distribution; abundance estimates increased from 5 otters to>5,000 otters, and they have spread faster than 2.7 km/yr. By explicitly linking animal movement models and survey design, we are able to reduce uncertainty associated with forecasting occupancy, abundance, and distribution compared to other potential random designs. The framework we describe is general, and we outline steps to applying it to novel systems and taxa.
      PubDate: 2018-01-25T10:32:27.548644-05:
      DOI: 10.1002/ecy.2120
       
  • The dynamic life of arbuscular mycorrhizal fungal symbionts
    • Authors: Elizabeth M. Bach; Giselle Narvaez-Rivera, Kira Murray, Jonathan T. Bauer, Kirsten S. Hofmockel
      PubDate: 2018-01-24T12:00:29.23163-05:0
      DOI: 10.1002/ecy.2096
       
  • A Canadian upland forest soil profile and carbon stocks database
    • Authors: Cindy Shaw; Arlene Hilger, Michelle Filiatrault, Werner Kurz
      Abstract: “A Canadian upland forest soil profile and carbon stocks database” was compiled in phases over a period of 10 years to address various questions related to modeling upland forest soil carbon in a national forest carbon accounting model. For 3,253 pedons, the SITES table contains estimates for soil organic carbon stocks (tonnes [t] ha−1) in organic horizons and mineral horizons to a 100-cm depth, soil taxonomy, leading tree species, mean annual temperature, annual precipitation, province or territory, terrestrial ecozone, and latitude and longitude, with an assessment of the quality of information about location.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-24T08:50:30.60397-05:0
      DOI: 10.1002/ecy.2159
       
  • First record on stranding of a live giant squid Architeuthis dux outside
           Japanese waters
    • Authors: Angel Guerra; Ángel F. González, Graham J. Pierce
      PubDate: 2018-01-23T13:00:48.116338-05:
      DOI: 10.1002/ecy.2073
       
  • Contrasting effects of specialist and generalist herbivores on resistance
           evolution in invasive plants
    • Authors: Zhijie Zhang; Xiaoyun Pan, Dana Blumenthal, Mark Kleunen, Mu Liu, Bo Li
      Abstract: Invasive alien plants are likely to be released from specialist herbivores and at the same time encounter biotic resistance from resident generalist herbivores in their new ranges. The Shifting Defense Hypothesis predicts that this will result in evolution of decreased defense against specialist herbivores and increased defense against generalist herbivores. To test this, we performed a comprehensive meta-analysis of 61 common garden studies that provide data on resistance and/or tolerance for both introduced and native populations of 32 invasive plant species. We demonstrate that introduced populations, relative to native populations, decreased their resistance against specialists, and increased their resistance against generalists. These differences were significant when resistance was measured in terms of damage caused by the herbivore, but not in terms of performance of the herbivore. Furthermore, we found the first evidence that the magnitude of resistance differences between introduced and native populations depended significantly on herbivore origin (i.e. whether the test herbivore was collected from the native or non-native range of the invasive plant). Finally, tolerance to generalists was found to be higher in introduced populations, while neither tolerance to specialists nor that to simulated herbivory differed between introduced and native plant populations. We conclude that enemy release from specialist herbivores and biotic resistance from generalist herbivores have contrasting effects on resistance evolution in invasive plants. Our results thus provide strong support for the Shifting Defense Hypothesis.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-20T01:50:27.690838-05:
      DOI: 10.1002/ecy.2155
       
  • Temporal heterogeneity increases with spatial heterogeneity in ecological
           communities
    • Authors: Scott L. Collins; Meghan L. Avolio, Corinna Gries, Lauren M. Hallett, Sally E. Koerner, Kimberly J. La Pierre, Andrew L. Rypel, Eric R. Sokol, Samuel B. Fey, Dan F. B. Flynn, Sydney K. Jones, Laura M. Ladwig, Julie Ripplinger, Matt B. Jones
      Abstract: Heterogeneity is increasingly recognized as a foundational characteristic of ecological systems. Under global change, understanding temporal community heterogeneity is necessary for predicting the stability of ecosystem functions and services. Indeed, spatial heterogeneity is commonly used in alternative stable state theory as a predictor of temporal heterogeneity and therefore an early indicator of regime shifts. To evaluate whether spatial heterogeneity in species composition is predictive of temporal heterogeneity in ecological communities, we analyzed 68 community datasets spanning freshwater and terrestrial systems where measures of species abundance were replicated over space and time. Of the 68 data sets 55 (81%) had a weak to strongly positive relationship between spatial and temporal heterogeneity, while in the remaining communities the relationship was weak to strongly negative (19%). Based on a mixed model analysis, we found a significant but weak overall positive relationship between spatial and temporal heterogeneity across all data sets combined, and within aquatic and terrestrial data sets separately. In addition, lifespan and successional stage were negatively and positively related to temporal heterogeneity, respectively. We conclude that spatial heterogeneity may be a predictor of temporal heterogeneity in ecological communities, and that this relationship may be a general property of many terrestrial and aquatic communities.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-20T01:45:21.455038-05:
      DOI: 10.1002/ecy.2154
       
  • Experimental evidence that density dependence strongly influences plant
           invasions through fragmented landscapes
    • Authors: Jennifer L. Williams; Jonathan M. Levine
      Abstract: Populations of range expanding species encounter patches of both favorable and unfavorable habitat as they spread across landscapes. Theory shows that increasing patchiness slows the spread of populations modeled with continuously varying population density when dispersal is not influence by the environment or individual behavior. However, as is found in uniformly favorable landscapes, spread remains driven by fecundity and dispersal from low density individuals at the invasion front. In contrast, when modeled populations are composed of discrete individuals, patchiness causes populations to build up to high density before dispersing past unsuitable habitat, introducing an important influence of density dependence on spread velocity. To test the hypothesized interaction between habitat patchiness and density dependence, we simultaneously manipulated these factors in a greenhouse system of annual plants spreading through replicated experimental landscapes. We found that increasing the size of gaps and amplifying the strength of density dependence both slowed spread velocity, but contrary to predictions, the effect of amplified density dependence was similar across all landscape types. Our results demonstrate that the discrete nature of individuals in spreading populations has a strong influence on how both landscape patchiness and density dependence influence spread through demographic and dispersal stochasticity. Both finiteness and landscape structure should be critical components to theoretical predictions of future spread for range expanding native species or invasive species colonizing new habitat.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-20T01:20:47.920436-05:
      DOI: 10.1002/ecy.2156
       
  • Temperature-dependency of intraguild predation between native and invasive
           crabs
    • Authors: Tanya L. Rogers; Tarik C. Gouhier, David L. Kimbro
      Abstract: Environmental factors such as temperature can affect the geographical distribution of species directly by exceeding physiological tolerances, or indirectly by altering physiological rates that dictate the sign and strength of species interactions. Although the direct effects of environmental conditions are relatively well studied, the effects of environmentally-mediated species interactions have garnered less attention. In this study, we examined the temperature-dependency of size-structured intraguild predation (IGP) between native blue crabs (Callinectes sapidus, the IG predator) and invasive green crabs (Carcinus maenas, the IG prey) to evaluate how the effect of temperature on competitive and predatory rates may influence the latitudinal distribution of these species. In outdoor mesocosm experiments, we quantified interactions between blue crabs, green crabs, and shared prey (mussels) at 3 temperatures reflective of those across their range, using 2 size classes of blue crab. At low temperatures, green crabs had a competitive advantage and IGP by blue crabs on green crabs was low. At high temperatures, size-matched blue and green crabs were competitively similar, large blue crabs had a competitive advantage, and IGP on green crabs was high. We then used parameter values generated from these experiments (temperature- and size-dependent attack rates and handling times) in a size-structured IGP model in which we varied IGP attack rate, maturation rate of the blue crab from the non-predatory to predatory size class, and resource carrying capacity at each of the 3 temperatures. In the model, green crabs were likely to competitively exclude blue crabs at low temperature, whereas blue crabs were likely to competitively and consumptively exclude green crabs at higher temperatures, particularly when resource productivities and rates of IGP were high. While many factors may play a role in delimiting species ranges, our results suggest that temperature-dependent interactions can influence local coexistence and are worth considering when developing mechanistic species distribution models and evaluating responses to environmental change.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-20T01:20:46.145845-05:
      DOI: 10.1002/ecy.2157
       
  • Competitive ability, stress tolerance and plant interactions along stress
           gradients
    • Authors: Man Qi; Tao Sun, SuFeng Xue, Wei Yang, DongDong Shao, Javier Martínez-López
      Abstract: Exceptions to the generality of the stress-gradient hypothesis (SGH) may be reconciled by considering species-specific traits and stress tolerance strategies. Studies have tested stress tolerance and competitive ability in mediating interaction outcomes, but few have incorporated this to predict how species interactions shift between competition and facilitation along stress gradients. We used field surveys, salt tolerance and competition experiments to develop a predictive model interspecific interaction shifts across salinity stress gradients. Field survey and greenhouse tolerance tests revealed trade-offs between stress tolerance and competitive ability. Modelling showed that along salinity gradients, 1) plant interactions shifted from competition to facilitation at high salinities within the physiological limits of salt-intolerant plants, 2) facilitation collapsed when salinity stress exceeded the physiological tolerance of salt-intolerant plants, and 3) neighbor removal experiments overestimate interspecific facilitation by including intraspecific effects. A community-level field experiment, suggested that 1) species interactions are competitive in benign and, facilitative in harsh condition, but fuzzy under medium environmental stress due to niche differences of species and weak stress amelioration, and 2) the SGH works on strong but not weak stress gradients, so SGH confusion arises when it is applied across questionable stress gradients. Our study clarifies how species interactions vary along stress gradients. Moving forward, focusing on SGH applications rather than exceptions on weak or nonexistent gradients would be most productive.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-18T08:15:50.765486-05:
      DOI: 10.1002/ecy.2147
       
  • Microbial Mitigation-Exacerbation Continuum: A novel framework for
           microbiome effects on hosts in the face of stress
    • Authors: Aaron S. David; Khum B. Thapa-Magar, Michelle E. Afkhami
      Abstract: A key challenge to understanding microbiomes and their role in ecological processes is contextualizing their effects on host organisms, particularly when faced with environmental stress. One influential theory, the Stress Gradient Hypothesis, might predict that the frequency of positive interactions increases with stressful conditions such that microbial taxa would mitigate harmful effects on host performance. Yet, equally plausible is that microbial taxa could exacerbate these effects. Here, we introduce the “Mitigation-Exacerbation Continuum” as a novel framework to conceptualize microbial mediation of stress. We (1) use this continuum to quantify microbial mediation of stress for six plant species, and (2) test the association between these continuum values and natural species abundance. We factorially manipulated a common stress (allelopathy) and the presence of soil microbes to quantify microbial effects in benign and stressed environments for two critical early life-history metrics, seed germination and seedling biomass. Although we found evidence of both mitigation and exacerbation among the six species, exacerbation was more common. Across species, the degree of microbial-mediated effects on germination explained>80% of the variation of natural field abundances. Our results suggest a critical role of soil microbes in mediating plant stress responses, and a potential microbial mechanism underlying species abundance.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-18T08:15:19.842809-05:
      DOI: 10.1002/ecy.2153
       
  • Toward more robust plant-soil feedback research
    • Authors: Matthew J. Rinella; Kurt O. Reinhart
      Abstract: Understanding if and how plant-soil biota feedbacks (PSFs) shape plant communities has become a major research priority. In this paper, we draw on a recent, high-profile PSF study to illustrate that certain widely used experimental methods cannot reliably determine if PSFs occur. One problem involves gathering soil samples adjacent to multiple conditioning plants, mixing the samples and then growing phytometers in the mixtures to test for PSFs. This mixed soil approach does not establish that the conditioning plant being present caused the soil biota to be present, the first step of a PSF. Also, soil mixing approximates replacing raw data with averages prior to analysis, a move certain to generate falsely precise statistical estimates. False precision also results from sample sizes being artificially inflated when phytometers are misinterpreted as experimental units. Plant biomass ratios become another source of false precision when individual plant values contribute to multiple ratio observations. Any one of these common missteps can cause still living null hypotheses to be pronounced dead, and risks of this increase with numbers of missteps. If soil organisms truly structure plant communities, then null hypotheses indicating otherwise will not survive proper testing. We discuss conceptual, experimental and analytical refinements to facilitate accurate testing.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-18T08:00:40.541621-05:
      DOI: 10.1002/ecy.2146
       
  • Anthropogenic nitrogen deposition ameliorates the decline in tree growth
           caused by a drier climate
    • Authors: Inés Ibáñez; Donald R. Zak, Andrew J. Burton, Kurt S. Pregitzer
      Abstract: Most forest ecosystems are simultaneously affected by concurrent global change drivers. However, when assessing these effects, studies have mainly focused on the responses to single factors and have rarely evaluated the joined effects of the multiple aspects of environmental change. Here, we analyzed the combined effects of anthropogenic nitrogen (N) deposition and climatic conditions on the radial growth of Acer saccharum, a dominant tree species in eastern North American forests. We capitalized on a long-term N deposition study, replicated along a latitudinal gradient, that has been taking place for more than 20 yr. We analyzed tree radial growth as a function of anthropogenic N deposition (ambient and experimental addition) and of summer temperature and soil water conditions. Our results reveal that experimental N deposition enhances radial growth of this species, an effect that was accentuated as temperature increased and soil water became more limiting. The spatial and temporal extent of our data also allowed us to assert that the positive effects of growing under the experimental N deposition are likely due to changes in the physiological performance of this species, and not due to the positive correlation between soil N and soil water holding capacity, as has been previously speculated in other studies. Our simulations of tree growth under forecasted climate scenarios specific for this region also revealed that although anthropogenic N deposition may enhance tree growth under a large array of environmental conditions, it will not mitigate the expected effects of growing under the considerably drier conditions characteristic of our most extreme climatic scenario.
      PubDate: 2018-01-17T10:00:03.974038-05:
      DOI: 10.1002/ecy.2095
       
  • Variation and drivers of airflow patterns associated with olfactory
           concealment and habitat selection
    • Authors: Dillon T. Fogarty; R. Dwayne Elmore, Samuel D. Fuhlendorf, Scott R. Loss
      Abstract: Many terrestrial predators rely on olfaction to detect prey; therefore, prey should select habitat to reduce detectability of their odor cues. One way prey can potentially conceal their odor is by selecting locations with high turbulence and/or updrafts, conditions that disperse odor plumes and make odor sources difficult to locate. However, it is unclear how these conditions vary among vegetation cover types and which vegetative features drive them. We assessed variation and drivers of variables hypothesized to influence olfactory concealment (turbulence intensity and airflow slope) and experimentally evaluated whether these variables indeed influence predator detection of simulated prey. Specifically, we compared vegetation patch-scale values of turbulence intensity and airflow slope among grassland, shrubland, and forest and assessed relationships among these airflow variables and local-scale vegetative features within each vegetation type. Additionally, we experimentally investigated the importance of turbulence intensity, airflow slope, and visual concealment for predicting predator detection of scented quail eggs. In all vegetation types, we documented high variability in airflow conditions. At the patch scale, turbulence intensity was greater in shrubland and grassland than in forest, and updrafts were most common in shrubland whereas downdrafts were most common in grassland. Grassland was the only vegetation type with strong relationships among turbulence intensity and local vegetation features; both visual concealment and vegetation height were positively related to turbulence intensity. Additionally, persistence of scented quail eggs in grassland was best predicted by turbulence intensity; egg persistence increased with turbulence intensity. Our characterization of differences in olfactory variables among vegetation types provides an important step towards building a clearer understanding of olfactory landscapes. Further, our observation of both patch- and local-scale variation in olfactory variables suggests that prey can potentially select for olfactory concealment at multiple scales. We hypothesize that olfactory concealment provided by high levels of turbulence intensity is an important component of cover in grassland, and that in grassland/shrubland landscapes, prey selection of shrubland patches reduces odor detectability. Our finding of a positive relationship between turbulence intensity and visual concealment also suggests that olfactory concealment may be a previously underappreciated confounding factor in studies of habitat selection.
      PubDate: 2018-01-17T10:00:03.10928-05:0
      DOI: 10.1002/ecy.2102
       
  • Non-volant mammals from the Upper Paraná River Basin: a data set from a
           critical region for conservation in Brazil
    • Authors: Fernando Gonçalves; Wellington Hannibal, Mauricio N. Godoi, Fernando I. Martins, Roniel F. Oliveira, Valquiria V. Figueiredo, Janaina Casella, Érica F. G. G. Sá
      Abstract: The data set represents the first attempt at a large-scale inventory of non-volant mammals, with potential applications to performing macroecological studies, developing conservation strategies, and undertaking population and community ecology research, but also to evaluate the ecological consequences of fragmentation and defaunation. Our objectives for compiling these data were to summarize information about inventories of non-volant mammals in the critically important area of the Upper Paraná River Basin by focusing on species richness and index of frequency of occurrence and to identify gaps in knowledge regarding non-volant mammal communities in order to guide future sampling efforts. The data set comprises studies on communities of non-volant mammals from 52 locations covering more than 1,000 km2 and comprises portion of four Brazilian states in the Upper Paraná River Basin. We listed 81 species of non-volant mammals distributed among 58 genera, 22 families, and 9 orders. Rodentia (28 species) was the richest order, followed by Carnivora (17 spp.) and Didelphimorphia (15 spp.). The richest family was Cricetidae (20 spp.), followed by Didelphidae (15 spp.), and Dasypodidae and Felidae (six spp.). Considering national conservation status, one species are considered endangered and 16 vulnerable. Considering global conservation status, 7 species are considered vulnerable, 10 are considered near threatened, and 6 are data deficient. According to the index of frequency of occurrence, Myrmecophaga tridactyla was the most frequent species, occurring at 88.64% of all sites, while 25 species were considered very restricted, occurring in just 2.56% of all sites. In general, the non-volant mammal fauna was composed of mainly very restricted (VR, 25 species) and localized species (L, 25 species), which account for 61.7% of the known species, while 38.3% are restricted (R, 8 species), common (C, 16 species), and widespread (W, 7 species). Seven marsupials and five small rodents had their distributions extended in the central-south of Brazil. All of these species are considered data deficient or threatened, which highlights the importance of these records. No copyright restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications. We also request that researchers and teachers inform us of how they are using the data.
      PubDate: 2018-01-17T10:00:01.361279-05:
      DOI: 10.1002/ecy.2107
       
  • Recent Publications of Interest
    • PubDate: 2018-01-16T11:00:20.113411-05:
      DOI: 10.1002/ecy.2117
       
  • The century experiment: the first twenty years of UC Davis' Mediterranean
           agroecological experiment
    • Authors: Kristina M. Wolf; Emma E. Torbert, Dennis Bryant, Martin Burger, R. Ford Denison, Israel Herrera, Jan Hopmans, Will Horwath, Stephen Kaffka, Angela Y. Y. Kong, R. F. Norris, Johan Six, Thomas P. Tomich, Kate M. Scow
      Abstract: The Century Experiment at the Russell Ranch Sustainable Agriculture Facility at the University of California, Davis provides long-term agroecological data from row crop systems in California's Central Valley starting in 1993. The Century Experiment was initially designed to study the effects of a gradient of water and nitrogen availability on soil properties and crop performance in ten different cropping systems to measure tradeoffs and synergies between agricultural productivity and sustainability. Currently systems include 11 different cropping systems–consisting of four different crops and a cover crop mixture–and one native grass system. This paper describes the long-term core data from the Century Experiment from 1993–2014, including crop yields and biomass, crop elemental contents, aerial-photo-based Normalized Difference Vegetation Index data, soil properties, weather, chemical constituents in irrigation water, winter weed populations, and operational data including fertilizer and pesticide application amounts and dates, planting dates, planting quantity and crop variety, and harvest dates. This data set represents the only known long-term set of data characterizing food production and sustainability in irrigated and rainfed Mediterranean annual cropping systems. There are no copyright restrictions associated with the use of this dataset.
      PubDate: 2018-01-16T10:51:34.670238-05:
      DOI: 10.1002/ecy.2105
       
  • Drivers and demographic consequences of seasonal mass changes in an alpine
           ungulate
    • Authors: Mathieu Douhard; Simon Guillemette, Marco Festa-Bianchet, Fanie Pelletier
      Abstract: We know little about the determinants and demographic consequences of the marked seasonal mass changes exhibited by many northern and alpine mammals. We analysed 43 years of data on individual winter mass loss (the difference between mass in early June and mass in mid-September the previous year) and summer mass gain (the difference between mass in mid-September and in early June of the same year) in adult bighorn sheep (Ovis canadensis). We calculated relative seasonal mass change as a proportion of individual body mass at the start of each season. We first examined the effects of weather and population density on relative changes in body mass. We then assessed the consequences of relative seasonal mass changes on reproduction. Mean April-May temperature was the main driver of relative seasonal mass changes: warm springs reduced both relative winter mass loss and summer mass gain of both sexes, likely partially due to a trade-off between growth rate of plants and duration of access to high-quality forage. Because these effects cancelled each other, spring temperature did not influence mass in mid-September. Mothers that lost relatively more mass during the winter had lambs that gained less mass during summer, likely because these females allocated fewer resources to lactation. Winter survival of lambs increased with their summer mass gain. In males, relative mass loss during winter, which includes the rut, did not influence the probability of siring at least one lamb, possibly indicating that greater mating effort did not necessarily translate into greater reproductive success. Our findings improve our understanding of how weather influences recruitment and underline the importance of cryptic mechanisms behind the effects of climate change on demographic traits.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-16T06:58:25.837584-05:
      DOI: 10.1002/ecy.2141
       
  • Species co-occurrence networks: can they reveal trophic and non-trophic
           interactions in ecological communities'
    • Authors: Mara A. Freilich; Evie Wieters, Bernardo R. Broitman, Pablo A. Marquet, Sergio A. Navarrete
      Abstract: Co-occurrence methods are increasingly utilized in ecology to infer networks of species interactions where detailed knowledge based on empirical studies is difficult to obtain. Their use is particularly common, but not restricted to, microbial networks constructed from metagenomic analyses. In this study, we test the efficacy of this procedure by comparing an inferred network constructed using spatially intensive co-occurrence data from the rocky intertidal zone in central Chile to a well-resolved, empirically-based, species interaction network from the same region. We evaluated the overlap in the information provided by each network and whether there is a bias for co-occurrence data to better detect known trophic or non-trophic, positive or negative interactions. We found a poor correspondence between the co-occurrence network and the known species interactions with overall sensitivity (probability of true link detection) equal to 0.469, and specificity (true non-interaction) equal to 0.527. The ability to detect interactions varied with interaction type. Positive non-trophic interactions such as commensalism and facilitation were detected at the highest rates. These results demonstrate that co-occurrence networks do not represent well classical ecological networks in which interactions are defined by direct observations or experimental manipulations. Co-occurrence networks provide information about the joint spatial effects of environmental conditions, recruitment, and, to some extent, biotic interactions, and among the latter, they tend to better detect niche-expanding interactions such as positive non-trophic interactions including habitat engineering. Detection of links (sensitivity or specificity) was not higher for well-known intertidal keystone species than for the rest of consumers in the community. Thus, as observed in previous empirical and theoretical studies, patterns of interactions in co-occurrence networks must be interpreted with caution, especially when extending interaction-based ecological theory to interpret network variability and stability. Co-occurrence networks may be particularly valuable for analysis of community dynamics that blends interactions and environment, rather than pairwise interactions alone.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-16T06:40:27.021375-05:
      DOI: 10.1002/ecy.2142
       
  • Litter removal in a tropical rain forest reduces fine root biomass and
           production but litter addition has few effects
    • Authors: C. Rodtassana; E.V.J. Tanner
      Abstract: Many old-growth lowland tropical rain forests are potentially nutrient limited, and it has long been thought that many such forests maintain growth by recycling nutrients from decomposing litter. We investigated this by continuously removing (for ten years) freshly fallen litter from five (45 m x 45 m) plots, adding it to five other plots, there were five controls. From monthly measures over one year we show that litter removal caused lower: fine root (≤2 mm diameter) standing mass, fine root standing length, fine root length production and fine root length survivorship. Litter addition did not significantly change fine root mass or length or production. Nutrient concentrations in fine roots in litter removal plots were lower than those in controls for nitrogen (N), calcium (Ca) and magnesium (Mg), concentrations in fine roots in litter addition plots were higher for N and Ca. Chronic litter removal has resulted in reduced forest growth due to lack of nutrients, probably nitrogen. Conversely, long-term litter addition has had fewer effects.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-16T06:40:24.718191-05:
      DOI: 10.1002/ecy.2143
       
  • Mapping environmental ethics in the age of climate change
    • Authors: Thomas Bretz
      PubDate: 2018-01-12T10:45:43.836934-05:
      DOI: 10.1002/ecy.2114
       
  • Books and Monographs Received through November 2017
    • PubDate: 2018-01-12T10:45:42.722968-05:
      DOI: 10.1002/ecy.2113
       
  • Biogeophysical history, fragility and future of a global biodiversity and
           cultural hotspot: the Himalaya
    • Authors: Dave M. Augeri
      PubDate: 2018-01-12T10:45:41.774377-05:
      DOI: 10.1002/ecy.2112
       
  • Economy of scale: third partner strengthens a keystone ant-plant mutualism
    • Authors: Kirsten M. Prior; Todd M. Palmer
      Abstract: While foundation species can stabilize ecosystems at landscape scales, their ability to persist is often underlain by keystone interactions occurring at smaller scales. Acacia drepanolobium is a foundation tree, comprising>95% of woody cover in East African black-cotton savanna ecosystems. Its dominance is underlain by a keystone mutualistic interaction with several symbiotic ant species in which it provides housing (swollen thorns) and carbohydrate-rich nectar from extra-floral nectaries (EFN). In return, it gains protection from catastrophic damage from mega-herbivores. Crematogaster mimosae is the ecologically dominant symbiotic ant in this system, also providing the highest protection services. In addition to tending EFN, C. mimosae tend scale insects for carbohydrate-rich honeydew. We investigated the role of scale insects in this specialized ant-plant interaction. Specifically, does this putatively redundant third partner strengthen the ant-plant mutualism by making the ant a better protector of the tree' Or does it weaken the mutualism by being costly to the tree while providing no additional benefit to the ant-plant mutualism' We coupled observational surveys with two scale-manipulation experiments and found evidence that this third partner strengthens the ant-plant mutualism. Trees with scale insects experimentally removed experienced a 2.5X increase in elephant damage compared to trees with scale insects present over 10 months. Reduced protection was driven by scale removal causing a decrease in ant colony size and per capita baseline activity and defensive behavior. We also found that ants increased scale-tending and the density of scale insects on trees when EFN were experimentally reduced. Thus, in this system, scale insects and EFN are likely complementary, rather than redundant, resources with scale insects benefitting ants when EFN production is low (such as during annual dry periods in this semi-arid ecosystem). This study reveals that a third-partner strengthens an ant-plant mutualism that serves to stabilize a whole ecosystem.
      PubDate: 2018-01-12T10:45:40.605176-05:
      DOI: 10.1002/ecy.2104
       
  • High refuge availability on coral reefs increases the vulnerability of
           reef-associated predators to overexploitation
    • Authors: Alice Rogers; Julia L. Blanchard, Steven P. Newman, Charlie S. Dryden, Peter J. Mumby
      Abstract: Refuge availability and fishing alter predator-prey interactions on coral reefs, but our understanding of how they interact to drive food web dynamics, community structure and vulnerability of different trophic groups is unclear. Here, we apply a size-based ecosystem model of coral reefs, parameterized with empirical measures of structural complexity, to predict fish biomass, productivity and community structure in reef ecosystems under a broad range of refuge availability and fishing regimes. In unfished ecosystems, the expected positive correlation between reef structural complexity and biomass emerges, but a non-linear effect of predation refuges is observed for the productivity of predatory fish. Reefs with intermediate complexity have the highest predator productivity, but when refuge availability is high and prey are less available, predator growth rates decrease, with significant implications for fisheries. Specifically, as fishing intensity increases, predators in habitats with high refuge availability exhibit vulnerability to over-exploitation, resulting in communities dominated by herbivores. Our study reveals mechanisms for threshold dynamics in predators living in complex habitats and elucidates how predators can be food-limited when most of their prey are able to hide. We also highlight the importance of nutrient recycling via the detrital pathway, to support high predator biomasses on coral reefs.
      PubDate: 2018-01-12T10:45:33.997572-05:
      DOI: 10.1002/ecy.2103
       
  • Applied ecology in the 21st century
    • Authors: Nathalie Pettorelli
      PubDate: 2018-01-12T10:45:22.923318-05:
      DOI: 10.1002/ecy.2116
       
  • Wildfire in the American West
    • Authors: Andrew J. Larson
      PubDate: 2018-01-12T10:45:19.918849-05:
      DOI: 10.1002/ecy.2115
       
  • Positive diversity-functioning relationships in model communities of
           methanotrophic bacteria
    • Authors: Elvira Schnyder; Paul L.E. Bodelier, Martin Hartmann, Ruth Henneberger, Pascal A. Niklaus
      Abstract: Biodiversity enhances ecosystem functions such as biomass production and nutrient cycling. Although the majority of the terrestrial biodiversity is hidden in soils, very little is known about the importance of the diversity of microbial communities for soil functioning. Here, we tested effects of biodiversity on the functioning of methanotrophs, a specialized group of soil bacteria that plays a key role in mediating greenhouse gas emissions from soils. Using pure strains of methanotrophic bacteria, we assembled artificial communities of different diversity levels, with which we inoculated sterile soil microcosms. To assess the functioning of these communities, we measured methane oxidation by gas chromatography throughout the experiment and determined changes in community composition and community size at several time points by quantitative PCR and sequencing. We demonstrate that microbial diversity had a positive overyielding-effect on methane oxidation, in particular at the beginning of the experiment. This higher assimilation of CH4 at high diversity translated into increased growth and significantly larger communities towards the end of the study. The overyielding of mixtures with respect to CH4 consumption and community size was positively correlated. The temporal CH4 consumption profiles of strain monocultures differed, raising the possibility that temporal complementarity of component strains drove the observed community-level strain richness effects; however, the community niche metric we derived from the temporal activity profiles did not explain the observed strain richness effect. The strain richness effect also was unrelated to both the phylogenetic and functional trait diversity of mixed communities. Overall, our results suggest that positive biodiversity–ecosystem function relationships show similar patterns across different scales and may be widespread in nature. Additionally, biodiversity is probably also important in natural methanotrophic communities for the ecosystem function methane oxidation. Therefore, maintaining soil conditions that support a high diversity of methanotrophs may help to reduce the emission of the greenhouse gas methane.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-11T08:35:23.929497-05:
      DOI: 10.1002/ecy.2138
       
  • Ecological drivers of soil microbial diversity and soil biological
           networks in the Southern Hemisphere
    • Authors: Manuel Delgado-Baquerizo; Frank Reith, Paul G. Dennis, Kelly Hamonts, Jeff R. Powell, Andrew Young, Brajesh K. Singh, Andrew Bissett
      Abstract: The ecological drivers of soil biodiversity in the Southern Hemisphere remain underexplored. Here, in a continental survey comprising 647 sites, across 58 degrees of latitude between tropical Australia and Antarctica, we evaluated the major ecological patterns in soil biodiversity and relative abundance of ecological clusters within a co-occurrence network of soil bacteria, archaea and eukaryotes. Six major ecological clusters (modules) of co-occurring soil taxa were identified. These clusters exhibited strong shifts in their relative abundances with increasing distance from the equator. Temperature was the major environmental driver of the relative abundance of ecological clusters when Australia and Antarctica are analyzed together. Temperature, aridity, soil properties and vegetation types were the major drivers of the relative abundance of different ecological clusters within Australia. Our data supports significant reductions in the diversity of bacteria, archaea and eukaryotes in Antarctica vs. Australia linked to strong reductions in temperature. However, we only detected small latitudinal variations in soil biodiversity within Australia. Different environmental drivers regulate the diversity of soil archaea (temperature and soil carbon), bacteria (aridity, vegetation attributes and pH) and eukaryotes (vegetation type and soil carbon) across Australia. Together, our findings provide new insights into the mechanisms driving soil biodiversity in the Southern Hemisphere.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-09T11:10:52.176232-05:
      DOI: 10.1002/ecy.2137
       
  • Climate sensitivity functions and net primary production: A framework for
           incorporating climate mean and variability
    • Authors: Jennifer A. Rudgers; Y.Anny Chung, Gregory E. Maurer, Douglas I. Moore, Esteban H. Muldavin, Marcy E. Litvak, Scott L. Collins
      Abstract: Understanding controls on net primary production (NPP) has been a long-standing goal in ecology. Climate is a well-known control on NPP, although the temporal differences among years within a site are often weaker than the spatial pattern of differences across sites. Climate sensitivity functions describe the relationship between an ecological response (e.g., NPP) and both the mean and variance of its climate driver (e.g., aridity index), providing a novel framework for understanding how climate trends in both mean and variance vary with NPP over time. Nonlinearities in these functions predict whether an increase in climate variance will have a positive effect (convex nonlinearity) or negative effect (concave nonlinearity) on NPP. The influence of climate variance may be particularly intense at ecosystem transition zones, if species reach physiological thresholds that create nonlinearities at these ecotones. Long-term data collected at the confluence of three dryland ecosystems in central New Mexico revealed that each ecosystem exhibited a unique climate sensitivity function that was consistent with long-term vegetation change occurring at their ecotones. Our analysis suggests that rising temperatures in drylands could alter the nonlinearities that determine the relative costs and benefits of variance in precipitation for primary production.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-09T11:10:48.722278-05:
      DOI: 10.1002/ecy.2136
       
  • An ignored role of sartenejas to mitigate water shortage hazards for
           tropical forest vertebrates
    • Authors: Carlos M. Delgado-Martínez; Fredy Alvarado, Eduardo Mendoza, Sandra Flores-Hernández, Audomaro Navarrete, Eutimio Navarrete, Francisco Botello
      PubDate: 2018-01-09T10:51:29.446038-05:
      DOI: 10.1002/ecy.2078
       
  • Mixing alters the lytic activity of viruses in the dark ocean
    • Authors: Christian Winter; Nicole Köstner, Carl-Philip Kruspe, Damaris Urban, Simone Muck, Thomas Reinthaler, Gerhard J. Herndl
      Abstract: In aquatic habitats, viral lysis of prokaryotic cells lowers the overall efficiency of the microbial loop, by which dissolved organic carbon is transfered to higher trophic levels. Mixing of water masses in the dark ocean occurs on a global scale and may have far reaching consequences for the different prokaryotic and virus communities found in these waters by altering the environmental conditions these communities experience. We hypothesize that mixing of deep ocean water masses enhances the lytic activity of viruses infecting prokaryotes. To address this hypothesis, major deep-sea water masses of the Atlantic Ocean such as North Atlantic Deep Water, Mediterranean Sea Overflow Water, Antarctic Intermediate Water, and Antarctic Bottom Water were sampled at five locations. Prokaryotic cells from these samples were collected by filtration and subsequently incubated in virus-reduced water from either the same (control) or a different water mass (transplantation treatment). Additionally, mixtures of prokaryotes obtained from two different water masses were incubated in a mixture of virus-reduced water from the same water masses (control) or in virus-reduced water from the source water masses separately (mixing treatments). Pronounced differences in productivity-related parameters (prokaryotic leucine incorporation, prokaryotic and viral abundance) between water masses caused strong changes in viral lysis of prokaryotes. Often, mixing of water masses increased viral lysis of prokaryotes, indicating that lysogenic viruses were induced into the lytic cycle. Mixing-induced changes in viral lysis had a strong effect on the community composition of prokaryotes and viruses. Our data show that mixing of deep-sea water masses alters levels of viral lysis of prokaryotes and in many cases weakens the efficiency of the microbial loop by enhancing the recycling of organic carbon in the deep ocean.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-08T03:44:13.479504-05:
      DOI: 10.1002/ecy.2135
       
  • Resource competition model predicts zonation and increasing nutrient use
           efficiency along a wetland salinity gradient
    • Authors: D. R. Schoolmaster; C. L. Stagg
      Abstract: A trade-off between competitive ability and stress tolerance has been hypothesized and empirically supported to explain the zonation of species across stress gradients for a number of systems. Since stress often reduces plant productivity, one might expect a pattern of decreasing productivity across the zones of the stress gradient. However, this pattern is often not observed in coastal wetlands that show patterns of zonation along a salinity gradient. To address the potentially complex relationship between stress, zonation and productivity in coastal wetlands, we developed a model of plant biomass as a function of resource competition and salinity stress. Analysis of the model confirms the conventional wisdom that a trade-off between competitive ability and stress tolerance is a necessary condition for zonation. It also suggests that a negative relationship between salinity and production can be overcome if 1) the supply of the limiting resource increases with greater salinity stress or 2) nutrient use efficiency increases with increasing salinity. We fit the equilibrium solution of the dynamic model to data from Louisiana coastal wetlands to test its ability to explain patterns of production across the landscape gradient and derive predictions that could be tested with independent data. We found support for a number of the model predictions, including patterns of decreasing competitive ability and increasing nutrient use efficiency across a gradient from freshwater to saline wetlands. In addition to providing a quantitative framework to support the mechanistic hypotheses of zonation, these results suggest that this simple model is a useful platform to further build upon, simulate and test mechanistic hypotheses of more complex patterns and phenomena in coastal wetlands.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-08T03:42:46.696792-05:
      DOI: 10.1002/ecy.2131
       
  • Predation risk and patch size jointly determine perceived patch quality in
           ovipositing treefrogs, Hyla chrysoscelis
    • Authors: William J. Resetarits; Jason R. Bohenek, Tyler Breech, Matthew R. Pintar
      Abstract: Two of the most important factors determining community structure and diversity within and among habitat patches are patch size and patch quality. Despite the importance of patch size in existing paradigms in island biogeography, metapopulation biology, landscape ecology, and metacommunity ecology, and growing conservation concerns with habitat fragmentation, there has been little investigation into how patch size interacts with patch quality. We crossed three levels of patch size (1.13 m2, 2.54 m2 and 5.73 m2) with two levels of patch quality [fish presence/absence - green sunfish (Lepomis cyanellus) and golden shiners (Notemigonus chrysoleucus) in 6 replicate experimental landscapes (3 x 2 x 6 = 36 patches). Both fish predators have been previously shown to elicit avoidance in ovipositing treefrogs. We examined how patch size and patch quality, as well as the interaction between size and quality, affected female oviposition preference and male calling site choice in a natural population of treefrogs (Hyla chrysoscelis). Females almost exclusively oviposited in the largest fishless patches, indicating that females use both risk, in the form of fish predators, and size itself, as components of patch quality. Females routinely use much smaller natural and experimental patches, suggesting that the responses to patch size are highly context dependent. Responses to fish were unaffected by patch size. Male responses largely mimicked those of females, but did not drive female oviposition. We suggest that patch size itself functions as another aspect of patch quality for Hyla chrysoscelis, and serves as another niche dimension across which species may behaviorally sort in natural systems. Because of strong, shared avoidance of fish (as well as other predators), among many colonizing taxa, patch size may be a critical factor in species sorting and processes of community assembly in freshwater habitats, allowing species to behaviorally segregate along gradients of patch size in fishless ponds. Conversely, lack of variation in patch size may concentrate colonization activity, leading to intensification of species interactions and/or increased use of lesser quality patches.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-07T22:50:22.703525-05:
      DOI: 10.1002/ecy.2130
       
  • Fasting or fear: Disentangling the roles of predation risk and food
           deprivation in the nitrogen metabolism of consumers
    • Authors: Christopher M. Dalton; Karen E. Tracy, Nelson G. Hairston, Alexander S. Flecker
      Abstract: Predators can alter nutrient cycles simply by inducing stress in prey. This stress accelerates prey's protein catabolism, nitrogen waste production, and nitrogen cycling. Yet predators also reduce the feeding rates of their prey, inducing food deprivation that is expected to slow protein catabolism and nitrogen cycling. The physiology of prey under predation risk thus balances the influences of predation risk and food deprivation, and this balance is central to understanding the role of predators in nutrient cycles. We explored the separate and combined effects of predation risk and food deprivation on prey physiology and nutrient cycling by exposing guppies (Poecilia reticulata) to predation risk and food deprivation in a 2 x 2 design. We simulated predation risk using chemical cues from a natural predator of guppies, and we created food deprivation by rationing food availability. We measured guppy response as food consumption, growth, tissue energy density, tissue carbon:nitrogen, and nitrogen (N) excretion and assimilation. We found that N-linked physiological processes (N consumption, assimilation, excretion) were strongly affected by predation risk, independent of food consumption. Guppies excreted substantially less under predation risk than they did under food deprivation or control conditions. These results suggest that predation risk, per se, triggers physiological changes in guppies that increase N retention and decrease N excretion. We suggest that slower N metabolism under predation risk is an adaptive response that minimizes protein loss in the face of predictable, predator-induced food restriction. Notably, N metabolism shares common hormonal control with food seeking behavior, and we speculate that increased N retention is a direct and immediate result of reduced food-seeking under predation risk. Contrary to predation-stress-based hypotheses for how predators affect nutrient cycling by prey, our result indicates that even short-term exposure to predators may decelerate, rather than accelerate, the speed of N cycling by suppressing N turnover by prey.This article is protected by copyright. All rights reserved.
      PubDate: 2018-01-07T22:50:20.650982-05:
      DOI: 10.1002/ecy.2132
       
  • Observed trends of soil fauna in the Antarctic Dry Valleys: early signs of
           shifts predicted under climate change
    • Authors: W. S. Andriuzzi; B. J. Adams, J. E. Barrett, R. A. Virginia, D. H. Wall
      Abstract: Long-term observations of ecological communities are necessary for generating and testing predictions of ecosystem responses to climate change. We investigated temporal trends and spatial patterns of soil fauna along similar environmental gradients in three sites of the McMurdo Dry Valleys, Antarctica, spanning two distinct climatic phases: a decadal cooling trend from the early 1990s through the austral summer of February 2001, followed by a shift to the current trend of warming summers and more frequent discrete warming events. After February 2001, we observed a decline in the dominant species (the nematode Scottnema lindsayae) and increased abundance and expanded distribution of less common taxa (rotifers, tardigrades, and other nematode species). Such diverging responses have resulted in slightly greater evenness and spatial homogeneity of taxa. However, total abundance of soil fauna appears to be declining, as positive trends of the less common species so far have not compensated for the declining numbers of the dominant species. Interannual variation in the proportion of juveniles in the dominant species was consistent across sites, whereas trends in abundance varied more. Structural equation modeling supports the hypothesis that the observed biological trends arose from dissimilar responses by dominant and less common species to pulses of water availability resulting from enhanced ice melt. No direct effects of mean summer temperature were found, but there is evidence of indirect effects via its weak but significant positive relationship with soil moisture. Our findings show that combining an understanding of species responses to environmental change with long-term observations in the field can provide a context for validating and refining predictions of ecological trends in the abundance and diversity of soil fauna.
      PubDate: 2018-01-05T08:50:40.163487-05:
      DOI: 10.1002/ecy.2090
       
  • Issue Information
    • Pages: 255 - 258
      PubDate: 2018-02-05T02:43:26.676313-05:
      DOI: 10.1002/ecy.2144
       
  • ATLANTIC MAMMAL TRAITS: a data set of morphological traits of mammals in
           the Atlantic Forest of South America
    • Authors: Fernando Gonçalves; Ricardo S. Bovendorp, Gabrielle Beca, Carolina Bello, Raul Costa-Pereira, Renata L. Muylaert, Raisa R. Rodarte, Nacho Villar, Rafael Souza, Maurício E. Graipel, Jorge J. Cherem, Deborah Faria, Julio Baumgarten, Martín R. Alvarez, Emerson M. Vieira, Nilton Cáceres, Renata Pardini, Yuri L. R. Leite, Leonora P. Costa, Marco A. R. Mello, Erich Fischer, Fernando C. Passos, Luiz H. Varzinczak, Jayme A. Prevedello, Ariovaldo P. Cruz-Neto, Fernando Carvalho, Alexandre R. Percequillo, Agustin Paviolo, Alessandra Nava, José M. B. Duarte, Noé U. Sancha, Enrico Bernard, Ronaldo G. Morato, Juliana F. Ribeiro, Rafael G. Becker, Gabriela Paise, Paulo S. Tomasi, Felipe Vélez-Garcia, Geruza L. Melo, Jonas Sponchiado, Felipe Cerezer, Marília A. S. Barros, Albérico Q. S. Souza, Cinthya C. Santos, Gastón A. F. Giné, Patricia Kerches-Rogeri, Marcelo M. Weber, Guilherme Ambar, Lucía V. Cabrera-Martinez, Alan Eriksson, Maurício Silveira, Carolina F. Santos, Lucas Alves, Eder Barbier, Gabriela C. Rezende, Guilherme S. T. Garbino, Élson O. Rios, Adna Silva, Alexandre Túlio A. Nascimento, Rodrigo S. Carvalho, Anderson Feijó, Juan Arrabal, Ilaria Agostini, Daniela Lamattina, Sebastian Costa, Ezequiel Vanderhoeven, Fabiano R. Melo, Plautino Oliveira Laroque, Leandro Jerusalinsky, Mônica M. Valença-Montenegro, Amely B. Martins, Gabriela Ludwig, Renata B. Azevedo, Agustin Anzóategui, Marina X. Silva, Marcela Figuerêdo Duarte Moraes, Alexandre Vogliotti, Andressa Gatti, Thomas Püttker, Camila S. Barros, Thais K. Martins, Alexine Keuroghlian, Donald P. Eaton, Carolina L. Neves, Marcelo S. Nardi, Caryne Braga, Pablo R. Gonçalves, Ana Carolina Srbek-Araujo, Poliana Mendes, João A. Oliveira, Fábio A. M. Soares, Patrício A. Rocha, Peter Crawshaw, Milton C. Ribeiro, Mauro Galetti
      Pages: 498 - 498
      Abstract: Measures of traits are the basis of functional biological diversity. Numerous works consider mean species-level measures of traits while ignoring individual variance within species. However, there is a large amount of variation within species and it is increasingly apparent that it is important to consider trait variation not only between species, but also within species. Mammals are an interesting group for investigating trait-based approaches because they play diverse and important ecological functions (e.g., pollination, seed dispersal, predation, grazing) that are correlated with functional traits. Here we compile a data set comprising morphological and life history information of 279 mammal species from 39,850 individuals of 388 populations ranging from −5.83 to −29.75 decimal degrees of latitude and −34.82 to −56.73 decimal degrees of longitude in the Atlantic forest of South America. We present trait information from 16,840 individuals of 181 species of non-volant mammals (Rodentia, Didelphimorphia, Carnivora, Primates, Cingulata, Artiodactyla, Pilosa, Lagomorpha, Perissodactyla) and from 23,010 individuals of 98 species of volant mammals (Chiroptera). The traits reported include body mass, age, sex, reproductive stage, as well as the geographic coordinates of sampling for all taxa. Moreover, we gathered information on forearm length for bats and body length and tail length for rodents and marsupials. No copyright restrictions are associated with the use of this data set. Please cite this data paper when the data are used in publications. We also request that researchers and teachers inform us of how they are using the data.
      PubDate: 2018-02-05T02:43:25.642793-05:
      DOI: 10.1002/ecy.2106
       
  • Will a small randomly-assembled community be feasible and stable'
    • Authors: Chuliang Song; Serguei Saavedra
      Abstract: How likely is that few species can randomly assemble into a feasible and stable community' Some studies have answered that as long as the community is feasible, it will nearly always be stable. In contrast, other studies have answered that the likelihood is almost null. Here, we show that the origin of this debate has been the underestimation of the association of the parameter space of intrinsic growth rates with the feasibility and stability properties of small randomly-assembled communities. In particular, we demonstrate that not all parameterizations and sampling distributions of intrinsic growth rates lead to the same probabilities of stability and feasibility, which could mistakenly lead to under or overestimate the stability properties of feasible communities. Additionally, we find that stability imposes a filtering of species abundances towards more even distributions in small feasible randomly-assembled communities. This indicates that the stability of feasible communities is inherently linked to the starting distribution of species abundances, a characteristic that many times has been ignored, but should be incorporated in manageable lab and field experiments. Overall, the return to this debate is a central reminder that a more systematic exploration of the feasible parameter space is necessary to derive general conclusions about the stability properties of ecological communities.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T23:00:26.716189-05:
      DOI: 10.1002/ecy.2125
       
  • The dimensionality of individual niche variation
    • Authors: Travis Ingram; Raul Costa-Pereira, Márcio S. Araújo
      Abstract: The inherently multidimensional nature of the niche has not yet been integrated into the investigation of individual niche specialization within populations. We propose a framework for modeling the between- and within-individual components of the population niche as a set of variance-covariance matrices, which can be visualized with ellipses or ellipsoids. These niche components can be inferred using multiple response mixed models, and can incorporate diverse types of data, including diet composition, stable isotopes, spatial location, and other continuous measures of niche dimensions. We outline how considering both individual and population niches in multiple dimensions may enhance our understanding of key concepts in ecology and evolution. Considering multiple dimensions as well as the within-individual component of variation can lead to more meaningful measures of niche overlap between species. The impact of a population on its food web or ecosystem can depend on the degree of individual variation (via Jensen's inequality), and we suggest how the dimensionality of individual specialization could amplify this effect. Finally, we draw from concepts in quantitative genetics and the study of animal personalities to propose new hypotheses about the ecological and evolutionary basis of niche shifts in multiple dimensions. We illustrate key ideas using empirical data from sea otters, wetland frogs, and threespine stickleback, and discuss outstanding questions about the consequences of multidimensional niche variation. Setting variation among individuals in an explicitly multivariate framework has the potential to transform our understanding of a range of ecological and evolutionary processes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T01:45:49.840969-05:
      DOI: 10.1002/ecy.2129
       
  • Bottom-up processes mediated by social systems drive demographic traits of
           coral-reef fishes
    • Authors: Brett M. Taylor; Simon J. Brandl, Maia Kapur, William D. Robbins, Garrett Johnson, Charlie Huveneers, Phil Renaud, J. Howard Choat
      Abstract: Ectotherms exhibit considerable plasticity in their life-history traits. This plasticity can reflect variability in environmental and social factors, but the causes of observed patterns are often obscured with increasing spatial scales. We surveyed dichromatic parrotfishes across the northern Great Barrier Reef to examine variation in body size distributions and concomitant size at sex change (L∆50) against hypotheses of directional influence from biotic and abiotic factors known to affect demography. By integrating top-down, horizontal, and bottom-up processes, we demonstrate a strong association between exposure regimes (which are known to influence nutritional ecology and mating systems) and both body size distribution and L∆50 (median length at female-to-male sex change), with an accompanying lack of strong empirical support for other biotic drivers previously hypothesized to affect body size distributions. Across sites, body size was predictably linked to variation in temperature and productivity, but the strongest predictor was whether subpopulations occurred at sheltered mid and inner shelf reefs or at wave-exposed outer shelf reef systems. Upon accounting for the underlying influence of body size distribution, this habitat-exposure gradient was highly associated with further L∆50 variation across species, demonstrating that differences in mating systems across exposure gradients affect the timing of sex change beyond variation concomitant with differing overall body sizes. We posit that exposure-driven differences in habitat disturbance regimes have marked effects on the nutritional ecology of parrotfishes, leading to size-related variation in mating systems, which underpin the observed patterns. Our results call for better integration of life-history, social factors, and ecosystem processes to foster an improved understanding of complex ecosystems such as coral reefs.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-28T01:41:01.036784-05:
      DOI: 10.1002/ecy.2127
       
  • Predator-prey interactions cause apparent competition between marine
           zooplankton groups
    • Authors: Leif Christian Stige; Kristina Ø. Kvile, Bjarte Bogstad, Øystein Langangen
      Abstract: Predator-mediated apparent competition is an indirect negative interaction between two prey species mediated by a shared predator. Quantifying such indirect ecosystem effects is methodologically challenging but important for understanding ecosystem functioning. Still, there are few examples of apparent competition from pelagic marine environments. Using state-space statistical modelling, we here provide evidence for apparent competition between two dominant zooplankton groups in a large marine ecosystem, i.e., krill and copepods in the Barents Sea. This effect is mediated by a positive association between krill biomass and survival of the main planktivorous fish in the Barents Sea, capelin Mallotus villosus, and a negative association between capelin and copepod biomasses. The biomass of Atlantic krill species is expected to increase in the Barents Sea due to ongoing climate change, thereby potentially negatively affecting copepods through apparent competition. By demonstrating and quantifying apparent competition in a large marine ecosystem, our study paves the way for more realistic projections of indirect ecosystem effects of climate change and harvesting.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-27T13:50:29.743208-05:
      DOI: 10.1002/ecy.2126
       
  • Associations among arbuscular mycorrhizal fungi and seedlings are
           predicted to change with tree successional status
    • Authors: Bachelot Benedicte; María Uriarte, Robert Muscarella, Jimena Forero-Montaña, Jill Thompson, Krista McGuire, Jess Zimmerman, Nathan G. Swenson, James S. Clark
      Abstract: Arbuscular mycorrhizal (AM) fungi in the soil may influence tropical tree dynamics and forest succession. The mechanisms are poorly understood, because the functional characteristics and abundances of tree species and AM fungi are likely to be codependent. We used generalized joint attribute modeling to evaluate if AM fungi are associated with three forest community metrics for a sub-tropical montane forest in Puerto Rico. The metrics chosen to reflect changes during forest succession are: the abundance of seedlings of different successional status, the amount of foliar damage on seedlings of different successional status, and community-weighted mean functional trait values (adult specific leaf area (SLA), adult wood density, and seed mass). We used high-throughput DNA sequencing to identify fungal operational taxonomic units (OTUs) in the soil. Model predictions showed that seedlings of mid- and late-successional species had less leaf damage when the 12 most common AM fungi were abundant compared to when these fungi were absent. We also found that seedlings of mid-successional species were predicted to be more abundant when the 12 most common AM fungi were abundant compared to when these fungi were absent. In contrast, early-successional tree seedlings were predicted to be less abundant when the 12 most common AM fungi were abundant compared to when these fungi were absent. Finally, we showed that, among the 12 most common AM fungi, different AM fungi were correlated with functional trait characteristics of early- or late-successional species. Together, these results suggest that early-successional species might not rely as much as mid- and late-successional species on AM fungi, and AM fungi might accelerate forest succession.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-27T13:45:29.155994-05:
      DOI: 10.1002/ecy.2122
       
  • The interaction of drought and habitat explain space-time patterns of
           establishment in saguaro (Carnegiea gigantea)
    • Authors: Daniel E. Winkler; Joshua L. Conver, Travis E. Huxman, Don E. Swann
      Abstract: The long-lived columnar saguaro cactus (Carnegiea gigantea) is among the most studied plants in the world. Long-term studies have shown saguaro establishment to be generally episodic and strongly influenced by precipitation and temperature. Water limitation through lower-than-average seasonal rainfall and elevated temperatures increasing evaporative loss can reduce survivorship of recent germinates. Thus, multi-year, extended drought could cause populations to decline as older saguaros die without replacement. Previous studies have related establishment to temporal variation in rainfall, but most studies have been on non-randomized plots in ideal habitat and thus might not have captured the full variability within the local area. We studied how saguaro establishment varied in space and which habitat features may buffer responses to drought on 36, 4 ha plots located randomly across an elevation gradient, including substantial replication in landscape position (bajada, foothills, and slopes) in the two disjunct districts of Saguaro National Park in southern Arizona, USA. Recent, severe drought coincided with drastic declines in saguaro establishment across this ca. 25,000 ha area. Establishment patterns derived from the park-wide dataset was strongly correlated with drought, but the Park's two districts and diversity of plots demonstrated substantially different population outcomes. Saguaro establishment was best explained by the interaction of drought and habitat type; establishment in bajada and foothill plots dropped to near-zero under the most severe periods of water limitation but remained higher in slope plots during the same time span. Combined with saguaro density estimates, these data suggest that the most suitable habitat type for saguaro establishment shifted to higher elevations during the time span of the recent drought. These results place into context the extent to which historical patterns of demography provide insight into future population dynamics in a changing climate and reveal the importance of understanding dynamics across the distribution of possible local habitat types with response to variation in weather.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-27T13:45:26.413972-05:
      DOI: 10.1002/ecy.2124
       
  • Can overcompensation increase crop production'
    • Authors: Katja Poveda; María F. Díaz, Augusto Ramirez
      Abstract: The two most pressing challenges to agriculture worldwide are feeding a rapidly growing human population and developing more sustainable agricultural practices that do not threaten human and ecosystem health. We address these challenges through research in plant-herbivore interactions, specifically overcompensatory responses in potato to herbivore damage. While herbivory is usually detrimental to most crops, some potato cultivars can overcompensate and increase crop productivity up to two-fold in response to herbivore damage. However, biotic and abiotic factors are known to influence compensatory responses. Here we tested if compensatory plant responses to herbivory increase productivity of potatoes under field conditions along gradients of altitude and landscape simplification in 15 different farms. Our results suggest that compensatory plant responses could double the mean productivity of a potato farm in relation to the productivity of undamaged plants. The compensatory response is best predicted by pest pressure on a farm with potato plants having the maximum productivity when 10% of the tubers are damaged and decreasing in productivity as pest pressure increases. To a lesser extent an interaction between altitude and landscape simplification did affect the compensatory response, suggesting that abiotic factors play an important role in compensation. Our results suggest that overcompensation-based management practices could be used to maximize yields on working potato farms. Further research is required to determine action thresholds (i.e. the damage levels at which pest control needs to be enacted to maximize yields and minimize insecticide use) to develop more sustainable ways of increasing yields in the future.
      PubDate: 2017-12-27T09:57:26.740649-05:
      DOI: 10.1002/ecy.2088
       
  • Size, growth, and density data for shallow-water sea urchins from Mexico
           to the Aleutian Islands, Alaska, 1956–2016
    • Authors: Thomas A. Ebert; Louis M. Barr, James L. Bodkin, Dirk Burcham, Dominique Bureau, Henry S. Carson, Nancy L Caruso, Jennifer E. Caselle, Jeremy T. Claisse, Sabrina Clemente, Kathryn Davis, Paul M. Detwiler, John D. Dixon, David O. Duggins, John M. Engle, James A. Estes, Scott D. Groth, Benjamin M. Grupe, Peter Halmay, Kyle P. Hebert, José C. Hernández, Laura J. Jurgens, Peter E. Kalvass, Michael C. Kenner, Brenda Kenner, David J. Kushner, Lynn C. Lee, David L. Leighton, Gabriela Montaño-Moctezuma, J. Eric Munk, Irma Olguin, Julio S. Palleiro, David O. Parker, John S. Pearse, Daniel J. Pondella, Laura Rogers-Bennett, Stephen C. Schroeter, A. Ole Shelton, Jorge Sonnenholzner, Ian K. Taniguchi, Glenn R. VanBlaricom, Jane C. Watson, Benjamin P. Weitzman, Jonathan P. Williams, Jennifer Yakimishyn, Zane Zhang
      Abstract: Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus, S. droebachiensis, S. polyacanthus, Mesocentrotus (Strongylocentrotus) franciscanus, Lytechinus pictus, Centrostephanus coronatus, and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. Numerous peer-reviewed publications have used some of these data but some data have appeared only in graduate theses or the gray literature. There also are data that have never appeared outside original data sheets. Motivation for studies has included fisheries management and environmental monitoring of sewer and power plant outfalls as well as changes associated with disease epidemics. Studies also have focused on kelp restoration, community effects of sea otters, basic sea urchin biology, and monitoring. The data sets presented here are a historical record of size, density and growth for a common group of marine invertebrates in intertidal and nearshore environments that can be used to test hypotheses concerning future changes associated with fisheries practices, shifts of predator distributions, climate and ecosystem changes, and ocean acidification along the Pacific Coast of North America and islands of the north Pacific. No copyright restrictions apply. Please credit this paper when using the data.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-27T08:35:56.781472-05:
      DOI: 10.1002/ecy.2123
       
  • Emma Lucy Braun's forest plots in eastern North America
    • Authors: Robert E. Ricklefs
      Abstract: Relative abundances of tree species are presented for the 348 forest plots described in E. Lucy Braun's (1950) book, Deciduous Forests of Eastern North America (Hafner, New York, facsimile reprint 1972). Information about the plots includes forest type, location with latitude and longitude, WorldClim climate variables, and sources of original studies where applicable. No copyright restrictions are associated with the use of this data set. Please cite this article when the data are used in other publications.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-21T10:40:19.711741-05:
      DOI: 10.1002/ecy.2121
       
  • Litter P content drives consumer production in detritus-based streams
           spanning an experimental N:P gradient
    • Authors: Lee M. Demi; Jonathan P. Benstead, Amy D. Rosemond, John C. Maerz
      Abstract: Ecological stoichiometry theory (EST) is a key framework for predicting how variation in N:P supply ratios influences biological processes, at molecular to ecosystem scales, by altering the availability of C, N and P relative to organismal requirements. We tested EST predictions by fertilizing five forest streams at different dissolved molar N:P ratios (2, 8, 16, 32, 128) for two years and tracking responses of macroinvertebrate consumers to the resulting steep experimental gradient in basal resource stoichiometry (leaf litter %N, %P and N:P). Nitrogen and P content of leaf litter, the dominant basal resource, increased in all five streams following enrichment, with steepest responses in litter %P and N:P ratio. Additionally, increases in primary consumer biomass and production occurred in all five streams following N and P enrichment (averages across all streams: biomass by 1.2×, production by 1.6×). Patterns of both biomass and production were best predicted by leaf litter N:P and %P and were unrelated to leaf litter %N. Primary consumer production increased most in streams where decreases in leaf litter N:P were largest. Macroinvertebrate predator biomass and production were also strongly positively related to litter %P, providing robust experimental evidence for the primacy of P limitation at multiple trophic levels in these ecosystems. However, production of predatory macroinvertebrates was not related directly to primary consumer production, suggesting the importance of additional controls for macroinvertebrates at upper trophic positions. Our results reveal potential drivers of animal production in detritus-based ecosystems, including the relative importance of resource quality vs. quantity. Our study also sheds light on the more general impacts of variation in N:P supply ratio on nutrient-poor ecosystems, providing strong empirical support for predictions that nutrient enrichment increases food web productivity whenever large elemental imbalances between basal resources and consumer demand are reduced.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-21T10:25:28.803-05:00
      DOI: 10.1002/ecy.2118
       
  • ATLANTIC BIRDS: a dataset of bird species from the Brazilian Atlantic
           Forest
    • Authors: Érica Hasui; Jean Paul Metzger, Rafael Guerra Pimentel, Luís Fábio Silveira, Alex Augusto de Abreu Bovo, Alexandre Camargo Martensen, Alexandre Uezu, André Luis Regolin, Arthur Ângelo Bispo de Oliveira, Cassiano Augusto Ferreira Rodrigues Gatto, Charles Duca, Christian Borges Andretti, Cristina Banks-Leite, Daniela Luz, Daniele Mariz, Eduardo Roberto Alexandrino, Fabio Monteiro de Barros, Felipe Martello, Iolanda Maria da Silva Pereira, José Nilton da Silva, Katia Maria Paschoaletto Micchi de Barros Ferraz, Luciano Nicolas Naka, Luiz dos Anjos, Márcio Amorim Efe, Marco Aurélio Pizo, Mauro Pichorim, Maycon Sanyvan Sigales Gonçalves, Paulo Henrique Chaves Cordeiro, Rafael Antunes Dias, Renata de Lara Muylaert, Rodolpho Credo Rodrigues, Thiago Vernaschi Vieira da Costa, Vagner Cavarzere, Vinicius Rodrigues Tonetti, Wesley Rodrigues Silva, Clinton N. Jenkins, Mauro Galetti, Milton Cezar Ribeiro
      Abstract: South America holds 30% of the world's avifauna, with the Atlantic Forest representing one of the richest region of the Neotropics. Here we compiled a dataset on Brazilian Atlantic Forest bird occurrence (150,423) and abundance samples (N=832 bird species; 33,119) using multiple methods, including qualitative surveys, mist-nets, point counts, and line transects). We used four main sources of data: museum collections, on-line databases, literature sources, and unpublished reports. The dataset comprises 4,122 localities and data from 1815 to 2017. Most studies were conducted in the “Florestas de Interior” (N=1510 localities) and “Serra do Mar” (1280) biogeographic sub-regions. Considering the three main quantitative methods (mist net, point count, and line transect), we compiled abundance data for 745 species in 576 communities. In the dataset, the most frequent species were Basileuterus culicivorus, Cyclaris gujanensis and Conophaga lineata. There were 71 singletons, such as Lipaugus conditus and Calyptura cristata. We suggest that these small number of records reinforce the critical situation of these taxa in the Atlantic Forest. The information provided in this dataset can be used for macroecological studies, and to foster conservation strategies in this biodiversity hotspot. No copyright restrictions are associated with the data set. Please cite this Data Paper if data are used in publications and teaching events.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-21T02:59:59.105084-05:
      DOI: 10.1002/ecy.2119
       
  • Active and colorful life under lake ice
    • Authors: Guillaume Grosbois; Milla Rautio
      PubDate: 2017-12-19T09:56:18.287121-05:
      DOI: 10.1002/ecy.2074
       
  • How to be a bee hunter
    • Authors: David E. Hibbs
      PubDate: 2017-12-18T10:41:12.563205-05:
      DOI: 10.1002/ecy.2083
       
  • Books and Monographs Received through October 2017
    • PubDate: 2017-12-18T10:41:11.592396-05:
      DOI: 10.1002/ecy.2082
       
  • The curious nature of a raptor researcher
    • Authors: Stan D. Rullman
      PubDate: 2017-12-18T10:40:35.976567-05:
      DOI: 10.1002/ecy.2085
       
  • Recent Publications of Interest
    • PubDate: 2017-12-18T10:40:27.640543-05:
      DOI: 10.1002/ecy.2086
       
  • Our common blood
    • Authors: G. A. Bradshaw
      PubDate: 2017-12-12T10:26:45.105044-05:
      DOI: 10.1002/ecy.2057
       
  • Our next, better parks
    • Authors: Kevin Van Tighem
      PubDate: 2017-12-12T10:26:43.845715-05:
      DOI: 10.1002/ecy.2059
       
  • Recent Publications of Interest
    • PubDate: 2017-12-12T10:26:23.408414-05:
      DOI: 10.1002/ecy.2061
       
  • Books and Monographs Received through September 2017
    • PubDate: 2017-12-12T10:26:21.76121-05:0
      DOI: 10.1002/ecy.2060
       
  • Documenting a regional forest journey
    • Authors: Mark E. Swanson
      PubDate: 2017-12-12T10:26:20.681021-05:
      DOI: 10.1002/ecy.2058
       
  • Mapping multi-scale vascular plant richness in a forest landscape with
           integrated LiDAR and hyperspectral remote-sensing
    • Authors: C.R Hakkenberg; K Zhu, R.K Peet, C. Song
      Abstract: The central role of floristic diversity in maintaining habitat integrity and ecosystem function has propelled efforts to map and monitor its distribution across forest landscapes. While biodiversity studies have traditionally relied largely on ground-based observations, the immensity of the task of generating accurate, repeatable, and spatially-continuous data on biodiversity patterns at large scales has stimulated the development of remote-sensing methods for scaling up from field plot measurements. One such approach is through integrated LiDAR and hyperspectral remote-sensing. However, despite their efficiencies in cost and effort, LiDAR-hyperspectral sensors are still highly constrained in structurally- and taxonomically-heterogeneous forests - especially when species’ cover is smaller than the image resolution, intertwined with neighboring taxa, or otherwise obscured by overlapping canopy strata. In light of these challenges, this study goes beyond the remote characterization of upper canopy diversity to instead model total vascular plant species richness in a continuous-cover North Carolina Piedmont forest landscape. We focus on two related, but parallel, tasks. First, we demonstrate an application of predictive biodiversity mapping, using nonparametric models trained with spatially-nested field plots and aerial LiDAR-hyperspectral data, to predict spatially-explicit landscape patterns in floristic diversity across seven spatial scales between 0.01m2–900m2. Second, we employ bivariate parametric models to test the significance of individual, remotely-sensed predictors of plant richness to determine how parameter estimates vary with scale. Cross-validated results indicate that predictive models were able to account for 15-70% of variance in plant richness, with LiDAR-derived estimates of topography and forest structural complexity, as well as spectral variance in hyperspectral imagery explaining the largest portion of variance in diversity levels. Importantly, bivariate tests provide evidence of scale-dependence among predictors, such that remotely-sensed variables significantly predict plant richness only at spatial scales that sufficiently subsume geolocational imprecision between remotely-sensed and field data, and best align with stand components including plant size and density, as well as canopy gaps and understory growth patterns. Beyond their insights into the scale-dependent patterns and drivers of plant diversity in Piedmont forests, these results highlight the potential of remotely-sensible essential biodiversity variables for mapping and monitoring landscape floristic diversity from air- and space-borne platforms.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-12T10:02:16.368422-05:
      DOI: 10.1002/ecy.2109
       
  • Symbioses with nitrogen-fixing bacteria: nodulation and phylogenetic data
           across legume genera
    • Authors: Michelle E. Afkhami; D. Luke Mahler, Jean H. Burns, Marjorie G. Weber, Martin F. Wojciechowski, Janet Sprent, Sharon Y. Strauss
      Abstract: How species interactions shape global biodiversity and influence diversification is a central – but also data-hungry – question in evolutionary ecology. Microbially-based mutualisms are widespread and could cause diversification by ameliorating stress and thus allowing organisms to colonize and adapt to otherwise unsuitable habitats. Yet the role of these interactions in generating species diversity has received limited attention, especially across large taxonomic groups. In the massive angiosperm family Leguminosae, plants often associate with root-nodulating bacteria that ameliorate nutrient stress by fixing atmospheric nitrogen. These symbioses are ecologically-important interactions, influencing community assembly, diversity, and succession, contributing ~100-290 million tons of N annually to natural ecosystems, and enhancing growth of agronomically-important forage and crop plants worldwide. In recent work attempting to determine whether mutualism with N-fixing bacteria led to increased diversification across legumes, we were unable to definitively resolve the relationship between diversification and nodulation. We did, however, succeed in compiling a very large searchable, analysis-ready database of nodulation data for 749 legume genera (98% of Leguminosae genera; LPWG 2017), which, along with associated phylogenetic information, will provide a valuable resource for future work addressing this question and others. For each legume genus, we provide information about the species richness, frequency of nodulation, subfamily association, and topological correspondence with an additional data set of 100 phylogenetic trees curated for database compatibility. We found 386 legume genera were confirmed nodulators (i.e., all species examined for nodulation nodulated), 116 were non-nodulating, 4 were variable (i.e., containing both confirmed nodulators and confirmed non-nodulators), and 243 had not been examined for nodulation in published studies. Interestingly, data exploration revealed that nodulating legume genera are ~3× more species-rich than non-nodulating genera, but we did not find evidence that this difference in diversity was due to differences in net diversification rate. Our metadata file describes in more detail the structure of these data that provide a foundational resource for future work as more nodulation data become available, and as greater phylogenetic resolution of this ca. 19,500-species family comes into focus.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-11T01:55:22.702192-05:
      DOI: 10.1002/ecy.2110
       
  • Growing competitive or tolerant' Significance of apical dominance in
           the overcompensating herb Gentianella campestris
    • Authors: Tommy Lennartsson; Satu Ramula, Juha Tuomi
      Abstract: As a compensatory response to herbivory, plants may branch vigorously when the growth of dormant meristems is triggered by shoot damage. Undamaged plants, on the other hand, often restrain branching, and this limitation on growth can be considered a cost of tolerance to herbivory. Restrained branching is caused by apical dominance and may, alternatively, be associated with fitness benefits in competitive environments that favor fast vertical growth. To test these hypotheses regarding selection for restrained branching, we compared the performance of two subspecies of the biennial grassland herb Gentianella campestris; the tall, apically dominant ssp. campestris and the short, multi-stemmed ssp. islandica, which shows reduced apical dominance. For both subspecies, we manipulated the height of surrounding vegetation (competition) and damage intensity in grasslands of differing productivity (high, medium, low), and examined population growth rates using matrix population models combined with life table response experiments (LTREs). In the absence of damage, ssp. campestris exhibited a higher population growth rate than ssp. islandica in the tallest vegetation, however with the growth rate still being below one. In the medium and low productivity environments where the vegetation was shorter, the population growth rate of ssp. islandica was considerably higher than that of ssp. campestris as long as no more than about 50% of the plants were damaged. When plants were damaged, the apically dominant ssp. campestris showed a positive population growth rate (λ> 1) and often overcompensatory seed production in all productivity levels, while ssp. islandica showed no compensation and therefore the population was predicted to decline (λ < 1). We conclude that restrained branching in Gentianella cannot be selected for by competition alone, but that episodes of apical damage are required to maintain the trait. Furthermore, because of the costs of restrained branching, apical dominance should be selected against in grasslands where competition and disturbance are low.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-02T10:32:52.586589-05:
      DOI: 10.1002/ecy.2101
       
  • Fitness consequences of occasional outcrossing in a functionally asexual
           plant (Oenothera biennis)
    • Authors: John L. Maron; Marc T.J. Johnson, Amy P. Hastings, Anurag A. Agrawal
      Abstract: Many clonal organisms occasionally outcross, but the long-term consequences of such infrequent events are often unknown. During five years, representing three to five plant generations, we followed 16 experimental field populations of the forb, Oenothera biennis, originally planted with the same 18 original genotypes. Oenothera biennis usually self-fertilizes, which due to its genetic system (Permanent Translocation Heterozygosity), results in seeds that are clones of the maternal plant. However, rare outcrossing produces genetically novel offspring (but without recombination or increased heterozygosity). We sought to understand whether novel genotypes produced through natural outcrossing had greater fecundity or different multigenerational dynamics compared to our original genotypes. We further assessed whether any differences in fitness or abundances through time between original and novel genotypes were exaggerated in the presence versus absence of insect herbivores. Over the course of the experiment, we genotyped>12,500 plants using microsatellite DNA markers to identify and track the frequency of specific genotypes and estimated fecundity on a subset (>3000) of plants. The effective outcrossing rate was 7.3% in the first year and ultimately 50% of the plants were of outcrossed origin by the final year of the experiment. Lifetime fruit production per plant was on average 32% higher across all novel genotypes produced via outcrossing compared to the original genotypes, and this fecundity advantage was significantly enhanced in populations lacking herbivores. Among 43 novel genotypes that were abundant enough to phenotype with replication, plants produced nearly 30% more fruits than the average of their specific two parental genotypes, and marginally more fruits (8%) than their most fecund parent. Mean per capita fecundity of novel genotypes predicted their relative frequencies at the end of the experiment. Novel genotypes increased more dramatically in herbivore-present compared to suppressed populations (45% vs. 27% of all plants), countering the increased competition from dandelions (Taraxacum officinale) that resulted from herbivore suppression. Increased interspecific competition likely also lead to the lower realized fitness of novel versus original genotypes in herbivore-suppressed populations. These results demonstrate that rare outcrossing and the generation of novel genotypes can create high-fecundity progeny, with the biotic environment influencing the dynamical outcome of such advantages.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-02T10:27:49.731969-05:
      DOI: 10.1002/ecy.2099
       
  • Phosphorus limitation of aboveground production in northern hardwood
           forests
    • Authors: Shinjini Goswami; Melany C. Fisk, Matthew A. Vadeboncoeur, Mariann Garrison-Johnston, Ruth D Yanai, Timothy J. Fahey
      Abstract: Forest productivity on glacially derived soils with weatherable phosphorus (P) is expected to be limited by nitrogen (N), according to theories of long-term ecosystem development. However, recent studies and model simulations based on resource optimization theory indicate that productivity can be co-limited by N and P. We conducted a full factorial N x P fertilization experiment in 13 northern hardwood forest stands of three age classes in central New Hampshire, USA, to test the hypothesis that forest productivity is co-limited by N and P. We also asked whether the response of productivity to N and P addition differs among species and whether differential species responses contribute to community-level co-limitation. Plots in each stand were fertilized with 30 kg N ha−1 yr−1, 10 kg P ha−1yr−1, N+P together, or neither nutrient (control) for four growing seasons. The productivity response to treatments was assessed using per-tree annual relative basal area increment (RBAI) as an index of growth. RBAI responded significantly to P (P=0.02) but not to N (P=0.73). However, evidence for P limitation was not uniform among stands. RBAI responded to P fertilization in mid-age (P = 0.02) and mature (P = 0.07) stands, each taken as a group, but was greatest in N-fertilized plots of two stands in these age classes, and there was no significant effect of P in the young stands. Both white birch (Betula papyrifera Marsh.) and beech (Fagus grandifolia Ehrh.) responded significantly to P; no species responded significantly to N. We did not find evidence for N and P co-limitation of tree growth. The response to N+P did not differ from that to P alone, and there was no significant N x P interaction (P=0.68). Our P limitation results support neither the N limitation prediction of ecosystem theory nor the N and P co-limitation prediction of resource optimization theory, but could be a consequence of long-term anthropogenic N deposition in these forests. Inconsistencies in response to P suggest that successional status and variation in site conditions influence patterns of nutrient limitation and recycling across the northern hardwood forest landscape.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-02T10:22:47.457107-05:
      DOI: 10.1002/ecy.2100
       
  • Can mesophotic reefs replenish shallow reefs' Reduced coral
           reproductive performance casts a doubt
    • Authors: Tom Shlesinger; Mila Grinblat, Hanna Rapuano, Tal Amit, Yossi Loya
      Abstract: Mesophotic coral ecosystems (i.e. deep coral reefs at 30-120 m depth) appear to be thriving while many shallow reefs in the world are declining. Amidst efforts to understand and manage their decline, it was suggested that mesophotic reefs might serve as natural refuges and a possible source of propagules for the shallow reefs. However, our knowledge of how reproductive performance of corals alters with depth is sparse. Here, we present a comprehensive study of the reproductive phenology, fecundity and abundance of seven reef-building conspecific corals in shallow and mesophotic habitats. Significant differences were found in the synchrony and timing of gametogenesis and spawning between shallow and mesophotic coral populations. Thus, mesophotic populations exhibited delayed or protracted spawning events, which led to spawning of the mesophotic colonies in large proportions at times where the shallow ones had long been depleted of reproductive material. All species investigated demonstrated a substantial reduction in fecundity and/or oocyte sizes at mesophotic depths (40–60 m). Two species (Seriatopora hystrix and Galaxea fascicularis) displayed a reduction in both fecundity and oocyte size at mesophotic depths. Turbinaria reniformis had only reduced fecundity and Acropora squarrosa and Acropora valida only reduced oocyte size. In Montipora verrucosa, reduced fecundity was found during one annual reproductive season while in the following year only reduced oocyte size was found. In contrast, reduced oocyte size in mesophotic populations of Acropora squarrosa was consistent along three studied years. One species, Acropora pharaonis, was found to be infertile at mesophotic depths along two studied years. The above indicate that reproductive performance decreases with depth; and that although some species are capable of reproducing at mesophotic depths, their contribution to the replenishment of shallow reefs may be inconsequential. Reduced reproductive performance with depth, combined with the possible narrower tolerance to environmental factors further suggests that mesophotic corals may in fact be more vulnerable than previously conceived. Furthermore, we posit that the observed temporal segregation in reproduction could lead to assortative mating, and this, in turn, may facilitate adaptive divergence across depth.This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-02T10:17:45.406416-05:
      DOI: 10.1002/ecy.2098
       
  • Variation in range size and dispersal capabilities of microbial taxa
    • Authors: Mallory J. Choudoir; Albert Barberán, Holly L. Menninger, Rob R. Dunn, Noah Fierer
      Abstract: Geographic range size can span orders of magnitude for plant and animal species, with the study of why range sizes vary having preoccupied biogeographers for decades. In contrast, there have been few comparable studies of how range size varies across microbial taxa and what traits may be associated with this variation. We determined the range sizes of 74,134 bacterial and archaeal taxa found in settled dust collected from 1,065 locations across the United States. We found that most microorganisms have small ranges and few have large ranges, a pattern similar to the range size distributions commonly observed for macrobes. However, contrary to expectations, those microbial taxa which were locally abundant did not necessarily have larger range sizes. The observed differences in microbial range sizes were generally predictable from taxonomic identity, phenotypic traits, genomic attributes, and habitat preferences, findings that provide insight into the factors shaping patterns of microbial biogeography.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-21T11:25:30.156169-05:
      DOI: 10.1002/ecy.2094
       
  • Identifiability in N-mixture models: a large-scale screening test with
           bird data
    • Authors: Marc Kéry
      Abstract: Binomial N-mixture models have proven very useful in ecology, conservation and monitoring: they allow estimation and modeling of abundance separately from detection probability using simple counts. Recently, doubts about parameter identifiability have been voiced. I conducted a large-scale screening test with 137 bird data sets from 2,037 sites. I found virtually no identifiability problems for Poisson and zero-inflated Poisson (ZIP) binomial N-mixture models, but negative-binomial (NB) models had problems in 25% of all data sets. The corresponding multinomial N-mixture models had no problems. Parameter estimates under Poisson and ZIP binomial and multinomial N-mixture models were extremely similar. Identifiability problems became a little more frequent with smaller sample sizes (267 and 50 sites), but were unaffected by whether the models did or did not include covariates. Hence, binomial N-mixture model parameters with Poisson and ZIP mixtures typically appeared identifiable. In contrast, NB mixtures were often unidentifiable, which is worrying since these were often selected by AIC. Identifiability of binomial N-mixture models should always be checked. If problems are found, simpler models, integrated models which combine different observation models or the use of external information via informative priors or penalized likelihoods may help.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-21T01:46:02.430017-05:
      DOI: 10.1002/ecy.2093
       
  • Large-scale bleaching of corals on the Great Barrier Reef
    • Authors: T. P. Hughes; J. T. Kerry, T. Simpson
      Abstract: In 2015–2016, record temperatures triggered a pan-tropical episode of coral bleaching. In the southern hemisphere summer of March–April 2016, we used aerial surveys to measure the level of bleaching on 1,156 individual reefs throughout the 2,300 km length of the Great Barrier Reef, the world's largest coral reef system. The accuracy of the aerial scores was ground-truthed with detailed underwater surveys of bleaching at 260 sites (104 reefs), allowing us to compare aerial and underwater bleaching data with satellite-derived temperatures and with associated model predictions of bleaching. The severity of bleaching on individual reefs in 2016 was tightly correlated with the level of local heat exposure: the southernmost region of the Great Barrier Reef escaped with only minor bleaching because summer temperatures there were close to average. Gradients in nutrients and turbidity from inshore to offshore across the Great Barrier Reef had minimal effect on the severity of bleaching. Similarly, bleaching was equally severe on reefs that are open or closed to fishing, once the level of satellite-derived heat exposure was accounted for. The level of post-bleaching mortality, measured underwater after 7–8 months, was tightly correlated with the aerial scores measured at the peak of bleaching. Similarly, reefs with a high aerial bleaching score also experienced major shifts in species composition due to extensive mortality of heat-sensitive species. Reefs with low bleaching scores did not change in composition, and some showed minor increases in coral cover. Two earlier mass bleaching events occurred on the Great Barrier Reef in 1998 and 2002, that were less severe than 2016. In 2016, less than 9% of scored reefs had no bleaching, compared to 42% in 2002 and 44% in 1998. Conversely, the proportion of reefs that were severely bleached (>60% of corals affected) was four times higher in 2016. The geographic footprint of each of the three events is distinctive, and matches satellite-derived sea surface temperature patterns. Our aerial surveys indicate that past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. This dataset of aerial bleaching scores provides a historical baseline for comparison with future bleaching events. No copyright restrictions apply to the use of this data set other than citing this publication.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-20T10:55:22.118212-05:
      DOI: 10.1002/ecy.2092
       
  • The China Plant Trait Database: towards a comprehensive regional
           compilation of functional traits for land plants
    • Authors: Han Wang; Sandy P. Harrison, I. Colin Prentice, Yanzheng Yang, Fan Bai, Henrique Furstenau Togashi, Meng Wang, Shuangxi Zhou, Jian Ni
      Abstract: Plant functional traits provide information about adaptations to climate and environmental conditions, and can be used to explore the existence of alternative plant strategies within ecosystems. Trait data are also increasingly being used to provide parameter estimates for vegetation models. Here we present a new database of plant functional traits from China. Most global climate and vegetation types can be found in China, and thus the database is relevant for global modelling. The China Plant Trait Database contains information on morphometric, physical, chemical and photosynthetic traits from 122 sites spanning the range from boreal to tropical, and from deserts and steppes through woodlands and forests, including montane vegetation. Data collection at each site was based either on sampling the dominant species or on a stratified sampling of each ecosystem layer. The database contains information on 1215 unique species, though many species have been sampled at multiple sites. The original field identifications have been taxonomically standardized to the Flora of China. Similarly, derived photosynthetic traits, such as electron-transport and carboxylation capacities, were calculated using a standardized method. To facilitate trait-environment analyses, the database also contains detailed climate and vegetation information for each site. The dataset is released under a Creative Commons BY licence. When using the dataset, we kindly request that you cite this article, recognizing the hard work that went into collecting the data and the authors’ willingness to make it publicly available.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-20T10:50:21.656184-05:
      DOI: 10.1002/ecy.2091
       
  • Hemiparasites can transmit indirect effects from their host plants to
           herbivores
    • Authors: Nathan L. Haan; Jonathan D. Bakker, M. Deane Bowers
      Abstract: Parasitic plants can serve as critical intermediaries between their hosts and other organisms; however these relationships are not well understood. To investigate the relative importance of plant traits in such interactions, we studied the role of the root hemiparasite, Castilleja levisecta (Orobanchaceae), as a mediator of interactions between the host plants it parasitizes and the lepidopteran herbivore Euphydryas editha (Nymphalidae), whose caterpillars feed on Castilleja and sequester iridoid glycosides from it. We tested whether the hemiparasite's size, leaf N concentration, and iridoid glycoside concentrations were influenced by the identity of its host plant, and then whether these traits influenced outcomes for the herbivore.We found that the hemiparasite's size and leaf N depended on the host it parasitized, and these traits in turn affected outcomes for E. editha. Specifically, Euphydryas editha survival increased with hemiparasite size and caterpillar mass increased with leaf N; caterpillars with greater mass were more likely to survive during diapause. We also found preliminary evidence that host identity influenced iridoid glycoside sequestration by the herbivore. Mean iridoid glycoside concentrations in caterpillars ranged from 1-12% depending on the host being parasitized by Castilleja. This study demonstrates that root parasitism can result in strong indirect effects on higher trophic levels, influencing organisms’ survival, growth, and chemical interactions.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-13T07:45:43.454143-05:
      DOI: 10.1002/ecy.2087
       
  • Analyzing community-weighted trait means across environmental gradients:
           should phylogeny stay or should it go'
    • Authors: Leandro D. S. Duarte; Vanderlei Julio Debastiani, Marcos Bergmann Carlucci, José Alexandre Felizola Diniz-Filho
      Abstract: Functional traits mediate ecological responses of organisms to the environment, determining community structure. Community-weighted trait means (CWM) are often used to characterize communities by combining information on species traits and distribution. Relating CWM variation to environmental gradients allows for evaluating species sorting across the metacommunity, either based on correlation tests or ordinary least squares (OLS) models. Yet, it is not clear if phylogenetic signal in both traits and species distribution affect those analyses. On one hand, phylogenetic signal might indicate niche conservatism along clade evolution, reinforcing the environmental signal in trait assembly patterns. On the other hand, it might introduce phylogenetic autocorrelation to mean trait variation among communities. Under this latter scenario, phylogenetic signal might inflate type I error in analysis relating CWM variation to environmental gradients. We explore multiple ways phylogenetic history may influence analysis relating CWM to environmental gradients. We propose the concept of neutral trait diffusion, which predicts that for a functional trait x, CWM variation among local communities does not deviate from the expectation that x evolved according to a neutral evolutionary process. Based on this framework we introduce a graphical tool called neutral trait diffusion representation (NTDR) that allows for the evaluation of whether it is necessary to carry out phylogenetic correction in the trait prior to analyzing the association between CWM and environmental gradients. We illustrate the NTDR approach using simulated traits, phylogenies and metacommunities. We show that even under moderate phylogenetic signal in both the trait used to define CWM and species distribution across communities, OLS models relating CWM variation to environmental gradients lead to inflated type I error when testing the null hypothesis of no association between CWM and environmental gradient. To overcome this issue, we propose a phylogenetic correction for OLS models and evaluate its statistical performance (type I error and power). Phylogeny-corrected OLS models successfully control for type I error in analysis relating CWM variation to environmental gradients but may show decreased power. Combining the exploratory tool of NTDR and phylogenetic correction in traits, when necessary, guarantees more precise inferences about the environmental forces driving trait-mediated species sorting across metacommunities.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-09T13:50:22.553632-05:
      DOI: 10.1002/ecy.2081
       
  • Dynamic preferential allocation to arbuscular mycorrhizal fungi explains
           fungal succession and coexistence
    • Authors: Benedicte Bachelot; Charlotte T. Lee
      Abstract: Evidence accumulates about the role of arbuscular mycorrhizal (AM) fungi in shaping plant communities, but little is known about the factors determining the biomass and coexistence of several types of AM fungi in a plant community. Here, using a consumer-resource framework that treats the relationship between plants and fungi as simultaneous, reciprocal exploitation, we investigated what patterns of dynamic preferential plant carbon allocation to empirically-defined fungal types (on-going partner choice) would be optimal for plants, and how these patterns depend on successional dynamics. We found that ruderal AM fungi can dominate under low steady-state nutrient availability, and competitor AM fungi can dominate at higher steady-state nutrient availability; these are conditions characteristic of early and late succession, respectively. We also found that dynamic preferential allocation alone can maintain a diversity of mutualists, suggesting that on-going partner choice is a new coexistence mechanism for mutualists. Our model can therefore explain both mutualist coexistence and successional strategy, providing a powerful tool to derive testable predictions.This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-09T13:45:29.780083-05:
      DOI: 10.1002/ecy.2080
       
  • Stabilizing effects in temporal fluctuations: management, traits and
           species richness in high-diversity communities
    • Authors: Jan Lepš; Maria Májeková, Alena Vítová, Jiří Doležal, Francesco de Bello
      Abstract: The loss of biodiversity is thought to have adverse effects on multiple ecosystem functions, including the decline of community stability. Decreased diversity reduces the strength of the portfolio effect, a mechanism stabilizing community temporal fluctuations. Community stability is also expected to decrease with greater variability in individual species populations and with synchrony of their fluctuations. In semi-natural meadows, eutrophication is one of the most important drivers of diversity decline; it is expected to increase species fluctuations and synchrony among them, all effects leading to lower community stability. With a 16 year time series of biomass data from a temperate species-rich meadow with fertilization and removal of the dominant species, we assessed population biomass temporal (co)variation under different management types and competition intensity, and in relation to species functional traits and to species diversity. Whereas the effect of dominant removal was relatively small (with a tendency towards lower stability), fertilization markedly decreased community stability (i.e. increased coefficient of variation in the total biomass) and species diversity. On average, the fluctuations of individual populations were mutually independent, with a slight tendency towards synchrony in unfertilized plots, and a tendency towards compensatory dynamics in fertilized plots and no effects of removal. The marked decrease of synchrony with fertilization, contrary to the majority of the results reported previously, follows the predictions of increased compensatory dynamics with increased asymmetric competition for light in a more productive environment. Synchrony increased also with species functional similarity stressing the importance of shared ecological strategies in driving similar species responses to weather fluctuations. As expected, the decrease of temporal stability of total biomass was mainly related to the decrease of species richness, with its effect remaining significant also after accounting for fertilization. The weakening of the portfolio effect with species richness decline is a crucial driver of community destabilization. However, the positive effect of species richness on temporal stability of total biomass was not due to increased compensatory dynamics, since synchrony increased with species richness. This shows that the negative effect of eutrophication on community stability does not operate through increasing synchrony, but through the reduction of diversity.This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-30T09:55:40.469216-05:
      DOI: 10.1002/ecy.2065
       
  • Fungi reduce preference and performance of insect herbivores on challenged
           plants
    • Authors: Pilar Fernandez-Conradi; Hervé Jactel, Cécile Robin, Ayco J. M. Tack, Bastien Castagneyrol
      Abstract: Although insect herbivores and fungal pathogens frequently share the same individual host plant, we lack general insights in how fungal infection affects insect preference and performance. We addressed this question in a meta-analysis of 1,113 case studies gathered from 101 primary papers that compared preference or performance of insect herbivores on control vs. fungus challenged plants. Generally, insects preferred, and performed better on, not challenged plants, regardless of experimental conditions. Insect response to fungus infection significantly differed according to fungus lifestyle, insect feeding guild and the spatial scale of the interaction (local/distant). Insect performance was reduced on plants challenged by biotrophic pathogens or endophytes but not by necrotrophic pathogens. For both chewing and piercing-sucking insects, performance was reduced on challenged plants when interactions occurred locally but not distantly. In plants challenged by biotrophic pathogens, both preference and performance of herbivores were negatively impacted, whereas infection by necrotrophic pathogens reduced herbivore preference more than performance and endophyte infection reduced only herbivore performance. Our study demonstrates that fungi are may be important but hitherto overlooked drivers of plant-herbivore interactions, suggesting both direct and plant-mediated effects of fungi on insect's behavior and development.This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-11T01:50:27.89435-05:0
      DOI: 10.1002/ecy.2044
       
  • Indirect effects of larvae dispersal following mass mortality events
    • Authors: Marcus A. Lashley; Heather R. Jordan, Jeffery K. Tomberlin, Brandon T. Barton
      Abstract: Mass mortality events are characterized by rapid die-offs of many individuals within a population at a specific location. These events produce a high concentration of remains within a given locale and the frequency and magnitude of these events may be increasing (Fey et al. 2015). Mass mortality events may be caused by physical (e.g., lightning strikes, fire), chemical (e.g., pollutants, hypoxia), or biological processes (e.g., disease, phenological mismatch with food source).This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-15T06:47:05.720516-05:
      DOI: 10.1002/ecy.2027
       
  • The “jack-in-the-box” stamens of Heliconia wagneriana
           (Heliconiaceae)
    • Authors: Dustin G. Gannon; Urs G. Kormann, Adam S. Hadley, Matthew G. Betts, Franklin Andrew Jones
      Pages: 488 - 490
      PubDate: 2017-12-04T11:06:45.741383-05:
      DOI: 10.1002/ecy.2042
       
  • Unique preening behavior may use light and heat to facilitate ectoparasite
           removal in green herons (Butorides virescens)
    • Authors: Loren Merrill
      Pages: 494 - 496
      PubDate: 2017-12-05T12:50:03.491643-05:
      DOI: 10.1002/ecy.2040
       
 
 
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