Journal Cover Ecology
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   ISSN (Print) 0012-9658 - ISSN (Online) 1939-9170
   Published by John Wiley and Sons Homepage  [1577 journals]
  • 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
       
  • Physical calculations of resistance to water loss improve species range
           models: Reply
    • Authors: Eric A. Riddell; Michael W. Sears
      Abstract: Christian et al. (2017) proposed several possible flaws in the methods and logic presented by Riddell et al. (2017) that included potential activity of salamanders during measurements, trimming of the agar model's legs, misinterpretations of the empirical data, limitations on agar models, and the relationship between body size and skin resistance to water loss (ri). We argue that these criticisms are easily addressable, and here, we reinforce our original claim that the agar method for determination of resistance to water loss is flawed. Before responding to these individual critiques, we begin with a deeper criticism of the agar model method and general methodology for determining resistance to water loss that has resulted in the reification of the boundary layer's ecological and physiological importance.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-13T10:45:19.086603-05:
      DOI: 10.1002/ecy.2022
       
  • Quantity and quality limit detritivore growth: mechanisms revealed by
           ecological stoichiometry and co-limitation theory
    • Authors: Halvor M. Halvorson; Erik Sperfeld, Michelle A. Evans-White
      Abstract: Resource quantity and quality are fundamental bottom-up constraints on consumers. Best understood in autotroph-based systems, co-occurrence of these constraints may be common but remains poorly studied in detrital-based systems. Here, we used a laboratory growth experiment to test limitation of the detritivorous caddisfly larvae Pycnopsyche lepida across a concurrent gradient of oak litter quantity (food supply) and quality (phosphorus:carbon, P:C ratios). Growth increased simultaneously with quantity and quality, indicating co-limitation across the resource gradients. We merged approaches of ecological stoichiometry and co-limitation theory, showing how co-limitation reflected shifts in C and P acquisition throughout homeostatic regulation. Increased growth was best explained by elevated consumption rates and improved P assimilation, which both increased with elevated quantity and quality. Notably, C assimilation efficiencies remained unchanged and achieved maximum 18% at low quantity despite pronounced C-limitation. Detrital C recalcitrance and substantive post-assimilatory C losses probably set a minimum quantity threshold to achieve positive C balance. Above this threshold, greater quality enhanced larval growth probably by improving P assimilation toward P-intensive growth. We suggest this interplay of C and P acquisition contributes to detritivore co-limitation, highlighting quantity and quality as potential simultaneous bottom-up controls in detrital-based ecosystems, including under anthropogenic change like nutrient enrichment.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-13T10:15:31.636898-05:
      DOI: 10.1002/ecy.2026
       
  • Biodiversity maintenance may be lower under partial niche differentiation
           than under neutrality
    • Authors: Rafael D'Andrea; Annette Ostling
      Abstract: Niche differentiation is normally regarded as a promoter of species coexistence in competitive systems, as it stabilizes species abundances. One might therefore expect lower extinction rates and higher species richness and local persistence times in niche-differentiated communities than in neutral assemblages. Here we compare stochastic niche and neutral dynamics in simulated assemblages, and find that when local dynamics combine with immigration from a regional pool, the effect of niches can be more complex. Trait variation that lessens competition between species will not necessarily give all immigrating species their own niche to occupy. Such partial niche differentiation protects certain species from local extinction, but expedites exclusion of others. Differences in regional abundances and intrinsic growth rates have similar impacts on the distribution of persistence times as niche differentiation and blur the distinction between niche and neutral dynamical patterns, though niche dynamics will influence which species persist longer. Ultimately, unless the number of niches available to species is sufficiently high, niches may actually heighten extinction rates and lower species richness and local persistence times. Our results help make sense of recent observations of community dynamics, and point to the dynamical observations needed to discern the influence of niche differentiation.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-12T06:00:23.528654-05:
      DOI: 10.1002/ecy.2020
       
  • Orthogonal fitness benefits of nitrogen and ants for nitrogen-limited
           plants in the presence of herbivores
    • Authors: Elizabeth G. Pringle; Ian Ableson, Jennifer Kerber, Rachel L. Vannette, Leiling Tao
      Abstract: Predictable effects of resource availability on plant growth-defense strategies provide a unifying theme in theories of direct anti-herbivore defense, but it is less clear how resource availability modulates plant indirect defense. Ant-plant-hemipteran interactions produce mutualistic trophic cascades when hemipteran-tending ants reduce total herbivory, and these interactions are a key component of plant indirect defense in most terrestrial ecosystems. Here we conducted an experiment to test how ant-plant-hemipteran interactions depend on nitrogen (N) availability by manipulating the presence of ants and aphids under different N fertilization treatments. Ants increased plant flowering success by decreasing the densities of herbivores, and the effects of ants on folivores were positively related to the density of aphids. Unexpectedly, N fertilization produced no changes in plant N concentrations. Plants grown in higher N grew and flowered more, but aphid honeydew chemistry stayed the same, and neither the density of aphids nor the rate of ant attraction per aphid changed with N addition. The positive effects of ants and N addition on plant fitness were thus independent of one another. We conclude that N was the plant's limiting nutrient and propose that addition of the limiting nutrient is unlikely to alter the strength of mutualistic trophic cascades.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-09T09:15:27.323804-05:
      DOI: 10.1002/ecy.2013
       
  • Influence of littoral periphyton on whole-lake metabolism relates to
           littoral vegetation in humic lakes
    • Authors: Jussi Vesterinen; Shawn P. Devlin, Jari Syväranta, Roger I. Jones
      Abstract: The role of littoral habitats in lake metabolism has been underrated, especially in humic lakes, based on an assumption of low benthic primary production (PP) due to low light penetration into water. This assumption has been challenged by recent recognition of littoral epiphyton dominance of whole-lake PP in a small highly humic lake and of epiphyton as an important basal food source for humic lake biota. However, as these studies have mostly concerned single lakes, there is a need to test their wider generality. We studied the whole-lake PP and community respiration (CR) in eight small humic lakes in southern Finland during July 2015 using 14C incorporation to measure pelagic PP and the changes in dissolved inorganic carbon in light and dark in situ incubations to measure CR and littoral PP by epiphyton. Changes in O2 concentration in both pelagic and littoral surface water were measured periodically from each lake and, additionally, continuously with a data logger from one lake during the study period. The results revealed that the littoral dominated whole-lake net primary production (NPP) in five of the eight lakes, which was supported by observed O2 supersaturation in the littoral surface water in most of the lakes. Calculated pelagic:littoral ratios by area correlated negatively with both littoral NPP and littoral contribution to whole-lake NPP. Moreover, there was a significant positive relationship between littoral proportion of whole-lake NPP and the fraction of lake surface area covered by littoral aquatic vegetation. This demonstrates that increased aquatic littoral vegetation cover increases the overall importance of the littoral to whole-lake PP in highly humic lakes. Littoral NPP also correlated strongly with littoral O2 saturation, and the continuously measured O2 revealed substantial temporal variation in O2 saturation, particularly in the littoral zone. Whole-lake gross primary production:community respiration (GPP:CR) ratios revealed that accounting for littoral metabolism produced a marked shift towards lake metabolic balance, although all the eight lakes remained net heterotrophic. This study emphasizes that littoral metabolism needs to be accounted for when estimating whole-lake C fluxes in all lakes, even in highly colored humic waters.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-09T09:10:28.70721-05:0
      DOI: 10.1002/ecy.2012
       
  • The little things that run: a general scaling of invertebrate exploratory
           speed with body mass
    • Authors: Myriam R. Hirt; Tobias Lauermann, Ulrich Brose, Lucas P.J.J. Noldus, Anthony I. Dell
      Abstract: Speed is a key trait of animal movement, and while much is already known about vertebrate speed and how it scales with body mass, studies on invertebrates are sparse, especially across diverse taxonomic groups. Here, we used automated image-based tracking to characterize the exploratory (voluntary) speed of 173 invertebrates comprising 57 species across 6 taxonomic groups (Arachnida, Chilopoda, Diplopoda, Entognatha, Insecta, Malacostraca) and 4 feeding types (carnivore, detritivore, herbivore, omnivore). Across all individuals, exploratory speed scaled with body mass following a power-law relationship with a scaling exponent of 0.19 (±0.04 standard error) and an intercept of 14.33 (±1.2). These parameters varied substantially with taxonomic group and feeding type. For the first time, we provide general empirically-derived allometric scaling relationships of exploratory speed across broad taxonomic groups of invertebrates. As exploratory speed drives key components of species interactions – such as encounter and attack rates, or competition – our study contributes to a deeper understanding of the role of individual movement in population and community level processes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-08T20:45:30.539817-05:
      DOI: 10.1002/ecy.2006
       
  • Long-Term Research in Ecology and Evolution (LTREE): 2015 survey data
    • Authors: Mark A. Bradford; Anthony Leiserowitz, Geoffrey Feinberg, Seth A. Rosenthal, Jennifer A. Lau
      Abstract: To systematically assess views on contributions and future activities for long-term research in ecology and evolution (LTREE), we conducted and here provide data responses and associated metadata for a survey of ecological and evolutionary scientists. The survey objectives were to: 1) Identify and prioritize research questions that are important to address through long-term, ecological field experiments; and 2) Understand the role that these experiments might play in generating and applying ecological and evolutionary knowledge. The survey was developed adhering to the standards of the American Association for Public Opinion Research. It was administered online using Qualtrics Survey Software. Survey creation was a multi-step process, with questions and format developed and then revised with, for example, input from an external advisory committee comprising senior and junior ecological and evolutionary researchers. The final questionnaire was released to ~100 colleagues to ensure functionality and then fielded two days later (January 7th 2015). Two professional societies distributed it to their membership, including the Ecological Society of America, and it was posted to three list serves. The questionnaire was available through February 8th 2015 and completed by 1,179 respondents. The distribution approach targeted practicing ecologists and evolutionary biologists in the U.S. Quantitative (both ordinal and categorical) closed-ended questions used a pre-defined set of response categories, facilitating direct comparison across all respondents. Qualitative, open-ended questions, provided respondents the opportunity to develop their own answers. We employed quantitative questions to score views on the extent to which long-term experimental research has contributed to understanding in ecology and evolutionary biology; its role compared to other approaches (e.g. short-term experiments); justifications for and caveats to long-term experiments; and the relative importance of incentives for conducting long-term research. Qualitative questions were used to assess community views on the most important topics and questions for long-term research to address, and primary incentives and challenges to realizing this work. Finally, demographic data were collected to determine if views were conditional on such things as years of experience and field of expertise. The final questionnaire and all responses are provided for unrestricted use.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-08T01:25:27.465656-05:
      DOI: 10.1002/ecy.1999
       
  • Live long and prosper: plant-soil feedback, lifespan and landscape
           abundance covary
    • Authors: Andrew Kulmatiski; Karen H. Beard, Jeanette Norton, Justin Heavilin, Leslie Forero, Josephine Grenzer
      Abstract: Plant soil feedbacks (PSFs) are thought to be important to plant growth and species coexistence, but most support for these hypotheses is derived from short-term greenhouse experiments. Here we use a seven-year, common garden experiment to measure PSFs for seven native and six non-native species common to the western USA. We use these long-term, field-based estimates to test correlations between PSF and plant landscape abundance, species origin, functional type and lifespan. To assess potential PSF mechanisms, we also measured soil microbial community composition, root biomass, nitrogen cycling, bulk density, penetration resistance, and shear strength. Plant abundance on the landscape and plant lifespan were positively correlated with PSFs, though this effect was due to the relationships for native plants. PSFs were correlated with indices of soil microbial community composition. Soil nutrient and physical traits and root biomass differed among species but were not correlated with PSF. While results must be taken with caution because only 13 species were examined, these species represent most of the dominant plant species in the system. Results suggest that native plant abundance is associated with the ability of long-lived plants to create positive plant-soil microbe interactions, while short-lived non-native plants maintain dominance by avoiding soil-borne antagonists, increasing nitrogen cycling and dedicating resources to aboveground growth and reproduction rather than to belowground growth. Broadly, results suggest that PSFs are correlated with a suite of traits that determine plant abundance.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-07T05:55:23.799412-05:
      DOI: 10.1002/ecy.2011
       
  • Drivers of synchrony of acorn production in the valley oak (Quercus
           lobata) at two spatial scales
    • Authors: Walter D. Koenig; Johannes M. H. Knops, Mario B. Pesendorfer, David N. Zaya, Mary V. Ashley
      Abstract: We investigated spatial synchrony of acorn production by valley oaks (Quercus lobata) among individual trees at the within-population, local level and at the among-population, statewide level spanning the geographic range of the species. At the local level, the main drivers of spatial synchrony were water availability and flowering phenology of individual trees, while proximity, temperature differences between trees, and genetic similarity failed to explain a significant proportion of variance in spatial synchrony. At the statewide level, annual rainfall was the primary driver, while proximity was significant by itself but not when controlling for rainfall; genetic similarity was again not significant. These results support the hypothesis that environmental factors—the Moran effect—are key drivers of spatial synchrony in acorn production at both small and large geographic scales. The specific environmental factors differed depending on the geographic scale, but were in both cases related to water availability. In addition, flowering phenology, potentially affecting either density-independent pollination failure (the pollination Moran effect) or density-dependent pollination efficiency (pollen coupling), plays a key role in driving spatial synchrony at the local geographic scale.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-07T05:50:19.802177-05:
      DOI: 10.1002/ecy.2010
       
  • Drivers of nitrogen transfer in stream food webs across continents
    • Authors: B. C. Norman; M. R. Whiles, S. M. Collins, A. S. Flecker, S. K. Hamilton, S. L. Johnson, E. J. Rosi-Marshall, L. R. Ashkenas, W. B. Bowden, C. L. Crenshaw, T. Crowl, W. K. Dodds, R. O. Hall, R. El-Sabaawi, N. A. Griffiths, E. Marti, W. H. McDowell, S. D. Peterson, H. M. Rantala, T. Riis, K. S. Simon, J. L. Tank, S. A. Thomas, D. von Schiller, J. R. Webster
      Abstract: Studies of trophic-level material and energy transfers are central to ecology. The use of isotopic tracers has now made it possible to measure trophic transfer efficiencies of important nutrients and to better understand how these materials move through food webs. We analyzed data from thirteen 15N-ammonium tracer addition experiments to quantify N transfer from basal resources to animals in headwater streams with varying physical, chemical, and biological features. N transfer efficiencies from primary uptake compartments (PUCs; heterotrophic microorganisms and primary producers) to primary consumers was lower (mean: 11.5%, range: 100%). Total N transferred (as a rate) was greater in streams with open compared to closed canopies and overall N transfer efficiency generally followed a similar pattern, although was not statistically significant. We used principal component analysis to condense a suite of site characteristics into two environmental components. Total N uptake rates among trophic levels were best predicted by the component that was correlated with latitude, DIN:SRP, GPP:ER, and % canopy cover. N transfer efficiency did not respond consistently to environmental variables. Our results suggest that canopy cover influences N movement through stream food webs because light availability and primary production facilitate N transfer to higher trophic levels.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-07T04:20:29.652809-05:
      DOI: 10.1002/ecy.2009
       
  • Influence of neighboring plants on the dynamics of an ant-acacia
           protection mutualism
    • Authors: Todd M. Palmer; Corinna Riginos, Rachel E. Damiani, Natalya Morgan, John S. Lemboi, James Lengingiro, Juan Carlos Ruiz-Guajardo, Robert M. Pringle
      Abstract: Ant-plant protection symbioses, in which plants provide food and/or shelter for ants in exchange for protection from herbivory, are model systems for understanding the ecology of mutualism. While interactions between ants, host plants, and herbivores have been intensively studied, we know little about how plant-plant interactions influence the dynamics of these mutualisms—despite strong evidence that plants compete for resources, that hosting ants can be costly, and that host-plant provisioning to ants can therefore be constrained by resource availability. We used field experiments in a semi-arid Kenyan savanna to examine interactions between the ant-plant Acacia drepanolobium, neighboring grasses, and two species of symbiotic acacia-ants with divergent behaviors: Crematogaster mimosae, an aggressive symbiont that imposes high costs to host trees via consumption of extrafloral nectar, and Tetraponera penzigi, a less-protective symbiont that imposes lower costs because it does not consume nectar. We hypothesized that by competing with acacias for resources, neighboring grasses (a) reduce hosts’ ability to support costly C. mimosae, while having little or no effect on the ability of hosts to support low-cost T. penzigi, and (b) reduce sapling growth rates irrespective of ant occupant. We factorially manipulated the presence/absence of grasses and the identity of ant occupants on saplings and evaluated effects on colony survivorship and sapling growth rates over 40 weeks. Contrary to prediction, the high-cost/high-reward nectar-dependent mutualist C. mimosae had higher colony-survival rates on saplings with grass neighbors present. Grasses appear to have indirectly facilitated the survival of C. mimosae by reducing water stress on host plants; soils under saplings shaded by grasses had higher moisture content, and these saplings produced more active nectaries than grass-removal saplings. Consistent with prediction, survival of low-cost/low-reward T. penzigi did not differ significantly between grass-removal treatments. Saplings occupied by low-cost/low-reward T. penzigi grew 100% more on average than saplings occupied by high-cost/high-reward C. mimosae, demonstrating that mutualist-partner identity strongly and differentially influences demographic rates of young plants. In contrast, contrary to prediction, grass neighbors had no significant net impact on sapling growth rates. Our results suggest that neighboring plants can exert strong and counterintuitive effects on ant-plant protection symbioses, highlighting the need to integrate plant-plant interactions into our understanding of these mutualisms.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-06T03:05:31.817263-05:
      DOI: 10.1002/ecy.2008
       
  • Abundance of small mammals in the Atlantic Forest (ASMAF): a data set for
           analyzing tropical community patterns
    • Authors: Marcos S. L. Figueiredo; Camila S. Barros, Ana C. Delciellos, Edú B. Guerra, Pedro Cordeiro-Estrela, Maja Kajin, Martin R. Alvarez, Paulo H. Asfora, Diego Astúa, Helena G. Bergallo, Rui Cerqueira, Lena Geise, Rosana Gentile, Carlos Eduardo V. Grelle, Gilson E. Iack-Ximenes, Leonardo C. Oliveira, Marcelo Weksler, Marcus V. Vieira
      Abstract: Local abundance results from the interaction between populational and environmental processes. The abundance of the species in a community is also one of the most basic descriptors of its structure. Despite its importance, information about species abundances is fragmentary, creating a knowledge gap about species abundances known as Prestonian Shortfall. Here we present a comprehensive dataset of small mammal abundance in the Atlantic Forest. Data were extracted from 114 published sources and from unpublished data collected by our research groups spanning from 1943 to 2017. The data set includes 1,902 records of at least 111 species in 155 localities, totaling 42,617 individuals represented. We selected studies that (i) were conducted in forested habitats of the Atlantic Forest, (ii) had a minimum sampling effort of at least 500 trap-nights, and (iii) contained species abundance data in detail. For each study, we recorded (i) latitude and longitude, (ii) name of the locality, (iii) employed sampling effort, (iv) type of traps used, (v) study year, (vi) country, and (vii) species name with (viii) its respective abundances. For every locality, we also obtained information regarding its (ix) ecoregion, (x) predominant vegetation type, and (xi) biogeographic subdivision. Whenever necessary, we also (xii) updated the species names as new species were described and some genera suffered taxonomic revision since the publication. The localities are spread across the Atlantic Forest and most of the small mammal species known for to occur in Atlantic Forest are present in the data set, making it representative of communities of the entire biome. This data set can be used to address various patterns in community ecology and geographical ecology, as the relation between local abundance and environmental suitability, hypothesis regarding local and regional factors on community structuring, species abundance distributions (SAD), and functional and phylogenetic mechanisms on community assembling.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-06T03:01:28.874285-05:
      DOI: 10.1002/ecy.2005
       
  • ATLANTIC BATS: a dataset of bat communities from the Atlantic Forests of
           South America
    • Authors: Renata Lara Muylaert; Richard D. Stevens, Carlos Eduardo Lustosa Esbérard, Marco Aurelio Ribeiro Mello, Guilherme Siniciato Terra Garbino, Luiz H. Varzinczak, Deborah Faria, Marcelo Moraes Weber, Patricia Kerches Rogeri, André Luis Regolin, Hernani Fernandes Magalhães Oliveira, Luciana de Moraes Costa, Marília A. S. Barros, Gilberto Sabino-Santos, Mara Ariane Crepaldi de Morais, Vinicius Silva Kavagutti, Fernando C. Passos, Emma-Liina Marjakangas, Felipe Gonçalves Motta Maia, Milton Cezar Ribeiro, Mauro Galetti
      Abstract: Bats are the second most diverse mammal order and they provide vital ecosystem functions (e.g., pollination, seed dispersal, and nutrient flux in caves) and services (e.g., crop pest suppression). Bats are also important vectors of infectious diseases, harboring more than 100 different virus types. In the present study, we compiled information on bat communities from the Atlantic Forests of South America, a species-rich biome that are highly threatened by habitat loss and fragmentation. ATLANTIC BATS dataset comprises 135 quantitative studies carried out in 205 sites, which cover most vegetation types of the tropical and subtropical Atlantic Forest: dense ombrophilous forest, mixed ombrophilous forest, semideciduous forest, deciduous forest, savanna, steppe, and open ombrophilous forest. The dataset includes information on more than 90,000 captures of 98 bat species of 8 families. Species richness averaged 12.1 per site, with a median value of 10 species (ranging from 1 to 53 species). Six species occurred in more than 50% of the communities: Artibeus lituratus, Carollia perspicillata, Sturnira lilium, Artibeus fimbriatus, Glossophaga soricina, and Platyrrhinus lineatus. The number of captures divided by sampling effort, a proxy for abundance, varied from 0.000001 to 0.77 individuals/hour*m2 (0.04+0.007 individuals/hour*m2). Our dataset reveals a hyper-dominance of eight species that together that comprise 80% of all captures: Platyrrhinus lineatus (2.3%), Molossus molossus (2.8%), Artibeus obscurus (3.4%), Artibeus planirostris (5.2%), Artibeus fimbriatus (7%), Sturnira lilium (14.5%), Carollia perspicillata (15.6%), and Artibeus lituratus (29.2%).This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-06T03:00:35.699505-05:
      DOI: 10.1002/ecy.2007
       
  • Increased consumer density reduces the strength of neighborhood effects in
           a model system
    • Authors: Andrew C. Merwin; Nora Underwood, Brian D. Inouye
      Abstract: An individual's susceptibility to attack can be influenced by conspecific and heterospecifics neighbors. Predicting how these neighborhood effects contribute to population-level processes such as competition and evolution requires an understanding of how the strength of neighborhood effects is modified by changes in the abundances of both consumers and neighboring resource species. We show for the first time that consumer density can interact with the density and frequency of neighboring organisms to determine the magnitude of neighborhood effects. We used the bean beetle, Callosobruchus maculatus, and two of its host beans, Vigna unguiculata and V. radiata, to perform a response-surface experiment with a range of resource densities and three consumer densities. At low beetle density, damage to beans was reduced with increasing conspecific density (i.e. resource dilution) and damage to the less preferred host, V. unguiculata, was reduced with increasing V. radiata frequency (i.e. frequency-dependent associational resistance). As beetle density increased, however, neighborhood effects were reduced; at the highest beetle densities neither focal nor neighboring resource density nor frequency influenced damage. These findings illustrate the importance of consumer density in mediating indirect effects among resources, and suggest that accounting for consumer density may improve our ability to predict population-level outcomes of neighborhood effects and to use them in applications such as mixed-crop pest management.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-04T13:57:17.692794-05:
      DOI: 10.1002/ecy.2004
       
  • Genetic variation of a foundation rockweed species affects associated
           communities
    • Authors: Veijo Jormalainen; Maria Danelli, Karine Gagnon, Helmut Hillebrand, Eva Rothäusler, Juha-Pekka Salminen, Joakim Sjöroos
      Abstract: Genetic variation in a foundation species may affect the composition of associated communities as well as modify ecosystem function. While the ecological consequences of genetic diversity of foundation species have been widely reported, the ability of individual genotypes to support dissimilar communities has been documented only in forest ecosystems. Here, for the first time in a marine ecosystem, we test whether the different genotypes of the rockweed Fucus vesiculosus harbor distinct community phenotypes and whether the genetic similarity of individual genotypes or their defensive compound content can explain the variation of the associated communities. We reared replicated genotypes in a common garden in the sea and analyzed their associated communities of periphytic algae and invertebrates as well as determined their contents of defense compounds, phlorotannins, and genetic distance based on neutral molecular markers. The periphytic community was abundant in mid-summer and its biovolume, diversity and community composition varied among the rockweed genotypes. The diversity of the periphytic community decreased with its increasing biovolume. In autumn, when grazers were abundant, periphytic community biomass was lower and less variable among rockweed genotypes, indicating different relative importance of bottom-up regulation through heritable variation of the foundation species and top-down regulation through grazing intensity. Similarly, composition of the invertebrate community varied among the rockweed genotypes. Although the genotype explained about 10 - 18% of the variation in associated communities, the variation was explained neither by the genetic distance nor the phlorotannin content. Thus, neither neutral genetic markers nor a single phenotypic trait could provide a mechanistic understanding of the genetic basis of community specificity. Therefore, a more comprehensive mapping of quantitative trait variation is needed to understand the underlying mechanisms. The community specificity implies that genetic variation within a foundation species is crucial for the biodiversity and assembly of associated organisms and, thus, for the functioning of associated communities. The result highlights the importance of ensuring the genetic variation of foundation species as a conservation target.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-04T13:50:56.192203-05:
      DOI: 10.1002/ecy.2002
       
  • Plant diversity maintains long-term ecosystem productivity under frequent
           drought by increasing short-term variation
    • Authors: Cameron Wagg; Michael J. O'Brien, Anja Vogel, Michael Scherer-Lorenzen, Nico Eisenhauer, Bernhard Schmid, Alexandra Weigelt
      Abstract: Increasing frequency of extreme climatic events can disrupt ecosystem processes and destabilize ecosystem functioning. Biodiversity may dampen these negative effects of environmental perturbations to provide greater ecosystem stability. We assessed the effects of plant diversity on the resistance, recovery and stability of experimental grassland ecosystems in response to recurring summer drought over seven years. Plant biomass production was reduced during the summer drought treatment compared with control plots. However, the negative effect of drought was relatively less pronounced at high than at low plant diversity, demonstrating that biodiversity increased ecosystem resistance to environmental perturbation. Furthermore, more diverse plant communities compensated for the reduced productivity during drought by increasing spring productivity compared to control plots. The drought-induced compensatory recovery led to increased short-term variations in productivity across growing seasons in more diverse communities that stabilized the longer-term productivity across years. Our findings show that short-term variation between seasons in the face of environmental perturbation can lead to longer-term stability of annual productivity in diverse ecosystems compared to less diverse ecosystems.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-04T13:50:54.25827-05:0
      DOI: 10.1002/ecy.2003
       
  • Deciphering the Enigma of Undetected Species, Phylogenetic, and Functional
           Diversity Based on Good-Turing Theory
    • Authors: Anne Chao; Chun-Huo Chiu, Robert K. Colwell, Luiz Fernando S. Magnago, Robin L. Chazdon, Nicholas J. Gotelli
      Abstract: Estimating the species, phylogenetic, and functional diversity of a community is challenging because rare species are often undetected, even with intensive sampling. The Good-Turing frequency formula, originally developed for cryptography, estimates in an ecological context the true frequencies of rare species in a single assemblage based on an incomplete sample of individuals. Until now, this formula has never been used to estimate undetected species, phylogenetic, and functional diversity. Here, we first generalize the Good-Turing formula to incomplete sampling of two assemblages. The original formula and its two-assemblage generalization provide a novel and unified approach to notation, terminology, and estimation of undetected biological diversity. For species richness, the Good-Turing framework offers an intuitive way to derive the non-parametric estimators of the undetected species richness in a single assemblage, and of the undetected species shared between two assemblages. For phylogenetic diversity, the unified approach leads to an estimator of the undetected Faith's phylogenetic diversity (PD, the total length of undetected branches of a phylogenetic tree connecting all species), as well as a new estimator of undetected PD shared between two phylogenetic trees. For functional diversity based on species traits, the unified approach yields a new estimator of undetected Walker et al.'s functional attribute diversity (FAD, the total species-pairwise functional distance) in a single assemblage, as well as a new estimator of undetected FAD shared between two assemblages. Although some of the resulting estimators have been previously published (but derived with traditional mathematical inequalities), all taxonomic, phylogenetic, and functional diversity estimators are now derived under the same framework. All the derived estimators are theoretically lower bounds of the corresponding undetected diversities; our approach reveals the sufficient conditions under which the estimators are nearly unbiased, thus offering new insights. Simulation results are reported to numerically verify the performance of the derived estimators. We illustrate all estimators and assess their sampling uncertainty with an empirical dataset for Brazilian rain forest trees. These estimators should be widely applicable to many current problems in ecology, such as the effects of climate change on spatial and temporal beta diversity and the contribution of trait diversity to ecosystem multi-functionality.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-04T13:45:52.880007-05:
      DOI: 10.1002/ecy.2000
       
  • A geographic cline in the ability to self-fertilize is unrelated to the
           pollination environment
    • Authors: Matthew H. Koski; Dena L. Grossenbacher, Jeremiah W. Busch, Laura F. Galloway
      Abstract: The reproductive assurance (RA) hypothesis predicts that the ability to autonomously self-fertilize (hereafter, autonomy) in plants should be favored in environments where a lack of mates or pollinators limits outcross reproduction. Because such limits to outcrossing are predicted to be most severe at range edges, elevated autonomy in peripheral populations is often attributed to RA. We test this hypothesis in 24 populations spanning the range of Campanula americana, including range interior and populations at three geographic range edges. We scored autonomous fruit set in a pollinator-free environment and detected clinal variation—autonomy increased linearly from the southern to the northern edge, and from the eastern to the western edge. We then address whether the cline reflects the contemporary pollination environment. We measured population size, plant density, pollinator visitation, outcross pollen limitation and RA in natural populations over two years. Most populations were pollen limited, and those that experienced higher visitation rates by bumblebees had reduced pollen limitation. Reproductive assurance, however, was generally low across populations and was unrelated to pollen limitation or autonomy. Neither pollen limitation nor RA displayed geographic clines. Finally, autonomy was not associated with pollinator visitation rates or mate availability. Thus, the data do not support the RA hypothesis; clinal variation in autonomy is unrelated to the current pollination environment. Therefore, geographic patterns of autonomy are likely the result of historical processes rather than contemporary natural selection for RA.This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-04T13:45:41.430537-05:
      DOI: 10.1002/ecy.2001
       
  • ATLANTIC-CAMTRAPS: a dataset of medium and large terrestrial mammal
           communities in the Atlantic Forest of South America
    • Authors: Fernando Lima; Gabrielle Beca, Renata de Lara Muylaert, Clinton N. Jenkins, Miriam Lucia Lages Perilli, Ana Maria de Oliveira Paschoal, Rodrigo Lima Massara, Adriano Pereira Paglia, Adriano Garcia Chiarello, Maurício Eduardo Graipel, Jorge José Cherem, André Luis Regolin, Luiz Gustavo Rodrigues Oliveira Santos, Carlos Rodrigo Brocardo, Agustín Paviolo, Mario S. Di Bitetti, Leandro Moraes Scoss, Fabiana Lopes Rocha, Roberto Fusco-Costa, Clarissa Alves da Rosa, Marina Xavier da Silva, Ludmila Hufnagel, Paloma Marques Santos, Gabriela Teixeira Duarte, Luiza Neves Guimarães, Larissa Lynn Bailey, Flávio Henrique Guimarães Rodrigues, Heitor Morais Cunha, Felipe Moreli Fantacini, Graziele Oliveira Batista, Juliano André Bogoni, Marco Adriano Tortato, Micheli Ribeiro Luiz, Nivaldo Peroni, Pedro Volkmer de Castilho, Thiago Bernardes Maccarini, Vilmar Picinatto Filho, Carlos De Angelo, Paula Cruz, Verónica Quiroga, María Eugenia Iezzi, Diego Varela, Sandra Maria Cintra Cavalcanti, Alexandre Camargo Martensen, Erica Vanessa Maggiorini, Fabíola Ferreira Keesen, André Valle Nunes, Gisele Mendes Lessa, Pedro Cordeiro-Estrela, Mayara Guimarães Beltrão, Anna Carolina Figueiredo de Albuquerque, Bianca Ingberman, Camila Righetto Cassano, Laury Cullen Junior, Milton Cezar Ribeiro, Mauro Galetti
      Abstract: Our understanding of mammal ecology has always been hindered by the difficulties of observing species in closed tropical forests. Camera trapping has become a major advance for monitoring terrestrial mammals in biodiversity rich ecosystems. Here we compiled one of the largest datasets of inventories of terrestrial mammal communities for the Neotropical region based on camera trapping studies. The dataset comprises 170 surveys of medium to large terrestrial mammals using camera traps conducted in 144 areas by 74 studies, covering six vegetation types of tropical and subtropical Atlantic Forest of South America (Brazil and Argentina), and present data on species composition and richness. The complete dataset comprises 53,438 independent records of 83 species of mammals, includes 10 species of marsupials, 15 rodents, 20 carnivores, 8 ungulates and 6 armadillos. Species richness averaged 13 species (± 6.07 SD) per site. Only six species occurred in more than 50% of the sites: the domestic dog Canis familiaris, crab-eating fox Cerdocyon thous, tayra Eira barbara, south American coati Nasua nasua, crab-eating raccoon Procyon cancrivorus and the nine-banded armadillo Dasypus novemcinctus. The information contained in this dataset can be used to understand macroecological patterns of biodiversity, community, and population structure, but also to evaluate the ecological consequences of fragmentation, defaunation, and trophic interactions.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-31T02:30:34.505186-05:
      DOI: 10.1002/ecy.1998
       
  • Remotely sensed canopy height reveals three pantropical ecosystem states:
           comment
    • Authors: Alexis D. Synodinos; David Eldridge, Katja Geißler, Florian Jeltsch, Dirk Lohmann, Guy Midgley, Niels Blaum
      Abstract: Xu et al. (2016) recently demonstrated the existence of three ecosystem states in the tropics: forest, savanna and ‘treeless’. Using remotely sensed tree cover and canopy height measurements, they conclude that 1) savannas and forest represent alternative states due to their climatic overlap in moist conditions (1,500-2,000 mm mean annual precipitation (MAP)), and 2) that ‘treeless’ and savanna ecosystems do not occur in the same MAP range, and that an abrupt shift from one ecosystem state to the other occurs at 600 mm MAP. While the first conclusion accords with existing studies (Hirota et al. 2011, Staver et al. 2011, Ratajczak and Nippert 2012), the second one contradicts our own observations from Africa and Australia as well as empirical data from published studies (February et al. 2007, Ward et al. 2013, Dohn et al. 2017), all of which indicate that savanna ecosystems certainly do occur within this dry rainfall range (
      PubDate: 2017-08-29T03:22:00.641566-05:
      DOI: 10.1002/ecy.1997
       
  • The southernmost parakeet might be enhancing pollination of a dioecious
           conifer
    • Authors: Gabriela Gleiser; Sergio A. Lambertucci, Karina L. Speziale, Fernando Hiraldo, José L. Tella, Marcelo A. Aizen
      PubDate: 2017-08-28T13:46:33.258823-05:
      DOI: 10.1002/ecy.1938
       
  • A historical perspective of nutrient change impact on an infectious
           disease in Daphnia
    • Authors: Lien Reyserhove; Giovanni Samaey, Koenraad Muylaert, Vincent Coppé, Willem Van Colen, Ellen Decaestecker
      Abstract: Changes in food quality can play a substantial role in the vulnerability of hosts to infectious diseases. In this study, we focused on the genetic differentiation of the water flea Daphnia magna towards food of different quality (by manipulating C:N:P ratios) and its impact on the interaction with a virulent infectious disease, “White Fat Cell Disease (WFCD)”. Via a resurrection ecology approach, we isolated two Daphnia subpopulations from different depths in a sediment core, which were exposed to parasites and a nutrient ratio gradient in a common garden experiment. Our results showed a genetic basis for sensitivity towards food deprivation. Both fecundity and host survival was differently affected when fed with low-quality food. This strongly impacted the way both subpopulations interacted with this parasite. A historical reconstruction of nutrient changes in a sediment core reflected an increase in organic material and phosphorus concentration (more eutrophic conditions) over time in the studied pond. These results enable us to relate patterns of genetic differentiation in sensitivity towards food deprivation to an increasing level of eutrophication of the subpopulations, which ultimately impacts parasite virulence effects. This finding was confirmed via a dynamic energy budgets (DEB), in which energy was partitioned for the host and the parasite. The model was tailored to our study by integrating (i) increased growth and a fecundity shift in the host upon parasitism and (ii) differences of food assimilation in the subpopulations showing that a reduced nutrient assimilation resulted in increased parasite virulence. The combination of our experiment with the DEB model shows that it is important to consider genetic diversity when studying the impact of nutritional stress on species interactions, especially in the context of changing environments and emerging infectious diseases.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-28T03:20:56.510857-05:
      DOI: 10.1002/ecy.1994
       
  • An arthropod survival strategy in a frequently burned forest
    • Authors: Jane Dell; Joseph O'Brien, Lydia Doan, Lora Richards, Lee Dyer
      PubDate: 2017-08-24T14:50:33.110609-05:
      DOI: 10.1002/ecy.1939
       
  • Macroevolutionary constraints to tolerance: trade-offs with drought
           tolerance and phenology, but not resistance
    • Authors: Ian S. Pearse; Jessica Aguilar, John Schroder, Sharon Y. Strauss
      Abstract: Plant tolerance of herbivory, i.e., the ability to recover after damage, is an important component of how plants cope with herbivores. Tolerance has long been hypothesized to be constrained evolutionarily by plant resistance to herbivores, traits that allow plants to cope with stressful growing conditions, and traits that influence the timing of damage in relation to reproduction. Variation in tolerance and resistance can be caused by differences in the identity of the plant (e.g. genotype, species, clade) and by the context of the herbivore threat (e.g. identity of the herbivore, type of damage it causes, abiotic conditions in which the plant is growing). To date, the vast majority of studies have explored trade-offs with tolerance within species. Here, we test hypotheses of constraints on tolerance using comparative approaches in a clade of mustards, emphasizing the variety of contexts in which damage is realistically tolerated. We estimated tolerance to leaf damage, tolerance to apical clipping at the bolting stage– simulating browsing–, and resistance to a specialist and generalist lepidopteran herbivore for a group of native mustards, grown in field soils unique to each population and in a common potting soil. Resistance to herbivores was soil dependent, while surprisingly, tolerance was not. Phylogenetic signal in resistance to specialist and generalist lepidopteran herbivores was present, but only when plants were grown in field soils. Tolerance had low phylogenetic signal. Tolerance to leaf damage was unrelated to tolerance to simulated browse. We found no evidence for a resistance-tolerance trade-off, and some evidence for a soil-dependent positive correlation between tolerance and resistance to both herbivores. Drought-tolerant species had poorer ability to tolerate browse damage, and earlier flowering species tended to be less tolerant to leaf damage. Our results suggest that tolerance trades off with traits that allow mostly annual, monocarpic Streptanthus (s.l.) to persist in drought-prone conditions but is largely unrelated to resistance to herbivores. Our study highlights a need for a new framework for tolerance to herbivory that explicitly acknowledges that the relationship between tolerance, resistance, and traits that ameliorate abiotic stress.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-24T00:10:24.573393-05:
      DOI: 10.1002/ecy.1995
       
  • Bearded versus thorny: the fireworm Hermodice carunculata preys on the sea
           urchin Paracentrotus lividus
    • Authors: Roberto Simonini; Sara Righi, Isabella Maletti, Sergio Fai, Daniela Prevedelli
      PubDate: 2017-08-22T14:04:03.841653-05:
      DOI: 10.1002/ecy.1919
       
  • LCE: Leaf carbon exchange dataset for tropical, temperate, and boreal
           species of North and Central America
    • Authors: Nicholas G. Smith; Jeffrey S. Dukes
      Abstract: Leaf canopy carbon exchange processes, such as photosynthesis and respiration, are substantial components of the global carbon cycle. Climate models base their simulations of photosynthesis and respiration on an empirical understanding of the underlying biochemical processes, and the responses of those processes to environmental drivers. As such, data spanning large spatial scales are needed to evaluate and parameterize these models. Here, we present data on four important biochemical parameters defining leaf carbon exchange processes from 626 individuals of 98 species at 12 North and Central American sites spanning ~53° of latitude. The four parameters are the maximum rate of Rubisco carboxylation (Vcmax), the maximum rate of electron transport for the regeneration of Ribulose-1,5,-bisphosphate (Jmax), the maximum rate of phosphoenolpyruvate carboxylase carboxylation (Vpmax), and leaf dark respiration (Rd). The raw net photosynthesis by intercellular CO2 (A/Ci) data used to calculate Vcmax, Jmax, and Vpmax rates are also presented. Data were gathered on the same leaf of each individual (one leaf per individual), allowing for the examination of each parameter relative to others. Additionally, the dataset contains a number of covariates for the plants measured. Covariate data include (a) leaf-level traits (leaf mass, leaf area, leaf nitrogen and carbon content, predawn leaf water potential), (b) plant-level traits (plant height for herbaceous individuals and diameter at breast height for trees), (c) soil moisture at the time of measurement, (d) air temperature from nearby weather stations for the day of measurement and each of the 90 days prior to measurement, and (e) climate data (growing season mean temperature, precipitation, photosynthetically active radiation, vapor pressure deficit, and aridity index). We hope that the data will be useful for obtaining greater understanding of the abiotic and biotic determinants of these important biochemical parameters and for evaluating and improving large-scale models of leaf carbon exchange.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-20T21:35:30.552664-05:
      DOI: 10.1002/ecy.1992
       
  • Demographic drivers of functional composition dynamics
    • Authors: Robert Muscarella; Madelon Lohbeck, Miguel Martínez-Ramos, Lourens Poorter, Jorge Enrique Rodríguez-Velázquez, Michiel van Breugel, Frans Bongers
      Abstract: Mechanisms of community assembly and ecosystem function are often analyzed using community-weighted mean trait values (CWMs). We present a novel conceptual framework to quantify the contribution of demographic processes (i.e., growth, recruitment, and mortality) to temporal changes in CWMs. We used this framework to analyze mechanisms of secondary succession in wet tropical forests in Mexico. Seed size increased over time, reflecting a trade-off between colonization by small seeds early in succession, to establishment by large seeds later in succession. Specific leaf area (SLA) and leaf phosphorus content decreased over time, reflecting a trade-off between fast growth early in succession versus high survival late in succession. On average, CWM shifts were driven mainly (70%) by growth of surviving trees that comprise the bulk of standing biomass, then mortality (25%), and weakly by recruitment (5%). Trait shifts of growing and recruiting trees mirrored the CWM trait shifts, and traits of dying trees did not change during succession, indicating that these traits are important for recruitment and growth, but not for mortality, during the first 30 years of succession. Identifying the demographic drivers of functional composition change links population dynamics to community change, and enhances insights into mechanisms of succession.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-20T21:30:24.729527-05:
      DOI: 10.1002/ecy.1990
       
  • Gaps contribute tree diversity to a tropical floodplain forest
    • Authors: John Terborgh; Nohemi Huanca Nuñez, Patricia Alvarez Loayza, Fernando Cornejo Valverde
      Abstract: Treefall gaps have long been a central feature of discussions about the maintenance of tree diversity in both temperate and tropical forests. Gaps expose parts of the forest floor to direct sunlight and create a distinctive microenvironment that can favor the recruitment into the community of so-called gap pioneers. This traditional view enjoys strong empirical support yet has been cast into doubt by a much-cited article claiming that gaps are inherently “neutral” in their contribution to forest dynamics. We present concurrent data on seedfall and sapling recruitment into gaps vs. under a vertically structured canopy in an Amazonian floodplain forest in Perú. Our results strongly uphold the view of gaps as important generators of tree diversity. Our methods differed significantly from those employed by the neutralist group and can explain the contrasting outcomes. We found that seedfall into gaps differs both quantitatively and qualitatively from that falling under a multi-tiered canopy, being greatly enriched in wind-dispersed and autochorus species and sharply deficient in all types of zoochorous seeds. Despite a reduced input of zoochorous seeds, zoochorous species made up 79% of saplings recruiting into gaps, whereas wind-dispersed species made up only 1%. Cohorts of saplings recruiting into gaps are less diverse than those recruiting under a closed canopy (Fisher's alpha = 40 vs. 100) and compositionally distinct, containing many light-demanding species that rarely, if ever, recruit under shaded conditions. Saplings recruiting into gaps appear to represent a variable mix of shade-tolerant survivors of the initiating treefall and sun-demanding species that germinate subsequently.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-20T21:30:21.546063-05:
      DOI: 10.1002/ecy.1991
       
  • Physical calculations of resistance to water loss improve predictions of
           species range models: Comment
    • Authors: Keith A. Christian; Christopher R. Tracy, C.Richard Tracy
      Abstract: In an attempt to improve estimates of evaporative water loss (EWL) as a component of species distribution models, Riddell et al. (2017) compared the traditional method for empirically measuring skin resistance (ri) to that determined by a mathematical model based in physics. They argued that the resulting differences between these two approaches had implications for estimates of species range.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-08T06:01:09.438065-05:
      DOI: 10.1002/ecy.1982
       
  • Evolutionary agroecology: individual fitness and population yield in wheat
           (Triticum aestivum)
    • Authors: Jacob Weiner; Yan-Lei Du, Cong Zhang, Xiao-Liang Qin, Feng-Min Li
      Abstract: Although the importance of group selection in nature is highly controversial, several researchers have argued that plant breeding for agriculture should be based on group selection, because the goal in agriculture is to optimize population production, not individual fitness. A core hypothesis behind this claim is that crop genotypes with the highest individual fitness in a mixture of genotypes will not produce the highest population yield, because fitness is often increased by “selfish” behaviors, which reduce population performance. We tested this hypothesis by growing 35 cultivars of spring wheat (Triticum aestivum L.) in mixtures and monocultures, and analyzing the relationship between population yield in monoculture and individual yield in mixture. The relationship was unimodal, as predicted. The highest-yielding populations were from cultivars that had intermediate fitness, and these produced, on average, 35% higher yields than cultivars with the highest fitness. It is unlikely that plant breeding or genetic engineering can improve traits that natural selection has been optimizing for millions of years, but there is unutilized potential in traits that increase crop yield by decreasing individual fitness.
      PubDate: 2017-08-07T09:45:38.5431-05:00
      DOI: 10.1002/ecy.1934
       
  • Bottom-up processes influence the demography and life-cycle phenology of
           Hawaiian bird communities
    • Authors: Jared D. Wolfe; C.John Ralph, Andrew Wiegardt
      Abstract: Changes in climate can indirectly regulate populations at higher trophic levels by influencing the availability of food resources in the lower reaches of the food web. As such, species that rely on fruit and nectar food resources may be particularly sensitive to these bottom-up perturbations due to the strength of their trophic linkages with climatically-influenced plants. To measure the influence of climatically-mediated, bottom-up processes, we used climate, bird capture, bird count, and plant phenology data from the Big Island of Hawaii to construct a series of structural equation and abundance models. Our results suggest that fruit and nectar-eating birds arrange life cycle events around climatically-influenced food resources, while some of these same food resources also influence seasonal patterns of abundance. This trend was particularly strong for two native nectarivores, ‘I'iwi and ‘Apapane, where we found that the dissimilar timing of molting and breeding activity was associated with peak abundance of the two most common flowers at our study site which, in turn, were each driven by dissimilar climatic cues. Given the rapidly changing Hawaiian climate, we suggest that determining behavioral plasticity, or evolutionary capacity of birds to mitigate changes in climatically-influenced food resources, should be recognized as a future research priority.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-05T06:45:20.307455-05:
      DOI: 10.1002/ecy.1981
       
  • Living rain gauges: cumulative precipitation explains the emergence
           schedules of California protoperiodical cicadas
    • Authors: Will Chatfield-Taylor; Jeffrey A. Cole
      Abstract: Mass multi-species cicada emergences (broods) occur in California with variable periodicity. Here we present the first rule set that predicts the emergence of protoperiodical cicada communities. We tested two hypotheses with a dataset consisting of direct observations and georeferenced museum specimen records: first, that cicada broods are triggered to emerge by periodic ENSO events and second, that brood emergences occur after precipitation accumulates above a threshold value. The period of ENSO events does not explain the observed pattern of cicada brood emergence. Rather, broods emerged given two conditions: 1) that total precipitation exceeded a threshold of 1181 mm and 2) that a minimum 3 y period lapsed. The precipitation threshold is obeyed over an 800 km north-south distance in California and across a variety of habitats. We predict the next brood emergence at one study site in arid Los Angeles County desert foothills to occur in 2020 or, if drought conditions continue, in 2021.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-05T06:40:19.591026-05:
      DOI: 10.1002/ecy.1980
       
  • Mangrove microclimates alter seedling dynamics at the range edge
    • Authors: John L. Devaney; Michael Lehmann, Ilka C Feller, John D Parker
      Abstract: Recent climate warming has led to asynchronous species migrations, with major consequences for ecosystems worldwide. In woody communities, localized microclimates have the potential to create feedback mechanisms that can alter the rate of species range shifts attributed to macroclimate drivers alone. Mangrove encroachment into saltmarsh in many areas is driven by a reduction in freeze events, and this encroachment can further modify local climate, but the subsequent impacts on mangrove seedling dynamics are unknown. We monitored microclimate conditions beneath mangrove canopies and adjacent open saltmarsh at a freeze-sensitive mangrove-saltmarsh ecotone and assessed survival of experimentally transplanted mangrove seedlings. Mangrove canopies buffered night time cooling during the winter, leading to interspecific differences in freeze damage on mangrove seedlings. However, mangrove canopies also altered biotic interactions. Herbivore damage was higher under canopies, leading to greater mangrove seedling mortality beneath canopies relative to saltmarsh. While warming-induced expansion of mangroves can lead to positive microclimate feedbacks, simultaneous fluctuations in biotic drivers can also alter seedling dynamics. Thus, climate change can drive divergent feedback mechanisms through both abiotic and biotic channels, highlighting the importance of vegetation-microclimate interactions as important moderators of climate driven range shifts.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-05T06:35:22.506994-05:
      DOI: 10.1002/ecy.1979
       
  • Increased duration of aquatic resource pulse alters community and
           ecosystem responses in a subarctic plant community
    • Authors: Claudio Gratton; David Hoekman, Jamin Dreyer, Randall D. Jackson
      Abstract: Allochthonous resource movement across ecosystem boundaries creates episodic linkages between ecosystems. The sensitivity of the community to external resources of varying duration can alter the baseline upon which future pulses of allochthony can act. We explored the terrestrial ecosystem response to pulsed inputs of lake-derived resources with a manipulative experiment in a subarctic heathland where we assessed plant community and nutrient availability responses to additions of midge carcasses (Diptera: Chironomidae). Insect carcasses were added as either a one-time pulse or a 4-year press to simulate differing durations of allochthony, which is common in the area. We found that midge pulses significantly elevated soil inorganic [N] in the first year (7× over background levels) but were significantly diminished (1.5×) by the second year after the initial pulse. The press treatment continued to elevate total soil inorganic [N] to 13× over background levels by the fourth year of midge additions, but then declined to 3.6× background in year 5 when experimental midge additions had ceased. In contrast to the soil inorganic N response, plant biomass was similar in pulse-addition and control plots over the course of the experiment. However, by the second year of the study plant biomass in press-addition plots were significantly higher than controls (>50%), and continued to increase over the 4 years of the press treatment. Midge addition stimulated dominance of graminoids and thatch litter in plots that had previously been primarily heathland vegetation, a response that persisted four years post-midge addition. Our findings suggest that soil and plant community responses to persistent insect carcass deposition (e.g., press) into heathland vegetation has the potential to carry forward in a way that modifies the baseline ecosystem conditions upon which additional allochthony may act.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-03T10:50:28.168029-05:
      DOI: 10.1002/ecy.1977
       
  • Parallel environmental factors drive variation in insect density and plant
           resistance in the native and invaded ranges
    • Authors: Yuzu Sakata; Timothy P. Craig, Joanne K. Itami, Michimasa Yamasaki, Takayuki Ohgushi
      Abstract: Geographic variation in the traits of a species is shaped by variation in abiotic conditions, biotic interactions, and evolutionary history of its interactions with other species. We studied the geographic variation in the density of the lace bug, Corythucha marmorata, and the resistance of tall goldenrod Solidago altissima to the lace bug herbivory in their native range in the USA and invaded range in Japan. We conducted field surveys and reciprocal transplant experiments to examine what abiotic and biotic factors influence variation in lace bug density, and what ecological and evolutionary factors predict the resistance of the host plant between and within the native and invaded ranges. Lace bug density was higher throughout the invaded range than in the native range, higher in populations with warmer climates, and negatively affected by foliage damage by other insects in both ranges. The higher lace bug density in warmer climates was explained by the shorter developmental time of the lace bugs at higher temperatures. The resistance of S. altissima to lace bugs was higher in populations with lace bugs compared to populations without lace bugs in both native and invaded ranges, indicating that the evolutionary history of the interaction with the lace bugs was responsible for the variation in S. altissima resistance in both ranges. The present study revealed that abiotic and biotic factors, including temperature and other herbivorous insects, can drive the geographic variation in lace bug density, which in turn selects for variation in plant resistance in both in the native and invaded ranges. We conclude that the novel combination of factors such as higher temperature and lower number of other herbivorous insects is responsible for the higher lace bug density in the invaded range than in the native range.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-03T10:45:24.770317-05:
      DOI: 10.1002/ecy.1978
       
  • Climate change's biophysical impacts in the words of Inuit elders
    • Authors: Douglas A. Clark
      PubDate: 2017-08-02T11:50:22.432936-05:
      DOI: 10.1002/ecy.1901
       
  • Allocation, not male resistance, increases male frequency during
           epidemics: A case study in facultatively sexual hosts
    • Authors: Jessica L. Hite; Rachel M. Penczykowski, Marta S. Shocket, Katherine Griebel, Alexander T. Strauss, Meghan A. Duffy, Carla E. Cáceres, Spencer R. Hall
      Abstract: Why do natural populations vary in the frequency of sexual reproduction' Virulent parasites may help explain why sex is favored during disease epidemics. To illustrate, we show a higher frequency of males and sexually produced offspring in natural populations of a facultative parthenogenetic host during fungal epidemics. In a multi-year survey of 32 lakes, the frequency of males (an index of sex) was higher in populations of zooplankton hosts with larger epidemics. A lake mesocosm experiment established causality: experimental epidemics produced a higher frequency of males relative to disease-free controls. One common explanation for such a pattern involves Red Queen (RQ) dynamics. However, this particular system lacks key genetic specificity mechanisms required for the RQ, so we evaluated two other hypotheses. First, individual females, when stressed by infection, could increase production of male offspring vs. female offspring (a tenant of ‘Abandon Ship’ theory). Data from a life table experiment supports this mechanism. Second, higher male frequency during epidemics could reflect a purely demographic process (illustrated with a demographic model): males could resist infection more than females (via size-based differences in resistance and mortality). However, we found no support for this resistance mechanism. A size-based model of resistance, parameterized with data, revealed why: higher male susceptibility negated the lower exposure (a size-based advantage) of males. These results suggest that parasite-mediated increases in allocation to sex by individual females, rather than male resistance, increased the frequency of sex during larger disease epidemics.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-02T03:35:27.757728-05:
      DOI: 10.1002/ecy.1976
       
  • Warming effects on permafrost ecosystem carbon fluxes associated with
           plant nutrients
    • Authors: Fei Li; Yunfeng Peng, Susan M. Natali, Kelong Chen, Tianfeng Han, Guibiao Yang, Jinzhi Ding, Dianye Zhang, Guanqin Wang, Jun Wang, Jianchun Yu, Futing Liu, Yuanhe Yang
      Abstract: Large uncertainties exist in carbon (C)-climate feedback in permafrost regions, partly due to an insufficient understanding of warming effects on nutrient availabilities and their subsequent impacts on vegetation C sequestration. Although a warming climate may promote a substantial release of soil C to the atmosphere, a warming-induced increase in soil nutrient availability may enhance plant productivity, thus offsetting C loss from microbial respiration. Here, we present evidence that the positive temperature effect on carbon dioxide (CO2) fluxes may be weakened by reduced plant nitrogen (N) and phosphorous (P) concentrations in a Tibetan permafrost ecosystem. Although experimental warming initially enhanced ecosystem CO2 uptake, the increased rate disappeared after the period of peak plant growth during the early growing season, even though soil moisture was not a limiting factor in this swamp meadow ecosystem. We observed that warming did not significantly affect soil extractable N or P during the period of peak growth, but decreased both N and P concentrations in the leaves of dominant plant species, likely caused by accelerated plant senescence in the warmed plots. The attenuated warming effect on CO2 assimilation during the late growing season was associated with lowered leaf N and P concentrations. These findings suggest that warming-mediated nutrient changes may not always benefit ecosystem C uptake in permafrost regions, making our ability to predict the C balance in these warming-sensitive ecosystems more challenging than previously thought.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-02T03:30:47.472617-05:
      DOI: 10.1002/ecy.1975
       
  • Testing the niche breadth—range size hypothesis: Habitat specialization
           versus performance in Australian alpine daisies
    • Authors: Megan J. Hirst; Philippa C. Griffin, Jason P. Sexton, Ary A. Hoffmann
      Abstract: Relatively common species within a clade are expected to perform well across a wider range of conditions than their rarer relatives, yet experimental tests of this “niche breadth—range size” hypothesis remain surprisingly scarce. Rarity may arise due to trade-offs between specialization and performance across a wide range of environments. Here we use common garden and reciprocal transplant experiments to test the niche breadth—range size hypothesis, focusing on four common and three rare endemic alpine daisies (Brachyscome spp.) from the Australian Alps. We used three experimental contexts: 1) alpine reciprocal seedling experiment: a test of seedling survival and growth in three alpine habitat types differing in environmental quality and species diversity, 2) warm environment common garden: a test of whether common daisy species have higher growth rates and phenotypic plasticity, assessed in a common garden in a warmer climate and run simultaneously with experiment 1, and 3) alpine reciprocal seed experiment: a test of seed germination capacity and viability in the same three alpine habitat types as in experiment 1. In the alpine reciprocal seedling experiment, survival of all species was highest in the open heathland habitat where overall plant diversity is high, suggesting a general, positive response to a relatively productive, low-stress environment. We found only partial support for higher survival of rare species in their habitats of origin. In the warm environment common garden, three common daisies exhibited greater growth and biomass than two rare species, but the other rare species performed as well as the common species. In the alpine reciprocal seed experiment, common daisies exhibited higher germination across most habitats, but rare species maintained a higher proportion of viable seed in all conditions, suggesting different life history strategies. These results indicate that some but not all rare, alpine endemics exhibit stress tolerance at the cost of reduced growth rates in low-stress environments compared to common species. Finally, these findings suggest the seed stage is important in the persistence of rare species, and they provide only weak support at the seedling stage for the niche breadth —range size hypothesis.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-02T03:25:25.446402-05:
      DOI: 10.1002/ecy.1964
       
  • Predicting coexistence in species with continuous ontogenetic niche shifts
           and competitive asymmetry
    • Authors: Ronald D. Bassar; Joseph Travis, Tim Coulson
      Abstract: A longstanding problem in ecology is whether structured life cycles impede or facilitate coexistence between species. Theory based on populations with only two discrete stages in the life-cycle indicates that for two species to coexist, at least one must shift its niche between stages and each species must be a better competitor in one of the niches. However, in many cases, niche shifts are associated with changes in an underlying continuous trait like body size and we have few predictions concerning conditions for coexistence for such a widespread form of ontogenetic development. We develop a framework for analyzing species coexistence based on Integral Projection Models (IPMs) that incorporates continuous ontogenetic changes in both the resource niche and competitive ability. We parameterize the model using experimental data from Trinidadian guppies and show how niche shifts and competitive symmetries impact species coexistence. Overall, our results show that the effects of competition on fitness depend upon trait-mediated niche-separation, trait-mediated competitive asymmetry in the part of the niche that is shared across body sizes, and the sensitivity of fitness to body size. Interactions among these processes generate multiple routes to coexistence. We discuss how our modelling framework expands results from two-stage models to mutli-stage or continuous stage models and allows for deriving predictions that can be tested in populations displaying continuous changes in niche use and competitive ability.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-02T03:20:33.892351-05:
      DOI: 10.1002/ecy.1969
       
  • Can snowshoe hares control treeline expansions'
    • Authors: Justin Olnes; Knut Kielland, Glenn P. Juday, Daniel H. Mann, Hélène Genet, Roger W. Ruess
      Abstract: Treelines in Alaska are advancing in elevation and latitude because of climate warming, which is expanding the habitat available for boreal wildlife species, including snowshoe hares (Lepus americanus). Snowshoe hares are already present in tall shrub communities beyond treeline and are the main browser of white spruce (Picea glauca), the dominant tree species at treeline in Alaska. We investigated the processes involved in a ‘snowshoe hare filter’ to white spruce establishment near treeline in Denali National Park. We modeled the pattern of spruce establishment from 1970 to 2009 and found that fewer spruce established during periods of high hare abundance. Multiple factors interact to influence browsing of spruce, including the hare cycle, snow depth and the characteristics of surrounding vegetation. Hares are abundant at treeline and may exclude spruce from otherwise optimal establishment sites, particularly floodplain locations with closed shrub canopies. The expansion of white spruce treeline in response to warming climate will be strongly modified by the spatial and temporal dynamics of the snowshoe hare filter.This article is protected by copyright. All rights reserved.
      PubDate: 2017-08-02T02:21:14.528119-05:
      DOI: 10.1002/ecy.1968
       
  • Detecting population-environmental interactions with mismatched time
           series data
    • Authors: Jake M. Ferguson; Brian E. Reichert, Robert J. Fletcher, Henriëtte I. Jager
      Abstract: Time series analysis is an essential method for decomposing the influences of density and exogenous factors such as weather and climate on population regulation. However, there has been little work focused on understanding how well commonly collected data can reconstruct the effects of environmental factors on population dynamics. We show that analogous to similar scale issues in spatial data analysis, coarsely sampled temporal data can fail to detect covariate effects when interactions occur on timescales that are fast relative to the survey period. We propose a method for modeling mismatched time series data that couples high-resolution environmental data to low-resolution abundance data. We illustrate our approach with simulations and by applying it to Florida's southern snail kite population. Our simulation results show that our method can reliably detect linear environmental effects and that detecting nonlinear effects requires high-resolution covariate data even when the population turnover rate is slow. In the snail kite analysis our approach performed among the best in a suite of previously used environmental covariates explaining snail kite dynamics and was able to detect a potential phenological shift in the environmental dependence of snail kites. Our work provides a statistical framework for reliably detecting population-environment interactions from coarsely surveyed time series. An important implication of this work is that the low predictability of animal population growth by weather variables found in previous studies may be due, in part, to how these data are utilized as covariates.
      PubDate: 2017-07-31T10:45:20.132625-05:
      DOI: 10.1002/ecy.1966
       
  • Spatial and temporal drivers of avian population dynamics across the
           annual cycle
    • Authors: Clark S. Rushing; Jeffrey A. Hostetler, T. Scott Sillett, Peter P. Marra, James A. Rotenberg, Thomas B. Ryder
      Abstract: Untangling the spatial and temporal processes that influence population dynamics of migratory species is challenging, because changes in abundance are shaped by variation in vital rates across heterogeneous habitats and throughout the annual cycle. We developed a full-annual-cycle, integrated population model and used demographic data collected between 2011 and 2014 in southern Indiana and Belize to estimate stage-specific vital rates of a declining migratory songbird, the Wood Thrush (Hylocichla mustelina). Our primary objective was to understand how spatial and temporal variation in demography contributes to local and regional population growth. Our full-annual-cycle model allowed us to estimate: 1) age-specific, seasonal survival probabilities, including latent survival during both spring and autumn migration, and 2) how the relative contribution of vital rates to population growth differed among habitats. Wood Thrushes in our study populations experienced the lowest apparent survival rates during migration and apparent survival was lower during spring migration than during fall migration. Both mortality and high dispersal likely contributed to low apparent survival during spring migration. Population growth in high-quality habitat was most sensitive to variation in fecundity and apparent survival of juveniles during spring migration, whereas population growth in low-quality sites was most sensitive to adult apparent breeding-season survival. These results elucidate how full-annual-cycle vital rates, particularly apparent survival during migration, interact with spatial variation in habitat quality to influence population dynamics in migratory species.
      PubDate: 2017-07-30T06:20:23.792169-05:
      DOI: 10.1002/ecy.1967
       
  • Summer and winter drought drive the initiation and spread of spruce beetle
           outbreak
    • Authors: Sarah J. Hart; Thomas T. Veblen, Dominik Schneider, Noah P. Molotch
      Abstract: This study used Landsat-based detection of spruce beetle (Dendroctonus rufipennis) outbreak over the years 2000-2014 across the Southern Rocky Mountain Ecoregion to examine the spatiotemporal patterns of outbreak and assess the influence of temperature, drought, forest characteristics and previous spruce beetle activity on outbreak development. During the 1999-2013 period, time series of spruce beetle activity were highly spatially correlated (r>0.5) at distances 400 km. Furthermore, cluster analysis on time series of outbreak activity revealed the outbreak developed at multiple incipient locations and spread to unaffected forest, highlighting the importance of both local-scale dispersal and regional-scale drivers in synchronizing spruce beetle outbreak. Spatial overlay analysis and Random Forest modeling of outbreak development show that outbreaks initiate in areas characterized by summer, winter, and multi-year drought and that outbreak spread is strongly linked to the proximity and extent of nearby outbreak, but remains associated with drought. Notably, we find that spruce beetle outbreak is associated with low peak snow water equivalent, not just summer drought. As such, future alterations to both winter and summer precipitation regimes are likely to drive important changes in subalpine forests.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-28T03:05:28.623567-05:
      DOI: 10.1002/ecy.1963
       
  • Breeding habitat selection across spatial scales: is grass always greener
           on the other side'
    • Authors: Paul Acker; Aurélien Besnard, Jean-Yves Monnat, Emmanuelle Cam
      Abstract: Habitat selection theory predicts that natural selection should favor mechanisms allowing individuals to choose habitats associated with the highest fitness prospects. However, identifying sources of information on habitat quality that individuals use to choose their breeding habitat has proved to be difficult. It has also proven difficult to identify dispersal costs that prevent individuals from joining the highest-quality sites. A synthesis that integrates dispersal costs and habitat selection mechanisms across space has remained elusive. Because costs of dispersal are generally distance-dependent, we suggest that a habitat selection strategy of sequential proximity search (SPS) can be favored by natural selection. This strategy requires that animals make decisions at multiple scales: whether to stay or leave the previous breeding site, depending on reproductive success; then, if dispersal is chosen, use information on neighborhood habitat quality to decide whether to stay in the neighborhood or leave, expanding the search area until the nearest suitable site is chosen. SPS minimizes distance-dependent dispersal costs while maximizing benefits of gaining a better habitat.We found evidence of breeding dispersal behavior consistent with this strategy in a kittiwake population stratified into a spatial hierarchy from colonies to nest sites. We used a mixed sequential regression model to study dispersal decisions, indexed by breeding dispersal movement, of 2558 individuals over 32 years. Scale-dependent dispersal propensities of kittiwakes varied according to breeding status, breeding experience, sex and individual identity. We suggest that distance-dependent dispersal costs result from strong competition among kittiwakes for nest sites. Individual decisions regarding dispersal (whether to leave or not, and where to go) depend on nesting habitat quality as well as the competitive ability required to keep territory ownership in a previous site, or to acquire a new site; this ability varies according to distance between sites and individual characteristics. Additional studies are needed to establish the generality of SPS in habitat selection.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-26T17:26:06.064536-05:
      DOI: 10.1002/ecy.1962
       
  • Disentangling the role of seed bank and dispersal in plant metapopulation
           dynamics using patch occupancy surveys
    • Authors: F Manna; R Pradel, R Choquet, H Fréville, P.-O Cheptou
      Abstract: In plants, the presence of a seed bank challenges the application of classical metapopulation models to above-ground presence surveys; ignoring seed bank leads to overestimated extinction and colonization rates. In this article, we explore the possibility to detect seed bank using hidden Markov models in the analysis of above-ground patch occupancy surveys of an annual plant with limited dispersal. Patch occupancy data were generated by simulation under two metapopulation sizes (N = 200 and N = 1000 patches) and different metapopulation scenarios, each scenario being a combination of the presence/absence of a one-year seed bank and the presence/absence of limited dispersal in a circular 1-dimension configuration of patches. In addition, because local conditions often vary among patches in natural metapopulations, we simulated patch occupancy data with heterogeneous germination rate and patch disturbance. Seed bank is not observable from above-ground patch occupancy surveys, hence hidden Markov models were designed to account for uncertainty in patch occupancy. We explored their ability to retrieve the correct scenario. For 10 years surveys and metapopulation sizes of N = 200 or 1000 patches, the correct metapopulation scenario was detected at a rate close to 100%, whatever the underlying scenario considered. For smaller, more realistic, survey duration, the length for a reliable detection of the correct scenario depends on the metapopulation size: 3 years for N = 1000 and 6 years for N = 200 are enough. Our method remained powerful to disentangle seed bank from dispersal in the presence of patch heterogeneity affecting either seed germination or patch extinction. Our work shows that seed bank and limited dispersal generate different signatures on above-ground patch occupancy surveys. Therefore, our method provides a powerful tool to infer metapopulation dynamics in a wide range of species with an undetectable life form.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-22T09:45:56.847903-05:
      DOI: 10.1002/ecy.1960
       
  • Density dependence governs when population responses to multiple stressors
           are magnified or mitigated
    • Authors: Emma E. Hodgson; Timothy E. Essington, Benjamin S. Halpern
      Abstract: Population endangerment typically arises from multiple, potentially interacting anthropogenic stressors. Extensive research has investigated the consequences of multiple stressors on organisms, frequently focusing on individual life stages. Less is known about population-level consequences of exposure to multiple stressors, especially when exposure varies through life. We provide the first theoretical basis for identifying species at risk of magnified effects from multiple stressors across life history. By applying a population-modeling framework, we reveal conditions under which population responses from stressors applied to distinct life stages are either magnified (synergistic) or mitigated. We find that magnification or mitigation critically depends on the shape of density dependence, but not the life stage in which it occurs. Stressors are always magnified when density dependence is linear or concave, and magnified or mitigated when it is convex. Using Bayesian numerical methods, we estimated the shape of density dependence for eight species across diverse taxa, finding support for all three shapes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-22T09:45:43.859534-05:
      DOI: 10.1002/ecy.1961
       
  • Cophylogenetic signal is detectable in pollination interactions across
           ecological scales
    • Authors: Matthew C. Hutchinson; E.Fernando Cagua, Daniel B. Stouffer
      Abstract: That evolutionary history can influence the way that species interact is a basic tenet of evolutionary ecology. However, when the role of evolution in determining ecological interactions is investigated, focus typically centers on just one side of the interaction. A cophylogenetic signal—the congruence of evolutionary history across both sides of anecological interaction—extends these previous explorations and provides a more complete picture of how evolutionary patterns influence the way species interact. To date,cophylogenetic signal has most typically been studied in interactions that occur between fine taxonomic clades that show high intimacy. In this study, we took an alternative approach and made an exhaustive assessment of cophylogeny in pollination interactions To do so, we assessed the strength of cophylogenetic signal at four distinct scales of pollination interaction: (i) across plant-pollinator associations globally, (ii) in local pollination communities, (iii) within the modular structure of those communities, and (iv) in individual modules. We did so using a globally-distributed dataset comprised of 54 pollination networks, over 4000 species, and over 12,000 interactions. Within these data, we detected cophylogenetic signal at all four scales. Cophylogenetic signal was found at the level of plant-pollinator interactions on a global scale and in the majority of pollination communities. At the scale defined by the modular structure within those communities, however, we observed a much weaker cophylogenetic signal. Cophylogenetic signal was detectable in a significant proportion of individual modules and most typically when within-module phylogenetic diversity was low. In sum, the detection of cophylogenetic signal in pollination interactions across scales provides a new dimension to the story of how past evolution shapes extant pollinator-angiosperm interactions.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-22T04:10:39.729456-05:
      DOI: 10.1002/ecy.1955
       
  • Books and Monographs Received through April 2017
    • PubDate: 2017-07-21T07:16:59.307729-05:
      DOI: 10.1002/ecy.1900
       
  • Extensive wildfires, climate change, and an abrupt state change in
           subalpine ribbon forests, Colorado
    • Authors: W.John Calder; Bryan Shuman
      Abstract: Ecosystems may shift abruptly when the effects of climate change and disturbance interact, and landscapes with regularly patterned vegetation may be especially vulnerable to abrupt shifts. Here we use a fossil pollen record from a regularly patterned ribbon forest (alternating bands of forests and meadows) in Colorado to examine whether past changes in wildfire and climate produced abrupt vegetation shifts. Comparing the percentages of conifer pollen with sedimentary δ18O data (interpreted as an indicator of temperature or snow accumulation) indicates a first-order linear relationship between vegetation composition and climate change with no detectable lags over the past 2500 years (r = 0.55, P < 0.001). Additionally, however, we find that the vegetation changed abruptly within a century of extensive wildfires, which were recognized in a previous study to have burned approximately 80% of the surrounding 1000 km2 landscape 1000 years ago when temperatures rose ~0.5 °C. The vegetation change was larger than expected from the effects of climate change alone. Pollen assemblages changed from a composition associated with closed subalpine forests to one similar to modern ribbon forests. Fossil pollen assemblages then remained like those from modern ribbon forests for the following ~1000 years, providing a clear example of how extensive disturbances can trigger persistent new vegetation states and alter how vegetation responds to climate.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-21T03:10:22.395346-05:
      DOI: 10.1002/ecy.1959
       
  • Species richness and traits predict overyielding in stem growth in an
           early-successional tree diversity experiment
    • Authors: Jake J. Grossman; Jeannine Cavender-Bares, Sarah E. Hobbie, Peter B. Reich, Rebecca A. Montgomery
      Abstract: Over the last two decades, empirical work has established that higher biodiversity can lead to greater primary productivity; however, the importance of different aspects of biodiversity in contributing to such relationships is rarely elucidated. We assessed the relative importance of species richness, phylogenetic diversity, functional diversity, and identity of neighbors for stem growth three years after seedling establishment in a tree diversity experiment in eastern Minnesota. Generally, we found that community-weighted means of key functional traits (including mycorrhizal association, leaf nitrogen and calcium, and waterlogging tolerance) as well as species richness were strong, independent predictors of stem biomass growth. More phylogenetically diverse communities did not consistently produce more biomass than expected, and the trait values or diversity of individual functional traits better predicted biomass production than did a multidimensional functional diversity metric. Furthermore, functional traits and species richness best predicted growth at the whole-plot level (12 m2), whereas neighborhood composition best predicted growth at the focal tree level (0.25 m2). The observed effects of biodiversity on growth appear strongly driven by positive complementary effects rather than by species-specific selection effects, suggesting that synergistic species’ interactions rather than the influence of a few important species may drive overyielding.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-20T11:00:24.122408-05:
      DOI: 10.1002/ecy.1958
       
  • Density-mediated indirect effects from active predators and narrow habitat
           domain prey
    • Authors: S.A. Rinehart; S.C. Schroeter, J.D. Long
      Abstract: The hunting mode-habitat domain range framework suggests that the mechanism driving trophic cascades [i.e. trait-mediated indirect interactions (TMIIs) versus density-mediated indirect interactions (DMIIs)] should depend upon the functional traits of predators and prey. For example, trophic cascades containing active, broad habitat domain range (BHDR) predators interacting with narrow habitat domain range (NHDR) prey are predicted to arise primarily via TMIIs, because these prey should reduce their conspicuous activity in the presence of these predators. Unfortunately, this hypothesis is difficult to test given the strong bias against studies assessing trophic cascades containing NHDR prey. Furthermore, this hypothesis ignores evidence that 1) active predators can have high consumption rates on prey, 2) continuously responding to active predators foraging across broad areas is energetically costly for prey and 3) cues from active, BHDR predators may not influence prey density. We examined the TMIIs and total indirect interaction (TII) produced during interactions between an active, BHDR ladybeetle predator (Naemia seriata) and its NHDR prey (scale insects). We exposed scale insects to nonlethal and lethal ladybeetle predators in laboratory mesocosms for 15-weeks. We measured the growth of the scale insect's host plant (cordgrass) and the population density of scale insects. Contrary to theory, nonlethal ladybeetles did not induce TMIIs. However, lethal ladybeetles increased cordgrass total and root dry biomass by 36% and 44% (respectively), suggesting the presence of strong DMIIs. Additionally, both lethal and nonlethal ladybeetles reduced scale insect population density. Our findings suggest that DMIIs, rather than TMIIs, can result from interactions between active, BHDR predators and NHDR prey.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-20T09:00:46.134827-05:
      DOI: 10.1002/ecy.1956
       
  • Predator ontogeny affects expression of inducible defense morphology in
           rotifers
    • Authors: Huan Zhang; Christer Brönmark, Lars-Anders Hansson
      Abstract: Many prey organisms show induced morphological responses to predators including changes in protective spine length, such as in rotifers, although previous studies have mainly focused on how prey become larger than the predator gape-size optimum. Here we show that a large-sized predator makes prey rotifers escape below the gape-size optimum of the predator by reducing spine length. Hence, in experiments and field studies we show that during part of their ontogeny fish larvae feed intensively on the common rotifer Keratella cochlearis, and that larval fish predation reduces rotifer spine length both through induction of shorter spines and selective predation on long-spined individuals. We also, describe a global scale pattern in spine length of K. cochlearis, showing an increasing variance in spine length with latitude. This global scale pattern may be explained by differences in fish reproduction from once per year at high latitudes to several times per year at lower latitudes. That spine length is adaptively adjusted to the ontogeny of a dominant predator taxa provides a novel view on our understanding of factors affecting temporal and spatial variations in prey defense morphology.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-20T08:50:35.468246-05:
      DOI: 10.1002/ecy.1957
       
  • Masting in wind-pollinated trees: system-specific roles of weather and
           pollination dynamics in driving seed production
    • Authors: Michał Bogdziewicz; Jakub Szymkowiak, Idalia Kasprzyk, Łukasz Grewling, Zbigniew Borowski, Katarzyna Borycka, Władysław Kantorowicz, Dorota Myszkowska, Katarzyna Piotrowicz, Monika Ziemianin, Mario B. Pesendorfer
      Abstract: Masting, the highly variable production of synchronized large seed crops, is a common reproductive strategy in plant populations. In wind-pollinated trees, flowering and pollination dynamics are hypothesized to provide the mechanistic link for the well-known relationship between weather and population-level seed production. Several hypotheses make predictions about the effect of weather on annual pollination success. The pollen coupling hypothesis predicts that weather and plant resources drive the flowering effort of trees which directly translates into the size of seed crops through efficient pollination. In contrast, the pollination Moran effect hypothesis predicts that weather affects pollination efficiency, leading to occasional bumper crops. Furthermore, the recently formulated phenology synchrony hypothesis predicts that Moran effects can arise because of weather effects on flowering synchrony, which, in turn, drives pollination efficiency. We investigated the relationship between weather, airborne pollen, and seed production in common European trees, two oak species (Quercus petraea and Q. robur) and beech (Fagus sylvatica) with a 19-year data set from three sites in Poland. Our results show that warm summers preceding flowering correlated with high pollen abundance and warm springs resulted in short pollen seasons (i.e. high flowering synchrony) for all three species. Pollen abundance was the best predictor for seed crops in beech, as predicted under pollen coupling. In oaks, short pollen seasons, rather than pollen abundance, correlated with large seed crops, providing support for the pollination Moran effect and phenology synchrony hypotheses. Fundamentally different mechanisms may therefore drive masting in species of the family Fagacae.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-19T03:15:33.147857-05:
      DOI: 10.1002/ecy.1951
       
  • The double edge to parasite escape: invasive host is less infected but
           more infectable
    • Authors: Carolyn L. Keogh; Osamu Miura, Tomohiro Nishimura, James E. Byers
      Abstract: Non-native species that escape their native range parasites may benefit not only from reduced infection pathology, but also from relaxed selection on costly immune defenses, promoting reallocation of resources towards growth or reproduction. However, benefits accruing from a reduction in defense could come at the cost of increased infection susceptibility. We conducted common garden studies of the shore crab Hemigrapsus sanguineus from highly-parasitized native (Japan) populations and largely parasite-free invasive (USA) populations to test for differences in susceptibility to infection by native-range rhizocephalan parasites, and to explore differences in host resource allocation. Non-native individuals showed at least 1.8 times greater susceptibility to infection than their native counterparts, and had reduced standing metabolic rates, suggesting that less of their energy was spent on physiological self-maintenance. Our results support an indirect advantage to parasite escape via the relaxation of costly physiological defenses. However, this advantage comes at the cost of heightened susceptibility, a tradeoff of parasite escape that is seldom considered.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-19T02:45:33.940517-05:
      DOI: 10.1002/ecy.1953
       
  • The importance of species identity and interactions on multifunctionality
           depends on how ecosystem functions are valued
    • Authors: Eleanor M. Slade; Laura Kirwan, Thomas Bell, Christopher Philipson, Owen T. Lewis, Tomas Roslin
      Abstract: Studies investigating how biodiversity affects ecosystem functioning increasingly focus on multiple functions measured simultaneously (‘multifunctionality’). However, few such studies assess the role of species interactions, particularly under alternative environmental scenarios, despite interactions being key to ecosystem functioning. Here we address five questions of central importance to ecosystem multifunctionality using a terrestrial animal system: 1) Does the contribution of individual species differ for different ecosystem functions'; 2) Do inter-species interactions affect the delivery of single functions and multiple functions'; 3) Does the community composition which maximises individual functions also maximise multifunctionality'; 4) Is the functional role of individual species, and the effect of interspecific interactions, modified by changing environmental conditions'; and 5) How do these roles and interactions change under varying scenarios where ecosystem services are weighted to reflect different societal preferences' We manipulated species’ relative abundance in dung beetle communities and measured 16 functions contributing to dung decomposition, plant productivity, nutrient recycling, reduction of greenhouse gases, and microbial activity. Using the Multivariate Diversity-Interactions framework, we assessed how changes in species identity, composition, and interspecific interactions affected these functions in combination with an environmental driver (increased precipitation). This allowed us to identify key species and interactions across multiple functions. We then developed a Desirability Function Approach to examine how individual species and species mixtures contribute to a desired state of overall ecosystem functioning. Species contributed unequally to individual functions, and to multifunctionality, and individual functions were maximised by different community compositions. Moreover, the species and interactions important for maintaining overall multifunctionality depended on the weight given to individual functions. This combination of methodological approaches allows us to resolve the interactions and indirect effects among species that drive ecosystem functioning, revealing how multiple aspects of biodiversity can simultaneously drive ecosystem functioning. Optimal multifunctionality is therefore context-dependent, and is sensitive to the valuation of services. Our results highlight the importance of a multifunctionality perspective for complete assessment of species’ functional contributions.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-19T02:45:23.307481-05:
      DOI: 10.1002/ecy.1954
       
  • Contrasting outcomes of species- and community-level analyses of the
           temporal consistency of functional composition
    • Authors: Masatoshi Katabuchi; S. Joseph Wright, Nathan G. Swenson, Kenneth J. Feeley, Richard Condit, Stephen P. Hubbell, Stuart J. Davies
      Abstract: Multiple anthropogenic drivers affect every natural community, and there is broad interest in using functional traits to understand and predict the consequences for future biodiversity. There is, however, no consensus regarding the choice of analytical methods. We contrast species- and community-level analyses of change in the functional composition for four traits related to drought tolerance using three decades of repeat censuses of trees in the 50-ha Forest Dynamics Plot on Barro Colorado Island (BCI), Panama. Community trait distributions shifted significantly through time, which may indicate a shift towards more drought tolerant species. However, at the species level, changes in abundance were unrelated to trait values. To reconcile these seemingly contrasting results, we evaluated species-specific contributions to the directional shifts observed at the community level. Abundance changes of just one to six of 312 species were responsible for the community-level shifts observed for each trait. Our results demonstrate that directional changes in community-level functional composition can result from idiosyncratic change in a few species rather than widespread community-wide changes associated with functional traits. Future analyses of directional change in natural communities should combine community-, species- and possibly individual-level analyses to uncover relationships with function that can improve understanding and enable prediction.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-19T02:42:08.911746-05:
      DOI: 10.1002/ecy.1952
       
  • Drought-induced mortality patterns and rapid biomass recovery in a terra
           firme forest in the Colombian Amazon
    • Authors: Daniel Zuleta; Alvaro Duque, Dairon Cardenas, Helene C. Muller-Landau, Stuart Davies
      Abstract: Extreme climatic events affecting the Amazon region are expected to become more frequent under ongoing climate change. In this study, we assessed the responses to the 2010 drought of over 14,000 trees ≥ 10 cm dbh in a 25 ha lowland forest plot in the Colombian Amazon and how these responses varied among topographically defined habitats, with tree size, and with species wood density. Tree mortality was significantly higher during the 2010-2013 period immediately after the drought than in 2007-2010. The post-drought increase in mortality was stronger for trees located in valleys (+243%) than for those located on slopes (+67%) and ridges (+57%). Tree-based generalized linear mixed models showed a significant negative effect of species wood density on mortality and no effect of tree size. Despite the elevated post-drought mortality, aboveground biomass increased from 2007 to 2013 by 1.62 Mg ha−1 y−1 (95% CI 0.80-2.43 Mg ha−1 y−1). Biomass change varied among habitats, with no significant increase on the slopes (1.05, 95% CI -0.76 to 2.85 Mg ha−1 y−1), a significant increase in the valleys (1.33, 95% CI 0.37-2.34 Mg ha−1 y−1), and a strong increase on the ridges (2.79, 95% CI 1.20-4.21 Mg ha−1 y−1). These results indicate a high carbon resilience of this forest to the 2010 drought due to habitat-associated and interspecific heterogeneity in responses including directional changes in functional composition driven by enhanced performance of drought-tolerant species that inhabit the drier ridges.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-18T03:35:38.781908-05:
      DOI: 10.1002/ecy.1950
       
  • Dispersal, host genotype and environment shape the spatial dynamics of a
           parasite in the wild
    • Authors: Adam Ekholm; Tomas Roslin, Pertti Pulkkinen, Ayco JM Tack
      Abstract: Dispersal, environment and genetic variation may all play a role in shaping host-parasite dynamics. Yet, in natural systems, their relative importance remains unresolved. Here, we do so for the epidemiology of a specialist parasite (Erysiphe alphitoides) on the pedunculate oak (Quercus robur). For this purpose, we combine evidence from a multi-year field survey and two dispersal experiments, all conducted at the landscape scale. Patterns detected in the field survey suggest that the parasite is structured as a metapopulation, with trees in denser oak stands characterized by higher parasite occupancy, higher colonization rates and lower extinction rates. The dispersal experiments revealed a major impact of the environment and of host genotype on the presence and abundance of the parasite, with a weaker but detectable imprint of dispersal limitation. Overall, our findings emphasize that dispersal, host genotype and the environment jointly shape the spatial dynamics of a parasite in the wild.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-18T03:30:25.717123-05:
      DOI: 10.1002/ecy.1949
       
  • Molecular constraints on resistance-tolerance tradeoffs
    • Authors: J. Miles Mesa; Daniel R. Scholes, Jack Juvik, Ken N. Paige
      Abstract: Plants have numerous mechanisms to cope with the negative effects of herbivory, including plant resistance, structural and chemical traits that reduce damage, and plant tolerance, the ability to compensate for tissues lost. It has been argued that resistance and tolerance represent alternate strategies and thus there should be a tradeoff between resistance and tolerance. However, resistance and tolerance are controlled via the same molecular pathway, the oxidative pentose phosphate pathway and the process of endoreduplication. Endoreduplication is the replication of the genome without mitosis, which leads to an increase in cellular chromosome number. Increasing chromosome number and therefore gene copy number provides a means of increasing gene expression that has been shown to enhance compensation following herbivory. By measuring glucosinolate levels and seed production following the removal of apical dominance in genotypes of Arabidopsis thaliana we show that there is a positive association between tolerance and induced chemical defense. Similarly, the direct association between tolerance and resistance is demonstrated by genetically manipulating the endoreduplication pathway. By overexpressing ILP1, a positive regulator of endoreduplication, and thus compensation, we experimentally increased glucosinolate production and tolerance in the Col-0 genotype. We suggest that many herbaceous plants that endoreduplicate (~90%) would show a positive relationship between compensation and chemical defense, given that the molecular pathways are shared in common. We discuss these findings in light of contrasting results on measures of tolerance and resistance, given that the true relationship can be masked by ignoring genetic variation in endoreduplication and the timing of chemical measurement.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-17T10:10:54.979331-05:
      DOI: 10.1002/ecy.1948
       
  • Habitat availability drives the distribution–abundance relationship in
           phytophagous true bugs in managed grasslands
    • Authors: Nicolas Friess; Martin M. Gossner, Wolfgang W. Weisser, Roland Brandl, Martin Brändle
      Abstract: The nearly universal positive relationship between the distribution and abundance of species has been explained by several hypotheses but hitherto no consensus has been reached. Here, we used monitoring data of 105 phytophagous true bug species (Heteroptera) from 150 grassland sites over six years, to test how (1) range-position, (2) resource-use, (3) resource-availability, (4) density-dependent habitat selection, (5) metapopulation dynamics and (6) habitat-dispersal affect the distribution-abundance relationship. For the use in a confirmatory path analysis, we constructed causal pathways representing the hypothesized relationships and tested them separately and in a combined analysis. Our results show that the distribution-abundance relationship in phytophagous true bugs is driven by habitat-availability. An increasing local density of the host-plants increases the distribution of the species in the landscape, which in turn increases their local abundance. Thereby habitat availability facilitates dispersal success. We conclude that local abundance of herbivores facing habitat destruction could decline owing to a decrease in population dynamics between sites at the landscape scale. Finally, our results underline the potential of confirmatory path analysis for testing competing hypotheses.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-17T00:51:27.707167-05:
      DOI: 10.1002/ecy.1947
       
  • Environmental drivers of coral reef carbonate production and bioerosion: a
           multi-scale analysis
    • Authors: Nyssa J. Silbiger; Megan J. Donahue, Russell E. Brainard
      Abstract: The resilience of coral reefs depends on the balance between reef growth and reef breakdown, and their responses to changing environmental conditions. Across the 2500 km Hawaiian Archipelago, we quantified rates of carbonate production, bioerosion, and net accretion at regional, island, site, and within-site spatial scales and tested how carbonate production, bioerosion, and net accretion rates respond to environmental conditions across different spatial scales. Overall, there were four major outcomes from this study: 1) bioerosion rates were generally higher in the populated Main Hawaiian Islands (MHI) than the remote, protected Northwestern Hawaiian Islands (NWHI), while carbonate production rates did not vary significantly between the two regions; 2) variability in carbonate production, bioerosion, and net accretion rates was greatest at the smallest within-reef spatial scale; 3) carbonate production and bioerosion rates were associated with distinct sets of environmental parameters; and 4) the strongest correlates of carbonate production, bioerosion, and net accretion rates were different between the MHI region and the NWHI region: in the MHI, the dominant correlates were % cover of macroalgae and herbivorous fish biomass for carbonate production and bioerosion, respectively, whereas in the NWHI, the top correlates were total alkalinity and benthic cover. This study highlights the need to understand accretion and erosion processes as well as local environmental conditions to predict net coral reef responses to future environmental changes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-14T02:07:01.525435-05:
      DOI: 10.1002/ecy.1946
       
  • Seed production and predation in a changing climate - new roles for
           resource and seed predator feedback'
    • Authors: Christer Solbreck; Jonas Knape
      Abstract: Climate change may cause changes in the dynamics of populations beyond comparatively simple directional effects. To better understand complex effects on dynamics requires long-term studies of populations that experience changes in climatic conditions. We study the dynamics of a seed production - seed predation system, consisting of a perennial herb and its two seed predatory insects, over a 40 year period during which climate change has caused the annual growing season to increase by 20 days. During this period plant patches have increased almost threefold in size and seed production has slipped into a pattern of alternate high and low years with a higher variance than in the beginning of the period. We find that seed production is associated with precipitation of the present summer and a non-linear feedback from seed production of the previous year. When previous year′s seed production is low, weather forcing and unexplained noise determine the extent of seed production. When previous seed production is high, depleted resources limit seed production. Resource depletion happened frequently in the latter parts of the study but rarely in the beginning. The changing patterns of seed production in turn affect the dynamics of seed predation, which is dominated by one of the seed predators. Its dynamics is strongly linked to seed density fluctuations, but its population growth rate is satiated when resource fluctuations become too large. In the latter part of the study period when seed fluctuations were alternating between years of high and low density, satiation was common and there was a large increase in surviving seeds in good years. Our study illustrates that a changing climate can fundamentally influence patterns of long-term dynamics at multiple trophic levels.This article is protected by copyright. All rights reserved.
      PubDate: 2017-07-13T02:40:22.242381-05:
      DOI: 10.1002/ecy.1941
       
  • Terminal blades in Macrocystis and their unexplored links to functional
           biology
    • Authors: Tiffany A. Stephens
      PubDate: 2017-07-10T08:46:00.975325-05:
      DOI: 10.1002/ecy.1913
       
  • A biogeoscience view of ecosystems
    • Authors: Frederick J. Swanson
      PubDate: 2017-07-06T11:55:27.621216-05:
      DOI: 10.1002/ecy.1904
       
  • Past, present, and future land use of an iconic cape cod landscape
    • Authors: Richard B. Primack
      PubDate: 2017-07-06T11:55:22.53691-05:0
      DOI: 10.1002/ecy.1902
       
  • Recent Publications of Interest
    • PubDate: 2017-07-06T11:55:20.863887-05:
      DOI: 10.1002/ecy.1903
       
  • Within-lake habitat heterogeneity mediates community response to warming
           trends
    • Authors: Rachel A. Hovel; James T. Thorson, Jackie L. Carter, Thomas P. Quinn
      Abstract: Climate change is rapidly altering many aquatic systems, and life history traits and physiological diversity create differences in organism responses. In addition to biological diversity, habitat diversity may be expressed on small spatial scales, and it is therefore necessary to account for variation among both species and locations when evaluating climate impacts on biological communities. Here, we investigated the effects of temperature and spatial heterogeneity on long-term community composition in a large boreal lake. We used a five-decade time series of water temperature and relative abundance of fish species captured in the littoral zone throughout the summer at 10 discrete locations around the lake. We applied a spatial dynamic factor analysis (SDFA) model to this time series, which estimates the sensitivity of each species to changing water temperature while accounting for spatiotemporal variation. This analysis described the trend in community composition at each sampling location in the lake, given their different trends in temperature over time. The SDFA indicated different magnitude and direction of species responses to temperature; some species increased while others decreased in abundance. The model also identified five unique trends in species abundance across sites and time, indicating residual dynamics in abundance after accounting for temperature effects. Thus, different regions in the lake have experienced different trajectories in community change associated with different rates of temperature change. These results highlight the importance of considering habitat heterogeneity in explaining and predicting future species abundances, and our model provides a means of visualizing spatially-explicit temporal variation in species’ dynamics.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-29T21:21:03.592028-05:
      DOI: 10.1002/ecy.1944
       
  • Timing of stressors alters interactive effects on a coastal foundation
           species
    • Authors: Jillian M. Bible; Brian S. Cheng, Andrew L. Chang, Matthew C. Ferner, Kerstin Wasson, Chela J. Zabin, Marilyn Latta, Eric Sanford, Anna Deck, Edwin D. Grosholz
      Abstract: The effects of climate-driven stressors on organismal performance and ecosystem functioning have been investigated across many systems; however, manipulative experiments generally apply stressors as constant and simultaneous treatments, rather than accurately reflecting temporal patterns in the natural environment. Here, we assessed the effects of temporal patterns of high aerial temperature and low salinity on survival of Olympia oysters (Ostrea lurida), a foundation species of conservation and restoration concern. As single stressors, low salinity (5 and 10 psu) and the highest air temperature (40°C) resulted in oyster mortality of 55.8, 11.3, and 23.5%, respectively. When applied on the same day, low salinity and high air temperature had synergistic negative effects that increased oyster mortality. This was true even for stressor levels that were relatively mild when applied alone (10 psu and 35°C). However, recovery times of two or four weeks between stressors eliminated the synergistic effects. Given that most natural systems threatened by climate change are subject to multiple stressors that vary in the timing of their occurrence, our results suggest that it is important to examine temporal variation of stressors in order to more accurately understand the possible biological responses to global change.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-27T02:57:39.63859-05:0
      DOI: 10.1002/ecy.1943
       
  • Fluctuating effects of genetic and plastic changes in body mass on
           population dynamics in a large herbivore
    • Authors: Gabriel Pigeon; Thomas H. G. Ezard, Marco Festa-Bianchet, David W. Coltman, Fanie Pelletier
      Abstract: Recent studies suggest that evolutionary changes can occur on a contemporary time scale. Hence, evolution can influence ecology and vice-versa. To understand the importance of eco-evolutionary dynamics in population dynamics, we must quantify the relative contribution of ecological and evolutionary changes to population growth and other ecological processes. To date, however, most eco-evolutionary dynamics studies have not partitioned the relative contribution of plastic and evolutionary changes in traits on population, community and ecosystem processes. Here, we quantify the effects of heritable and non-heritable changes in body mass distribution on survival, recruitment and population growth in wild bighorn sheep (Ovis canadensis) and compare their importance to the effects of changes in age structure, population density and weather. We applied a combination of a pedigree-based quantitative genetics model, statistical analyses on demography and a new statistical decomposition technique, the Geber method, to a long-term dataset of bighorn sheep on Ram Mountain (Canada), monitored individually from 1975 to 2012. We show three main results: (1) The relative importance of heritable change in mass, non-heritable change in mass, age structure, density and climate on population growth rate changed substantially over time. (2) An increase in body mass was accompanied by an increase in population growth through higher survival and recruitment rate. (3) Over the entire study period, changes in the body mass distribution of ewes, mostly through non-heritable changes, affected population growth to a similar extent as changes in age structure or in density. The importance of evolutionary changes was small compared to that of other drivers of changes in population growth but increased with time as evolutionary changes accumulated. Evolutionary changes became increasingly important for population growth as the length of the study period considered increased. Our results highlight the complex ways in which ecological and evolutionary changes can affect population dynamics and illustrate the large potential effect of trait changes on population processes.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-24T09:18:17.527141-05:
      DOI: 10.1002/ecy.1940
       
  • Ordination with any dissimilarity measure: a weighted Euclidean solution
    • Authors: Michael Greenacre
      Abstract: The classical approach to ordination is to use variants of the Euclidean distance to measure differences between samples (e.g. sites in a community study) based on their observation vectors (e.g. abundance counts for a set of species). Examples are: Euclidean distance on standardized or log-transformed data, on which principal component analysis and redundancy analysis are based; chi-square distance, on which (canonical) correspondence analysis is based; and Hellinger distance, using square roots of relative values in each multivariate vector. Advantages of the Euclidean approach include the neat decomposition of variance and the ordination's optimal biplot display. To extend this approach to any non-Euclidean or non-metric dissimilarity, a simple solution is proposed, consisting of the estimation of a weighted Euclidean distance that optimally approximates the dissimilarities. This preliminary step preserves the good properties of the classical approach while giving two additional benefits as by-products. Firstly, the estimated species weights, quantifying each species’ contribution to the dissimilarities, can be interpreted, and weights equal or close to zero can assist in variable selection. Secondly, the dimensionality remains that of the number of species, not the dimensionality inherent in the dissimilarities, which depends on the number of samples and can be considerably higher.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-21T05:15:59.235196-05:
      DOI: 10.1002/ecy.1937
       
  • Deconstructing the landscape of fear in stable multi-species societies
    • Authors: A.E. Martínez; E. Parra, L.F. Collado, V.T. Vredenburg
      Abstract: Animal distributions are influenced by variation in predation risk in space, which has been described as the “landscape of fear.” Many studies suggest animals also reduce predation risk by eavesdropping on heterospecific alarm calls, allowing them to occupy otherwise risky habitats. One unexplored area of study is understanding how different species’ alarms vary in quality, and how this variation is distributed in the landscape. We tested this phenomenon in a unique system of avian mixed species flocks in Amazonian rainforests: flock mates (eavesdropping species) strongly associate with alarm-calling antshrikes (genus Thamnomanes), which act as sentinel species. Up to 70 species join these flocks, presumably following antshrike behavioral cues. Since flocks are exclusively led by a single antshrike species, this provides a unique natural system to compare differences in sentinel quality between flocks. We simulated predation threat by flying three species of live trained raptors (predators) towards flocks to compare sentinel probability to 1) emit alarm calls, and 2) encode information about magnitude and type of threat within such alarm calls. Our field experiments show significant differences in the probability of different sentinel species to emit alarm calls and distinguish predators. This variation may have important fitness consequences and shape the “landscape of fear” for eavesdropping species.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-20T13:15:58.30841-05:0
      DOI: 10.1002/ecy.1935
       
  • Habitat coupling writ large: pelagic-derived materials fuel benthivorous
           macroalgal reef fishes in an upwelling zone
    • Authors: Felipe Docmac; Miguel Araya, Ivan A Hinojosa, Cristina Dorador, Chris Harrod
      Abstract: Coastal marine upwelling famously supports elevated levels of pelagic biological production, but can also subsidise production in inshore habitats via pelagic-benthic coupling. Consumers inhabiting macroalgae-dominated rocky reef habitats are often considered to be members of a food web fuelled by energy derived from benthic primary production; conversely, they may also be subsidised by materials transported from pelagic habitats. Here, we used stable isotopes (δ13C, δ15N) to examine the relative contribution of pelagic and benthic materials to an ecologically and economically important benthivorous fish assemblage inhabiting subtidal macroalgae-dominated reefs along ~1000 km of the northern Chilean coast where coastal upwelling is active. Fish were isotopically most similar to the pelagic pathway and Bayesian mixing models indicated that production of benthivorous fish was dominated (median 98%, range 69–99%) by pelagic-derived C and N. Although the mechanism by which these materials enter the benthic food web remains unknown, our results clearly highlight the importance of pelagic-benthic coupling in the region. The scale of this subsidy has substantial implications for our basic understanding of ecosystem functioning and the management of nearshore habitats in northern Chile and other upwelling zones worldwide.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-20T13:15:54.255532-05:
      DOI: 10.1002/ecy.1936
       
  • Native-predator–invasive-prey trophic interactions in Tierra del Fuego:
           the beginning of biological resistance'
    • Authors: Simón P. Castillo; Ramiro D. Crego, Jaime E. Jiménez, Ricardo Rozzi
      PubDate: 2017-06-20T11:45:14.667618-05:
      DOI: 10.1002/ecy.1873
       
  • Pulse frequency and soil-litter mixing alter the control of cumulative
           precipitation over litter decomposition
    • Authors: François-Xavier Joly; Kelsey L. Kurupas, Heather L. Throop
      Abstract: Macroclimate has traditionally been considered the predominant driver of litter decomposition. However, in drylands, cumulative monthly or annual precipitation typically fails to predict decomposition. In these systems, the windows of opportunity for decomposer activity may rather depend on the precipitation frequency and local factors affecting litter desiccation, such as soil-litter mixing. We used a full-factorial microcosm experiment to disentangle the relative importance of cumulative precipitation, pulse frequency, and soil-litter mixing on litter decomposition. Decomposition, measured as litter carbon loss, saturated with increasing cumulative precipitation when pulses were large and infrequent, suggesting that litter moisture no longer increased and/or microbial activity was no longer limited by water availability above a certain pulse size. More frequent precipitation pulses led to increased decomposition at high levels of cumulative precipitation. Soil-litter mixing consistently increased decomposition, with greatest relative increase (+194%) under the driest conditions. Collectively, our results highlight the need to consider precipitation at finer temporal scale and incorporate soil-litter mixing as key driver of decomposition in drylands.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-19T07:56:53.542542-05:
      DOI: 10.1002/ecy.1931
       
  • Abiotic and biotic factors modulate carrion fate and vertebrate scavenging
           communities
    • Authors: Kelsey L. Turner; Erin F. Abernethy, L. Mike Conner, Olin E. Rhodes, James C. Beasley
      Abstract: Carrion is a valuable nutrient resource used by a diversity of vertebrates across the globe. However, vertebrate scavenging ecology remains an understudied area of science, especially in regards to how biotic and abiotic factors influence scavenging community composition. Here we elucidate how fundamental biotic and abiotic factors interact to modulate the efficiency and composition of vertebrate scavengers by investigating scavenging dynamics across a large gradient in carcass sizes and habitat types representative of many temperate ecosystems, as well as between two seasons reflecting differences in invertebrate activity. We found carcass size and season influenced carcass fate and persistence, as well as the richness and composition of vertebrate scavenger communities utilizing carrion resources. Species richness, which increased as carcass size increased and was higher during the cool season, had a significant effect on carcass persistence. In addition, habitat type influenced carcass detection times by vertebrates, and we observed relatively distinct scavenging communities associated with carcasses of differing sizes. This research highlights a pervasive limitation to the interpretation of results of previous studies as research failing to incorporate carcass size and habitat type could result in the over or underrepresentation of vertebrate scavengers in food web dynamics.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-19T07:56:22.742983-05:
      DOI: 10.1002/ecy.1930
       
  • Disturbance-mediated facilitation by an intertidal ecosystem engineer
    • Authors: Jeffrey T. Wright; Paul E. Gribben
      Abstract: Ecosystem engineers facilitate communities by providing a structural habitat that reduces abiotic stress or predation pressure for associated species. However, disturbance may damage or move the engineer to a more stressful environment, possibly increasing the importance of facilitation for associated communities. In this study we determined how disturbance to intertidal boulders (i. e. flipping) and the subsequent movement of a structural ecosystem engineer, the tube-forming serpulid worm Galeolaria caespitose, from the bottom (natural state, low abiotic stress) to the top (disturbed state, high abiotic stress) surface of boulders influenced the importance of facilitation for intertidal communities across two intertidal zones. Theory predicts stronger relative facilitation should occur in the harsher environments of the top of boulders and the high intertidal zone. To test this prediction, we experimentally positioned boulders with the serpulids either face up or face down for 12 months in low and high zones in an intertidal boulder field. There were very different communities associated with the different boulders and serpulids had the strongest facilitative effects on the more stressful top surface of boulders with approximately double the species richness compared to boulders lacking serpulids. Moreover, within the serpulid matrix itself there was also approximately double the species richness (both zones) and abundance (high zone only) of small invertebrates on the top of boulders compared to the bottom. The high relative facilitation on the top of boulders reflected a large reduction in temperature by the serpulid matrix on that surface (up to 10 °C) highlighting a key role for modification of the abiotic environment in determining the community-wide facilitation. This study has demonstrated that disturbance and subsequent movement of an ecosystem engineer to a more stressful environment increased the importance of facilitation and allowed species to persist that would otherwise be unable to survive in that environment.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-19T07:55:41.588098-05:
      DOI: 10.1002/ecy.1932
       
  • Germination phenology determines the propensity for facilitation and
           competition
    • Authors: Lindsay D. Leverett
      Abstract: A single plant can interact both positively and negatively with its neighbors through the processes of facilitation and competition, respectively. Much of the variation in the balance of facilitation and competition that individuals experience can be explained by the degree of physical stress and the sizes or ages of plants during the interaction. Germination phenology partly controls both of these factors, but its role in defining the facilitation-competition balance has not been explicitly considered. I performed an experiment in a population of the winter annual Arabidopsis thaliana (Brassicaceae) to test whether germinating during physically stressful periods leads to facilitation while germinating during periods that promote growth and reproduction leads to competition. I manipulated germination and neighbor presence across two years in order to quantify the effects of the local plant community on survival, fecundity, and total fitness as a function of germination phenology. Neighbors increased survival when germination occurred under conditions that were unsuitable for survival, but they reduced fecundity in germinants that were otherwise the most fecund. Later germination was associated with facilitation in the first year but competition in the second year. These episodes of facilitation and competition opposed each other, leading to no net effect of neighbors when averaged over all cohorts. These results indicate that variation in germination timing can explain some of the variation in the facilitation-competition balance in plant communities.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-19T07:55:37.298802-05:
      DOI: 10.1002/ecy.1933
       
  • Host taxonomy constrains the properties of trophic transmission routes for
           parasites in lake food webs
    • Authors: Alyssa R. Cirtwill; Clement Lagrue, Robert Poulin, Daniel B. Stouffer
      Abstract: Some parasites move from one host to another via trophic transmission— the consumption of the parasite (inside its current host) by its future host. Feeding links among free-living species can thus be understood as potential transmission routes for parasites. As these links have different dynamic and structural properties, they may also vary in their effectiveness as trophic transmission routes. That is, some links may be better than others in allowing parasites to complete their complex life cycles. However, not all links are accessible to parasites as most are restricted to a small number of host taxa. This restriction means that differences between links involving host and non-host taxa must be considered when assessing whether transmission routes for parasites have different food web properties than other links. Here we use four New Zealand lake food webs to test whether link properties (contribution of a link to the predator's diet, prey abundance, prey biomass, amount of biomass transferred, centrality, and asymmetry) affect trophic transmission of parasites. Critically, we do this both using models that neglect the taxonomy of free-living species and models that explicitly include information about which free-living species are members of suitable host taxa. Although the best-fit model excluding taxonomic information suggested that transmission routes have different properties than other feeding links, when including taxonomy the best-fit model included only an intercept. This means that the taxonomy of free-living species is a key determinant of parasite transmission routes and that food-web properties of transmission routes are constrained by the properties of host taxa. In particular, many intermediate hosts (prey) attain high biomasses and are involved in highly central links while links connecting intermediate to definitive (predator) hosts tend to be dynamically weak.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-13T13:35:26.937246-05:
      DOI: 10.1002/ecy.1927
       
  • Non-random species loss in a forest herbaceous layer following nitrogen
           addition
    • Authors: Christopher A. Walter; Mary Beth Adams, Frank S. Gilliam, William T. Peterjohn
      Abstract: Nitrogen (N) additions have decreased species richness (S) in hardwood forest herbaceous layers, yet the functional mechanisms for these decreases have not been explicitly evaluated. We tested two hypothesized mechanisms – random species loss (RSL) and non-random species loss (NRSL) – in the hardwood forest herbaceous layer of a long-term, plot-scale fertilization experiment in the central Appalachian Mountains, USA. Using a random thinning algorithm, we simulated changes in species densities under RSL and compared the simulated densities to the observed densities among N-fertilized (+N), N-fertilized and limed (+N+L), and reference (REF) plots in regenerating forest stands. We found a lower S in the +N treatment across all survey years and determined that the reduction in S was a function of NRSL. Furthermore, non-random effects were observed in certain species, as they occurred at densities that were either higher or lower than expected due to RSL. Differential advantages were also observed among species between +N and +N+L treatments, suggesting that species responded to either the fertilization or acidification effects of N, though no consistent pattern emerged. Species nitrophily status was not a useful trait for predicting specific species losses, but was a significant factor when averaged across all treatments and sampling years. Our results provide strong evidence that declines in S in the forest herbaceous layer under N fertilization are due largely to NRSL and not simply a function of species rarity.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-13T13:35:25.93244-05:0
      DOI: 10.1002/ecy.1928
       
  • Scavengers that fit beneath a microscope lens
    • Authors: Carlos M. Herrera
      PubDate: 2017-06-12T08:45:20.99523-05:0
      DOI: 10.1002/ecy.1874
       
  • An empirical examination of consumer effects across twenty degrees of
           latitude
    • Authors: James T. Lavender; Katherine A. Dafforn, Melanie J. Bishop, Emma L. Johnston
      Abstract: The strength and importance of consumer effects are predicted to increase towards low latitudes, but this hypothesis has rarely been tested using a spatially consistent methodology. In a consumer-exclusion experiment spanning twenty degrees of latitude along the east Australian coast, the magnitude of consumer effects on assemblage-level metrics of sub-tidal sessile assemblage composition was no greater at low than high latitudes. Across caged and control assemblages, Shannon's diversity, Pielou's evenness and richness of functional groups decreased with increasing latitude, but the magnitude of consumer effects on these metrics did not display consistent latitudinal gradients. Instead, latitudinal gradients in consumer effects were apparent for individual functional groups. Solitary ascidians displayed the pattern consistent with predictions of greater direct effects of predators at low than high latitude. As consumers reduced the biomass of this and other competitive dominants, groups less prone to predation (e.g. hydroids, various groups of bryozoans) were able to take advantage of freed space in the presence of predators and show increased abundances there. This large-scale empirical study demonstrates the complexity of species interactions, and the failure of assemblage-level metrics to adequately capture consumer effects over large spatial gradients.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-10T00:26:00.887703-05:
      DOI: 10.1002/ecy.1926
       
  • Wet Years Have More Caterpillars: Interacting Roles of Plant Litter and
           Predation by Ants
    • Authors: Richard Karban; Patrick Grof-Tisza, Marcel Holyoak
      Abstract: Climate is widely recognized as an important factor that affects temporal and spatial patterns of occurrence and abundance of herbivorous insects, although the ecological mechanisms responsible are poorly understood. We found that precipitation and standing water were positively correlated with locations and years of high abundance of caterpillars of the ranchman's tiger moth, Platyprepia virginalis. We analyzed 30 years of survey data and found that the number of large rainfall events was a better predictor of caterpillar abundance than total annual accumulation. We considered three ecological mechanisms that could drive this relationship and conducted observations and manipulative experiments to evaluate these mechanisms. 1) Rainfall facilitates more plant growth, although we found no evidence that increased food quality or quantity was causing the positive association between precipitation and caterpillar abundance. 2) Large rainfall events cause predatory, ground nesting, ants to be less abundant and we found that the number of ants that recruited to local sites was negatively associated with survival and abundance of caterpillars. 3) We found that litter from wet sites provided a refuge from ant predation; litter from wet sites was not beneficial to caterpillars in the absence of ants. Both abiotic factors (precipitation) and biotic factors (predatory ants) affected the temporal and spatial abundance of caterpillars directly and interactively. Climate models predict that rainfall will become more variable, suggesting that populations of this caterpillar may also become more variable in the future.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-07T08:17:03.339918-05:
      DOI: 10.1002/ecy.1917
       
  • Declines in plant palatability from polar to tropical latitudes depend on
           herbivore and plant identity
    • Authors: Alyssa M. Demko; Charles D. Amsler, Mark E. Hay, Jeremy D. Long, James B. McClintock, Valerie J. Paul, Erik E. Sotka
      Abstract: Long-standing theory predicts that the intensity of consumer-prey interactions declines with increasing latitude, yet for plant-herbivore interactions, latitudinal changes in herbivory rates and plant palatability have received variable support. The topic is of growing interest given that lower-latitude species are moving poleward at an accelerating rate due to climate change, and predicting local interactions will depend partly on whether latitudinal gradients occur in these critical biotic interactions. Here, we assayed the palatability of 50 seaweeds collected from polar (Antarctica), temperate (northeastern Pacific; California), and tropical (central Pacific; Fiji) locations to two herbivores native to the tropical and subtropical Atlantic, the generalist crab Mithraculus sculptus and sea urchin Echinometra lucunter. Red seaweeds (Rhodophyta) of polar and temperate origin were more readily consumed by urchins than were tropical reds. The decline in palatability with decreasing latitude is explained by shifts in tissue organic content along with the quantity and quality of secondary metabolites, degree of calcification or both. We detected no latitudinal shift in palatability of red seaweeds to crabs, nor any latitudinal shifts in palatability of brown seaweeds (Phaeophyta) to either crabs or urchins. Our results suggest that evolutionary pressure from tropical herbivores favored red seaweeds with lower palatability, either through the production of greater levels of chemical defenses, calcification or both. Moreover, our results tentatively suggest that the ‘tropicalization’ of temperate habitats is facilitated by the migration of tropical herbivores into temperate areas dominated by weakly defended and more nutritious foods, and that the removal of these competing seaweeds may facilitate the invasion of better-defended tropical seaweeds.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-07T08:17:02.351042-05:
      DOI: 10.1002/ecy.1918
       
  • Intraspecific variation shapes community-level behavioral responses to
           urbanization in spiders
    • Authors: Maxime Dahirel; Jasper Dierick, Maarten De Cock, Dries Bonte
      Abstract: Urban areas are an extreme example of human-changed environments, exposing organisms to multiple and strong selection pressures. Adaptive behavioral responses are thought to play a major role in animals’ success or failure in such new environments. Approaches based on functional traits have proven especially valuable to understand how species communities respond to environmental gradients. Until recently, they have, however, often ignored the potential consequences of intraspecific trait variation (ITV). When ITV is prevalent, it may highly impact ecological processes and resilience against stressors. This may be especially relevant in animals, in which behavioral traits can be altered very flexibly at the individual level to track environmental changes. We investigated how species turnover and ITV influenced community-level behavioral responses in a set of 62 sites of varying levels of urbanization, using orb web spiders and their webs as models of foraging behavior. ITV alone explained around a third of the total trait variation observed among communities. Spider web structure changed according to urbanization, in ways that increase the capture efficiency of webs in a context of smaller urban prey. These trait shifts were partly mediated by species turnover, but ITV increased their magnitude, potentially helping to buffer the effects of environmental changes on communities. The importance of ITV varied depending on traits and on the spatial scale at which urbanization was considered. Despite being neglected from community-level analyses in animals, our results highlight the importance of accounting for intraspecific trait variation to fully understand trait responses to (human-induced) environmental changes and their impact on ecosystem functioning.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-06T05:42:04.97316-05:0
      DOI: 10.1002/ecy.1915
       
  • Toward a community ecology of landscapes: predicting multiple
           predator-prey interactions across geographic space
    • Authors: Oswald J. Schmitz; Jennifer R. B. Miller, Anne M. Trainor, Briana Abrahms
      Abstract: Community ecology was traditionally an integrative science devoted to studying interactions between species and their abiotic environments in order to predict species’ geographic distributions and abundances. Yet for philosophical and methodological reasons it has become divided into two enterprises: one devoted to local experimentation on species interactions to predict community dynamics; the other devoted to statistical analyses of abiotic and biotic information to describe geographic distribution. Our goal here is to instigate thinking about ways to reconnect the two enterprises and thereby return to a tradition to do integrative science. We focus specifically on the community ecology of predators and prey, which is ripe for integration. This is because there is active, simultaneous interest in experimentally resolving the nature and strength of predator-prey interactions as well as explaining pattern across landscapes and seascapes. We begin by describing a conceptual theory rooted in classical analyses of non-spatial food web modules used to predict species interactions. We show how such modules can be extended to consideration of spatial context using the concept of habitat domain. Habitat domain describes the spatial extent of habitat space that predators and prey use while foraging, which differs from home range, the spatial extent used by an animal to meet all of its daily needs. This conceptual theory can be used to predict how different spatial relations of predators and prey could lead to different emergent multiple predator-prey interactions such as whether predator consumptive or non-consumptive effects should dominate, and whether intraguild predation, predator interference or predator complementarity are expected. We then review the literature on studies of large predator-prey interactions that make conclusions about the nature of multiple predator-prey interactions. This analysis reveals that while many studies provide sufficient information about predator or prey spatial locations, and thus meet necessary conditions of the habitat domain conceptual theory for drawing conclusions about the nature of the predator-prey interactions, several studies do not. We therefore elaborate how modern technology and statistical approaches for animal movement analysis could be used to test the conceptual theory, using experimental or quasi-experimental analyses at landscape scales.This article is protected by copyright. All rights reserved.
      PubDate: 2017-06-06T04:46:10.043692-05:
      DOI: 10.1002/ecy.1916
       
  • Worldwide hemisphere-dependent lean in Cook pines
    • Authors: Jason W. Johns; Jennifer M. Yost, Dean Nicolle, Boris Igic, Matt K. Ritter
      PubDate: 2017-05-30T10:10:25.252995-05:
      DOI: 10.1002/ecy.1850
       
  • Endless forms most hidden: katydids that masquerade as moss
    • Authors: David W. Kikuchi; Gustavo H. Kattan, Carolina Murcia, Fernando Montealegre
      PubDate: 2017-05-17T09:00:00.985499-05:
      DOI: 10.1002/ecy.1845
       
  • Fire catalyzed rapid ecological change in lowland coniferous forests of
           the Pacific Northwest over the past 14,000 years
    • Authors: Shelley D. Crausbay; Philip E. Higuera, Douglas G. Sprugel, Linda B. Brubaker
      Abstract: Disturbance can catalyze rapid ecological change by causing widespread mortality and initiating successional pathways, and during times of climate change, disturbance may contribute to ecosystem state changes by initiating a new successional pathway. In the Pacific Northwest of North America (PNW), disturbance by wildfires strongly shapes the composition and structure of lowland forests, but understanding the role of fire over periods of climate change is challenging, because fire-return intervals are long (e.g., millennia) and the coniferous trees dominating these forests can live for many centuries. We developed stand-scale paleorecords of vegetation and fire that span nearly the past 14,000 years to study how fire was associated with state changes and rapid dynamics in forest vegetation at the stand scale (1–3 ha). We studied forest history with sediment cores from small hollow sites in the Marckworth State Forest, located ~1 km apart in the Tsuga heterophylla Zone in the Puget Lowland ecoregion of western Washington, USA. The median rate of change in pollen/spore assemblages was similar between sites (0.12 and 0.14% per year), but at both sites, rates of change increased significantly following fire events (ranging up to 1% per year, with a median of 0.28 and 0.38%, p < 0.003). During times of low climate velocity, forest composition was resilient to fires, which initiated successional pathways leading back to the dominant vegetation type. In contrast, during times of high climate variability and velocity (e.g., the early Holocene) forests were not resilient to fires, which triggered large-scale state changes. These records provide clear evidence that disturbance, in the form of an individual fire event, can be an important catalyst for rapid state changes, accelerating vegetation shifts in response to large-scale climate change.This article is protected by copyright. All rights reserved.
      PubDate: 2017-05-13T08:45:32.945356-05:
      DOI: 10.1002/ecy.1897
       
  • Dissimilar responses of larch stands in northern Siberia to increasing
           temperatures – a field and simulation based study
    • Authors: Mareike Wieczorek; Stefan Kruse, Laura S. Epp, Alexei Kolmogorov, Anatoly N Nikolaev, Ingo Heinrich, Florian Jeltsch, Lyudmila A Pestryakova, Romy Zibulski, Ulrike Herzschuh
      Abstract: Arctic and alpine treelines worldwide differ in their reactions to climate change. A northward advance of or densification within the treeline ecotone will likely influence climate-vegetation feedback mechanisms. In our study, which was conducted in the Taimyr Depression in the North Siberian Lowlands, w present a combined field- and model-based approach helping us to better understand the population processes involved in the responses of the whole treeline ecotone, spanning from closed forest to single-tree tundra, to climate warming. Using information on stand structure, tree age, and seed quality and quantity from seven sites, we investigate effects of intra-specific competition and seed availability on the specific impact of recent climate warming on larch stands. Field data show that tree density is highest in the forest-tundra, and average tree size decreases from closed forest to single-tree tundra. Age-structure analyses indicate that the trees in the closed forest and forest-tundra have been present for at least ~240 years. At all sites except the most southerly ones, past establishment is positively correlated with regional temperature increase. In the single-tree tundra however, a change in growth form from krummholz to erect trees, beginning ~130 years ago, rather than establishment date has been recorded. Seed mass decreases from south to north, while seed quantity increases. Simulations with LAVESI (Larix Vegetation Simulator) further suggest that relative density changes strongly in response to a warming signal in the forest-tundra while intra-specific competition limits densification in the closed forest and seed limitation hinders densification in the single-tree tundra. We find striking differences in strength and timing of responses to recent climate warming. While forest-tundra stands recently densified, recruitment is almost non-existent at the southern and northern end of the ecotone due to autecological processes. Palaeo-treelines may therefore be inappropriate to infer past temperature changes at a fine scale. Moreover, a lagged treeline response to past warming will, via feedback mechanisms, influence climate change in the future.This article is protected by copyright. All rights reserved.
      PubDate: 2017-05-05T09:25:36.030289-05:
      DOI: 10.1002/ecy.1887
       
  • Age and years to death disparately influence reproductive allocation in a
           short-lived bird
    • Authors: Corey E. Tarwater; Peter Arcese
      Abstract: Theory predicts that reproduction will change as individuals near the end of their lives by either increasing reproductive allocation (terminal allocation hypothesis) or decreasing allocation (senescence hypothesis) towards the end of life. Although senescence has received more support, few studies examine how both age and years to death influence late-life reproduction. We used a 37-year study of song sparrows (Melospiza melodia) to ask how age and years to death influenced reproductive allocation late in life. We observed both senescence and terminal allocation, and that age and years to death interacted to influence individual variation in allocation tactics. In particular, we observed a decline in allocation in older individuals (senescence), but only when comparing individuals with the same number of years to death. Likewise, we observed terminal allocation, but only in young females. Reproductive tactics were most variable in young females, with many exerting high effort but living 1-2 years, and others exerting low effort annually and living longer. Our results suggest that late-life reproductive tactics are influenced by both chronological age and years to death, and that short- and long-lived females with differing reproductive tactics exist within this population of song sparrows.This article is protected by copyright. All rights reserved.
      PubDate: 2017-04-07T02:15:45.387721-05:
      DOI: 10.1002/ecy.1851
       
  • Issue Information
    • Pages: 2237 - 2240
      PubDate: 2017-09-01T09:50:14.61299-05:0
      DOI: 10.1002/ecy.1984
       
 
 
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