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Journal Cover CELE Exchange, Centre for Effective Learning Environments
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   ISSN (Print) 2072-7925
   Published by OECD Homepage  [80 journals]
  • Assessing and predicting shifts in mountain forest composition across
           25¬†years of climate change
    • Authors: Daniel Scherrer; Stéphanie Massy, Sylvain Meier, Pascal Vittoz, Antoine Guisan
      Abstract: AimSpatial predictions of future communities under climate change can be obtained by stacking species distribution models (S-SDM), but proper evaluation of community S-SDM predictions across time with fully independent data has rarely been carried out. The aim of this study was to evaluate the predictive abilities of S-SDMs for whole forest communities across the last 25 years in a mountain region.LocationThe western Swiss Alps.MethodsWe used past vegetation surveys (2,984 plots) and environmental data from the 1990s to calibrate SDMs for 364 plant species and predict changes in forest composition under contemporary conditions. These projections were then evaluated by resurveying a random subset of 92 forest plots in summer 2014.ResultsSpecies distribution models showed the same accuracy in the past (calibration data) and present (evaluation data). The S-SDMs correctly predicted the general trends in species richness and shift of ecological conditions (i.e., temperature, moisture) at the regional level. However, it proved more difficult to identify precisely which forest communities or areas are most or least affected by climate change.Main conclusionOur results show that, across a period of a few decades, S-SDMs can usefully predict trends in macroecological properties such as richness or average ecological conditions, but fail to accurately predict changes in composition. This is likely due to the combined effects of the stochasticity of local colonization and extinction events, dispersal limitations, community assembly rules (e.g., competition), observer bias, model and location errors and interannual variation. Furthermore, these models cannot account for potential species adaptations leading to persistence in sites predicted unsuitable. This highlights the need for developing more accurate forest community predictions as support to help prioritizing conservation actions.
      PubDate: 2017-03-09T06:46:01.518939-05:
      DOI: 10.1111/ddi.12548
  • Birds as key vectors for the dispersal of some alien species: Further
    • Authors: Chevonne Reynolds; Graeme S. Cumming, Montserrat Vilà, Andy J. Green
      Abstract: W. Solarz, K. Najberek, A. Pociecha & E. Wilk-Woźniak (, Diversity and Distributions, 23, 113–117) published a letter in Diversity and Distributions debating our view that waterbirds are important vectors of alien species (C. Reynolds, N. A. F. Miranda & G. S. Cumming, Diversity and Distributions, 21, 744–754; A. J. Green, Diversity and Distributions, 22, 239–247) and question whether future research into the mechanisms under-pinning this phenomenon can be advantageous for the practical management of alien species. Additionally, Solarz et al. suggest that human activities are the primary source of all alien species introductions and that waterbirds may only act as vectors of secondary dispersal. In this letter, we respond to several arguments raised by the authors surrounding the relevance of waterbird-mediated dispersal in the introduction and spread of alien species. We emphasize the partly deterministic nature of waterbird dispersal and the significance of long-distance dispersal events (and hence the potential for primary introductions of new alien species across political boundaries). Finally, we reaffirm the importance of further research into dispersal by birds to improve our capacity to foresee and manage invasions of those alien species with strong capacity to spread via avian vectors.
      PubDate: 2017-03-09T06:36:15.530477-05:
      DOI: 10.1111/ddi.12549
  • Species invasions threaten the antiquity of China's freshwater fish fauna
    • Authors: Chunlong Liu; Dekui He, Yifeng Chen, Julian D. Olden
      Abstract: AimHuman-mediated species introductions and extirpations have resulted in the homogenization of biotas over time. However, there remains considerable uncertainty in our understanding of homogenization process for megadiverse regions of the world. Here, we investigate the consequences of widespread species invasions and extirpations for the biogeography of China's unique freshwater fish fauna.LocationChina.MethodsBy assembling a comprehensive dataset for distribution of Chinese freshwater fishes, we quantify how non-native fish species, from both overseas introductions and domestic translocations, has led to taxonomic homogenization of fish faunas at watershed, basin, ecoregion and country scales. We explore how the observed patterns in homogenization vary geographically, and identify those species most responsible for the faunal changes. Lastly, we simulate how China's fish fauna may continue to homogenize according to different scenarios of anticipated species introductions and extirpations.ResultsWe demonstrate that species introductions and extirpations have homogenized freshwater fish faunas across China. Overall compositional similarity of watersheds increased by 7.0% (from a historical 14.9% to 21.9% in the present day; Sørensen index). Compositional similarity of 96 of 103 (93.2%) watersheds increased, with western basins exhibiting the highest magnitude. Translocated non-native species associated with aquaculture practices contributed the most to faunal homogenization when compared to alien species (7.3% and 0.4%, respectively). Furthermore, faunal homogenization is predicted to intensify an additional 0.5–4.2% with increasing numbers of new non-native species introductions and the extirpation of native species.Main conclusionsSpecies introductions and extirpations have resulted in the significant impoverishment, and thus the loss of antiquity, of China's freshwater fish fauna over the past century. In the light of the growing realization that species composition (not richness) defines the role that biodiversity plays in maintaining ecosystem function, our study highlights the need for conservation strategies in China that consider changing patterns of β diversity.
      PubDate: 2017-02-14T07:55:26.103463-05:
      DOI: 10.1111/ddi.12541
  • The use of range size to assess risks to biodiversity from stochastic
    • Authors: Nicholas J. Murray; David A. Keith, Lucie M. Bland, Emily Nicholson, Tracey J. Regan, Jon Paul Rodríguez, Michael Bedward
      Abstract: AimStochastic threats such as disease outbreak, pollution events, fire, tsunami and drought can cause rapid species extinction and ecosystem collapse. The ability of a species or ecosystem to persist after a stochastic threat is strongly related to the extent and spatial pattern of its geographical distribution. Consequently, protocols for assessing risks to biodiversity typically include geographic range size criteria for assessing risks from stochastic threats. However, owing in part to the rarity of such events in nature, the metrics for assessing risk categories have never been tested. In this study, we investigate the performance of alternative range size metrics, including the two most widely used, extent of occurrence (EOO) and area of occupancy (AOO), as predictors of ecosystem collapse in landscapes subject to stochastic threats.MethodsWe developed a spatially explicit stochastic simulation model to investigate the impacts of four threat types on a dataset of 1350 simulated geographic distributions of varying pattern and size. We empirically estimated collapse probability in response to each threat type and evaluated the ability of a set of spatial predictors to predict risk.ResultsThe probability of ecosystem collapse increased rapidly as range size declined. While AOO and EOO were the most important predictors of collapse risk for the three spatially explicit threats included in our model (circle, swipe and cluster), core area, patch density and mean patch size were better predictors for edge effect threats.Main conclusionsOur study is the first to quantitatively assess the range size metrics employed in biodiversity risk assessment protocols. We show that the current methods for measuring range size are the best spatial metrics for estimating risks from stochastic threats. Our simulation framework delivers an objective assessment of the performance of hitherto untested but widely used measures of geographic range size for risk assessment.
      PubDate: 2017-01-17T23:15:39.379625-05:
      DOI: 10.1111/ddi.12533
  • Floods affect the abundance of invasive Impatiens glandulifera and its
           spread from river corridors
    • Authors: Jan Čuda; Zuzana Rumlerová, Josef Brůna, Hana Skálová, Petr Pyšek
      Pages: 342 - 354
      Abstract: AimRiparian habitats are amongst the most invaded ecosystems world-wide. The great abundance of invasive species in river corridors is attributed to the efficient transport of alien species’ propagules and reduced competition from native plants due to regular flooding. Once an invasive species has become established, river corridors can serve as stepping stones for spread into other habitats. We have chosen the Himalayan balsam Impatiens glandulifera Royle, highly invasive annual in riparian areas, as a model for spread of invasive species from linear river corridors.LocationCentral Europe.MethodsWe mapped its distribution and recorded its abundance in over 1200 patches along four rivers in central Europe, differing in the time of balsam's introduction (1900–1995). The patches were characterized in terms of the distance from the riverbank, height above the river surface, degree of soil disturbance and flooding regime.ResultsThe patches at sites subject to flooding had twice as many individuals as those that were not subject to flooding, regardless of their distance from the riverbank and height above the river surface. There was a strong effect of the river identity, with river invaded 20 years ago being less infested than those invaded earlier. The distance from the riverbank at which the populations occurred differed and did not depend on river identity/residence time. The patches in tributaries were on average two times further from the bank of the main river than those located elsewhere.Main conclusionsFlooding is an important factor affecting the abundance of I. glandulifera, and accounts for its spread and dominance along river corridors probably due to spreading the seeds, increasing nutrient availability and disturbing native vegetation. It is likely that the number of I. glandulifera populations will increase in the future, especially along small water courses.
      PubDate: 2017-01-26T20:21:11.343396-05:
      DOI: 10.1111/ddi.12524
  • Urbanization may limit impacts of an invasive predator on native mammal
    • Authors: Brian E. Reichert; Adia R. Sovie, Brad J. Udell, Kristen M. Hart, Rena R. Borkhataria, Mathieu Bonneau, Robert Reed, Robert McCleery
      Pages: 355 - 367
      Abstract: AimOur understanding of the effects of invasive species on faunal diversity is limited in part because invasions often occur in modified landscapes where other drivers of community diversity can exacerbate or reduce the net impacts of an invader. Furthermore, rigorous assessments of the effects of invasive species on native communities that account for variation in sampling, species-specific detection and occurrence of rare species are lacking. Invasive Burmese pythons (Python molurus bivittatus) may be causing declines in medium- to large-sized mammals throughout the Greater Everglades Ecosystem (GEE); however, other factors such as urbanization, habitat changes and drastic alteration in water flow may also be influential in structuring mammal communities. The aim of this study was to gain an understanding of how mammal communities simultaneously facing invasive predators and intensively human-altered landscapes are influenced by these drivers and their interactions.LocationFlorida, USA.MethodsWe used data from trail cameras and scat searches with a hierarchical community model that accounts for undetected species to determine the relative influence of introduced Burmese pythons, urbanization, local hydrology, habitat types and interactive effects between pythons and urbanization on mammal species occurrence, site-level species richness, and turnover.ResultsPython density had significant negative effects on all species except coyotes. Despite these negative effects, occurrence of some generalist species increased significantly near urban areas. At the community level, pythons had the greatest impact on species richness, while turnover was greatest along the urbanization gradient where communities were increasingly similar as distance to urbanization decreased.Main conclusionsWe found evidence for an antagonistic interaction between pythons and urbanization where the impacts of pythons were reduced near urban development. Python-induced changes to mammal communities may be mediated near urban development, but elsewhere in the GEE, pythons are likely causing a fundamental restructuring of the food web, declines in ecosystem function, and creating complex and unpredictable cascading effects.
      PubDate: 2017-01-26T20:30:31.243876-05:
      DOI: 10.1111/ddi.12531
  • The role of criteria in selecting important areas for conservation in
           biodiversity-rich territories
    • Authors: Rut Sánchez de Dios; Ciro Cabal Ruano, Felipe Domínguez Lozano, Helios Sainz Ollero, Juan Carlos Moreno Saiz
      Pages: 368 - 380
      Abstract: AimTo improve our knowledge of the process of selection of important plant areas (IPAs), a recent requirement of the Global Strategy for Plant Conservation. The study was conducted at a hotspot of plant conservation in the European continent, using a comprehensive database of plant species distribution in the area.LocationSpain.MethodsWe used range distribution data for 3218 vascular plants found in Spain, in the form of 10 km UTM squares, totalling 169,124 species occurrences across 5508 UTM cells. We identified IPAs by scoring threat status, endemism, rarity, phylogeny and species richness. We then performed two different analyses, with and without incorporating the species richness score of every square. Finally, a null model was used to obtain a general pattern of species occurrences, we computed an index of occurrence richness (SI), and then we selected a number of specific territories of different sizes to reveal differences in sampling effort within the study area.ResultsWe identified IPAs in Spain according to the proposed scoring method. We detected a positive relationship among richness and total score calculated with the rest of the criteria. However, endemism and threat status produced certain specific effects for species-poor squares. Regarding sample bias, we detected over- and under-recorded areas. This bias seems to be due to the accumulation of field prospecting in species-rich areas in detriment to poor areas.Main conclusionsWe envisage two different approaches to address IPA selection in hotspots. First, we advocate a complementary scoring-mapping method for areas where a relatively large amount of range distribution data and plant knowledge is available. Secondly, as richness per se encompasses a great amount of biogeographical information, we suggest using species richness or any other environmental surrogate to delineate preliminary IPAs in poorly known but species-rich territories.
      PubDate: 2017-01-23T00:05:43.559341-05:
      DOI: 10.1111/ddi.12535
  • Environmental DNA genetic monitoring of the nuisance freshwater diatom,
           Didymosphenia geminata, in eastern North American streams
    • Authors: Stephen R. Keller; Robert H. Hilderbrand, Matthew K. Shank, Marina Potapova
      Pages: 381 - 393
      Abstract: AimEstablishing the distribution and diversity of populations in the early stages of invasion when populations are at low abundance is a core challenge for conservation biologists. Recently, genetic monitoring for environmental DNA (eDNA) has become an effective approach for the early detection of invaders, especially for microscopic organisms where visual detection is challenging. Didymosphenia geminata is a globally distributed freshwater diatom that shows a recent emergence of nuisance blooms, but whose native versus exotic status in different areas has been debated. We address the hypothesis that the distribution and genetic diversity of D. geminata in eastern North America is related to the recent introduction of non-native lineages, and contrast that with the alternative hypothesis that D. geminata is cryptically native to the region (i.e. at low abundance) and only forms nuisance blooms when triggered by a change in environment.LocationThe Mid-Atlantic region of North America.MethodsWe analysed 118 stream samples for D. geminata eDNA, validated our results for a subset of sites using direct visual enumeration by microscopy and used molecular cloning to sequence D. geminata from two sites where eDNA was detected.Results(1) D. geminata eDNA was detected at seven spatially unique sites, six of which were previously documented to contain recent D. geminata blooms. (2) Sites where D. geminata eDNA was detected exhibited no difference in environmental conditions compared to sites with no-detected D. geminata eDNA. (3) Sequencing of D. geminata eDNA showed that blooms were composed of multiple genetic lineages, closely related to those sampled elsewhere across the globe.Main conclusionsWe interpret these results as most consistent with the hypothesis that D. geminata is an exotic invader in the Mid-Atlantic region, still in its early stages of invasion; thus, genetic monitoring and management efforts may still be effective at controlling its spread.
      PubDate: 2017-02-03T01:50:38.80344-05:0
      DOI: 10.1111/ddi.12536
  • Predicting cetacean distributions in data-poor marine ecosystems
    • Authors: Jessica V. Redfern; Thomas J. Moore, Paul C. Fiedler, Asha Vos, Robert L. Brownell, Karin A. Forney, Elizabeth A. Becker, Lisa T. Ballance
      Pages: 394 - 408
      Abstract: AimHuman activities are creating conservation challenges for cetaceans. Spatially explicit risk assessments can be used to address these challenges, but require species distribution data, which are limited for many cetacean species. This study explores methods to overcome this limitation. Blue whales (Balaenoptera musculus) are used as a case study because they are an example of a species that have well-defined habitat and are subject to anthropogenic threats.LocationEastern Pacific Ocean, including the California Current (CC) and eastern tropical Pacific (ETP), and northern Indian Ocean (NIO).MethodsWe used 12 years of survey data (377 blue whale sightings and c. 225,400 km of effort) collected in the CC and ETP to assess the transferability of blue whale habitat models. We used the models built with CC and ETP data to create predictions of blue whale distributions in the data-poor NIO because key aspects of blue whale ecology are expected to be similar in these ecosystems.ResultsWe found that the ecosystem-specific blue whale models performed well in their respective ecosystems, but were not transferable. For example, models built with CC data could accurately predict distributions in the CC, but could not accurately predict distributions in the ETP. However, the accuracy of models built with combined CC and ETP data was similar to the accuracy of the ecosystem-specific models in both ecosystems. Our predictions of blue whale habitat in the NIO from the models built with combined CC and ETP data compare favourably to hypotheses about NIO blue whale distributions, provide new insights into blue whale habitat, and can be used to prioritize research and monitoring efforts.Main conclusionsPredicting cetacean distributions in data-poor ecosystems using habitat models built with data from multiple ecosystems is potentially a powerful marine conservation tool and should be examined for other species and regions.
      PubDate: 2017-02-03T01:50:53.337401-05:
      DOI: 10.1111/ddi.12537
  • Multiple founder effects are followed by range expansion and admixture
           during the invasion process of the raccoon (Procyon lotor) in Europe
    • Authors: Marietta L. Fischer; Iván Salgado, Joscha Beninde, Roland Klein, Alain C. Frantz, Mike Heddergott, Catherine I. Cullingham, Christopher J. Kyle, Axel Hochkirch
      Pages: 409 - 420
      Abstract: AimUnderstanding colonization dynamics is crucial for management of invasive species. We compare the genetic structure of historical (Central Europe) and recent (Spain) invasive populations with native and captive populations of the North American raccoon (Procyon lotor). Our aim was to analyse the effects of colonization age on genetic population structure, understand the role of captive individuals as potential founders and test the role of rivers for the dispersal of the species.LocationNorth America, Spain, Central Europe.MethodsWe genotyped wild-caught raccoons from Spain and Central Europe (N = 596), zoos (N = 57) and the native range (N = 153) at 16 microsatellite loci and sequenced a mitochondrial DNA fragment (Control Region). We analysed population genetic structuring with Bayesian assignment methods and a FCA. In a landscape genetic analysis, we tested the effect of waterways in the dispersal of the species.ResultsWe detected 16 genetic clusters (in baps), supporting the hypothesis of multiple introductions and ongoing releases in the invasive range. The native population showed nearly no genetic structure, the Central European clusters showed signals of admixture, whereas the Spanish clusters were clearly separated. Admixture of the Central European clusters was probably caused by recent contact of populations with different origin. The landscape genetic analysis showed that rivers represent neither barriers nor corridors in Central Europe.Main conclusionsAs the Spanish populations are genetically more diverse than the Central European, we expect increased within-population diversity when the still isolated populations merge after range expansion. As our results provide evidence for gene flow between zoos and free-ranging populations, better control of pet trade is essential in the management efforts concerning this invasive species. Our study shows that genetic analyses can help to reconstruct invasion processes, which is important for better understanding and effective management of invasive species.
      PubDate: 2017-01-31T01:20:41.31362-05:0
      DOI: 10.1111/ddi.12538
  • Climate variability drives population cycling and synchrony
    • Authors: Lars Y. Pomara; Benjamin Zuckerberg
      Pages: 421 - 434
      Abstract: AimThere is mounting concern that climate change will lead to the collapse of cyclic population dynamics, yet the influence of climate variability on population cycling remains poorly understood. We hypothesized that variability in survival and fecundity, driven by climate variability at different points in the life cycle, scales up from local populations to drive regional characteristics of population cycling and spatial synchronization.LocationForest in the US Upper Midwest and Great Lakes region.MethodsWe tested hypotheses linking variation in vital rates of Ruffed Grouse (Bonasa umbellus), a declining species that displays decadal population cycles, to temperature and precipitation anomalies and land use intensity, using rate estimates from multiple locations in eastern North America. We used climate-demographic linkages to simulate spatially explicit population dynamics from 1982 to 2069, evaluated predictions against monitoring data and assessed predicted population dynamics under future climate projections.ResultsNest success and winter survival were linked to temperature and precipitation anomalies, and demographic models explained important spatio-temporal characteristics of cycling and synchrony in monitoring data. The climate-driven vital rates were necessary for cycling and synchrony in models, even though the four included climate variables were not individually periodic. Cycling and synchrony were stronger at more northerly latitudes, but this transition occurred abruptly, reflecting regional variation in winter conditions. Forecasts suggested climate-driven cycling through mid-century, followed by desynchronization and dampening.Main conclusionsClimate variability can drive spatio-temporal variation in demographic rates, and population cycling can result from these relationships. Pathways linking climate to broad-scale population dynamics involve responses of vital rates to several climate variables at different times of year and may be more complex than direct responses to known modes of climate variability. The wide-ranging impact of climate change on the demographics of northerly adapted species has the potential to degrade patterns of population synchrony and cycling.
      PubDate: 2017-02-06T23:25:32.243905-05:
      DOI: 10.1111/ddi.12540
  • Using coarse-scale species distribution data to predict extinction risk in
    • Authors: Sarah E. Darrah; Lucie M. Bland, Steven P. Bachman, Colin P. Clubbe, Anna Trias-Blasi
      Pages: 435 - 447
      Abstract: AimLess than 6% of the worlds described plant species have been assessed on the IUCN Red List, leaving many species invisible to conservation prioritization. Large-scale Red List assessment of plant species is a challenge, as most species’ ranges have only been resolved to a coarse scale. As geographic distribution is a key assessment criterion on the IUCN Red List, we evaluate the use of coarse-scale distribution data in predictive models to assess the global scale and drivers of extinction risk in an economically important plant group, the bulbous monocotyledons.LocationGlobal.MethodsUsing coarse-scale species distribution data, we train a machine learning model on biological and environmental variables for 148 species assessed on the IUCN Red List in order to identify correlates of extinction risk. We predict the extinction risk of 6439 ‘bulbous monocot’ species with the best of 13 models and map our predictions to identify potential hotspots of threat.ResultsOur model achieved 91% classification accuracy, with 88% of threatened species and 93% of non-threatened species accurately predicted. The model predicted 35% of bulbous monocots presently ‘Not Evaluated’ under IUCN criteria to be threatened and human impacts were a key correlate of threat. Spatial analysis identified some hotspots of threat where no bulbous monocots are yet on the IUCN Red List, for example central Chile.Main conclusionsThis is the first time a machine learning model has been used to determine extinction risk at a global scale in a species-rich plant group. As coarse-scale distribution data exist for many plant groups, our methods can be replicated to provide extinction risk predictions across the plant kingdom. Our approach can be used as a low-cost prioritization tool for targeting field-based assessments.
      PubDate: 2017-03-03T05:07:02.864711-05:
      DOI: 10.1111/ddi.12532
  • A systematic conservation strategy for crop wild relatives in the Czech
    • Authors: Nigel G. Taylor; Shelagh P. Kell, Vojtěch Holubec, Mauricio Parra-Quijano, Karel Chobot, Nigel Maxted
      Pages: 448 - 462
      Abstract: AimTo create a crop wild relative (CWR) conservation strategy for the Czech Republic: the first national CWR conservation strategy for Central and Eastern Europe.LocationCzech Republic.MethodsWe generated a CWR checklist for the Czech Republic and then prioritized taxa, using widely adopted criteria modified with input from local experts, to create a national CWR inventory. For 204 priority CWR species, we collated 206,760 presence records. We carried out spatial analyses to identify patterns in species richness, gaps in existing conservation actions, complementary conservation networks and collecting strategies to increase representativeness of gene bank accessions. We considered both specific and genetic conservation, using geographic and ecogeographic proxies for the latter.ResultsPassive in situ conservation of CWR in the Czech Republic is comprehensive at present, with all but one priority CWR species being contained in protected areas. Active in situ CWR conservation could be focussed within 11 ca. 10-km-by-10-km grid cells containing 94% of priority species, or their overlapping protected areas. To augment the genetic coverage of the in situ conservation network, active CWR conservation is encouraged within 11 supplementary areas. Meanwhile, there are huge gaps in ex situ collections, with no known conserved material for 134 of the 204 priority species. Furthermore, existing accessions are generally unrepresentative of genetic diversity.Main conclusionsIn the Czech Republic, active in situ conservation of priority CWR should be instigated within the 22 recommended grid cell areas or their 14 overlapping protected areas. For ex situ conservation, strategic and targeted collection of germplasm would markedly increase the value of gene bank collections. Diversity of priority Czech CWR is concentrated in South Moravia, making this a particularly important CWR area for the country and for Europe.
      PubDate: 2017-02-08T20:10:43.676121-05:
      DOI: 10.1111/ddi.12539
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