The Experts below are selected from a list of 212475 Experts worldwide ranked by ideXlab platform
Brian J Mcgill - One of the best experts on this subject based on the ideXlab platform.
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shifts in trait means and variances in north american tree assemblages species richness patterns are loosely related to the Functional Space
Ecography, 2015Co-Authors: Irena Simova, Cyrille Violle, Nathan J B Kraft, David Storch, Jenschristian Svenning, Brad Boyle, John C Donoghue, Peter M Jorgensen, Brian J McgillAbstract:One of the key hypothesized drivers of gradients in species richness is environmental filtering, where environmental stress limits which species from a larger species pool gain membership in a local community owing to their traits. Whereas most studies focus on small-scale variation in Functional traits along environmental gradient, the effect of large-scale environmental filtering is less well understood. Furthermore, it has been rarely tested whether the factors that constrain the niche Space limit the total number of coexisting species. We assessed the role of environmental filtering in shaping tree assemblages across North America north of Mexico by testing the hypothesis that colder, drier, or seasonal environments (stressful conditions for most plants) constrain tree trait diversity and thereby limit species richness. We assessed geographic patterns in trait filtering and their relationships to species richness pattern using a comprehensive set of tree range maps. We focused on four key plant Functional traits reflecting major life history axes (maximum height, specific leaf area, seed mass, and wood density) and four climatic variables (annual mean and seasonality of temperature and precipitation). We tested for significant spatial shifts in trait means and variances using a null model approach. While we found significant shifts in mean species’ trait values at most grid cells, trait variances at most grid cells did not deviate from the null expectation. Measures of environmental harshness (cold, dry, seasonal climates) and lower species richness were weakly associated with a reduction in variance of seed mass and specific leaf area. The pattern in variance of height and wood density was, however, opposite. These findings do not support the hypothesis that more stressful conditions universally limit species and trait diversity in North America. Environmental filtering does, however, structure assemblage composition, by selecting for certain optimum trait values under a given set of conditions.
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shifts in trait means and variances in north american tree assemblages species richness patterns are loosely related to the Functional Space
Ecography, 2015Co-Authors: Irena Simova, Cyrille Violle, Nathan J B Kraft, David Storch, Jenschristian Svenning, Brad Boyle, John C Donoghue, Peter M Jorgensen, Brian J McgillAbstract:One of the key hypothesized drivers of gradients in species richness is environmental filtering, where environmental stress limits which species from a larger species pool gain membership in a local community owing to their traits. Whereas most studies focus on small-scale variation in Functional traits along environmental gradient, the effect of large-scale environmental filtering is less well understood. Furthermore, it has been rarely tested whether the factors that constrain the niche Space limit the total number of coexisting species. We assessed the role of environmental filtering in shaping tree assemblages across North America north of Mexico by testing the hypothesis that colder, drier, or seasonal environments (stressful conditions for most plants) constrain tree trait diversity and thereby limit species richness. We assessed geographic patterns in trait filtering and their relationships to species richness pattern using a comprehensive set of tree range maps. We focused on four key plant Functional traits reflecting major life history axes (maximum height, specific leaf area, seed mass, and wood density) and four climatic variables (annual mean and seasonality of temperature and precipitation). We tested for significant spatial shifts in trait means and variances using a null model approach. While we found significant shifts in mean species’ trait values at most grid cells, trait variances at most grid cells did not deviate from the null expectation. Measures of environmental harshness (cold, dry, seasonal climates) and lower species richness were weakly associated with a reduction in variance of seed mass and specific leaf area. The pattern in variance of height and wood density was, however, opposite. These findings do not support the hypothesis that more stressful conditions universally limit species and trait diversity in North America. Environmental filtering does, however, structure assemblage composition, by selecting for certain optimum trait values under a given set of conditions.
David Storch - One of the best experts on this subject based on the ideXlab platform.
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shifts in trait means and variances in north american tree assemblages species richness patterns are loosely related to the Functional Space
Ecography, 2015Co-Authors: Irena Simova, Cyrille Violle, Nathan J B Kraft, David Storch, Jenschristian Svenning, Brad Boyle, John C Donoghue, Peter M Jorgensen, Brian J McgillAbstract:One of the key hypothesized drivers of gradients in species richness is environmental filtering, where environmental stress limits which species from a larger species pool gain membership in a local community owing to their traits. Whereas most studies focus on small-scale variation in Functional traits along environmental gradient, the effect of large-scale environmental filtering is less well understood. Furthermore, it has been rarely tested whether the factors that constrain the niche Space limit the total number of coexisting species. We assessed the role of environmental filtering in shaping tree assemblages across North America north of Mexico by testing the hypothesis that colder, drier, or seasonal environments (stressful conditions for most plants) constrain tree trait diversity and thereby limit species richness. We assessed geographic patterns in trait filtering and their relationships to species richness pattern using a comprehensive set of tree range maps. We focused on four key plant Functional traits reflecting major life history axes (maximum height, specific leaf area, seed mass, and wood density) and four climatic variables (annual mean and seasonality of temperature and precipitation). We tested for significant spatial shifts in trait means and variances using a null model approach. While we found significant shifts in mean species’ trait values at most grid cells, trait variances at most grid cells did not deviate from the null expectation. Measures of environmental harshness (cold, dry, seasonal climates) and lower species richness were weakly associated with a reduction in variance of seed mass and specific leaf area. The pattern in variance of height and wood density was, however, opposite. These findings do not support the hypothesis that more stressful conditions universally limit species and trait diversity in North America. Environmental filtering does, however, structure assemblage composition, by selecting for certain optimum trait values under a given set of conditions.
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shifts in trait means and variances in north american tree assemblages species richness patterns are loosely related to the Functional Space
Ecography, 2015Co-Authors: Irena Simova, Cyrille Violle, Nathan J B Kraft, David Storch, Jenschristian Svenning, Brad Boyle, John C Donoghue, Peter M Jorgensen, Brian J McgillAbstract:One of the key hypothesized drivers of gradients in species richness is environmental filtering, where environmental stress limits which species from a larger species pool gain membership in a local community owing to their traits. Whereas most studies focus on small-scale variation in Functional traits along environmental gradient, the effect of large-scale environmental filtering is less well understood. Furthermore, it has been rarely tested whether the factors that constrain the niche Space limit the total number of coexisting species. We assessed the role of environmental filtering in shaping tree assemblages across North America north of Mexico by testing the hypothesis that colder, drier, or seasonal environments (stressful conditions for most plants) constrain tree trait diversity and thereby limit species richness. We assessed geographic patterns in trait filtering and their relationships to species richness pattern using a comprehensive set of tree range maps. We focused on four key plant Functional traits reflecting major life history axes (maximum height, specific leaf area, seed mass, and wood density) and four climatic variables (annual mean and seasonality of temperature and precipitation). We tested for significant spatial shifts in trait means and variances using a null model approach. While we found significant shifts in mean species’ trait values at most grid cells, trait variances at most grid cells did not deviate from the null expectation. Measures of environmental harshness (cold, dry, seasonal climates) and lower species richness were weakly associated with a reduction in variance of seed mass and specific leaf area. The pattern in variance of height and wood density was, however, opposite. These findings do not support the hypothesis that more stressful conditions universally limit species and trait diversity in North America. Environmental filtering does, however, structure assemblage composition, by selecting for certain optimum trait values under a given set of conditions.
Irena Simova - One of the best experts on this subject based on the ideXlab platform.
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shifts in trait means and variances in north american tree assemblages species richness patterns are loosely related to the Functional Space
Ecography, 2015Co-Authors: Irena Simova, Cyrille Violle, Nathan J B Kraft, David Storch, Jenschristian Svenning, Brad Boyle, John C Donoghue, Peter M Jorgensen, Brian J McgillAbstract:One of the key hypothesized drivers of gradients in species richness is environmental filtering, where environmental stress limits which species from a larger species pool gain membership in a local community owing to their traits. Whereas most studies focus on small-scale variation in Functional traits along environmental gradient, the effect of large-scale environmental filtering is less well understood. Furthermore, it has been rarely tested whether the factors that constrain the niche Space limit the total number of coexisting species. We assessed the role of environmental filtering in shaping tree assemblages across North America north of Mexico by testing the hypothesis that colder, drier, or seasonal environments (stressful conditions for most plants) constrain tree trait diversity and thereby limit species richness. We assessed geographic patterns in trait filtering and their relationships to species richness pattern using a comprehensive set of tree range maps. We focused on four key plant Functional traits reflecting major life history axes (maximum height, specific leaf area, seed mass, and wood density) and four climatic variables (annual mean and seasonality of temperature and precipitation). We tested for significant spatial shifts in trait means and variances using a null model approach. While we found significant shifts in mean species’ trait values at most grid cells, trait variances at most grid cells did not deviate from the null expectation. Measures of environmental harshness (cold, dry, seasonal climates) and lower species richness were weakly associated with a reduction in variance of seed mass and specific leaf area. The pattern in variance of height and wood density was, however, opposite. These findings do not support the hypothesis that more stressful conditions universally limit species and trait diversity in North America. Environmental filtering does, however, structure assemblage composition, by selecting for certain optimum trait values under a given set of conditions.
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shifts in trait means and variances in north american tree assemblages species richness patterns are loosely related to the Functional Space
Ecography, 2015Co-Authors: Irena Simova, Cyrille Violle, Nathan J B Kraft, David Storch, Jenschristian Svenning, Brad Boyle, John C Donoghue, Peter M Jorgensen, Brian J McgillAbstract:One of the key hypothesized drivers of gradients in species richness is environmental filtering, where environmental stress limits which species from a larger species pool gain membership in a local community owing to their traits. Whereas most studies focus on small-scale variation in Functional traits along environmental gradient, the effect of large-scale environmental filtering is less well understood. Furthermore, it has been rarely tested whether the factors that constrain the niche Space limit the total number of coexisting species. We assessed the role of environmental filtering in shaping tree assemblages across North America north of Mexico by testing the hypothesis that colder, drier, or seasonal environments (stressful conditions for most plants) constrain tree trait diversity and thereby limit species richness. We assessed geographic patterns in trait filtering and their relationships to species richness pattern using a comprehensive set of tree range maps. We focused on four key plant Functional traits reflecting major life history axes (maximum height, specific leaf area, seed mass, and wood density) and four climatic variables (annual mean and seasonality of temperature and precipitation). We tested for significant spatial shifts in trait means and variances using a null model approach. While we found significant shifts in mean species’ trait values at most grid cells, trait variances at most grid cells did not deviate from the null expectation. Measures of environmental harshness (cold, dry, seasonal climates) and lower species richness were weakly associated with a reduction in variance of seed mass and specific leaf area. The pattern in variance of height and wood density was, however, opposite. These findings do not support the hypothesis that more stressful conditions universally limit species and trait diversity in North America. Environmental filtering does, however, structure assemblage composition, by selecting for certain optimum trait values under a given set of conditions.
Sebastien Villeger - One of the best experts on this subject based on the ideXlab platform.
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how many dimensions are needed to accurately assess Functional diversity a pragmatic approach for assessing the quality of Functional Spaces
Global Ecology and Biogeography, 2015Co-Authors: Eva Maire, Gael Grenouillet, Sebastien Brosse, Sebastien VillegerAbstract:Aim Functional diversity is a key facet of biodiversity that is increasingly being measured to quantify its changes following disturbance and to understand its effects on ecosystem functioning. Assessing the Functional diversity of assemblages based on species traits requires the building of a Functional Space (dendrogram or multidimensional Space) where indices will be computed. However, there is still no consensus on the best method for measuring the quality of Functional Spaces. Innovation Here we propose a framework for evaluating the quality of a Functional Space (i.e. the extent to which it is a faithful representation of the initial Functional trait values). Using simulated datasets, we analysed the influence of the number and type of Functional traits used and of the number of species studied on the identity and quality of the best Functional Space. We also tested whether the quality of the Functional Space affects Functional diversity patterns in local assemblages, using simulated datasets and a real study case. Main conclusions The quality of Functional Space strongly varied between situations. Spaces having at least four dimensions had the highest quality, while Functional dendrograms and two-dimensional Functional Spaces always had a low quality. Importantly, we showed that using a poor-quality Functional Space could led to a biased assessment of Functional diversity and false ecological conclusions. Therefore, we advise a pragmatic approach consisting of computing all the possible Functional Spaces and selecting the most parsimonious one.
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a Functional approach reveals community responses to disturbances
Trends in Ecology and Evolution, 2013Co-Authors: Norman W. H. Mason, David Mouillot, Sebastien Villeger, Nicholas A J Graham, David R BellwoodAbstract:Understanding the processes shaping biological communities under multiple disturbances is a core challenge in ecology and conservation science. Traditionally, ecologists have explored linkages between the severity and type of disturbance and the taxonomic structure of communities. Recent advances in the application of species traits, to assess the Functional structure of communities, have provided an alternative approach that responds rapidly and consistently across taxa and ecosystems to multiple disturbances. Importantly, trait-based metrics may provide advanced warning of disturbance to ecosystems because they do not need species loss to be reactive. Here, we synthesize empirical evidence and present a theoretical framework, based on species positions in a Functional Space, as a tool to reveal the complex nature of change in disturbed ecosystems.
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the multidimensionality of the niche reveals Functional diversity changes in benthic marine biotas across geological time
Ecology Letters, 2011Co-Authors: David Mouillot, Sebastien Villeger, Philip M NovackgottshallAbstract:Despite growing attention on the influence of Functional diversity changes on ecosystem functioning, a palaeoecological perspective on the long-term dynamic of Functional diversity, including mass extinction crises, is still lacking. Here, using a novel multidimensional Functional framework and comprehensive null-models, we compare the Functional structure of Cambrian, Silurian and modern benthic marine biotas. We demonstrate that, after controlling for increases in taxonomic diversity, Functional richness increased incrementally between each time interval with benthic taxa filling progressively more Functional Space, combined with a significant Functional dissimilarity between periods. The modern benthic biota Functionally overlaps with fossil biotas but some modern taxa, especially large predators, have new trait combinations that may allow more functions to be performed. From a methodological perspective, these results illustrate the benefits of using multidimensional instead of lower dimensional Functional frameworks when studying changes in Functional diversity over Space and time.
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new multidimensional Functional diversity indices for a multifaceted framework in Functional ecology
Ecology, 2008Co-Authors: Sebastien Villeger, Norman W. H. Mason, David MouillotAbstract:Functional diversity is increasingly identified as an important driver of ecosystem functioning. Various indices have been proposed to measure the Functional diversity of a community, but there is still no consensus on which are most suitable. Indeed, none of the existing indices meets all the criteria required for general use. The main criteria are that they must be designed to deal with several traits, take into account abundances, and measure all the facets of Functional diversity. Here we propose three indices to quantify each facet of Functional diversity for a community with species distributed in a multidimensional Functional Space: Functional richness (volume of the Functional Space occupied by the community), Functional evenness (regularity of the distribution of abundance in this volume), and Functional divergence (divergence in the distribution of abundance in this volume). Functional richness is estimated using the existing convex hull volume index. The new Functional evenness index is based on the minimum spanning tree which links all the species in the multidimensional Functional Space. Then this new index quantifies the regularity with which species abundances are distributed along the spanning tree. Functional divergence is measured using a novel index which quantifies how species diverge in their distances (weighted by their abundance) from the center of gravity in the Functional Space. We show that none of the indices meets all the criteria required for a Functional diversity index, but instead we show that the set of three complementary indices meets these criteria. Through simulations of artificial data sets, we demonstrate that Functional divergence and Functional evenness are independent of species richness and that the three Functional diversity indices are independent of each other. Overall, our study suggests that decomposition of Functional diversity into its three primary components provides a meaningful framework for its quantification and for the classification of existing Functional diversity indices. This decomposition has the potential to shed light on the role of biodiversity on ecosystem functioning and on the influence of biotic and abiotic filters on the structure of species communities. Finally, we propose a general framework for applying these three Functional diversity indices.
David Mouillot - One of the best experts on this subject based on the ideXlab platform.
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a Functional approach reveals community responses to disturbances
Trends in Ecology and Evolution, 2013Co-Authors: Norman W. H. Mason, David Mouillot, Sebastien Villeger, Nicholas A J Graham, David R BellwoodAbstract:Understanding the processes shaping biological communities under multiple disturbances is a core challenge in ecology and conservation science. Traditionally, ecologists have explored linkages between the severity and type of disturbance and the taxonomic structure of communities. Recent advances in the application of species traits, to assess the Functional structure of communities, have provided an alternative approach that responds rapidly and consistently across taxa and ecosystems to multiple disturbances. Importantly, trait-based metrics may provide advanced warning of disturbance to ecosystems because they do not need species loss to be reactive. Here, we synthesize empirical evidence and present a theoretical framework, based on species positions in a Functional Space, as a tool to reveal the complex nature of change in disturbed ecosystems.
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the multidimensionality of the niche reveals Functional diversity changes in benthic marine biotas across geological time
Ecology Letters, 2011Co-Authors: David Mouillot, Sebastien Villeger, Philip M NovackgottshallAbstract:Despite growing attention on the influence of Functional diversity changes on ecosystem functioning, a palaeoecological perspective on the long-term dynamic of Functional diversity, including mass extinction crises, is still lacking. Here, using a novel multidimensional Functional framework and comprehensive null-models, we compare the Functional structure of Cambrian, Silurian and modern benthic marine biotas. We demonstrate that, after controlling for increases in taxonomic diversity, Functional richness increased incrementally between each time interval with benthic taxa filling progressively more Functional Space, combined with a significant Functional dissimilarity between periods. The modern benthic biota Functionally overlaps with fossil biotas but some modern taxa, especially large predators, have new trait combinations that may allow more functions to be performed. From a methodological perspective, these results illustrate the benefits of using multidimensional instead of lower dimensional Functional frameworks when studying changes in Functional diversity over Space and time.
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new multidimensional Functional diversity indices for a multifaceted framework in Functional ecology
Ecology, 2008Co-Authors: Sebastien Villeger, Norman W. H. Mason, David MouillotAbstract:Functional diversity is increasingly identified as an important driver of ecosystem functioning. Various indices have been proposed to measure the Functional diversity of a community, but there is still no consensus on which are most suitable. Indeed, none of the existing indices meets all the criteria required for general use. The main criteria are that they must be designed to deal with several traits, take into account abundances, and measure all the facets of Functional diversity. Here we propose three indices to quantify each facet of Functional diversity for a community with species distributed in a multidimensional Functional Space: Functional richness (volume of the Functional Space occupied by the community), Functional evenness (regularity of the distribution of abundance in this volume), and Functional divergence (divergence in the distribution of abundance in this volume). Functional richness is estimated using the existing convex hull volume index. The new Functional evenness index is based on the minimum spanning tree which links all the species in the multidimensional Functional Space. Then this new index quantifies the regularity with which species abundances are distributed along the spanning tree. Functional divergence is measured using a novel index which quantifies how species diverge in their distances (weighted by their abundance) from the center of gravity in the Functional Space. We show that none of the indices meets all the criteria required for a Functional diversity index, but instead we show that the set of three complementary indices meets these criteria. Through simulations of artificial data sets, we demonstrate that Functional divergence and Functional evenness are independent of species richness and that the three Functional diversity indices are independent of each other. Overall, our study suggests that decomposition of Functional diversity into its three primary components provides a meaningful framework for its quantification and for the classification of existing Functional diversity indices. This decomposition has the potential to shed light on the role of biodiversity on ecosystem functioning and on the influence of biotic and abiotic filters on the structure of species communities. Finally, we propose a general framework for applying these three Functional diversity indices.
