The Experts below are selected from a list of 625158 Experts worldwide ranked by ideXlab platform
Michael Doebeli - One of the best experts on this subject based on the ideXlab platform.
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high taxonomic variability despite stable Functional Structure across microbial communities
Nature Ecology and Evolution, 2017Co-Authors: Stilianos Louca, Saulo M S Jacques, Aliny P F Pires, Juliana S Leal, Laura Wegener Parfrey, Diane S. Srivastava, Vinicius F. Farjalla, Michael DoebeliAbstract:Understanding the processes that are driving variation of natural microbial communities across space or time is a major challenge for ecologists. Environmental conditions strongly shape the metabolic function of microbial communities; however, other processes such as biotic interactions, random demographic drift or dispersal limitation may also influence community dynamics. The relative importance of these processes and their effects on community function remain largely unknown. To address this uncertainty, here we examined bacterial and archaeal communities in replicate ‘miniature’ aquatic ecosystems contained within the foliage of wild bromeliads. We used marker gene sequencing to infer the taxonomic composition within nine metabolic Functional groups, and shotgun environmental DNA sequencing to estimate the relative abundances of these groups. We found that all of the bromeliads exhibited remarkably similar Functional community Structures, but that the taxonomic composition within individual Functional groups was highly variable. Furthermore, using statistical analyses, we found that non-neutral processes, including environmental filtering and potentially biotic interactions, at least partly shaped the composition within Functional groups and were more important than spatial dispersal limitation and demographic drift. Hence both the Functional Structure and taxonomic composition within Functional groups of natural microbial communities may be shaped by non-neutral and roughly separate processes. Microbial communities in the foliage of wild bromeliads exhibit remarkably stable Functional community Structure despite large variation in taxonomic composition, indicating that non-neutral processes drive changes in community composition.
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high taxonomic variability despite stable Functional Structure across microbial communities
Nature Ecology and Evolution, 2017Co-Authors: Stilianos Louca, Saulo M S Jacques, Aliny P F Pires, Juliana S Leal, Laura Wegener Parfrey, Diane S. Srivastava, Vinicius F. Farjalla, Michael DoebeliAbstract:Understanding the processes that are driving variation of natural microbial communities across space or time is a major challenge for ecologists. Environmental conditions strongly shape the metabolic function of microbial communities; however, other processes such as biotic interactions, random demographic drift or dispersal limitation may also influence community dynamics. The relative importance of these processes and their effects on community function remain largely unknown. To address this uncertainty, here we examined bacterial and archaeal communities in replicate 'miniature' aquatic ecosystems contained within the foliage of wild bromeliads. We used marker gene sequencing to infer the taxonomic composition within nine metabolic Functional groups, and shotgun environmental DNA sequencing to estimate the relative abundances of these groups. We found that all of the bromeliads exhibited remarkably similar Functional community Structures, but that the taxonomic composition within individual Functional groups was highly variable. Furthermore, using statistical analyses, we found that non-neutral processes, including environmental filtering and potentially biotic interactions, at least partly shaped the composition within Functional groups and were more important than spatial dispersal limitation and demographic drift. Hence both the Functional Structure and taxonomic composition within Functional groups of natural microbial communities may be shaped by non-neutral and roughly separate processes.
David Mouillot - One of the best experts on this subject based on the ideXlab platform.
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Disentangling the pathways of land use impacts on the Functional Structure of fish assemblages in Amazon streams
Ecography, 2018Co-Authors: Rafael P. Leitão, David Mouillot, Sébastien Villéger, Jansen Zuanon, Cecilia G. Leal, Robert M. Hughes, Philip R. Kaufmann, Paulo S. Pompeu, Daniele Kasper, Felipe R. PaulaAbstract:Agricultural land use is a primary driver of environmental impacts on streams. However, the causal processes that shape these impacts operate through multiple pathways and at several spatial scales. This complexity undermines the development of more effective management approaches, and illustrates the need for more in-depth studies to assess the mechanisms that determine changes in stream biodiversity. Here we present results of the most comprehensive multi-scale assessment of the biological condition of streams in the Amazon to date, examining Functional responses of fish assemblages to land use. We sampled fish assemblages from two large human-modified regions, and characterized stream conditions by physical habitat attributes and key landscape-change variables, including density of road crossings (i.e. riverscape fragmentation), deforestation, and agricultural intensification. Fish species were Functionally characterized using ecomorphological traits describing feeding, locomotion, and habitat preferences, and these traits were used to derive indices that quantitatively describe the Functional Structure of the assemblages. Using structural equation modeling, we disentangled multiple drivers operating at different spatial scales, identifying causal pathways that significantly affect stream condition and the Structure of the fish assemblages. Deforestation at catchment and riparian network scales altered the channel morphology and the stream bottom Structure, changing the Functional identity of assemblages. Local deforestation reduced the Functional evenness of assemblages (i.e. increased dominance of specific trait combinations) mediated by expansion of aquatic vegetation cover. Riverscape fragmentation reduced Functional richness, evenness and divergence, suggesting a trend toward Functional homogenization and a reduced range of ecological niches within assemblages following the loss of regional connectivity. These results underscore the often-unrecognized importance of different land use changes, each of which can have marked effects on stream biodiversity. We draw on the relationships observed herein to suggest priorities for the improved management of stream systems in the multiple-use landscapes that predominate in human-modified tropical forests.
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Rare species contribute disproportionately to the Functional Structure of species assemblages
Proceedings of the Royal Society B: Biological Sciences, 2016Co-Authors: Rafael P. Leitão, Sébastien Villéger, Jansen Zuanon, Stephen E. Williams, Christopher Baraloto, Claire Fortunel, Fernando P. Mendonça, David MouillotAbstract:There is broad consensus that the diversity of Functional traits within species assemblages drives several ecological processes. It is also widely recognized that rare species are the first to become extinct following human-induced disturbances. Surprisingly, however, the Functional importance of rare species is still poorly understood, particularly in tropical species-rich assemblages where the majority of species are rare, and the rate of species extinction can be high. Here, we investigated the consequences of local and regional extinctions on the Functional Structure of species assemblages. We used three extensive datasets (stream fish from the Brazilian Amazon, rainforest trees from French Guiana, and birds from the Australian Wet Tropics) and built an integrative measure of species rarity versus commonness, combining local abundance, geographical range, and habitat breadth. Using different scenarios of species loss, we found a disproportionate impact of rare species extinction for the three groups, with significant reductions in levels of Functional richness, specialization, and originality of assemblages, which may severely undermine the integrity of ecological processes. The whole breadth of Functional abilities within species assemblages, which is disproportionately supported by rare species, is certainly critical in maintaining ecosystems particularly under the ongoing rapid environmental transitions.
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Functional Structure of Biological Communities Predicts Ecosystem MultiFunctionality
PloS one, 2011Co-Authors: David Mouillot, Sébastien Villéger, Michael Scherer-lorenzen, Norman W. H. MasonAbstract:The accelerating rate of change in biodiversity patterns, mediated by ever increasing human pressures and global warming, demands a better understanding of the relationship between the Structure of biological communities and ecosystem functioning (BEF). Recent investigations suggest that the Functional Structure of communities, i.e. the composition and diversity of Functional traits, is the main driver of ecological processes. However, the predictive power of BEF research is still low, the integration of all components of Functional community Structure as predictors is still lacking, and the multiFunctionality of ecosystems (i.e. rates of multiple processes) must be considered. Here, using a multiple-processes framework from grassland biodiversity experiments, we show that Functional identity of species and Functional divergence among species, rather than species diversity per se, together promote the level of ecosystem multiFunctionality with a predictive power of 80%. Our results suggest that primary productivity and decomposition rates, two key ecosystem processes upon which the global carbon cycle depends, are primarily sustained by specialist species, i.e. those that hold specialized combinations of traits and perform particular functions. Contrary to studies focusing on single ecosystem functions and considering species richness as the sole measure of biodiversity, we found a linear and non-saturating effect of the Functional Structure of communities on ecosystem multiFunctionality. Thus, sustaining multiple ecological processes would require focusing on trait dominance and on the degree of community specialization, even in species-rich assemblages.
Stilianos Louca - One of the best experts on this subject based on the ideXlab platform.
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high taxonomic variability despite stable Functional Structure across microbial communities
Nature Ecology and Evolution, 2017Co-Authors: Stilianos Louca, Saulo M S Jacques, Aliny P F Pires, Juliana S Leal, Laura Wegener Parfrey, Diane S. Srivastava, Vinicius F. Farjalla, Michael DoebeliAbstract:Understanding the processes that are driving variation of natural microbial communities across space or time is a major challenge for ecologists. Environmental conditions strongly shape the metabolic function of microbial communities; however, other processes such as biotic interactions, random demographic drift or dispersal limitation may also influence community dynamics. The relative importance of these processes and their effects on community function remain largely unknown. To address this uncertainty, here we examined bacterial and archaeal communities in replicate ‘miniature’ aquatic ecosystems contained within the foliage of wild bromeliads. We used marker gene sequencing to infer the taxonomic composition within nine metabolic Functional groups, and shotgun environmental DNA sequencing to estimate the relative abundances of these groups. We found that all of the bromeliads exhibited remarkably similar Functional community Structures, but that the taxonomic composition within individual Functional groups was highly variable. Furthermore, using statistical analyses, we found that non-neutral processes, including environmental filtering and potentially biotic interactions, at least partly shaped the composition within Functional groups and were more important than spatial dispersal limitation and demographic drift. Hence both the Functional Structure and taxonomic composition within Functional groups of natural microbial communities may be shaped by non-neutral and roughly separate processes. Microbial communities in the foliage of wild bromeliads exhibit remarkably stable Functional community Structure despite large variation in taxonomic composition, indicating that non-neutral processes drive changes in community composition.
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high taxonomic variability despite stable Functional Structure across microbial communities
Nature Ecology and Evolution, 2017Co-Authors: Stilianos Louca, Saulo M S Jacques, Aliny P F Pires, Juliana S Leal, Laura Wegener Parfrey, Diane S. Srivastava, Vinicius F. Farjalla, Michael DoebeliAbstract:Understanding the processes that are driving variation of natural microbial communities across space or time is a major challenge for ecologists. Environmental conditions strongly shape the metabolic function of microbial communities; however, other processes such as biotic interactions, random demographic drift or dispersal limitation may also influence community dynamics. The relative importance of these processes and their effects on community function remain largely unknown. To address this uncertainty, here we examined bacterial and archaeal communities in replicate 'miniature' aquatic ecosystems contained within the foliage of wild bromeliads. We used marker gene sequencing to infer the taxonomic composition within nine metabolic Functional groups, and shotgun environmental DNA sequencing to estimate the relative abundances of these groups. We found that all of the bromeliads exhibited remarkably similar Functional community Structures, but that the taxonomic composition within individual Functional groups was highly variable. Furthermore, using statistical analyses, we found that non-neutral processes, including environmental filtering and potentially biotic interactions, at least partly shaped the composition within Functional groups and were more important than spatial dispersal limitation and demographic drift. Hence both the Functional Structure and taxonomic composition within Functional groups of natural microbial communities may be shaped by non-neutral and roughly separate processes.
Pantaleo K. T. Munishi - One of the best experts on this subject based on the ideXlab platform.
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Species composition and Functional Structure of herbaceous vegetation in a tropical wetland system
Biodiversity and Conservation, 2012Co-Authors: Samora M. Andrew, Ørjan Totland, Pantaleo K. T. MunishiAbstract:Understanding driving factors of spatial heterogeneity in plant species composition and Functional Structure is a key step towards wetland ecosystems restoration and biodiversity conservation. We surveyed 60 randomly selected plots of 20 × 50 m each and collected 12 explanatory variables to understand potential impacts of natural environmental conditions, human disturbance and spatial position of plots variables on plant Functional groups (PFGs) and species composition within grasslands of the Kilombero Valley Floodplain wetland, Tanzania. Ordination analyses were used to identify important vegetation gradients and establish significant natural environmental conditions, human disturbance and spatial position of plots correlates. Partial redundancy analysis (RDA) and partial canonical correspondence analysis (CCA) were used to determine the individual and shared effects of these three sets of explanatory variables on the PFGs and species composition, respectively. In total, 115 plant species, including 22 weed and 3 invasive species, and five PFGs were registered. Annual graminoid was the most abundant, whereas perennial forb the least abundant PFG with 50 and 1 % relative covers, respectively. Overall, spatial position, altitude, total organic carbon, cow dung, distance to the river and distance to kraal (cattle enclosure near human settlement commonly made of wood materials for animal protection) were important descriptors of both PFGs and overall species composition. Separate CCA of only weed and invasive plant species showed that some species, particularly the invasive Polygala paniculata were strongly associated with cow dung, indicating that present increase in cattle numbers may result in future problems associated with this species. Intensification of human activities and alteration of natural environmental conditions associated with these factors should be discouraged to maintain plant species composition and Functional Structure for wetland restoration and sustainable biodiversity conservation.
Rafael P. Leitão - One of the best experts on this subject based on the ideXlab platform.
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Disentangling the pathways of land use impacts on the Functional Structure of fish assemblages in Amazon streams
Ecography, 2018Co-Authors: Rafael P. Leitão, David Mouillot, Sébastien Villéger, Jansen Zuanon, Cecilia G. Leal, Robert M. Hughes, Philip R. Kaufmann, Paulo S. Pompeu, Daniele Kasper, Felipe R. PaulaAbstract:Agricultural land use is a primary driver of environmental impacts on streams. However, the causal processes that shape these impacts operate through multiple pathways and at several spatial scales. This complexity undermines the development of more effective management approaches, and illustrates the need for more in-depth studies to assess the mechanisms that determine changes in stream biodiversity. Here we present results of the most comprehensive multi-scale assessment of the biological condition of streams in the Amazon to date, examining Functional responses of fish assemblages to land use. We sampled fish assemblages from two large human-modified regions, and characterized stream conditions by physical habitat attributes and key landscape-change variables, including density of road crossings (i.e. riverscape fragmentation), deforestation, and agricultural intensification. Fish species were Functionally characterized using ecomorphological traits describing feeding, locomotion, and habitat preferences, and these traits were used to derive indices that quantitatively describe the Functional Structure of the assemblages. Using structural equation modeling, we disentangled multiple drivers operating at different spatial scales, identifying causal pathways that significantly affect stream condition and the Structure of the fish assemblages. Deforestation at catchment and riparian network scales altered the channel morphology and the stream bottom Structure, changing the Functional identity of assemblages. Local deforestation reduced the Functional evenness of assemblages (i.e. increased dominance of specific trait combinations) mediated by expansion of aquatic vegetation cover. Riverscape fragmentation reduced Functional richness, evenness and divergence, suggesting a trend toward Functional homogenization and a reduced range of ecological niches within assemblages following the loss of regional connectivity. These results underscore the often-unrecognized importance of different land use changes, each of which can have marked effects on stream biodiversity. We draw on the relationships observed herein to suggest priorities for the improved management of stream systems in the multiple-use landscapes that predominate in human-modified tropical forests.
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Rare species contribute disproportionately to the Functional Structure of species assemblages
Proceedings of the Royal Society B: Biological Sciences, 2016Co-Authors: Rafael P. Leitão, Sébastien Villéger, Jansen Zuanon, Stephen E. Williams, Christopher Baraloto, Claire Fortunel, Fernando P. Mendonça, David MouillotAbstract:There is broad consensus that the diversity of Functional traits within species assemblages drives several ecological processes. It is also widely recognized that rare species are the first to become extinct following human-induced disturbances. Surprisingly, however, the Functional importance of rare species is still poorly understood, particularly in tropical species-rich assemblages where the majority of species are rare, and the rate of species extinction can be high. Here, we investigated the consequences of local and regional extinctions on the Functional Structure of species assemblages. We used three extensive datasets (stream fish from the Brazilian Amazon, rainforest trees from French Guiana, and birds from the Australian Wet Tropics) and built an integrative measure of species rarity versus commonness, combining local abundance, geographical range, and habitat breadth. Using different scenarios of species loss, we found a disproportionate impact of rare species extinction for the three groups, with significant reductions in levels of Functional richness, specialization, and originality of assemblages, which may severely undermine the integrity of ecological processes. The whole breadth of Functional abilities within species assemblages, which is disproportionately supported by rare species, is certainly critical in maintaining ecosystems particularly under the ongoing rapid environmental transitions.
