[show abstract][hide abstract] ABSTRACT: AimWe investigate patterns of phylogenetic diversity in relation to species diversity for European birds, mammals and amphibians to evaluate their congruence and highlight areas of particular evolutionary history. We estimate the extent to which the European network of protected areas (PAs) network retains interesting evolutionary history areas for the three groups separately and simultaneously. LocationEurope Methods
Phylogenetic (QEPD) and species diversity (SD) were estimated using the Rao's quadratic entropy at 10′ resolution. We determined the regional relationship between QEPD and SD for each taxa with a spatial regression model and used the tails of the residuals (QERES) distribution to identify areas of higher and lower QEPD than predicted. Spatial congruence of biodiversity between groups was assessed with Pearson correlation coefficient. A simple classification scheme allowed building a convergence map where a convergent pixel equalled to a QERES value of the same sign for the three groups. This convergence map was overlaid to the current PAs network to estimate the level of protection in convergent pixels and compared it to a null expectation built on 1000 randomization of PAs over the landscape. ResultsQERES patterns across vertebrates show a strong spatial mismatch highlighting different evolutionary histories. Convergent areas represent only 2.7% of the Western Palearctic, with only 8.4% of these areas being covered by the current PAs network while a random distribution would retain 10.4% of them. QERES are unequally represented within PAs: areas with higher QEPD than predicted are better covered than expected, while low QEPD areas are undersampled. Main conclusionsPatterns of diversity strongly diverge between groups of vertebrates in Europe. Although Europe has the world's most extensive PAs network, evolutionary history of terrestrial vertebrates is unequally protected. The challenge is now to reconcile effective conservation planning with a contemporary view of biodiversity integrating multiple facets.
Diversity and Distributions 02/2014; · 6.12 Impact Factor
[show abstract][hide abstract] ABSTRACT: Despite the recognized joint impact of climate and land cover change on facets of biodiversity and their associated functions, risk assessments have primarily evaluated impacts on species ranges and richness. Here we quantify the sensitivity of the functional structure of European avian assemblages to changes in both regional climate and land cover. We combine species range forecasts with functional-trait information. We show that species sensitivity to environmental change is randomly distributed across the functional tree of the European avifauna and that functionally unique species are not disproportionately threatened by 2080. However, projected species range changes will modify the mean species richness and functional diversity of bird diets and feeding behaviours. This will unequally affect the spatial structure of functional diversity, leading to homogenization across Europe. Therefore, global changes may alter the functional structure of species assemblages in the future in ways that need to be accounted for in conservation planning.
[show abstract][hide abstract] ABSTRACT: Aim Phylogenetic diversity patterns are increasingly being used to better understand the role of ecological and evolutionary processes in community assembly. Here, we quantify how these patterns are influenced by scale choices in terms of spatial and environmental extent and organismic scales. LocationEuropean Alps.
Methods We applied 42 sampling strategies differing in their combination of focal scales. For each resulting sub-dataset, we estimated the phylogenetic diversity of the species pools, phylogenetic α-diversities of local communities, and statistics commonly used together with null models in order to infer non-random diversity patterns (i.e. phylogenetic clustering versus over-dispersion). Finally, we studied the effects of scale choices on these measures using regression analyses.
Results Scale choices were decisive for revealing signals in diversity patterns. Notably, changes in focal scales sometimes reversed a pattern of over-dispersion into clustering. Organismic scale had a stronger effect than spatial and environmental extent. However, we did not find general rules for the direction of change from over-dispersion to clustering with changing scales. Importantly, these scale issues had only a weak influence when focusing on regional diversity patterns that change along abiotic gradients.
Main conclusions Our results call for caution when combining phylogenetic data with distributional data to study how and why communities differ from random expectations of phylogenetic relatedness. These analyses seem to be robust when the focus is on relating community diversity patterns to variation in habitat conditions, such as abiotic gradients. However, if the focus is on identifying relevant assembly rules for local communities, the uncertainty arising from a certain scale choice can be immense. In the latter case, it becomes necessary to test whether emerging patterns are robust to alternative scale choices.
Global Ecology and Biogeography 01/2014; · 7.22 Impact Factor
[show abstract][hide abstract] ABSTRACT: Biological invasions can transform our understanding of how the interplay of historical isolation and contemporary (human-aided) dispersal affects the structure of intraspecific diversity in functional traits, and in turn, how changes in functional traits affect other scales of biological organization such as communities and ecosystems. Because biological invasions frequently involve the admixture of previously isolated lineages as a result of human-aided dispersal, studies of invasive populations can reveal how admixture results in novel genotypes and shifts in functional trait variation within populations. Further, because invasive species can be ecosystem engineers within invaded ecosystems, admixture-induced shifts in the functional traits of invaders can affect the composition of native biodiversity and alter the flow of resources through the system. Thus, invasions represent promising yet under-investigated examples of how the effects of short-term evolutionary changes can cascade across biological scales of diversity. Here, we propose a conceptual framework that admixture between divergent source populations during biological invasions can reorganize the genetic variation underlying key functional traits, leading to shifts in the mean and variance of functional traits within invasive populations. Changes in the mean or variance of key traits can initiate new ecological feedback mechanisms that result in a critical transition from a native ecosystem to a novel invasive ecosystem. We illustrate the application of this framework with reference to a well-studied plant model system in invasion biology and show how a combination of quantitative genetic experiments, functional trait studies, whole ecosystem field studies and modeling can be used to explore the dynamics predicted to trigger these critical transitions.
[show abstract][hide abstract] ABSTRACT: Aim: The origins of ecological diversity in continental species assemblages have
long intrigued biogeographers. We apply phylogenetic comparative analyses to
disentangle the evolutionary patterns of ecological niches in an assemblage of
European birds.We compare phylogenetic patterns in trophic, habitat and climatic
Methods: From polygon range maps and handbook data we inferred the realized
climatic, habitat and trophic niches of 405 species of breeding birds in Europe.We
fitted Pagel’s lambda and kappa statistics, and conducted analyses of disparity
through time to compare temporal patterns of ecological diversification on all
niche axes together. All observed patterns were compared with expectations based
on neutral (Brownian) models of niche divergence.
Results: In this assemblage, patterns of phylogenetic signal (lambda) suggest that
related species resemble each other less in regard to their climatic and habitat niches
than they do in their trophic niche. Kappa estimates show that ecological divergence
does not gradually increase with divergence time, and that this punctualism
is stronger in climatic niches than in habitat and trophic niches. Observed niche
disparity markedly exceeds levels expected from a Brownian model of ecological
diversification, thus providing no evidence for past phylogenetic niche conservatism
in these multivariate niches. Levels of multivariate disparity are greatest for the
climatic niche, followed by disparity of the habitat and the trophic niches.
Main conclusions: Phylogenetic patterns in the three niche components differ
within this avian assemblage.Variation in evolutionary rates (degree of gradualism,
constancy through the tree) and/or non-random macroecological sampling probably
lead here to differences in the phylogenetic structure of niche components.
Testing hypotheses on the origin of these patterns requires more complete
phylogenetic trees of the birds, and extended ecological data on different niche
components for all bird species.
Global Ecology and Biogeography 11/2013; · 7.22 Impact Factor
[show abstract][hide abstract] ABSTRACT: Around the world, the human-induced collapses of populations and species have triggered a sixth mass extinction crisis, with rare species often being the first to disappear. Although the role of species diversity in the maintenance of ecosystem processes has been widely investigated, the role of rare species remains controversial. A critical issue is whether common species insure against the loss of functions supported by rare species. This issue is even more critical in species-rich ecosystems where high functional redundancy among species is likely and where it is thus often assumed that ecosystem functioning is buffered against species loss. Here, using extensive datasets of species occurrences and functional traits from three highly diverse ecosystems (846 coral reef fishes, 2,979 alpine plants, and 662 tropical trees), we demonstrate that the most distinct combinations of traits are supported predominantly by rare species both in terms of local abundance and regional occupancy. Moreover, species that have low functional redundancy and are likely to support the most vulnerable functions, with no other species carrying similar combinations of traits, are rarer than expected by chance in all three ecosystems. For instance, 63% and 98% of fish species that are likely to support highly vulnerable functions in coral reef ecosystems are locally and regionally rare, respectively. For alpine plants, 32% and 89% of such species are locally and regionally rare, respectively. Remarkably, 47% of fish species and 55% of tropical tree species that are likely to support highly vulnerable functions have only one individual per sample on average. Our results emphasize the importance of rare species conservation, even in highly diverse ecosystems, which are thought to exhibit high functional redundancy. Rare species offer more than aesthetic, cultural, or taxonomic diversity value; they disproportionately increase the potential breadth of functions provided by ecosystems across spatial scales. As such, they are likely to insure against future uncertainty arising from climate change and the ever-increasing anthropogenic pressures on ecosystems. Our results call for a more detailed understanding of the role of rarity and functional vulnerability in ecosystem functioning.
[show abstract][hide abstract] ABSTRACT: Predicting how and when adaptive evolution might rescue species from global change, and integrating this process into tools of biodiversity forecasting, has now become an urgent task. Here, we explored whether recent population trends of species can be explained by their past rate of niche evolution, which can be inferred from increasingly available phylogenetic and niche data. We examined the assemblage of 409 European bird species for which estimates of demographic trends between 1970 and 2000 are available, along with a species-level phylogeny and data on climatic, habitat and trophic niches. We found that species' proneness to demographic decline is associated with slow evolution of the habitat niche in the past, in addition to certain current-day life-history and ecological traits. A similar result was found at a higher taxonomic level, where families prone to decline have had a history of slower evolution of climatic and habitat niches. Our results support the view that niche conservatism can prevent some species from coping with environmental change. Thus, linking patterns of past niche evolution and contemporary species dynamics for large species samples may provide insights into how niche evolution may rescue certain lineages in the face of global change.
Philosophical Transactions of The Royal Society B Biological Sciences 01/2013; 368(1610):20120091. · 6.23 Impact Factor
[show abstract][hide abstract] ABSTRACT: Dispersal is a key determinant of a population's evolutionary potential. It facilitates the propagation of beneficial alleles throughout the distributional range of spatially outspread populations and increases the speed of adaptation. However, when habitat is heterogeneous and individuals are locally adapted, dispersal may, at the same time, reduce fitness through increasing maladaptation. Here, we use a spatially explicit, allelic simulation model to quantify how these equivocal effects of dispersal affect a population's evolutionary response to changing climate. Individuals carry a diploid set of chromosomes, with alleles coding for adaptation to non-climatic environmental conditions and climatic conditions, respectively. Our model results demonstrate that the interplay between gene flow and habitat heterogeneity may decrease effective dispersal and population size to such an extent that substantially reduces the likelihood of evolutionary rescue. Importantly, even when evolutionary rescue saves a population from extinction, its spatial range following climate change may be strongly narrowed, that is, the rescue is only partial. These findings emphasize that neglecting the impact of non-climatic, local adaptation might lead to a considerable overestimation of a population's evolvability under rapid environmental change.
Philosophical Transactions of The Royal Society B Biological Sciences 01/2013; 368(1610):20120083. · 6.23 Impact Factor
[show abstract][hide abstract] ABSTRACT: Aim: Metacommunity theories attribute different relative degrees of importance to dispersal, environmental filtering, biotic interactions and stochastic processes in community assembly, but the role of spatial scale remains uncertain. Here we used two complementary statistical tools to test: (1) whether or not the patterns of community structure and environmental influences are consistent across resolutions; and (2) whether and how the joint use of two fundamentally different statistical approaches provides a complementary interpretation of results. Location: Grassland plants in the French Alps. Methods: We used two approaches across five spatial resolutions (ranging from 1 km × 1 km to 30 km × 30 km): variance partitioning, and analysis of metacommunity structure on the site-by-species incidence matrices. Both methods allow the testing of expected patterns resulting from environmental filtering, but variance partitioning allows the role of dispersal and environmental gradients to be studied, while analysis of the site-by-species metacommunity structure informs an understanding of how environmental filtering occurs and whether or not patterns differ from chance expectation. We also used spatial regressions on species richness to identify relevant environmental factors at each scale and to link results from the two approaches. Results: Major environmental drivers of richness included growing degree-days, temperature, moisture and spatial or temporal heterogeneity. Variance partitioning pointed to an increase in the role of dispersal at coarser resolutions, while metacommunity structure analysis pointed to environmental filtering having an important role at all resolutions through a Clementsian assembly process (i.e. groups of species having similar range boundaries and co-occurring in similar environments). Main conclusions: The combination of methods used here allows a better understanding of the forces structuring ecological communities than either one of them used separately. A key aspect in this complementarity is that variance partitioning can detect effects of dispersal whereas metacommunity structure analysis cannot. Moreover, the latter can distinguish between different forms of environmental filtering (e.g. individualistic versus group species responses to environmental gradients).
Journal of Biogeography 01/2013; 40:1560-1571. · 4.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: Questions: Traditional null models used to reveal assembly processes from functional diversity patterns are not tailored for comparing different spatial and evolutionary scales. In this study, we present and explore a family of null models that can help disentangling assembly processes at their appropriate scales and thereby elucidate the ecological drivers of community assembly. Location: French Alps. Methods: Our approach gradually constrains null models by: (1) filtering out species not able to survive in the regional conditions in order to reduce the spa-tial scale, and (2) shuffling species only within lineages of different ages to reduce the evolutionary scale of the analysis. We first tested and validated this approach using simulated communities. We then applied it to study the func-tional diversity patterns of the leaf–height–seed strategy of plant communities in the French Alps. Results: Using simulations, we found that reducing the spatial scale correctly detected a signature of competition (functional divergence) even when environ-mental filtering produced an overlaying signal of functional convergence. How-ever, constraining the evolutionary scale did not change the identified functional diversity patterns. In the case study of alpine plant communities, investigating scale effects revealed that environmental filtering had a strong influence at larger spatial and evolutionary scales and that neutral processes were more important at smaller scales. In contrast to the simulation study results, decreasing the evolutionary scale tended to increase patterns of func-tional divergence. Conclusion: We argue that the traditional null model approach can only iden-tify a single main process at a time and suggest to rather use a family of null models to disentangle intertwined assembly processes acting across spatial and evolutionary scales.
Journal of Vegetation Science 01/2013; 24:853-864. · 2.82 Impact Factor
[show abstract][hide abstract] ABSTRACT: 1. Functional variability (FV) of populations can be decomposed into three main features: the individual variability of multiple traits, the strength of correlations between those traits and the main direction of these correlations, the latter two being known as 'phenotypic integration'. Evolutionary biology has long recognized that FV in natural populations is key to determining potential evolutionary responses, but this topic has been little studied in functional ecology. 2. Here, we focus on the arctico-alpine perennial plant species Polygonum viviparum L.. We used a comprehensive sampling of seven functional traits in 29 wild populations covering the whole environmental niche of the species. The niche of the species was captured by a temperature gradient, which separated alpine stressful habitats from species-rich, competitive subalpine ones. We sought to assess the relative roles of abiotic stress and biotic interactions in shaping different aspects of functional variation within and among populations, that is, the multi-trait variability, the strength of correlations between traits and the main directions of functional trade-offs. 3. Populations with the highest extent of functional variability were found in the warm end of the gradient, whereas populations exhibiting the strongest degree of phenotypic integration were located in sites with intermediate temperatures. This could reveal both the importance of environmental filtering and population demography in structuring FV. Interestingly, we found that the main axes of multivariate functional variation were radically different within and across population. 4. Although the proximate causes of FV structure remain uncertain, our study presents a robust methodology for the quantitative study of functional variability in connection with species' niches. It also opens up new perspectives for the conceptual merging of intraspecific functional patterns with community ecology.
[show abstract][hide abstract] ABSTRACT: The demand for projections of the future distribution of biodiversity has triggered an upsurge in modelling
at the crossroads between ecology and evolution. Despite the enthusiasm around these so-called biodiversity
models, most approaches are still criticised for not integrating key processes known to shape species ranges
and community structure. Developing an integrative modelling framework for biodiversity distribution promises
to improve the reliability of predictions and to give a better understanding of the eco-evolutionary
dynamics of species and communities under changing environments. In this article, we briefly review some
eco-evolutionary processes and interplays among them, which are essential to provide reliable projections of
species distributions and community structure. We identify gaps in theory, quantitative knowledge and data
availability hampering the development of an integrated modelling framework. We argue that model development
relying on a strong theoretical foundation is essential to inspire new models, manage complexity and
maintain tractability. We support our argument with an example of a novel integrated model for species
distribution modelling, derived from metapopulation theory, which accounts for abiotic constraints, dispersal,
biotic interactions and evolution under changing environmental conditions. We hope such a perspective will
motivate exciting and novel research, and challenge others to improve on our proposed approach.
[show abstract][hide abstract] ABSTRACT: Darwin proposed two seemingly contradictory hypotheses for a better understanding of biological invasions. Strong relatedness of invaders to native communities as an indication of niche overlap could promote naturalization because of appropriate niche adaptation, but could also hamper naturalization because of negative interactions with native species (' Darwin ' s naturalization hypothesis '). Although these hypotheses provide clear and opposing predictions for expected patterns of species relatedness in invaded communities, so far no study has been able to clearly disentangle the underlying mechanisms. We hypothesize that confl icting past results are mainly due to the neglected role of spatial resolution of the community sampling. In this study, we corroborate both of Darwin ' s expectations by using phylogenetic relatedness as a measure of niche overlap and by testing the eff ects of sampling resolution in highly invaded coastal plant communities. At spatial resolutions fi ne enough to detect signatures of biotic interactions, we fi nd that most invaders are less related to their nearest relative in invaded plant communities than expected by chance (phylogenetic overdispersion). Yet at coarser spatial resolutions, native assemblages become more invasible for closely-related species as a consequence of habitat fi lter-ing (phylogenetic clustering). Recognition of the importance of the spatial resolution at which communities are studied allows apparently contrasting theoretical and empirical results to be reconciled. Our study opens new perspectives on how to better detect, diff erentiate and understand the impact of negative biotic interactions and habitat fi ltering on the ability of invaders to establish in native communities. Species transported far from their original range that spread and maintain viable populations (i.e. naturalized non-native species sensu Richardson and Pysek 2006) often pose signifi cant challenges to conserving native biodiver-sity. Predicting which species can invade which commu-nities is essential if control measures are to be successfully implemented (Marco et al . 2010). Th e composition of local native assemblages and the phylogenetic relatedness of an invader to these communities can infl uence inva-sion success and thus provide a predictive tool. Closely related species are more likely to be ecologically similar, provided that traits determining responses of species to environment and co-existence show a signal along the phylogeny (sensu Blomberg and Garland 2002; i.e. similar trait values between closely-related species). Under these conditions, species ' phylogenetic distances can be used as a proxy for ecological similarity and have the advantage of combining multiple functional trait information. Th ere are two opposing hypotheses originally proposed by Darwin to link the phylogenetic relatedness between potential invaders and native communities with probabilities
[show abstract][hide abstract] ABSTRACT: Functional trait differences among species are increasingly used to infer the effects of biotic and abiotic processes on species coexistence. Commonly, the trait diversity observed within communities is compared to patterns simulated in randomly generated communities based on sampling within a region. The resulting patterns of trait convergence and divergence are assumed to reveal abiotic and biotic processes, respectively. However, biotic processes such as competition can produce both trait divergence and convergence, through either excluding similar species (niche differences, divergence) or excluding dissimilar species (weaker competitor exclusion, convergence). Hence, separating biotic and abiotic processes that can produce identical patterns of trait diversity, or even patterns that neutralize each other, is not feasible with previous methods. We propose an operational framework in which the functional trait dissimilarity within communities (FDcomm) is compared to the corresponding trait dissimilarity expected from the species pool (i.e., functional species pool diversity, FDpool). FDpool includes the set of potential species for a site delimited by the operating environmental and dispersal limitation filters. By applying these filters, the resulting pattern of trait diversity is consistent with biotic processes, i.e., trait divergence (FDcomm > FDpool) indicates niche differentiation, while trait convergence (FDcomm < FDpool) indicates weaker competitor exclusion. To illustrate this framework, with its potential application and constraints, we analyzed both simulated and field data. The functional species pool framework more consistently detected the simulated trait diversity patterns than previous approaches. In the field, using data from plant communities of typical Northern European habitats in Estonia, we found that both niche-based and weaker competitor exclusion influenced community assembly, depending on the traits and community considered. In both simulated and field data, we demonstrated that only by estimating the species pool of a site is it possible to differentiate the patterns of trait dissimilarity produced by operating biotic processes. The framework, which can be applied with both functional and phylogenetic diversity, enables a reinterpretation of community assembly processes. Solving the challenge of defining an appropriate reference species pool for a site can provide a better understanding of community assembly.
[show abstract][hide abstract] ABSTRACT: Aim The biotic mechanisms by which land bridges influence the formation of regional floras remain poorly understood. We tested the hypothesis that some land bridges have biased the migration of species between landmasses accord-ing to their biological traits, and that this relative spatial isolation has caused some lineages to diversify more than others. Location The Strait of Gibraltar Floristic Region, a major biodiversity hotspot of the Mediterranean Basin.
Methods We compiled the angiosperm flora of the study region to examine patterns of narrow endemism and species disjunctions between southern Iberia and northern Morocco. We focused on species that occur in the western portion of the Mediterranean Basin (n = 566) but not further east in this region, in order to test for the specific effect of the Strait of Gibraltar. Using phylogenetic super-trees, we tested whether species' life-history traits were related to their probability of occurring on both sides of the strait. We looked at patterns of narrow ende-mism in different families and computed birth–death model estimates of local diversification within the region.
Results Species with a short life cycle and propagules dispersed by wind or externally on animals were disproportionately likely to occur on both sides of the strait. Different plant lineages exhibited disparate distribution and ende-mism patterns across the strait. Some families have experienced disproportion-ately high rates of local diversification, and these families were systematically characterized by a low migration rate across the strait. We detected no differ-ence of overall rates of local diversification between the southern Iberian and northern Moroccan parts of the study region.
Main conclusions Our results indicate that the Strait of Gibraltar has biased species migration between northern Morocco and southern Iberia and that reduced migration through the strait may have triggered local speciation in certain plant families. This pinpoints the fundamental interplay between species migration and evolutionary diversification in the construction of hotspots of biodiversity and narrow endemism.
Journal of Biogeography 09/2012; 40:24-36. · 4.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: The relative importance of competition vs. environmental filtering in the assembly of communities is commonly inferred from their functional and phylogenetic structure, on the grounds that similar species compete most strongly for resources and are therefore less likely to coexist locally. This approach ignores the possibility that competitive effects can be determined by relative positions of species on a hierarchy of competitive ability. Using growth data, we estimated 275 interaction coefficients between tree species in the French mountains. We show that interaction strengths are mainly driven by trait hierarchy and not by functional or phylogenetic similarity. On the basis of this result, we thus propose that functional and phylogenetic convergence in local tree community might be due to competition-sorting species with different competitive abilities and not only environmental filtering as commonly assumed. We then show a functional and phylogenetic convergence of forest structure with increasing plot age, which supports this view.