An increase in management actions has compensated for past climate change effects on desert locust gregarization in western Africa.

In response to high population density, the desert locust, Schistocerca gregaria, becomes gregarious and forms swarms that can cause significant damage to crops and pastures, threatening food security of human populations from western Africa to India. This switch from solitary to gregarious populations is highly dependent on favorable weather conditions. Climate change, which has been hypothesized to shift conditions towards increasing risks of gregarization, is therefore likely to have significant impacts on the spatial distribution and likelihood of outbreak events. However, the desert locust is intensely managed at large scales, which possibly counteracts any increased risk of outbreaks due to a more favorable climate. Consequently, understanding the changes in risks in the future involves teasing out the effects of climate change and management actions. Here we studied the dynamics of gregarization at the very early stages of potential outbreaks, in parallel with trends in climate and management, between 1985 and 2018 in western Africa. We used three different spatial scales, with the goal to have a better understanding of the potential effects of climate change per se while controlling for management. Our first approach was to look at a regional scale, where we observed an overall decrease in gregarization events. However, this scale includes very heterogeneous environments and management efforts. To consider this heterogeneity, we divided the area into a grid of 0.5° cells. For each cell, a climate analysis was performed for rainfall and temperature, with trends obtained by a harmonic decomposition model on monthly data. Analyses of gregarization showed only a few significant trends, both positive and negative, mainly found in western Mauritania where management effort has increased. To improve the statistical power, these cells were then grouped into larger homogeneous climatic clusters, i.e. groups of cells with similar climatic conditions and similar climatic trends over the study period. At this scale, gregarization events depend on the intersection between climate conditions and management efforts. The clusters where gregarization increased were also the ones with the highest increase of management. These results highlight the important effect of preventive management, which may counteract the positive effects of climate change on locust proliferation.

Ecological and genomic vulnerability to climate change across native populations of Robusta coffee (Coffea canephora).

The assessment of population vulnerability under climate change is crucial for planning conservation as well as for ensuring food security. Coffea canephora is, in its native habitat, an understorey tree that is mainly distributed in the lowland rainforests of tropical Africa. Also known as Robusta, its commercial value constitutes a significant revenue for many human populations in tropical countries. Comparing ecological and genomic vulnerabilities within the species' native range can provide valuable insights about habitat loss and the species' adaptive potential, allowing to identify genotypes that may act as a resource for varietal improvement. By applying species distribution models, we assessed ecological vulnerability as the decrease in climatic suitability under future climatic conditions from 492 occurrences. We then quantified genomic vulnerability (or risk of maladaptation) as the allelic composition change required to keep pace with predicted climate change. Genomic vulnerability was estimated from genomic environmental correlations throughout the native range. Suitable habitat was predicted to diminish to half its size by 2050, with populations near coastlines and around the Congo River being the most vulnerable. Whole-genome sequencing revealed 165 candidate SNPs associated with climatic adaptation in C. canephora, which were located in genes involved in plant response to biotic and abiotic stressors. Genomic vulnerability was higher for populations in West Africa and in the region at the border between DRC and Uganda. Despite an overall low correlation between genomic and ecological vulnerability at broad scale, these two components of vulnerability overlap spatially in ways that may become damaging. Genomic vulnerability was estimated to be 23% higher in populations where habitat will be lost in 2050 compared to regions where habitat will remain suitable. These results highlight how ecological and genomic vulnerabilities are relevant when planning on how to cope with climate change regarding an economically important species.

Occurrence data for the two cryptic species of Cacopsylla pruni (Hemiptera: Psylloidea).

BACKGROUND: Cacopsylla pruni is a psyllid that has been known since 1998 as the vector of the bacterium 'Candidatus Phytoplasma prunorum', responsible for the European stone fruit yellows (ESFY), a disease that affects species of Prunus. This disease is one of the major limiting factors for the production of stone fruits, most notably apricot (Prunus armeniaca) and Japanese plum (P. salicina), in all EU stone fruit-growing areas. The psyllid vector is widespread in the Western Palearctic and evidence for the presence of the phytoplasma that it transmits to species of Prunus has been found in 15 of the 27 EU countries.Recent studies showed that C. pruni is actually composed of two cryptic species that can be differentiated by molecular markers. A literature review on the distribution of C. pruni was published in 2012, but it only provided presence or absence information at the country level and without distinction between the two cryptic species.Since 2012, numerous new records of the vector in several European countries have been published. We ourselves have acquired a large amount of data from sampling in France and other European countries. We have also carried out a thorough systematic literature review to find additional records, including all the original sources mentioning C. pruni (or its synonyms) since the first description by Scopoli in 1763. Our aim was to create an exhaustive georeferenced occurrence catalogue, in particular in countries that are occasionally mentioned in literature with little detail. Finally, for countries that seem suitable for the proliferation of C. pruni (USA, Canada, Japan, China etc.), we dug deeper into literature and reliable sources (e.g. published checklists) to better substantiate its current absence from those regions.Information on the distribution ranges of these vector psyllids is of crucial interest in order to best predict the vulnerability of stone fruit producing countries to the ESFY threat in the foreseeable future. NEW INFORMATION: We give free access to a unique file of 1975 records of all occurrence data in our possession concerning C. pruni, that we have gathered through more than twenty years of sampling efforts in Europe or through intensive text mining.We have made every effort to retrieve the source information for the records extracted from literature (1201 records). Thus, we always give the title of the original reference, together with the page(s) citing C. pruni and, if possible, the year of sampling. To make the results of this survey publicly available, we give a URL to access the literature sources. In most cases, this link allows free downloads of a PDF file.We also give access to information extracted from GBIF (162 exploitable data points on 245 occurrences found in the database), which we thoroughly checked and often supplemented to make the information more easily exploitable.We give access to our own unpublished georeferenced and genotyped records from 612 samples taken over the last 20 years in several European countries (Switzerland, Belgium, Netherlands, Spain etc.). These include two countries (Portugal and North Macedonia), for which the presence of C. pruni had not been reported before. As our specimens have been genotyped (74 sites with species A solely, 202 with species B solely and 310 with species A+B), our new data enable a better overview of the geographical distribution of the two cryptic species at the Palaearctic scale.

A young age of subspecific divergence in the desert locust inferred by ABC random forest.

Dating population divergence within species from molecular data and relating such dating to climatic and biogeographic changes is not trivial. Yet it can help formulating evolutionary hypotheses regarding local adaptation and future responses to changing environments. Key issues include statistical selection of a demographic and historical scenario among a set of possible scenarios, and estimation of the parameter(s) of interest under the chosen scenario. Such inferences greatly benefit from (a) independent information on evolutionary rate and pattern at genetic markers; and (b) new statistical approaches, such as approximate Bayesian computation-random forest (ABC-RF), which provides reliable inference at a low computational cost and the possibility to measure prediction quality at the exact position of the observed data set. Here, we show full potential of the ABC-RF approach including prior knowledge on microsatellite genetic markers to decipher the evolutionary history of the African arid-adapted pest locust, Schistocerca gregaria, with support for a southern colonization of Africa, from a low number of founders of northern origin, dating back 2.6 Ky (90% CI: 0.9-6.6 Ky). We verify that this divergence time estimate accurately reflected true divergence time values by computing accuracy at a local posterior scale from simulated pseudo-observed data sets. The inferred divergence history is better explained by the peculiar biology of S. gregaria, which involves a density-dependent swarming phase with some exceptional spectacular migrations, rather than a continuous colonization resulting from the continental expansion of open vegetation habitats during more ancient Quaternary glacial climatic episodes.

On the relative role of climate change and management in the current desert locust outbreak in East Africa.

While large-scale monitoring, early detection and control can greatly reduce desert locust invasions, global change is most likely to affect conditions that promote the transition from solitary to gregarious populations. Although climate change scenarios point to an increase in aridity and further desertification in vast areas of Africa, some regions that have been at the origin of past outbreaks are likely to see a reversed trend (i.e., increase in frequency and intensity of rains), potentially favoring the formation of swarms. This makes reinforcing early detection and keeping a sustained monitoring effort in place even more important under climate change.

On the relative importance of space and environment in farmland bird community assembly.

The relative contribution of ecological processes in shaping metacommunity dynamics in heavily managed landscapes is still unclear. Here we used two complementary approaches to disentangle the role of environment and spatial effect in farmland bird community assembly in an intensive agro-ecosystem. We hypothesized that the interaction between habitat patches and dispersal should play a major role in such unstable and unpredictable environments. First, we used a metacommunity patterns analysis to characterize species co-occurrences and identify the main drivers of community assembly; secondly, variation partitioning was used to disentangle environmental and geographical factors (such as dispersal limitation) on community structure and composition. We used high spatial resolution data on bird community structure and composition distributed among 260 plots in an agricultural landscape. Species were partitioned into functional classes, and point count stations were classified according to landscape characteristics before applying metacommunity and partitioning analyses within each. Overall we could explain around 20% of the variance in species composition in our system, revealing that stochasticity remains very important at this scale. However, this proportion varies depending on the scale of analysis, and reveals potentially important contributions of environmental filtering and dispersal. These conclusions are further reinforced when the analysis was deconstructed by bird functional classes or by landscape habitat classes, underlining trait-related filters, thus reinforcing the idea that wooded areas in these agroecosystems may represent important sources for a specific group of bird species. Our analysis shows that deconstructing the species assemblages into separate functional groups and types of landscapes, along with a combination of analysis strategies, can help in understanding the mechanisms driving community assembly.

Climate-driven geographic distribution of the desert locust during recession periods: Subspecies' niche differentiation and relative risks under scenarios of climate change.

The desert locust is an agricultural pest that is able to switch from a harmless solitarious stage, during recession periods, to swarms of gregarious individuals that disperse long distances and affect areas from western Africa to India during outbreak periods. Large outbreaks have been recorded through centuries, and the Food and Agriculture Organization keeps a long-term, large-scale monitoring survey database in the area. However, there is also a much less known subspecies that occupies a limited area in Southern Africa. We used large-scale climatic and occurrence data of the solitarious phase of each subspecies during recession periods to understand whether both subspecies climatic niches differ from each other, what is the current potential geographical distribution of each subspecies, and how climate change is likely to shift their potential distribution with respect to current conditions. We evaluated whether subspecies are significantly specialized along available climate gradients by using null models of background climatic differences within and between southern and northern ranges and applying niche similarity and niche equivalency tests. The results point to climatic niche conservatism between the two clades. We complemented this analysis with species distribution modeling to characterize current solitarious distributions and forecast potential recession range shifts under two extreme climate change scenarios at the 2050 and 2090 time horizon. Projections suggest that, at a global scale, the northern clade could contract its solitarious recession range, while the southern clade is likely to expand its recession range. However, local expansions were also predicted in the northern clade, in particular in southern and northern margins of the current geographical distribution. In conclusion, monitoring and management practices should remain in place in northern Africa, while in Southern Africa the potential for the subspecies to pose a threat in the future should be investigated more closely.

A spatially explicit estimate of the prewhaling abundance of the endangered North Atlantic right whale.

The North Atlantic right whale (NARW) (Eubalaena glacialis) is one of the world's most threatened whales. It came close to extinction after nearly a millennium of exploitation and currently persists as a population of only approximately 500 individuals. Setting appropriate conservation targets for this species requires an understanding of its historical population size, as a baseline for measuring levels of depletion and progress toward recovery. This is made difficult by the scarcity of records over this species' long whaling history. We sought to estimate the preexploitation population size of the North Atlantic right whale and understand how this species was distributed across its range. We used a spatially explicit data set on historical catches of North Pacific right whales (NPRWs) (Eubalaena japonica) to model the relationship between right whale relative density and the environment during the summer feeding season. Assuming the 2 right whale species select similar environments, we projected this model to the North Atlantic to predict how the relative abundance of NARWs varied across their range. We calibrated these relative abundances with estimates of the NPRW total prewhaling population size to obtain high and low estimates for the overall NARW population size prior to exploitation. The model predicted 9,075-21,328 right whales in the North Atlantic. The current NARW population is thus <6% of the historical North Atlantic carrying capacity and has enormous potential for recovery. According to the model, in June-September NARWs concentrated in 2 main feeding areas: east of the Grand Banks of Newfoundland and in the Norwegian Sea. These 2 areas may become important in the future as feeding grounds and may already be used more regularly by this endangered species than is thought.

Asynchrony of taxonomic, functional and phylogenetic diversity in birds.

AIM: We assessed the temporal trends of taxonomic, functional and phylogenetic diversities in the French avifauna over the last two decades. Additionally, we investigated whether and how this multifaceted approach to biodiversity dynamics can reveal an increasing similarity of local assemblages in terms of species, traits and/or lineages. LOCATION: France. METHODS: We analysed a large-scale dataset that recorded annual changes in the abundance of 116 breeding birds in France between 1989 and 2012. We decomposed and analysed the spatio-temporal dynamics of taxonomic, phylogenetic and functional diversities and each of their α-, ß- and γ-components. We also calculated the trend in the mean specialization of bird communities to track the relative success of specialist versus generalist species within communities during the same period. RESULTS: We found large variation within and among the temporal trends of each biodiversity facet. On average, we found a marked increase in species and phylogenetic diversity over the period considered, but no particular trend was found for functional diversity. Conversely, changes in ß-diversities for the three facets were characterized by independent and nonlinear trends. We also found a general increase in the local occurrence and abundance of generalist species within local communities. MAIN CONCLUSIONS: These results highlight a relative asynchrony of the different biodiversity facets occurring at large spatial scales. We show why a multifaceted approach to biodiversity dynamics is needed to better describe and understand changes in community composition in macroecology and conservation biogeography.

Uncertainties in predicting species distributions under climate change: a case study using Tetranychus evansi (Acari: Tetranychidae), a widespread agricultural pest.

Many species are shifting their distributions due to climate change and to increasing international trade that allows dispersal of individuals across the globe. In the case of agricultural pests, such range shifts may heavily impact agriculture. Species distribution modelling may help to predict potential changes in pest distributions. However, these modelling strategies are subject to large uncertainties coming from different sources. Here we used the case of the tomato red spider mite (Tetranychus evansi), an invasive pest that affects some of the most important agricultural crops worldwide, to show how uncertainty may affect forecasts of the potential range of the species. We explored three aspects of uncertainty: (1) species prevalence; (2) modelling method; and (3) variability in environmental responses between mites belonging to two invasive clades of T. evansi. Consensus techniques were used to forecast the potential range of the species under current and two different climate change scenarios for 2080, and variance between model projections were mapped to identify regions of high uncertainty. We revealed large predictive variations linked to all factors, although prevalence had a greater influence than the statistical model once the best modelling strategies were selected. The major areas threatened under current conditions include tropical countries in South America and Africa, and temperate regions in North America, the Mediterranean basin and Australia. Under future scenarios, the threat shifts towards northern Europe and some other temperate regions in the Americas, whereas tropical regions in Africa present a reduced risk. Analysis of niche overlap suggests that the current differential distribution of mites of the two clades of T. evansi can be partially attributed to environmental niche differentiation. Overall this study shows how consensus strategies and analysis of niche overlap can be used jointly to draw conclusions on invasive threat considering different sources of uncertainty in species distribution modelling.

Disentangling the drivers of metacommunity structure across spatial scales.

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).

Evidence of environmental niche differentiation in the striped mouse (Rhabdomys sp.): inference from its current distribution in southern Africa.

The aim of this study was to characterize environmental differentiation of lineages within Rhabdomys and provide hypotheses regarding potential areas of contact between them in the Southern African subregion, including the Republic of South Africa, Lesotho, and Namibia. Records of Rhabdomys taxa across the study region were compiled and georeferenced from the literature, museum records, and field expeditions. Presence records were summarized within a 10 × 10 km grid covering the study area. Environmental information regarding climate, topography, land use, and vegetation productivity was gathered at the same resolution. Multivariate statistics were used to characterize the current environmental niche and distribution of the whole genus as well as of three mitochondrial lineages known to occur in southern Africa. Distribution modeling was carried out using MAXENT in order to generate hypotheses regarding current distribution of each taxa and their potential contact zones. Results indicate that the two species within Rhabdomys appear to have differentiated across the precipitation/temperature gradient present in the region from east to west. R. dilectus occupies the wettest areas in eastern southern Africa, while R. pumilio occupies the warmer and drier regions in the west, but also penetrates in the more mesic central part of the region. We provide further evidence of environmental differentiation within two lineages of R. dilectus. Contact zones between lineages appear to occur in areas of strong environmental gradients and topographic complexity, such as the transition zones between major biomes and the escarpment area where a sharp altitudinal gradient separates coastal and plateau areas, but also within more homogeneous areas such as within grassland and savannah biomes. Our results indicate that Rhabdomys may be more specialized than previously thought when considering current knowledge regarding mitochondrial lineages. The genus appears to have differentiated along two major environmental axes in the study region, but results also suggest dispersal limitations and biological interactions having a role in limiting current distribution boundaries. Furthermore, the projection of the potential geographic distribution of the different lineages suggests several contact zones that may be interesting study fields for understanding the interplay between ecological and evolutionary processes during speciation.

A phylogenetic perspective on the evolution of Mediterranean teleost fishes.

The Mediterranean Sea is a highly diverse, highly studied, and highly impacted biogeographic region, yet no phylogenetic reconstruction of fish diversity in this area has been published to date. Here, we infer the timing and geographic origins of Mediterranean teleost species diversity using nucleotide sequences collected from GenBank. We assembled a DNA supermatrix composed of four mitochondrial genes (12S ribosomal DNA, 16S ribosomal DNA, cytochrome c oxidase subunit I and cytochrome b) and two nuclear genes (rhodopsin and recombination activating gene I), including 62% of Mediterranean teleost species plus 9 outgroups. Maximum likelihood and Bayesian phylogenetic and dating analyses were calibrated using 20 fossil constraints. An additional 124 species were grafted onto the chronogram according to their taxonomic affinity, checking for the effects of taxonomic coverage in subsequent diversification analyses. We then interpreted the time-line of teleost diversification in light of Mediterranean historical biogeography, distinguishing non-endemic natives, endemics and exotic species. Results show that the major Mediterranean orders are of Cretaceous origin, specifically ~100-80 Mya, and most Perciformes families originated 80-50 Mya. Two important clade origin events were detected. The first at 100-80 Mya, affected native and exotic species, and reflects a global diversification period at a time when the Mediterranean Sea did not yet exist. The second occurred during the last 50 Mya, and is noticeable among endemic and native species, but not among exotic species. This period corresponds to isolation of the Mediterranean from Indo-Pacific waters before the Messinian salinity crisis. The Mediterranean fish fauna illustrates well the assembly of regional faunas through origination and immigration, where dispersal and isolation have shaped the emergence of a biodiversity hotspot.

Ecophylogenetics: advances and perspectives.

Ecophylogenetics can be viewed as an emerging fusion of ecology, biogeography and macroevolution. This new and fast-growing field is promoting the incorporation of evolution and historical contingencies into the ecological research agenda through the widespread use of phylogenetic data. Including phylogeny into ecological thinking represents an opportunity for biologists from different fields to collaborate and has provided promising avenues of research in both theoretical and empirical ecology, towards a better understanding of the assembly of communities, the functioning of ecosystems and their responses to environmental changes. The time is ripe to assess critically the extent to which the integration of phylogeny into these different fields of ecology has delivered on its promise. Here we review how phylogenetic information has been used to identify better the key components of species interactions with their biotic and abiotic environments, to determine the relationships between diversity and ecosystem functioning and ultimately to establish good management practices to protect overall biodiversity in the face of global change. We evaluate the relevance of information provided by phylogenies to ecologists, highlighting current potential weaknesses and needs for future developments. We suggest that despite the strong progress that has been made, a consistent unified framework is still missing to link local ecological dynamics to macroevolution. This is a necessary step in order to interpret observed phylogenetic patterns in a wider ecological context. Beyond the fundamental question of how evolutionary history contributes to shape communities, ecophylogenetics will help ecology to become a better integrative and predictive science.

Protected and threatened components of fish biodiversity in the Mediterranean sea.

The Mediterranean Sea (0.82% of the global oceanic surface) holds 4%-18% of all known marine species (~17,000), with a high proportion of endemism [1, 2]. This exceptional biodiversity is under severe threats [1] but benefits from a system of 100 marine protected areas (MPAs). Surprisingly, the spatial congruence of fish biodiversity hot spots with this MPA system and the areas of high fishing pressure has not been assessed. Moreover, evolutionary and functional breadth of species assemblages [3] has been largely overlooked in marine systems. Here we adopted a multifaceted approach to biodiversity by considering the species richness of total, endemic, and threatened coastal fish assemblages as well as their functional and phylogenetic diversity. We show that these fish biodiversity components are spatially mismatched. The MPA system covers a small surface of the Mediterranean (0.4%) and is spatially congruent with the hot spots of all taxonomic components of fish diversity. However, it misses hot spots of functional and phylogenetic diversity. In addition, hot spots of endemic species richness and phylogenetic diversity are spatially congruent with hot spots of fishery impact. Our results highlight that future conservation strategies and assessment efficiency of current reserve systems will need to be revisited after deconstructing the different components of biodiversity.

Dispersal scales up the biodiversity-productivity relationship in an experimental source-sink metacommunity.

The influence of biodiversity on ecosystem functioning is a major concern of ecological research. However, the biodiversity-ecosystem functioning relationship has very often been studied independently from the mechanisms allowing coexistence. By considering the effects of dispersal and niche partitioning on diversity, the metacommunity perspective predicts a spatial scale-dependence of the shape of the relationship. Here, we present experimental evidence of such scale-dependent patterns. After approximately 500 generations of diversification in a spatially heterogeneous environment, we measured functional diversity (FD) and productivity at both local and regional scales in experimental source-sink metacommunities of the bacterium Pseudomonas fluorescens SBW25. At the regional scale, environmental heterogeneity yielded high levels of FD and we observed a positive correlation between diversity and productivity. At the local scale, intermediate dispersal increased local FD through a mass effect but there was no correlation between diversity and productivity. These experimental results underline the importance of considering the mechanisms maintaining biodiversity and the appropriate spatial scales in understanding its relationship with ecosystem functioning.

Bird metacommunities in temperate South American forest: vegetation structure, area, and climate effects.

Spatial structure in metacommunities and their relationships to environmental gradients have been linked to opposing theories of community assembly. In particular, while the species sorting hypothesis predicts strong environmental influences, the neutral theory, the mass effect, and the patch dynamics frameworks all predict differing degrees of spatial structure resulting from dispersal and competition limitations. Here we study the relative influence of environmental gradients and spatial structure in bird assemblages of the Chilean temperate forest. We carried out bird and vegetation surveys in South American temperate forests at 147 points located in nine different protected areas in central Chile, and collected meteorological and productivity data for these localities. Species composition dissimilarities between sites were calculated, as well as three indices of bird local diversity: observed species richness, Chao estimate of richness, and Shannon diversity. A stepwise multiple regression and partial regression analyses were used to select a small number of environmental factors that predicted bird species diversity. Although diversity indices were spatially autocorrelated, environmental factors were sufficient to account for this autocorrelation. Moreover, community dissimilarities were not significantly related to distance between sites. We then tested a multivariate hypothesis about climate, vegetation, and avian diversity interactions using a structural equation modeling (SEM) approach. The SEM showed that climate and area of fragments have important indirect effects on avian diversity, mediated through changes in vegetation structure. Given the scale of this study, the metacommunity framework provides useful insights into the mechanisms driving bird assemblages in this region. Taken together, the weak spatial structure of community composition and diversity, as well as the strong environmental effects on bird diversity, support the interpretation that species sorting has a predominant role in structuring avian assemblages in the region.