Ecology Letters最新文献

Symbiotic relationships between microbes and hosts frequently involve the assembly of complex microbial communities. Community-level patterns influence life-history traits, ecological trajectories of partners, and are often critical for host health. These patterns are driven by mechanisms acting at the individual level, including microbial dispersal, host selection, and microbe–resource interactions. Critically, we still lack a clear picture of how these mechanisms interact to shape microbiome assembly. We present a model that describes how distinct community structures arise from those underlying mechanisms. To illustrate the approach, we simulate microbiome data from marine sponges, thereby bridging mechanistic models and empirical patterns. We further apply the model to human data to explore its relevance across systems, proposing that a small set of general mechanisms may govern diverse patterns of diversity and abundance. Our findings advance ecological theory by linking individual-level processes to community-scale patterns, illuminating key drivers of microbiome assembly.

Speciation is the ultimate source of biodiversity, yet because most species arise in spatial isolation (allopatry), it remains unclear how speciation history shapes patterns of sympatric species richness. Here, we examine how the timing of past speciation events influences the maximum sympatric species richness attained across 40 families of passerine birds. Using a phylogenetic model, we infer that the average waiting time for species to assemble in sympatry is remarkably long (~8 million years), occurring over macroevolutionary timescales comparable to the pace of speciation itself. Consequently, we find that the proportion of species in sympatry varies substantially across families, peaking in ancient or small clades comprised of older species, while remaining low in large, rapidly diversifying clades. Our analysis shows that macroevolutionary delays in colonisation are sufficient for speciation history to leave an indelible legacy on present-day assemblages, challenging the view that richness is strictly limited by contemporary environmental capacity.

The species-area relationship is a cornerstone of biodiversity theory and conservation. Yet, its temporal stability remains largely untested. Using nearly a century of disjunct vegetation-plot data from the Netherlands, we assess changes in the species-area relationship by constructing species-accumulation curves (SACs). We show that SACs have flattened significantly over time, indicating widespread biodiversity decline driven by habitat degradation and spatial homogenization, even within protected areas. Although grassland biodiversity has rebounded, forest biodiversity continues to decline, suggesting a greater extinction debt. These findings provide unprecedented evidence that biodiversity patterns captured by SACs shift over time. They also reveal a critical limitation of conservation strategies that rely solely on protected area expansion. As global biodiversity goals aim to halt biodiversity loss by 2030, our results emphasise the need for adaptive conservation strategies that integrate area-based protection with large-scale habitat restoration and improved ecosystem management.

Understanding how temperature-sensitive organisms respond to environmental change is central to addressing challenges in public health, biodiversity conservation and food security. For many ectotherms, abiotic and biotic factors shape their abundance and distribution by generating stage-specific variation in life history traits. Although previous studies have examined temperature, rainfall, competition and habitat quality in relation to maximal population growth rate ($��r_m�$), relative humidity has rarely been incorporated into trait-based thermal performance frameworks. Using laboratory experiments, we show that relative humidity alters juvenile life history trait responses in Anopheles stephensi, an important malaria vector. We then integrate these humidity-dependent juvenile trait responses into an analytic $��r_m�$ model to examine how relative humidity shifts the temperature dependence of projected population growth. Heuristic climate-suitability comparisons further illustrate that temperature–humidity interactions acting through juvenile traits alone can alter qualitative inference about when and where temperature-only models may over- or underestimate environmental suitability. These results highlight the importance of incorporating humidity alongside temperature when assessing ectotherm responses to climatic variation.

Understanding the effects of climate change on ecological communities has been limited by a lack of general theory for how temperature affects competition. To fill this knowledge gap, we integrated Modern Coexistence Theory and the Metabolic Theory of Ecology by incorporating empirically derived temperature sensitivities into Modern Coexistence Theory's central model. We then simulated warming in consumer-resource systems and found that warming reduced both niche and fitness differences, making species more ecologically similar and competitive interactions more neutral. The greatest shifts in competition occurred when temperature sensitivities among species were highly asymmetrical. Effects of warming on competition via niche differences were comparable to those on fitness differences, suggesting that the emphasis on vital rates in global change research may overlook key biodiversity drivers. This general theory expands the domains of two prominent ecological theories and provides predictions for how warming may alter competition even in benign regions of species' thermal niches.

Ecological forecasting is increasingly important for conservation. Predicting nocturnal bird migration events is a promising vehicle for forecasts but isn't often explored at fine temporal scales. We use weather surveillance radar to examine dynamic drivers of migration in 2-h periods throughout a night. We assess the relative importance of terrestrial, atmospheric and sampling predictors (which relate to radar position and scan timing) across spring and fall. Atmospheric conditions were consistently strong predictors. In contrast, terrestrial predictors contributed relatively little to explaining variation in activity. Sampling variables, such as time after sunset, varied in importance, with the highest influence shortly after sunset. We highlight the temporal variability in predictors of migration, emphasising it as a dynamic process, involving continuous decisions and adjustments rather than following fixed routes. We underscore the value of radar for capturing transitions between habitats while revealing key limitations and opportunities for understanding fine-scale migratory behaviour.

Understanding how species assemble across landscapes requires integration of data representing evolutionary, ecological, and biogeographic processes. We developed a comparative macrogenetic framework, applying it across 22 co-distributed rainforest trees, to identify replicated landscape-level genetic signatures. Diversity-migration analyses and genogeographic clustering identified shared spatial dynamics in relation to refugial areas and genetic turnover, but with no direct relation to simple functional trait combinations. Three broad patterns emerged: Higher Northern Diversity with southward migration, Higher Southern Diversity with northward migration, and Homogeneous Diversity with no directional migration. We identified five (post hoc) species groups sharing gene flow and isolation-by-distance dynamics in relation to recognised biogeographic barriers. Replicated genetic signatures highlight how assembly processes emerge from interacting ecological and historical filters rather than single traits or biogeographic histories alone. We present a statistically replicable interpretational framework to identify shared evolutionary and ecological dynamics, offering scalable, management relevant tools to support restoration planning and biodiversity conservation under environmental change across all types of vegetation.

Clonality, the process of vegetative reproduction through belowground organs (rhizomes, stolons), occurs in about half of all plant species. It influences key ecological and evolutionary phenomena, including effective population size, meiosis frequency and genet longevity, which may affect diversification rates. This study investigates how clonality impacts diversification in angiosperms by comparing clonal, mixed and non-clonal genera. Using genus-level phylogeny and data on clonal status of 16,465 species across 2997 genera, we estimated speciation and net diversification rates for each genus with MoM, DR and BAMM. Our results reveal lower diversification rates in clonal genera in non-phylogenetic models, consistent with the hypothesis that clonality constrains diversification. This effect weakens when accounting for phylogenetic non-independence but remains significant overall. We show that monocots show a slightly stronger effect of clonality on diversification than eudicots. Our findings suggest that clonality may limit long-term diversification in angiosperms, influencing evolutionary dynamics where clonal reproduction predominates.