ABSTRACT Aim Species may not fully track shifting climatic conditions when dispersal is limited, yet how species‐specific dispersal constraints scale up to shape biodiversity redistribution across taxa remains unclear. We evaluated how dispersal limitation modifies projected biodiversity dynamics under climate change. Location North America. Time Period Contemporary to late 21st century. Major Taxa Studied Terrestrial vertebrates. Methods We developed species distribution models for 256 terrestrial vertebrate species spanning dispersal rates from 0 to ~100 km/year. We compared climate‐driven projections based on climatic suitability with projections incorporating species‐specific dispersal constraints. We further assessed how dispersal capacity influences habitat accessibility and projected overlap with major land‐cover categories and protected areas. Results Dispersal limitation substantially altered the magnitude and spatial structure of projected biodiversity change. Climate‐driven projections predicted increasing species richness and poleward range expansion, whereas dispersal‐limited projections suppressed leading‐edge expansion, amplified range contraction and generated extensive climatically suitable but inaccessible habitat. These effects intensified under stronger climate forcing and were most pronounced at high latitudes. Species with lower dispersal capacities experienced substantially greater mismatches between climatically suitable and accessible habitat. Dispersal limitation also altered projected landscape overlap: overlap with forests, wetlands, and protected areas increased under climate‐driven projections but declined when dispersal constraints were incorporated, whereas dispersal limitation attenuated projected increases or amplified projected declines in other landscape categories. Main Conclusions Species‐specific dispersal capacity acts as a biological filter on climate tracking, and climate‐driven projections may therefore overestimate species' ability to track environmental change. These species‐level constraints scale up to alter continental biodiversity redistribution and its spatial correspondence with different landscape types. Incorporating dispersal processes is therefore essential for projecting future biodiversity change and informing conservation planning.
ABSTRACT Aim The Ediacaran Period (~635–538.5 Ma) records the initial rise and diversification of animals. While many studies have examined the evolving structure of these early animal communities, far fewer have examined evolving function. Here, we quantify change in functional diversity (i.e., the distribution of ecological traits within assemblages) in marine benthic communities throughout the Ediacaran. These metrics allow us to identify how biotic assemblages responded to ecological, environmental, and spatial pressures to form communities. Location Global. Time Period 575–538.5 Ma. Major Taxa Studied Marine macrofauna of the Ediacaran Period. Methods Genus occurrence and functional trait data were collected from museum collections and the primary literature. From those data, we assessed paleocommunity and global functional diversity using three indices: functional richness, evenness, and divergence, and used these to reconstruct aspects of trait variation. We then used a Jackknife approach to test how individual traits contributed to each functional diversity index. Finally, we quantified how functional beta diversity changed across the Ediacaran, testing whether spatial variation in functional diversity changed between assemblages. Results We found that functional richness and divergence significantly varied between chronostratigraphic ‘assemblages’, following rises and falls in paleocommunity taxonomic richness. We find that no single trait controlled functional diversity patterns across assemblages. However, in the last assemblage of the Ediacaran, we find evidence for increased trait filtering between global and paleocommunity functional richness—a pattern which is most strongly indicated by an increase in functional beta diversity. Conclusions We interpret our results as reflecting overlapping patterns of environmental and ecological change, reducing paleo‐community functional diversity across different spatial scales. Thus, the balance of pressures operating in tandem across different spatial scales (such as environmental filtering by anoxia and/or ecosystem engineering) may have substantially impacted animal evolution. These pressures and their spatial distribution patterns may have controlled which functional trait combinations survived and which functional groups diversified within the Ediacaran.
ABSTRACT Aim Understanding how climatic extremes influence species synchrony is crucial for predicting biodiversity responses to global change. We test whether spatial synchrony in bird abundances exhibits “synchrony at the extremes” (tail‐dependence), whereby populations synchronize more strongly during unusually low or high abundance events, and whether spatial synchrony in climatic extremes and dispersal traits explain these patterns. Location North America. Time Period 1979–2019. Major Taxa Studied Breeding birds. Methods We quantified spatial synchrony in bird abundance and climate (temperature and precipitation) using correlation‐ and tail‐dependence‐based approaches across sites separated by ≤ 250 km. Analyses were conducted for species monitored for ≥ 40 years (173 species), ≥ 36 years (276 species) and ≥ 32 years (328 species). We tested whether total and directional tail‐dependent climatic synchrony predicted corresponding abundance synchrony using phylogenetic regression, with hand‐wing index (HWI) as a proxy for dispersal ability. Results Across all temporal thresholds, 45%–73% of species exhibited significant spatial synchrony, of which 44%–52% also exhibited significant tail‐dependent synchrony (20%–38% of all species). In phylogenetic regression models, total tail‐dependent synchrony in precipitation consistently predicted total tail‐dependent synchrony in abundance across all temporal thresholds (≥ 32, ≥ 36 and ≥ 40 years), whereas total tail‐dependent synchrony in temperature was a significant factor only for the ≥ 32‐year dataset. These models explained up to 24% of the variation, while HWI showed little evidence of an association. Support for the climate‐abundance relationship weakened when analyses were restricted to narrower spatial distance classes. Directional tail‐dependent synchrony in climate and HWI showed limited support for explaining directional tail‐dependent synchrony in abundance. Main Conclusions Our findings demonstrate that synchronized climatic extremes, particularly in precipitation, are associated with synchronized bird population extremes across large spatial scales. Incorporating tail dependence into studies of spatial synchrony may improve our understanding of ecological responses to increasingly frequent climatic extremes.
ABSTRACT Aim Direct human impacts and climate change jeopardise the stability of ecological systems. Recent trends are built atop a long history of vegetation change from the Pleistocene deglaciation and Holocene human population expansion. We aimed to model a long‐term measure of ecological stability over the last 20,000 years, a period that includes both the most recent global warming and the spread of human civilisation. Location Europe and North America. Time Period 0–20,000 years before present. Major Taxa Studied Land plants. Methods We quantified persistence, a non‐equilibrium estimate of ecological stability, across millennia of plant assemblage change proxied within palynological sediment cores. We modeled trends in persistence over time and based on historical reconstructions of human population density, contrasting trends between Europe and North America, continents with broadly similar biomes but divergent land‐use histories. Results The late Pleistocene deglaciation produced a prolonged ( c. 10,000 years) period of vegetation destabilisation. Despite continental differences in persistence during the deglaciation, we observed a synchronised increase across Europe and North America at the start of the Holocene. Human land use was linked to greater stability of North American vegetation in the early‐mid Holocene, with some evidence of destabilisation after European colonisation. European assemblages began destabilising 3000 years ago, a trend that has become more severe over time and in areas of higher human population density. Main Conclusions We provide a quantitative measurement of assemblage persistence, with trends over time that map onto climatic and human pressures. While palynological trends include responses to climate change, human actions and other assembly filters, with accompanying time‐lagged responses and extinction debts, we found a detectable signal that human land use can suppress and amplify long‐term ecological stability. In recent millennia, human actions have systematically destabilised temperate vegetation, reducing the biosphere's resilience prior to modern anthropogenic climate change.
ABSTRACT Aim To assess the diversity, temporal dynamics, and global distribution of non‐native Lepidoptera. Location Global, encompassing 258 non‐overlapping geopolitical regions comprising countries and distinct insular territories. Time Period ~1500 ce to the present. Major Taxa Studied Lepidoptera species, with distinctions between moths and butterflies. Methods We developed a global dataset of the distribution and timing of first records of established non‐native Lepidoptera by integrating data from multiple, partly incomplete databases and scientific literature. Species were considered non‐native when established beyond their native range as a result of human‐mediated introduction. Using these data, we quantified global exchange flows and temporal trends in first records and identified spatial drivers of invasion using Generalized Linear Mixed Models (GLMMs) with region‐level climatic, economic, and land‐use predictors. Results A total of 969 species (55 butterflies, 914 moths) have established outside their native range, representing 0.62% of global lepidopteran diversity. First records date back to the 1500s, increased in the early 1900s, and rose sharply after 1960. Most species were recorded in one or two regions only; however, 63 species (2 butterflies, 61 moths) occur in 10 or more regions, with Galleria mellonella (110 regions), Phthorimaea absoluta (104 regions), and Spodoptera frugiperda (66 regions) being the most widespread. Over 65 regions host 10 or more non‐native species, with the conterminous United States (296 species), Canada (222), and Hawaii (192) being the most invaded. Non‐native richness is highest in temperate, economically developed regions and is positively associated with cropland extent and sampling effort. Europe and Asia emerge as the main source regions, whereas North America, Europe, and Oceania are among the primary recipients. Main Conclusions Non‐native Lepidoptera exhibit pronounced global asymmetries in species exchange, increasing recorded establishment rates since the mid‐20th century and elevated richness in temperate, economically developed regions. These patterns highlight the central role of global trade and associated pathways in shaping the redistribution of Lepidoptera worldwide.
