Aim Predictable relationships between temperature and animal size and shape are the basis for classic rules in macroecology. Body size is thought to covary negatively with temperature (Bergmann's Rule), broadly attributed to thermoregulatory demand for larger size in colder climates. However, ecophysiological principles suggest that changes in insulative materials may be a more effective thermoregulatory adaptation than change...

Understanding the impacts of different threats on species is key to successful conservation interventions and policies. The International Union for Conservation of Nature (IUCN) assesses threats to species, and the organization's Red List of Threatened Species is a key conservation tool. We quantified the degree to which threats in IUCN assessments for 3 vertebrate groups (birds, amphibians, and ray‐finned fishes) were based o...

There is growing evidence that morphological change is a widespread response to the warming climate. The empirical basis for understanding this process has, to date, largely been correlative analyses of morphological time series. However, it is not clear what constitutes sufficient temporal sampling for assessing long-term morphological change. We analyzed two long-term high-quality morphological datasets, one including 33 spe...

Aim The tendency for animals in warmer climates to be longer‐limbed (Allen's Rule) is widely attributed to the demands of thermoregulation. The role of thermoregulation in structuring bird wings, however, has been overshadowed by the selective demands placed on wings by flight. We test whether occurrence in warmer climates is associated with longer wing bones. Location Global. Time Period Current. Major Taxa Studied Aves: Pass...

Increases in biodiversity often lead to greater, and less variable, levels of ecosystem functioning. However, whether species are less likely to go extinct in more diverse ecosystems is unclear. We use comprehensive estimates of avian taxonomic, phylogenetic and functional diversity to characterise the global relationship between multiple dimensions of diversity and extinction risk in birds, focusing on contemporary threat sta...

Functional traits offer a rich quantitative framework for developing and testing theories in evolutionary biology, ecology and ecosystem science. However, the potential of functional traits to drive theoretical advances and refine models of global change can only be fully realised when species‐level information is complete. Here we present the AVONET dataset containing comprehensive functional trait data for all birds, includi...

Increasing temperatures associated with climate change are predicted to cause reductions in body size, a key determinant of animal physiology and ecology. Using a four‐decade specimen series of 70 716 individuals of 52 North American migratory bird species, we demonstrate that increasing annual summer temperature over the 40‐year period predicts consistent reductions in body size across these diverse taxa. Concurrently, wing l...

Ecosystems vary widely in their responses to biodiversity change, with some losing function dramatically while others are highly resilient. However, generalizations about how species‐ and community‐level properties determine these divergent ecosystem responses have been elusive because potential sources of variation (e.g., trophic structure, compensation, functional trait diversity) are rarely evaluated in conjunction. Ecosyst...

Aim We develop a conceptual framework for integrating evolutionary history and ecological processes into studies of biotic assembly. Location Global. Methods We use theoretical and empirical examples to demonstrate that species distributions are non‐random outcomes of first‐order processes of biotic evolution: allopatry (isolation of populations), speciation and dispersion of biotas across landscapes. We then outline generaliz...