Consistent energy-diversity relationships in terrestrial vertebrates.

Ecologists have long proposed that environments providing more energy can support more species, yet empirical evidence frequently contradicts this expectation. We argue that such inconsistencies result from confounding geographical influences that mask the true relationship between species richness and energy-related factors. Here, by comparing species richness across different climate conditions, we disentangle the direct effects of temperature, precipitation, and primary productivity from the confounding impacts of the area and isolation of various climates. Using a global analysis of terrestrial vertebrates, we reveal clear and consistent relationships between energy-related factors and species richness. Our findings clarify existing ecological theory and illustrate how adopting a climate space perspective advances biodiversity research, providing critical insights into biodiversity patterns and their responses to environmental change. Editor's summary: Theory predicts that areas of the globe with higher energy (warmer or more productive areas) will have a higher number of species. Empirical studies have found mixed support for this hypothesis, likely because other factors also influence geographical species richness patterns. Coelho et al. used an alternative approach to isolate the effects of climate on biodiversity by comparing vertebrate species richness across climate bins. When controlling for climate bins' area and isolation, both temperature and productivity had positive relationships with species richness, and there was an indirect effect of temperature on species richness in endotherms. In ectotherms, temperature-species richness relationships matched predictions of metabolic theory. —Bianca Lopez [ABSTRACT FROM AUTHOR]