title: Energetic Constraints on Species Coexistence in Birds.
abstract: The association between species richness and ecosystem energy availability is one of the major geographic trends in biodiversity. It is often explained in terms of energetic constraints, such that coexistence among competing species is limited in low productivity environments. However, it has proven challenging to reject alternative views, including the null hypothesis that species richness has simply had more time to accumulate in productive regions, and thus the role of energetic constraints in limiting coexistence remains largely unknown. We use the phylogenetic relationships and geographic ranges of sister species (pairs of lineages who are each other's closest extant relatives) to examine the association between energy availability and coexistence across an entire vertebrate class (Aves). We show that the incidence of coexistence among sister species increases with overall species richness and is elevated in more productive ecosystems, even when accounting for differences in the evolutionary time available for coexistence to occur. Our results indicate that energy availability promotes species coexistence in closely related lineages, providing a key step toward a more mechanistic understanding of the productivity-richness relationship underlying global gradients in biodiversity.
authors.affiliation: Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.|Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, United Kingdom.
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Pigot
authors.affiliation: Department of Life Sciences, Imperial College London, Silwood Park, Ascot, United Kingdom.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Tobias
authors.affiliation: Department of Life Sciences, Imperial College London, Silwood Park, Ascot, United Kingdom.|Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, United States of America.
authors.forename: Walter
authors.initials: W
authors.lastname: Jetz
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds; D017753:Ecosystem; D004734:Energy Metabolism; D005843:Geography