Global plant-frugivore trait matching is shaped by climate and biogeographic history

Ian R. McFadden, Niklaus E. Zimmermann, Loïc Pellissier and Catherine H. Graham, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland, Ian R. McFadden and Loïc Pellissier, Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland, Susanne A. Fritz and Matthias Schleuning, Senckenberg Biodiversity and Climate Research Centre, Frankfurt, Germany, Susanne A. Fritz, Department of Biological Sciences, Johann Wolfgang Goethe-University, Frankfurt, Germany, W. Daniel Kissling, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, Netherlands, Joseph A. Tobias, Department of Life Sciences, Imperial College London, Ascot, United Kingdom

Background/Question/Methods
The extent to which species interactions can shape the trait structure of multi-trophic communities at the global scale, especially given climatic constraints on traits, is an on-going debate. Here, we evaluate the relationship between functional traits of frugivorous birds and palms (Arecaceae) to address two key questions: 1) Is trait matching apparent at global scales; and to what extent is matching shaped, directly or indirectly, by climate? 2) How does the strength of trait matching vary across latitude and zoogeographic realms?

Results/Conclusions
We find a positive relationship between gape size and fruit size globally, which is influenced indirectly by climate and richness through effects on plant traits. In addition, we uncover a latitudinal gradient in the strength of trait matching- finding that matching strength increases towards the tropics and differs among zoogeographic realms. Taken together, our results suggest mutualistic interactions act in a consistent way across the globe to create trait matching, but that the abiotic environment also plays an important, though indirect, role in shaping the functional biogeography of mutualisms.