Biogeography of bird and mammal trophic structures

Does climate determine the trophic organization of communities around the
world? A recent study showed that a limited number of community trophic
structures emerge when co-occurrence of trophic guilds among large mammals
is examined globally. We ask whether the pattern is general across a all
terrestrial mammals (n=5272) and birds (n=9993). We found that the six
community-trophic structures previously identified with large mammals are
largely maintained when all mammals and birds are examined, both together
and separately, and that bioclimatic variables, including net primary
productivity (NPP), are strongly related to variation in the geographical
boundaries of community trophic structures. We argue that results are
consistent with the view that trophic communities are self-organized
structures optimizing energy flows, and that climate likely acts as the
main control parameter by modulating the amount of solar energy available
for conversion by plants and percolated through food webs across trophic
communities. Gradual changes in climate parameters would thus be expected
to trigger abrupt changes in energy flows resulting from phase transitions
(tipping points) between different dynamical stable states. We expect
future research to examine if our results are general across organisms,
ecosystems, scales, and methodologies, and whether inferences rooted in
complex systems theory are supported. The emergence of general patterns in
the functional properties of animal communities at broad scales supports
the emergence of food-web biogeography as a sub-discipline of biogeography
focused on the analysis of the geographical distributions of trophic
relationships among organisms.