Bending the rules of island biogeography: Microbiome diversity decreases with increased island size among insular reptilian hosts in the Philippines

We sampled the microbial communities of ecologically diverse reptilian hosts from four islands in the Philippines to elucidate the roles that host evolutionary history, host ecology, host microhabitat, geographic location, and island size play in reptilian gut microbiome assembly. This is the first assessment of variation in gut microbiomes among vertebrate species spanning true islands, and we apply theories in island biogeography to further investigate the mechanisms that shape the vertebrate gut microbiome. Results from our comparative study contribute to our growing understanding of the environmental, host-associated, and biogeographic processes that drive patterns of vertebrate gut microbiome diversity and assemblage among host communities inhabiting true islands.