Community structure of the gut microbiota in sympatric species of wild Drosophila.

Many aspects of animal ecology and physiology are influenced by the microbial communities within them. The underlying forces contributing to the assembly and diversity of gut microbiotas include chance events, host-based selection and interactions among microorganisms within these communities. We surveyed 215 wild individuals from four sympatric species of Drosophila that share a common diet of decaying mushrooms. Their microbiotas consistently contained abundant bacteria that were undetectable or at low abundance in their diet. Despite their deep phylogenetic divergence, all species had similar microbiotas, thus failing to support predictions of the phylosymbiosis hypothesis. Communities within flies were not random assemblages drawn from a common pool; instead, many bacterial operational taxonomic units (OTUs) were overrepresented or underrepresented relative to the neutral expectations, and OTUs exhibited checkerboard distributions among flies. These results suggest that selective factors play an important role in shaping the gut community structure of these flies.