Geography shapes the microbial community structure in Heliconius butterflies. undefined

The internal microbial communities of insects have important functional effects on both their biology and ecology. However, the importance of these interactions is still poorly understood in many groups. Heliconius butterflies are excellent organisms in which to study ecology, behavior, adaptation, and speciation. However, the study of the microbial communities associated with Heliconius has been limited, mainly focusing on host phylogenetic signal in microbiomes or the microbiome characterization in local communities of butterflies. In this study we evaluated the microbiomes of several species and populations of Heliconius occurring at distant localities that represent contrasting environments. We found that the microbiota of different species of Heliconius is taxonomically similar but vary in abundances, and importantly, this variation is associated with a major geographic barrier (i.e. the Central Cordillera of Colombia). We also confirmed this microbiota does not seem to be associated with pollen-feeding. Therefore, geographic location likely shapes the microbial abundance the butterfly carries, but not the composition of such microbial community. It is still unclear whether microbes are simply acquired by the insect from environment or if they confer some advantage to the insect. In summary, the current evidence suggests that the structured microbial communities we observed in Heliconius may be due to stochastic rather than deterministic processes.