Do Symbiotic Microbes Drive Chemical Divergence Between Colonies in the Pratt's Leaf-Nosed Bat, Hipposideros pratti?

Host odour may be affected by symbiotic microbes that produce metabolites. As a result, chemical signal production may be influenced. Few studies to date have assessed how symbiotic microbes influence variation in geography of animal chemical signals. This is important because chemical signal divergence can affect mate choice, species recognition, and ultimately speciation in a broad range of animals. However, the underlying driving forces of chemical signal divergence are still rather poorly understood. To study chemical signals, bats provide a good model system because they are such social mammals. Because males roost in dark spaces during the daytime, they rely on chemical and acoustic signals. We identified three colonies across a large geographic area and collected male forehead gland secretions from Pratt's leaf-nosed bats (Hipposideros pratti). We examined the role symbiotic microbes played in potential variation in the geography of chemical signals. We observed significant colony-level differences in compound categories and in the amount of specific compounds. We also found significant colony-level differences in forehead gland microbiota. However, there was no significant relationship between bat-gland bacterial community composition and variation in chemical composition across colonies. These results suggest that bacterial communities may fail to shape the chemical signalling profiles of the different colonies in Pratt's leaf-nosed bats.