Metacommunity theory predicts that strongly connected individuals harbour more similar gut microbiomes (GM) than weakly connected ones, and interacting with more individuals should increase GM diversity. This is true in highly social species, yet the applicability of the metacommunity framework for understanding the GM in other host social architectures needs to be tested. Additionally, bacterial transmission across species may play a role in facilitating their coexistence, yet whether this transmission can impact the GM is unknown. We examine the relationship between probability of encounter and the GM in sympatric deer mice (Peromyscus maniculatus) and red-backed voles (Myodes gapperi). We test the hypotheses that 1) similarity in GM composition between individuals of similar and different species correlates with their likelihood of association; and 2) GM diversity correlates with a host’s number of neighbours, either of similar or different species. We used capture and RFID data to construct encounter networks for each species and for both species together. We used RDA analyses to compare pair-wise GM similarity and probability of encounter within and across species, and regressions to test for correlations between host GM diversity and degree centrality obtained from networks constructed from the hosts’ respective species, and the opposite species.
Results/Conclusions
In mice, probability of encounter and habitat were confounded, and habitat was a slightly better predictor of GM composition. In voles, likelihood of encounter best explained at least part of the GM composition, and a second part varied with both habitat and encounter probability but was best explained by habitat. We found weak evidence for a relationship between GM composition and interspecific probability of encounter. GM diversity was not correlated with number of neighbours within each species’ respective network in either mice or voles. However, mouse GM diversity strongly correlated with number of vole neighbors. Our results indicate that the GM composition and diversity of less social species also follow, at least in part, a metacommunity theory framework and that the GM could play a role in regulating host communities, either through dispersal of beneficial or pathogenic bacteria.