Interaction between MHC diversity and constitution, gut microbiota and Astrovirus infections in a neotropical bat.

Astroviruses (AstVs) infect numerous mammalian species including reservoirs such as bats. Peptides encoded by the genes of the highly polymorphic Major Histocompatibility Complex (MHC) form the first line of host defence against pathogens. Aside from direct involvement in mounting adaptive immune responses, MHC class II genes are hypothesized to regulate gut commensal diversity and shape the production of immune-modulatory substances by microbes, indirectly affecting host susceptibility. Despite initial empirical evidence for the link between host MHC and the microbiota, associations among these factors remain largely unknown. To fill this gap, we examined MHC allelic diversity and constitution, the gut bacterial community and abundance pattern of a wild population of a neotropical bat (Artibeus jamaicensis) challenged by AstV infections. First, we show an age-dependent relationship between the host MHC class II diversity and constitution and the gut microbiota in AstV-uninfected bats. Crucially, these associations changed in AstV-infected bats. Additionally, we identify changes in the abundance of specific bacterial taxa linked to the presence of certain MHC supertypes and AstV infection. We suggest changes in the microbiota to be either a result of AstV infection or the MHC-mediated modulation of microbial communities. The latter could subsequently affect microbe-mediated immunity and resistance against AstV infection. Our results emphasize that the reciprocal nature of host immune genetics, gut microbial diversity and pathogen infection require attention, which are particularly important given their repercussions for disease susceptibility and severity in wild animal populations with a history of zoonotic spillover and frequent human contact.

Male-biased dispersal and the potential impact of human-induced habitat modifications on the Neotropical bat Trachops cirrhosus.

Gene flow, maintained through natal dispersal and subsequent mating events, is one of the most important processes in both ecology and population genetics. Among mammalian populations, gene flow is strongly affected by a variety of factors, including the species' ability to disperse, and the composition of the environment which can limit dispersal. Information on dispersal patterns is thus crucial both for conservation management and for understanding the social system of a species. We used 16 polymorphic nuclear microsatellite loci in addition to mitochondrial DNA sequences (1.61 kbp) to analyse the population structure and the sex-specific pattern of natal dispersal in the frog-eating fringe-lipped bat, Trachops cirrhosus, in Central Panama. Our study revealed that-unlike most of the few other investigated Neotropical bats-gene flow in this species is mostly male-mediated. Nevertheless, distinct genetic clusters occur in both sexes. In particular, the presence of genetic differentiation in the dataset only consisting of the dispersing sex (males) indicates that gene flow is impeded within our study area. Our data are in line with the Panama Canal in connection with the widening of the Río Chagres during the canal construction acting as a recent barrier to gene flow. The sensitivity of T. cirrhosus to human-induced habitat modifications is further indicated by an extremely low capture success in highly fragmented areas. Taken together, our genetic and capture data provide evidence for this species to be classified as less mobile and thus vulnerable to habitat change, information that is important for conservation management.