Association between the skin microbiome and MHC class II diversity in an amphibian

Abstract

It has become clear that the microbiome plays an important role in determining host health, diseases, and phenotypic variation. There is increasing evidence that the microbiome influences host fitness and its adaptation to the environment is changing our thinking on host-microbe interactions. However, it remains unclear how a host genotype shapes its microbiome. Here, we explored how genetic background and evolutionary history influence associated microbiome in amphibian populations. We studied how skin bacterial diversity is associated with the Major Histocompatibility Complex (MHC) class II exon 2 diversity in 12 moor frog populations belonging to two geographical clusters that show signatures of past and ongoing differential selection patterns. We found that bacterial alpha-diversity remained similar between the two clusters, while MHC haplotype-supertypes and genetic diversity differed between the clusters. Bacterial alpha-diversity was positively correlated with expected MHC heterozygosity and negatively with MHC nucleotide diversity. We also found that bacterial community composition differed significantly between the two geographic clusters and between specific MHC supertypes. These findings further suggest that population historical demographic events influence hologenomic variation and provide new insights into how immunogenetic host variability and microbial diversity may jointly influence host fitness with consequences for disease susceptibility and population persistence.