Habitat fragmentation in the Brazilian Atlantic Forest is associated with erosion of frog immunogenetic diversity and increased fungal infections

We examined the effects of habitat fragmentation in Brazil ’s Atlantic Forest on amphibian genetic diversity at an immune locus related to antigen presentation and detection (MHC IIB Exon 2). We used a custom high-throughput assay to sequence a fragment of MHC IIB and quantifiedBatrachochytrium dendrobatidis (Bd) infections in six frog species in two Atlantic Forest regions. Habitat fragmentation was associated with genetic erosion at MHC IIB Exon 2. This erosion was most severe in forest specialists. SignificantBd infections were detected only in one Atlantic Forest region, potentially due to relatively higher elevation. In this region, forest specialists showed an increase in bothBd prevalence and infection loads in fragmented habitats. Reduced population-level MHC IIB diversity was associated with increasedBd infection risk. On the individual level, MHC IIB heterozygotes exhibited a trend toward reducedBd infection risk, although this was marginally non-significant. Our results suggest that habitat fragmentation increasesBd infection susceptibility in amphibians, mediated at least in part through erosion of immunogenetic diversity. Our findings have implications for management of fragmented populations in the face of emerging infectious diseases.
Source: Immunogenetics - Category: Genetics & Stem Cells Source Type: research