Genomic associations with poxvirus across divergent island populations
in Berthelot's pipit
Abstract
Understanding the mechanisms and genes that enable animal populations to
adapt to pathogens is important from an evolutionary, health and
conservation perspective. Berthelot’s pipit (Anthus berthelotii)
experiences extensive and consistent spatial heterogeneity in avian pox
infection pressure across its range of island populations, thus
providing an excellent system with which to examine how
pathogen-mediated selection drives spatial variation in immunogenetic
diversity. Here we test for evidence of genetic variation associated
with avian pox at both an individual and population-level. At the
individual level, we find no evidence that variation in MHC class I and
TLR4 (both known to be important in recognising viral infection) was
associated with pox infection within two separate populations. However,
using genotype-environment association (Bayenv) in conjunction with
genome-wide (ddRAD-seq) data, we detected strong associations between
population-level avian pox prevalence and allele frequencies of single
nucleotide polymorphisms (SNPs) at a number of sites across the genome.
These sites were located within genes involved in cellular stress
signalling and immune responses, many of which have previously been
associated with responses to viral infection in humans and other
animals. Consequently, our analyses provide evidence that
pathogen-mediated selection has shaped genomic variation among
relatively recently colonised island bird populations, and highlights
the utility of genotype-environment associations for identifying
candidate genes involved in adaption to local pathogen pressures.