Genotype-environment associations reveal genes potentially linked to
avian malaria infection in populations of an endemic island bird
Abstract
Patterns of pathogen prevalence are, at least partially, the result of
coevolutionary host-pathogen interactions. Thus, exploring the
distribution of host genetic variation in relation to infection by a
pathogen within and across populations can provide important insights
into mechanisms of host defence and adaptation. Here we use a landscape
genomics approach (Bayenv) in conjunction with genome-wide data
(ddRADseq) to test for associations between avian malaria (Plasmodium)
prevalence and host genetic variation across 13 populations of the
island endemic Berthelot’s pipit (Anthus berthelotii). Considerable and
consistent spatial heterogeneity in malaria prevalence was observed
among populations over a period of 15 years, and the prevalence of
malaria infection was strongly correlated with pox (Avipoxvirus)
prevalence. Evidence of significant association with malaria was found
for multiple host loci after controlling for genome-wide divergence due
to neutral genetic structure. These sites were located near to or within
genes linked to metabolism, stress response, transcriptional regulation,
complement activity and the inflammatory response, many previously
implicated in vertebrate responses to malarial infection. Taken
together, our findings identify diverse genes - not just limited to the
immune system - that may be involved in host protection against malaria
and suggests that spatially variable pathogen pressure is an important
evolutionary driver of genetic divergence among wild animal populations,
such as Berthelot’s pipit. Further, our data indicate that
spatio-temporal variation in multiple different pathogens (e.g., malaria
and pox in this case) may have to be studied together to develop a more
holistic understanding of host pathogen-mediated evolution.