Data from: Landscape-scale variation in an anthropogenic factor shapes immune gene variation within a wild population

Understanding the spatial scale at which selection acts upon adaptive
genetic variation in natural populations is fundamental to our
understanding of evolutionary ecology, and has important ramifications for
conservation. The environmental factors to which individuals of a
population are exposed can vary at fine spatial scales, potentially
generating localized patterns of adaptation. Here, we compared patterns of
neutral and major histocompatibility complex (MHC) variation within an
island population of Berthelot's pipit (Anthus berthelotii) to assess
whether landscape-level differences in pathogen-mediated selection
generate fine-scale spatial structuring in these immune genes.
Specifically, we tested for spatial associations between the distribution
of avian malaria, and the factors previously shown to influence that
distribution, and MHC variation within resident individuals. Although we
found no overall genetic structure across the population for either
neutral or MHC loci, we did find localized associations between
environmental factors and MHC variation. One MHC class I allele (ANBE48)
was directly associated with malaria infection risk, while the presence of
the ANBE48 and ANBE38 alleles within individuals correlated (positively
and negatively, respectively) with distance to the nearest poultry farm,
an anthropogenic factor previously shown to be an important determinant of
disease distribution in the study population. Our findings highlight the
importance of considering small spatial scales when studying the patterns
and processes involved in evolution at adaptive loci.