Evidence for selection at cytokine loci in a natural population of field voles (Microtus agrestis)

Individuals in natural populations are frequently exposed to a wide range of pathogens. Given the diverse profile of gene products involved in responses to different types of pathogen, this potentially results in complex pathogen-specific selection pressures acting on a broad spectrum of immune system genes in wild animals. Thus far, studies into the evolution of immune genes in natural populations have focused almost exclusively on the Major Histocompatibility Complex (MHC). However, the MHC represents only a fraction of the immune system and there is a need to broaden research in wild species to include other immune genes. Here we examine the evidence for natural selection in a range of non-MHC genes in a natural population of field voles (Microtus agrestis). We concentrate primarily on genes encoding cytokines, signaling molecules critical in eliciting and mediating immune responses, and identify signatures of natural selection acting on several of these genes. In particular, genetic...