Data from: 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
diversity within Interleukin 1 beta and Interleukin 2 appears to have been
maintained through balancing selection. Taken together with previous
findings that polymorphism within these genes is associated with variation
in resistance to multiple pathogens, this suggests that pathogen-mediated
selection may be an important force driving genetic diversity at cytokine
loci in voles and other natural populations. These results also suggest
that, along with the MHC, preservation of genetic variation within
cytokine genes should be a priority for the conservation genetics of
threatened wildlife populations.