Determinants and causes of balancing selection on immune genes

Antagonistic interactions between species, for example between hosts and pathogens, are considered to be one of the most important drivers of balancing selection (i.e. natural selection that enhances and maintains genetic variation).

However, it is not well known what determines which of all the genes involved in antagonistic interactions that are the actual targets of balancing selection.

Moreover, balancing selection requires some form of trade-off, but the costs and benefits of alternative alleles at genes under balancing selection are rarely known. To address these issues, I will here focus on vertebrate immune genes, using a wild rodent as study system.

I will combine population genomics, transcriptomics and cell culture assays of immune responses to investigate (i) how gene function, pleiotropy and expression level interact to determine the likelihood of balancing selection on a gene, and (ii) whether balancing selection can be a result of a trade-off between responses to different pathogens.

This research will provide novel information for understanding how natural selection can maintain genetic variation — a fundamental question in evolutionary biology.

In particular, the results from our studies will help explain why alleles associated with susceptibility to infectious and inflammatory diseases often occur at high frequencies in natural populations, including humans. The project will involve two PhD students and one part time researcher (bioinformatics support).