Gene family phylogeny and the evolution of parasite cell surfaces

Parasite genomes typically contain unique contingency gene families encoding multi-copy effector proteins that are often expressed abundantly on the parasite cell surface and beyond. The functions of these gene families are incompletely understood but it is clear that they perform fundamental roles at the host-parasite interface. Over evolutionary timescales, the evolution of these gene families is likely to have decisive effects on the pathology and virulence of parasitic infections. In this review, I will compare the evolutionary dynamics of multiple examples from trypanosomatids and apicomplexan parasites to demonstrate how their inherent mutability makes their phylogeny very different to 'normal' gene families. I will argue that phylogenetic analyses could help to understand the functions of these enigmatic genes.