Adaptive genetic variation at three loci in South African vervet monkeys ( Chlorocebus pygerythrus ) and the role of selection within primates

Vervet monkeys ( ) are one of the most widely distributed non-human primate species found in South Africa. They occur across all the South African provinces, inhabiting a large variety of habitats. These habitats vary sufficiently that it can be assumed that various factors such as pathogen diversity could influence populations in different ways. In turn, these factors could lead to varied levels of selection at specific fitness linked loci. The Toll-like receptor ( ) gene family, which play an integral role in vertebrate innate immunity, is a group of fitness linked loci which has been the focus of much research. In this study, we assessed the level of genetic variation at partial sequences of two loci ( and ) and a reproductively linked gene, ( ), across the different habitat types within the vervet monkey distribution range. Gene variation and selection estimates were also made among 11-21 primate species. Low levels of genetic variation for all three gene regions were observed within vervet monkeys, with only two polymorphic sites identified for , three sites for and one site for variation was positively correlated with high mean annual rainfall, which was linked to increased pathogen abundance. The observed genetic variation at might have been influenced by numerous factors including pathogens and climatic conditions. The exonic regions showed no variation in vervet monkeys, which could point to the occurrence of a selective sweep. The and results for the among primate analyses was mostly in line with previous studies, indicating a higher rate of evolution for . Within primates, coding regions also showed signs of positive selection, which was congruent with previous reports on mammals. Important additional information to the already existing vervet monkey knowledge base was gained from this study, which can guide future research projects on this highly researched taxon as well as help conservation agencies with future management planning involving possible translocations of this species.