Selection and phylogenetics of salmonid MHC class I: wild brown trout (Salmo trutta) differ from a non-native introduced strain

We tested how variation at a gene of adaptive importance, MHC class I (UBA), in a wild, endemic Salmo trutta population compared to that in both a previously studied non-native S. trutta population and a co-habiting Salmo salar population ( a sister species). High allelic diversity is observed and allelic divergence is much higher than that noted previously for cohabiting S. salar. Recombination was found to be important to population-level divergence. The alpha 1 and alpha 2 domains of UBA demonstrate ancient lineages but novel lineages are also identified at both domains in this work. We also find examples of recombination between UBA and the non-classical locus, ULA. Evidence for strong diversifying selection was found at a discrete suite of S. trutta UBA amino acid sites. The pattern was found to contrast with that found in re-analysed UBA data from an artificially stocked S. trutta population.

Keywords

Major histocompatibility complex , Peptide binding region , Rainbow trout , Oncorhynchus mykiss , Atlantic salmon , Natural selection , Balancing selection , Transspecies polymorphism , Convergent evolution , Parasite resistance

Citation

O'Farrell B, Benzie JAH, McGinnity P, de Eyto E, Dillane E, Coughlan J, et al. (2013) Selection and Phylogenetics of Salmonid MHC Class I: Wild Brown Trout (Salmo trutta) Differ from a Non-Native Introduced Strain. PLoS ONE 8(5): e63035. doi:10.1371/journal.pone.0063035