MHC genetic structure and divergence across populations of Chinook salmon (Oncorhynchus tshawytscha)
Document Type
Article
Publication Date
2010
Publication Title
Heredity
Volume
104
Issue
5
First Page
449
Last Page
459
Abstract
The major histocompatibility complex (MHC) is thought to be under strong selection pressure because of its integral role in pathogen recognition. Consequently, patterns of MHC genetic variation should reflect selection pressures across the landscape. We examined genetic variation and population genetic structure at the MHC class I-A1 and class II-B1 exons in five Chinook salmon (Oncorhynchus tshawytscha) populations from two geographic regions in British Columbia, Canada. We then compared estimates of population structure at the MHC genes with neutral estimates based on microsatellites to examine the potential for local adaptation at the MHC. Chinook salmon are in decline throughout much of their native range and understanding the degree of local adaptation exhibited by the MHC may be important in conservation planning. Comparisons among populations yielded higher G(ST)' estimates for the MHC class I than expected under neutrality based on the microsatellites. In contrast, the MHC class II tended to exhibit lower G(ST)' values than did the microsatellites. These results suggest that across populations unique selection pressures are driving allele frequency differences at the MHC class I but that the MHC class II may be the subject of homogenizing selection. Rates of nonsynonymous versus synonymous substitutions found in codons associated within the MHC class I and II peptide-binding regions provided strong evidence of positive selection. Together, these results support the hypothesis that selection is influencing genetic variation at the MHC, but suggest that selection pressures may vary at the two classes of loci both at the sequence and population levels. Heredity (2010) 104, 449-459; doi:10.1038/hdy.2009.121; published online 23 September 2009
DOI
10.1038/hdy.2009.121
Recommended Citation
Evans, M. L.; Neff, B. D.; and Heath, Daniel D.. (2010). MHC genetic structure and divergence across populations of Chinook salmon (Oncorhynchus tshawytscha). Heredity, 104 (5), 449-459.
https://scholar.uwindsor.ca/glierpub/46
Comments
This is an accepted manuscript version of an article whose version of record was published in:Heredity: http://dx.doi.org/10.1038/hdy.2009.121