Loss of MHC and neutral variation in Peary caribou: genetic drift is not mitigated by balancing selection or exacerbated by MHC allele distributions.
Theory and empirical results suggest that the rate of loss of variation at Mhc and neutral microsatellite loci may differ because selection influences Mhc genes, and because a high proportion of rare alleles at Mhc loci may result in high rates of loss via drift. Most published studies compare Mhc and microsatellite variation in various contemporary populations to infer the effects of population size on genetic variation, even though different populations are likely to have different demographic histories that may also affect contemporary genetic variation. We directly compared loss of variation at Mhc and microsatellite loci in Peary caribou by comparing historical and contemporary samples. We observed that similar proportions of genetic variation were lost over time at each type of marker despite strong evidence for selection at Mhc genes. These results suggest that microsatellites can be used to estimate genome-wide levels of variation, but also that adaptive potential is likely to be lost following population bottlenecks. However, gene conversion and recombination at Mhc loci may act to increase variation following bottlenecks.
School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, Louisiana, United States of America. staylor@lsu.edu
Sabrina S
SS
Taylor
Deborah A
DA
Jenkins
Peter
P
Arcese
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D040961:Genetic Drift; D014644:Genetic Variation; D008285:Major Histocompatibility Complex; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D012053:Reindeer / Q000235:genetics*; D012641:Selection, Genetic