School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, Louisiana, United States of America.
PLoS One. 2012;7(5):e36748. doi: 10.1371/journal.pone.0036748. Epub 2012 May 24.
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.
理论和实证结果表明，MHC 和中性微卫星位点变异丧失率可能不同，因为选择会影响 MHC 基因，而且 MHC 位点的稀有等位基因比例较高可能会导致由于漂变而导致高的变异丧失率。大多数已发表的研究比较了不同当代群体的 MHC 和微卫星变异，以推断种群大小对遗传变异的影响，尽管不同的群体可能具有不同的种群历史，这也可能影响当代的遗传变异。我们通过比较历史和当代样本，直接比较了 Peary 驯鹿的 MHC 和微卫星位点的变异丧失。尽管 MHC 基因存在选择的强烈证据，但我们观察到，在每种类型的标记中，遗传变异随时间的丧失比例相似。这些结果表明，微卫星可以用于估计全基因组水平的变异，但也表明适应潜力可能会在种群瓶颈后丧失。然而，MHC 位点的基因转换和重组可能会在瓶颈后增加变异。
