Spatial pattern of MHC class II variation in the great snipe (Gallinago media)
Spatial pattern of MHC class II variation in the great snipe (Gallinago media)
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DOI：
10.1111/j.1365-294x.2007.03281.x
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发表时间：
2007-04-01
影响因子：
4.9
通讯作者：
Hoglund, Jacob
中科院分区：
文献类型：
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作者：
Ekblom, Robert;Saether, Stein Are;Hoglund, Jacob
主要组织相容性复合体 (MHC) 的基因编码参与抗原识别和适应性免疫反应触发的蛋白质，因此很可能受到寄生虫的选择。这些选择制度可能在空间和时间上有所不同。在这里，我们报告了候鸟大鹬（Gallinago media）的 MHC II B 类基因中强大的地理结构。使用部分曼特尔检验对选择性中性变异（微卫星）的影响进行统计控制后，两个生态不同的分布区域（斯堪的纳维亚山区种群与东欧低地种群）之间的 MHC 遗传分化仍然存在。这表明选择在生成这种空间结构中发挥着作用，并且它代表了对不同环境的局部适应。这两个地区的人口差异可以忽略不计。总体而言，我们发现了大量 MHC 等位基因（来自 175 个人的 50 个）。这与肽结合位点中非同义取代率高于同义取代率的趋势以及基因某些区域的高田岛 D 值一起，表明了平衡选择的历史。人们通常认为 MHC 变异是通过某种形式的平衡选择来维持的，但这种选择的本质仍不清楚。我们的结果支持这样的假设：选择机制的空间变化有助于高度多态性。
The genes of the major histocompatibility complex (MHC) code for proteins involved in antigen recognition and triggering of the adaptive immune response, and are therefore likely to be under selection from parasites. These selection regimes may vary in space and time. Here we report a strong geographical structure in MHC class II B genes of a migrating bird, the great snipe (Gallinago media). Genetic differentiation in the MHC between two ecologically distinct distributional regions (Scandinavian mountain populations vs. East European lowland populations) was still present after statistically controlling for the effect of selectively neutral variation (microsatellites) using partial Mantel tests. This suggests a role for selection in generating this spatial structure and that it represents local adaptation to different environments. Differentiation between populations within the two regions was negligible. Overall, we found a high number of MHC alleles (50, from 175 individuals). This, together with a tendency for a higher rate of nonsynonymous than synonymous substitutions in the peptide binding sites, and high Tajima's D in certain regions of the gene, suggests a history of balancing selection. MHC variation is often thought to be maintained by some form of balancing selection, but the nature of this selection remains unclear. Our results support the hypothesis that spatial variation in selection regimes contributes to the high polymorphism.