Detecting the signature of selection on immune genes in highly structured populations of wild sheep (Ovis dalli)
Detecting the signature of selection on immune genes in highly structured populations of wild sheep (Ovis dalli)
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DOI：
10.1111/j.1365-294x.2006.02829.x
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发表时间：
2006-03-01
影响因子：
4.9
通讯作者：
Coltman, DW
中科院分区：
文献类型：
--
作者：
Worley, K;Carey, J;Coltman, DW
种群结构的混杂效应使得在自然种群中识别受选择影响的基因组区域的努力变得复杂。在这里，我们测试的证据，选择在三个基因参与脊椎动物的免疫功能-主要组织相容性复合体WHO，干扰素γ（IFNG）和自然抗性相关的巨噬细胞多态性（NRAMP）-在高度结构化的野生thinhorn羊（绵羊dalli）的人口。我们研究了与这些基因区域相关的微卫星位点和DNA序列水平的变异模式。简单的沃特森测试表明，在所有三个基因区域平衡选择。然而，选择的证据被混淆的人口结构，从连锁标记的沃特森的测试统计数据并没有从非连锁和假定中性的微卫星值的范围之外。Thinhorn IFNG和NRAMP的翻译编码序列是固定的，与家养绵羊（Ovis aries）的编码序列相同。与此相反，thinhorn的MHC DRB基因座显示出显着的证据overdominance通过过度的非同义取代和跨物种的多态性。在与MHC连锁的微卫星基因座上未能检测到平衡选择可能是标记和表达基因区域之间重组的结果。
The confounding effects of population structure complicate efforts to identify regions of the genome under the influence of selection in natural populations. Here we test for evidence of selection in three genes involved in vertebrate immune function - the major histocompatibility complex WHO, interferon gamma (IFNG) and natural resistance associated macrophage polymorphism (NRAMP) - in highly structured populations of wild thinhorn sheep (Ovis dalli). We examined patterns of variation at microsatellite loci linked to these gene regions and at the DNA sequence level. Simple Watterson's tests indicated balancing selection at all three gene regions. However, evidence for selection was confounded by population structure, as the Watterson's test statistics from linked markers were not outside of the range of values from unlinked and presumably neutral microsatellites. The translated coding sequences of thinhorn IFNG and NRAMP are fixed and identical to those of domestic sheep (Ovis aries). In contrast, the thinhorn MHC DRB locus shows significant evidence of overdominance through both an excess of nonsynonymous substitution and trans-species polymorphism. The failure to detect balancing selection at microsatellite loci linked to the MHC is likely the result of recombination between the markers and expressed gene regions.