Reduced X-linked diversity in derived populations of house mice
Reduced X-linked diversity in derived populations of house mice
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DOI：
10.1534/genetics.106.069419
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发表时间：
2007-04-01
期刊：
影响因子：
3.3
通讯作者：
Harr, Bettina
中科院分区：
文献类型：
--
作者：
Baines, John F.;Harr, Bettina
X连锁与常染色体多样性的对比模式可能表明自然群体中的选择模式。许多观察表明，在各种生物体中，X连锁（或Z连锁）多样性相对于常染色体多样性减少，这表明遗传搭便车的影响很大。然而，其他力量的相对贡献，如人口瓶颈，两性生殖成功的变化，和差异渐渗仍然不清楚。在这里，我们调查13个位点，6个X连锁和7个常染色体，在自然种群的家鼠（小家鼠）亚种复杂。我们研究了三个不同亚种的七个种群，东部家鼠M。muscalus castaneus、中家鼠M. M. musculus和西方家鼠M. M.包括每一种的pupesticus祖先和衍生种群。相对于常染色体，所有种群在X染色体上显示出较低的多样性，这种效应在衍生种群中最为明显。为了评估人口统计学的作用，我们使用合并模拟拟合了给出数据最高可能性的人口统计学参数。我们发现，X连锁多样性的减少是太大了，不能解释一个简单的人口模型，在至少两个四个衍生人群。这些观察结果也不太可能用雄性和雌性之间生殖成功的差异来解释。它们与正选择对X染色体的更大影响一致，并且这得到啮齿动物X染色体上K-A和K-A/K-S比值升高的观察结果的支持。第二个贡献可能是X染色体不太容易跨亚种边界渗入。
Contrasting patterns of X-linked vs. autosomal diversity may be indicative of the mode of selection operating in natural populations. A number of observations have shown reduced X-linked (or Z-linked) diversity relative to autosomal diversity in various organisms, suggesting a large impact of genetic hitchhiking. However, the relative contribution of other forces such as population bottlenecks, variation in reproductive success of the two sexes, and differential introgression remains unclear. Here, we survey 13 loci, 6 X-linked and 7 autosomal, in natural populations of the house mouse (Mus musculus) subspecies complex. We studied seven populations of three different subspecies, the eastern house mouse M. muscalus castaneus, the central house mouse M. m. musculus, and the western house mouse M.. m. domesticus, including putatively ancestral and derived populations for each. All populations display lower diversity on the X chromosomes relative to autosomes, and this effect is most pronounced in derived populations. To assess the role of demography, we fit the demographic parameters that gave the highest likelihood of the data using coalescent simulations. We find that the reduction in X-linked diversity is too large to be explained by a simple demographic model in at least two of four derived populations. These observations are also not likely to be explained by differences in reproductive success between males and females. They are consistent with a greater impact of positive selection on the X chromosome, and this is supported by the observation of an elevated K-A and elevated K-A/K-S ratios on the rodent X chromosome. A second contribution may be that the X chromosome less readily introgresses across subspecies boundaries.