Higher differentiation among subspecies of the house mouse (Mus musculus) in genomic regions with low recombination.
Higher differentiation among subspecies of the house mouse (Mus musculus) in genomic regions with low recombination.
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DOI：
10.1111/j.1365-294x.2011.05285.x
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发表时间：
2011-11
影响因子：
4.9
通讯作者：
Nachman MW
中科院分区：
文献类型：
--
作者：
Geraldes A;Basset P;Smith KL;Nachman MW
在生殖隔离的早期阶段，减少重组的基因组区域预计将表现出更高水平的分化，这要么是因为物种之间的基因流在这些区域减少，要么是因为物种内连锁位点的选择效应在这些区域增强。本文研究了小家鼠（Mus musculus musculus）、小家鼠（M. M. altagicus和M. M. castaneus，具有共线性基因组的家鼠的三个亚种。我们发现，一些位点表现出相当大的共享变异亚种之间，而其他表现出固定的差异。我们使用了一个隔离与基因流模型来估计发散时间，有效的人口规模（Ne）和解开祖先的基因流的变化。对分歧时间的估计表明，这三个亚种在大约35万年前的很短时间内彼此分歧。总的来说，每个亚种的Ne与遗传分化程度有关：M。M. musculus的Ne最小，单系基因谱系比例最大，而M. M.栗的Ne最大，单系基因系谱比例最小。M. M. Acetylticus和M. M. musculus之间的分化程度高于M. M. castaneus，与M. M. Acetylticus和M. M.肌肉FST在经历低重组率的基因座上显著大于经历高重组率的基因座。M. castaneus和M. M. musculus或M. M.阿提库斯这些结果提供证据表明，即使在没有染色体重排的情况下，重组较少的基因组区域也显示出更大的分化。
In the early stages of reproductive isolation, genomic regions of reduced recombination are expected to show greater levels of differentiation, either because gene flow between species is reduced in these regions or because the effects of selection at linked sites within species is enhanced in these regions. Here we study patterns of DNA sequence variation at 27 autosomal loci among populations of Mus musculus musculus, M. m. domesticus, and M. m. castaneus, three subspecies of house mice with co-linear genomes. We found that some loci exhibit considerable shared variation among subspecies, while others exhibit fixed differences. We used an isolation-with-gene-flow model to estimate divergence times, effective population sizes (Ne) and to disentangle ancestral variation from gene flow. Estimates of divergence time indicate that all three subspecies diverged from one another within a very short period of time roughly 350,000 years ago. Overall, Ne for each subspecies was associated with the degree of genetic differentiation: M. m. musculus had the smallest Ne and the greatest proportion of monophyletic gene genealogies, while M. m. castaneus had the largest Ne and the smallest proportion of monophyletic gene genealogies. M. m. domesticus and M. m. musculus were more differentiated from each other than either was from M. m. castaneus, consistent with greater reproductive isolation between M. m. domesticus and M. m. musculus. FST was significantly greater at loci experiencing low recombination rates compared to loci experiencing high recombination rates in comparisons between M. m. castaneus and M. m. musculus or M. m. domesticus. These results provide evidence that genomic regions with less recombination show greater differentiation, even in the absence of chromosomal rearrangements.