Selection, recombination, and hybrid evolution Hybridization is an important force in evolution. The effects of hybridization across the whole genome are not understood. Using a fine-scale genetic map, Schumer et al. examined local ancestry in replicate natural hybrid populations of swordtail fish. Each parental species contributes different proportions of genetic material to the genomes of their descendants. Genes from the “minor” (less well-represented) parent occur in regions of the genome that are subject to higher recombination rates and where there are fewer potentially deleterious genes. Neanderthal ancestry in human genomes shows similar patterns. Science, this issue p. 656 In hybrid fish, the “minor” parent species can be predicted from local recombination rates. To investigate the consequences of hybridization between species, we studied three replicate hybrid populations that formed naturally between two swordtail fish species, estimating their fine-scale genetic map and inferring ancestry along the genomes of 690 individuals. In all three populations, ancestry from the “minor” parental species is more common in regions of high recombination and where there is linkage to fewer putative targets of selection. The same patterns are apparent in a reanalysis of human and archaic admixture. These results support models in which ancestry from the minor parental species is more likely to persist when rapidly uncoupled from alleles that are deleterious in hybrids. Our analyses further indicate that selection on swordtail hybrids stems predominantly from deleterious combinations of epistatically interacting alleles.

中文翻译：

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自然选择与重组相互作用，塑造杂交基因组的进化


选择、重组和杂交进化 杂交是进化的重要力量。杂交对整个基因组的影响尚不清楚。舒默等人使用精细尺度的遗传图谱。检查了复制剑尾鱼自然杂交种群的当地血统。每个亲本物种为其后代的基因组贡献不同比例的遗传物质。来自“次要”（代表性较差）亲本的基因出现在基因组中重组率较高且潜在有害基因较少的区域。人类基因组中的尼安德特人血统也显示出类似的模式。科学，本期第 14 页。 656 在杂交鱼类中，“次要”亲本物种可以根据局部重组率进行预测。为了研究物种之间杂交的后果，我们研究了两个剑尾鱼物种之间自然形成的三个复制杂交群体，估计了它们的精细遗传图谱并沿着 690 个个体的基因组推断了祖先。在所有三个种群中，来自“次要”亲本物种的祖先在高重组区域和与较少的假定选择目标相关的区域更为常见。在对人类和古代混合物的重新分析中，同样的模式也很明显。这些结果支持这样的模型：当与杂种中有害的等位基因快速分离时，来自次要亲本物种的祖先更有可能持续存在。我们的分析进一步表明，对剑尾杂交体的选择主要源于上位相互作用等位基因的有害组合。