Mutation load at a mimicry supergene sheds new light on the evolution of inversion polymorphisms
Mutation load at a mimicry supergene sheds new light on the evolution of inversion polymorphisms
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DOI：
10.1038/s41588-020-00771-1
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发表时间：
2021-01-25
期刊：
影响因子：
30.8
通讯作者：
Joron, Mathieu
中科院分区：
文献类型：
--
作者：
Jay, Paul;Chouteau, Mathieu;Joron, Mathieu
染色体倒位在基因组中普遍存在，并且通常协调复杂的表型，例如许多鸟类、鱼类、昆虫或哺乳动物中行为和形态的共变（1-11）。然而，倒位为什么以及如何与多态性状相关仍然不清楚。在这里，我们表明，尽管有很强的选择优势，当他们形成，倒位积累隐性有害突变，产生频率依赖性的选择，并促进其维持在中频。结合基因组学和在体内的健身分析，在一个模型蝴蝶的翅膀模式的多态性，Heliconius numata，我们发现，三个生态有利的倒位已经建立了一个沉重的突变负荷从顺序积累的有害突变和转座因子。当纯合子时，倒位与生存能力的急剧降低有关，这阻止了它们取代祖先的染色体排列。我们的研究结果表明，其他复杂的多态性，而不是代表适应竞争的生态优化，可以进化，因为染色体重排本质上容易携带隐性有害突变。
Chromosomal inversions are ubiquitous in genomes and often coordinate complex phenotypes, such as the covariation of behavior and morphology in many birds, fishes, insects or mammals(1-11). However, why and how inversions become associated with polymorphic traits remains obscure. Here we show that despite a strong selective advantage when they form, inversions accumulate recessive deleterious mutations that generate frequency-dependent selection and promote their maintenance at intermediate frequency. Combining genomics and in vivo fitness analyses in a model butterfly for wing-pattern polymorphism, Heliconius numata, we reveal that three ecologically advantageous inversions have built up a heavy mutational load from the sequential accumulation of deleterious mutations and transposable elements. Inversions associate with sharply reduced viability when homozygous, which prevents them from replacing ancestral chromosome arrangements. Our results suggest that other complex polymorphisms, rather than representing adaptations to competing ecological optima, could evolve because chromosomal rearrangements are intrinsically prone to carrying recessive harmful mutations.