小柯机器人

法国蒙彼利埃第三大学Mathieu Joron等研究人员通过一个拟态超基因的突变负荷，揭示出倒位多态性的进化机制。这一研究成果于2021年1月25日在线发表在国际学术期刊《自然—遗传学》上。

研究人员表明，尽管染色体倒位形成时具有很强的选择优势，但它们会累积隐性有害突变，从而产生依赖于频率的选择并促进其维持在中频。通过在翼型多态性的模式蝴蝶Heliconius numata中将基因组学和体内适应性分析相结合，研究人员发现，三个具有生态学优势的倒位从有害突变和转座因子的顺序积累中建立了沉重的突变负担。纯合时，倒位与活力急剧降低有关，这阻止了它们替换祖先的染色体排列。

这些结果表明，其他复杂的多态性可能会进化，而不会成为对竞争性生态最优的适应，因为染色体重排本质上倾向于携带隐性有害突变。 

据了解，染色体倒位在基因组中无处不在，通常参与调节复杂的表型，例如许多鸟类、鱼类、昆虫或哺乳动物的行为和形态的共变。但是，为什么以及如何将倒位与多态性状联系起来仍然不清楚。

附：英文原文

Title: Mutation load at a mimicry supergene sheds new light on the evolution of inversion polymorphisms

Author: Paul Jay, Mathieu Chouteau, Annabel Whibley, Hlose Bastide, Hugues Parrinello, Violaine Llaurens, Mathieu Joron

Issue&Volume: 2021-01-25

Abstract: 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 mammals1,2,3,4,5,6,7,8,9,10,11. 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.

DOI: 10.1038/s41588-020-00771-1

Source: https://www.nature.com/articles/s41588-020-00771-1

Nature Genetics：《自然—遗传学》，创刊于1992年。隶属于施普林格·自然出版集团，最新IF：41.307
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