密苏里大学Wesley C. Warren课题组近日取得一项新成果。经过不懈努力，他们的研究发现基因转换使无性系鱼类的自然选择成为可能。相关论文发表在2026年3月11日出版的《自然》杂志上。

在这里，该团队表明，尽管亚马逊molly积累突变的速度比其有性祖先物种快，但这并没有导致功能性突变的衰退，这违背了理论预期。相反，基因转换通过产生新的无性系来促进适应性选择和纯化选择，在这些无性系中，先前的突变要么被恢复，要么被固定，并且通过解决祖先单倍型之间的杂交不相容。向克隆性的转变改变了染色质结构，但亚马逊molly的无性单倍型仍然保持了其祖先物种的不同突变景观。总之，这些结果为长期存在的关于无性生殖的权衡问题提供了新的见解。

研究人员表示，有性生殖是古老而普遍的，尽管它有明显的缺点。理论预测，性别导致的等位基因的重新组合是自然选择对个体基因座有效作用的必要条件；因此，一个纯克隆生物应该迅速积累有害突变并走向灭绝。然而，许多无性物种存在的时间比理论预测的要长，例如亚马逊molly (Poecilia formosa)，这是一种克隆繁殖的鱼类，起源于10万多年前的一次杂交事件。

附：英文原文

Title: Gene conversion empowers natural selection in a clonal fish species

Author: Ricemeyer, Edward S., Schaefer, Nathan K., Du, Kang, da Cruz, Irene, Kneitz, Susanne, Acemel, Rafael D., Lupiez, Daro G., Carroll, Rachel A., Drinkwater, Rosie, Schartl, Manfred, Warren, Wesley C.

Issue&Volume: 2026-03-11

Abstract: Sexual reproduction is ancient and ubiquitous despite its obvious disadvantages1. Theory predicts that the reassortment of alleles that results from sex is necessary for natural selection to act effectively on individual loci; therefore, a purely clonal organism should rapidly accumulate deleterious mutations and go extinct2,3,4. Nevertheless, many asexual species have existed for longer than theory predicts is possible5,6,7, such as the Amazon molly (Poecilia formosa), a clonally reproducing fish arising from a single hybridization event more than 100,000 years ago8,9,10. Here we show that although the Amazon molly has accumulated mutations faster than its sexual progenitor species, this has not led to functional mutational decay, defying theoretical expectations. Instead, gene conversion facilitates both adaptive and purifying selection by generating new clonal lineages in which previous mutations are either reverted or fixed, and by resolving hybrid incompatibilities between the ancestral haplotypes. The transition to clonality altered chromatin structure, but the asexual haplotypes of the Amazon molly nonetheless maintain the divergent mutational landscapes of their progenitor species. Together, these results provide new insights into long-standing questions about the trade-offs involved in asexual reproduction.

DOI: 10.1038/s41586-026-10180-9

Source: https://www.nature.com/articles/s41586-026-10180-9