Wan Na, Duan Qijiao, Cai Zhenyuan, Zhu Zhanwu, Wang JingOu, Tian Yonghui, Shen Wei, Li Bowen, Kuang Zhuoran, Liang Xiaolong, Liu Sanyuan, An Xuan, Yang Xiaojie, Liu Xi, Mao Leyan, Chen Jiaqi, Wang Yinjia, Feng Zhilong, Liu Wenwen, Bu Yueting, Nevo Eviatar, Papa Riccardo, Meyer Axel, Liu Jianquan, Li Kexin
State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou, P. R. China.
Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China.
Sci Adv. 2025 Sep 5;11(36):eadt2282. doi: 10.1126/sciadv.adt2282.
Chromosomal fissions and fusions are common, yet the molecular mechanisms and implications in speciation remain poorly understood. Here, we confirm a fission event in one zokor species through multiple-omics and functional analyses. We traced this event to a mutation in a splicing enhancer of the DNA repair gene in the fission-bearing species, which caused exon skipping and produced a truncated protein that disrupted DNA repair. An intronic deletion in , known to facilitate neo-telomere formation when knocked out, reduced gene activity. These variants collectively drove chromosomal fission in this zokor species. The newly formed chromosome became fixed due to carrying essential genes and strong selective pressure. While geographic isolation likely initiated the divergence of this species and the sister one, the fission event and associated decline at the chromosome level in gene flow probably exacerbated the speciation process. Our work elucidates the genetic basis of chromosomal fission and underscores its role in speciation dynamics.
染色体的裂变和融合很常见，但其分子机制及在物种形成中的影响仍知之甚少。在此，我们通过多组学和功能分析证实了一种鼢鼠物种中的一次裂变事件。我们将此事件追溯至携带裂变染色体的物种中DNA修复基因的一个剪接增强子的突变，该突变导致外显子跳跃并产生一种截短的蛋白质，从而破坏了DNA修复。已知在敲除时会促进新端粒形成的一个基因的内含子缺失降低了基因活性。这些变异共同推动了该鼢鼠物种的染色体裂变。新形成的染色体因携带必需基因和强大的选择压力而得以固定。虽然地理隔离可能引发了该物种与其姐妹物种的分化，但染色体水平上的裂变事件及相关的基因流下降可能加剧了物种形成过程。我们的工作阐明了染色体裂变的遗传基础，并强调了其在物种形成动态中的作用。
