Szasz-Green Taylor, Shores Katherynne, Vanga Vineel, Zacharias Luke, Lawton Andrew K, Dapper Amy L
Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA.
Department of Biology, Appalachian State University, Boone, NC 28608, USA.
Mol Biol Evol. 2025 Apr 30;42(5). doi: 10.1093/molbev/msaf100.
Meiotic recombination is an integral cellular process, required for the production of viable gametes. Recombination rate is a fundamental genomic parameter, modulating genomic responses to selection. Our increasingly detailed understanding of its molecular underpinnings raises the prospect that we can gain insight into trait divergence by examining the molecular evolution of recombination genes from a pathway perspective, as in mammals, where protein-coding changes in later stages of the recombination pathway are connected to divergence in intra-clade recombination rate. Here, we leverage increased availability of avian and teleost genomes to reconstruct the evolution of the recombination pathway across two additional vertebrate clades: birds, which have higher and more variable rates of recombination and similar divergence times to mammals, and teleost fish, which have much deeper divergence times. Rates of molecular evolution of recombination genes are highly correlated between vertebrate clades and significantly elevated compared to control panels, suggesting that they experience similar selective pressures. Avian recombination genes are significantly more likely to exhibit signatures of positive selection than other clades, unrestricted to later stages of the pathway. Signatures of positive selection in genes linked to recombination rate variation in mammalian populations and those with signatures of positive selection across the avian phylogeny are highly correlated. In contrast, teleost fish recombination genes have significantly less evidence of positive selection despite high intra-clade recombination rate variability. Gaining clade-specific understanding of patterns of variation in recombination genes can elucidate drivers of recombination rate and thus, factors influencing genetic diversity, selection efficacy, and species divergence.
减数分裂重组是一个不可或缺的细胞过程，是产生有活力配子所必需的。重组率是一个基本的基因组参数，调节基因组对选择的反应。我们对其分子基础的理解越来越详细，这使得我们有可能通过从通路角度研究重组基因的分子进化来深入了解性状差异，就像在哺乳动物中一样，重组通路后期的蛋白质编码变化与进化枝内重组率的差异有关。在这里，我们利用鸟类和硬骨鱼基因组可用性的增加，来重建另外两个脊椎动物进化枝中重组通路的进化：鸟类的重组率更高且更具可变性，与哺乳动物的分化时间相似；硬骨鱼的分化时间则长得多。脊椎动物进化枝之间重组基因的分子进化速率高度相关，并且与对照组相比显著升高，这表明它们经历了相似的选择压力。与其他进化枝相比，鸟类重组基因更有可能表现出正选择的特征，且不限于通路的后期阶段。与哺乳动物群体中重组率变异相关的基因以及在鸟类系统发育中具有正选择特征的基因中的正选择特征高度相关。相比之下，尽管硬骨鱼进化枝内重组率变异性很高，但它们的重组基因的正选择证据却明显较少。了解进化枝特异性的重组基因变异模式可以阐明重组率的驱动因素，进而揭示影响遗传多样性、选择效率和物种分化的因素。
