Data from: The contribution of female meiotic drive to the evolution of neo-sex chromosomes

Sex chromosomes undergo rapid turnover in certain taxonomic groups. One of the mechanisms of sex chromosome turnover involves fusions between sex chromosomes and autosomes. Sexual antagonism, heterozygote advantage, and genetic drift have been proposed as the drivers for the fixation of this evolutionary event. However, all empirical patterns of the prevalence of multiple sex chromosome systems across different taxa cannot be simply explained by these three mechanisms. In this study, we propose that female meiotic drive may contribute to the evolution of neo-sex chromosomes. The results of this study showed that in mammals, the XY1Y2 sex chromosome system is more prevalent in species with karyotypes of more bi-armed chromosomes, whereas the X1X2Y sex chromosome system is more prevalent in species with predominantly acrocentric chromosomes. In species where bi-armed chromosomes are favored by female meiotic drive, X-autosome fusions (XY1Y2 sex chromosome system) will be also favored by female meiotic drive. In contrast, in species with more acrocentric chromosomes, Y-autosome fusions (X1X2Y sex chromosome system) will be favored just because of the biased mutation rate towards chromosomal fusions. Further consideration should be given to female meiotic drive as a mechanism in the fixation of neo-sex chromosomes.

某些生物类群的性染色体会经历快速的周转更替。性染色体周转的机制之一，涉及性染色体与常染色体之间的融合事件。此前已有研究提出，性拮抗、杂合优势与遗传漂变，可作为这一演化事件在种群中固定的驱动因素。然而，跨不同类群的多性染色体系统分布频率的所有实证观测模式，无法仅凭这三种机制得到简单解释。本研究提出，雌性减数分裂驱动（female meiotic drive）或许可助力新性染色体（neo-sex chromosomes）的演化。研究结果显示，在哺乳动物中，XY₁Y₂型性染色体系统在拥有更多双臂染色体核型的物种中更为常见；而X₁X₂Y型性染色体系统则主要存在于以近端着丝粒染色体为主的物种中。在雌性减数分裂驱动偏好双臂染色体的类群中，X-常染色体融合（即XY₁Y₂型性染色体系统）也会受到该驱动机制的青睐。与之相反，在拥有更多近端着丝粒染色体的类群中，由于染色体融合的突变率存在偏向性，Y-常染色体融合（即X₁X₂Y型性染色体系统）将更受偏爱。未来应将雌性减数分裂驱动，作为新性染色体固定过程中的一项重要机制加以进一步考量。