School of Life Sciences, University of Warwick, Coventry CV4 7AL, U.K.
Biochem Soc Trans. 2024 Aug 28;52(4):1777-1784. doi: 10.1042/BST20231411.
The non-Mendelian transmission of sex chromosomes during gametogenesis carries significant implications, influencing sex ratios and shaping evolutionary dynamics. Here we focus on known mechanisms that drive non-Mendelian inheritance of X chromosomes during spermatogenesis and their impact on population dynamics in species with different breeding systems. In Drosophila and mice, X-linked drivers targeting Y-bearing sperm for elimination or limiting their fitness, tend to confer unfavourable effects, prompting the evolution of suppressors to mitigate their impact. This leads to a complex ongoing evolutionary arms race to maintain an equal balance of males and females. However, in certain insects and nematodes with XX/X0 sex determination, the preferential production of X-bearing sperm through atypical meiosis yields wild-type populations with highly skewed sex ratios, suggesting non-Mendelian transmission of the X may offer selective advantages in these species. Indeed, models suggest X-meiotic drivers could bolster population size and persistence under certain conditions, challenging the conventional view of their detrimental effects. Furthering our understanding of the diverse mechanisms and evolutionary consequences of non-Mendelian transmission of X chromosomes will provide insights into genetic inheritance, sex determination, and population dynamics, with implications for fundamental research and practical applications.
性染色体在配子发生中非孟德尔式传递具有重要意义，影响性别比例并塑造进化动态。在这里，我们重点关注已知的驱动精子发生中非孟德尔性染色体遗传的机制，以及它们对具有不同繁殖系统的物种的种群动态的影响。在果蝇和小鼠中，针对携带 Y 染色体的精子进行消除或限制其适合度的 X 连锁驱动因素往往会产生不利影响，促使进化出抑制因子来减轻其影响。这导致了一场复杂的持续进化军备竞赛，以维持雌雄比例的平衡。然而，在某些具有 XX/X0 性别决定的昆虫和线虫中，通过非典型减数分裂优先产生携带 X 染色体的精子，导致野生型种群出现高度偏斜的性别比例，表明 X 的非孟德尔式传递在这些物种中可能具有选择优势。事实上，模型表明，X 减数分裂驱动因素可以在某些条件下增强种群规模和持久性，这挑战了其有害影响的传统观点。进一步了解 X 染色体非孟德尔式传递的多种机制和进化后果，将为遗传inheritance、性别决定和种群动态提供深入的见解，对基础研究和实际应用具有重要意义。
