The intricate relationship between sexually antagonistic selection and the evolution of sex chromosome fusions
The intricate relationship between sexually antagonistic selection and the evolution of sex chromosome fusions
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DOI：
10.1016/j.jtbi.2016.05.036
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发表时间：
2016-09-07
影响因子：
2
通讯作者：
Kitano, Jun
中科院分区：
文献类型：
--
作者：
Matsumoto, Tomotaka;Kitano, Jun
性染色体在某些动物群体中是进化上最不稳定的特征之一。导致性染色体结构变化的机制之一是与常染色体融合。最近的一项研究表明，在鱼类和爬行动物中，Y染色体-常染色体融合的建立率远远高于其他融合(即X-常染色体、W-常染色体和Z-常染色体融合)。尽管性拮抗选择可能是性染色体-常染色体融合最重要的驱动力之一，但先前的理论分析表明，单靠性拮抗选择不能解释这些类群中Y-常染色体融合的过度。然而，以前的分析是基于这样的假设：性拮抗选择是对称的，性拮抗等位基因只能通过选择-漂移平衡(即没有突变供应)来维持，并且在一个种群中只有一种类型的融合发生。在这里，我们去掉了这些假设，建立了一个基于个体的模型来模拟性染色体-常染色体融合的建立。我们的模拟表明，当Y-常染色体融合捕捉到罕见的男性有益等位基因时，如果重复突变率足够高，以维持具有不对称、性拮抗效应的等位基因的多态，则Y-常染色体融合的建立率最高。我们的结果表明，性拮抗选择可以影响性染色体结构变化的动态，但最常见的融合类型取决于融合率、重复突变率和选择制度。由于性染色体-常染色体融合的进化命运对参数高度敏感，进一步尝试在自然种群中对这些参数进行经验性测量对于更好地理解性拮抗选择在性染色体进化中的作用是至关重要的。(C)2016爱思唯尔有限公司。保留所有权利。
Sex chromosomes are among the most evolutionarily labile features in some groups of animals. One of the mechanisms causing structural changes of sex chromosomes is fusion with an autosome. A recent study showed that the establishment rates of Y chromosome-autosome fusions are much higher than those of other fusions (i.e., X-autosome, W-autosome, and Z-autosome fusions) in fishes and reptiles. Although sexually antagonistic selection may be one of the most important driving forces of sex chromosome-autosome fusions, a previous theoretical analysis showed that sexually antagonistic selection alone cannot explain the excess of Y-autosome fusions in these taxa. This previous analysis, however, is based on the assumption that sexually antagonistic selection is symmetric, sexually antagonistic alleles are maintained only by selection-drift balance (i.e., no supply of mutation), and only one type of fusion arises within a population. Here, we removed these assumptions and made an individual-based model to simulate the establishment of sex chromosome-autosome fusions. Our simulations showed that the highest establishment rate of Y-autosome fusion can be achieved when the fusion captures a rare male beneficial allele, if the recurrent mutation rates are high enough to maintain the polymorphism of alleles with asymmetric, sexually antagonistic effects. Our results demonstrate that sexually antagonistic selection can influence the dynamics of sex chromosome structural changes, but the type of fusion that becomes the most common depends on fusion rates, recurrent mutation rates, and selection regimes. Because the evolutionary fate of sex chromosome-autosome fusions is highly parameter-sensitive, further attempts to empirically measure these parameters in natural populations are essential for a better understanding of the roles of sexually antagonistic selection in sex chromosome evolution. (C) 2016 Elsevier Ltd. All rights reserved.