The degeneration of Y chromosomes
The degeneration of Y chromosomes
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DOI：
10.1098/rstb.2000.0717
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发表时间：
2000-11-29
影响因子：
6.3
通讯作者：
Charlesworth, D
中科院分区：
文献类型：
--
作者：
Charlesworth, B;Charlesworth, D
Y染色体在基因上是退化的，失去了祖先身上存在的大部分活跃基因。这种退化的原因引起了进化理论家的极大关注。本文综述了四种主要的理论：穆勒棘轮理论、背景选择理论、弱选择的Hill-Robertson效应理论和有利突变对有害等位基因的“搭便车”理论。所有这些都涉及到由于非重组基因组中发生的选择性事件而导致的有效种群规模的减少，以及随之而来的选择有效性的减弱。我们回顾了这些过程对Y染色体上分子进化和变异模式的影响，并讨论了对一些进化的Y染色体和新的Y染色体系统的这些模式的实证研究的结果。这些结果表明，如果导致退化的部分或全部假设过程是可操作的，那么进化中的Y或新Y染色体的有效种群大小就会像预期的那样严重减少。然而，目前尚不清楚各种进程中哪一种是最重要的；讨论了有助于解决这一问题的未来工作的一些方向。
Y chromosomes are genetically degenerate, having lost most of the active genes that were present in their ancestors. The causes of this degeneration have attracted much attention from evolutionary theorists. Four major theories are reviewed here: Muller's ratchet, background selection, the Hill-Robertson effect with weak selection, and the 'hitchhiking' of deleterious alleles by favourable mutations. All of these involve a reduction in effective population size as a result of selective events occurring in a non-recombining genome, and the consequent weakening of the efficacy of selection. Wie review the consequences of these processes for patterns of molecular evolution and variation at loci on Y chromosomes, and discuss the results of empirical studies of these patterns for some evolving Y-chromosome and neo-Y-chromosome systems. These results suggest that the effective population sizes of evolving Y or neo-Y chromosomes are severely reduced, as expected if some or all of the hypothesized processes leading to degeneration are operative. It is, however, currently unclear which of the various processes is most important; some directions for future work to help to resolve this question are discussed.