Evolutionary strata on the chicken Z chromosome: Implications for sex chromosome evolution
Evolutionary strata on the chicken Z chromosome: Implications for sex chromosome evolution
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DOI：
10.1534/genetics.167.1.367
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发表时间：
2004-05-01
期刊：
影响因子：
3.3
通讯作者：
Ellegren, H
中科院分区：
文献类型：
--
作者：
Handley, LL;Ceplitis, H;Ellegren, H
人类X染色体有四个“进化层”，被解释为代表在原X和原Y之间重组受阻的过程中的不同步骤。为了测试这是否是性染色体进化的一般特征，我们研究了鸟类的Z-W性染色体，这些性染色体具有雌性而不是雄性异婚制，并且是从与哺乳动物X和Y不同的常染色体对进化而来的。在这里，我们分析了所有五个已知的配子体Z-W基因对，以研究鸟类的“层”假说。对Z和W配子体的同义替换率和内含子差异的比较表明，鸡Z染色体的p和q臂上至少存在两个进化层。来自不同鸟类谱系的内含子序列的系统发育分析表明，Z-W重组在最古老的地层(ZQ；CHD1Z，Hintz和Spinz)102-1.7亿年前(MYA)停止，在Neoaves和Eoaves分裂之前。但在第二层(ZP；UBAP2Z和ATP5A1Z)，重组一直持续到现存鸟类目的分化之后，Z和W偏离58-85MYA。我们的数据表明，逐渐和逐步停止重组是性染色体进化背后的一个总体特征。
The human X chromosome exhibits four "evolutionary strata," interpreted to represent distinct steps in the process whereby recombination became arrested between the proto X and proto Y. To test if this is a general feature of sex chromosome evolution, we studied the Z-W sex chromosomes of birds, which have female rather than male heterogamety and evolved from a different autosome pair than the mammalian X and Y. Here we analyze all five known gametologous Z-W gene pairs to investigate the "strata" hypothesis in birds. Comparisons of the rates of synonymous substitution and intronic divergence between Z and W gametologs reveal the presence of at least two evolutionary strata spread over the p and q arms of the chicken Z chromosome. A phylogenetic analysis of intronic sequence data from different avian lineages indicates that Z-W recombination ceased in the oldest stratum (on Zq; CHD1Z, HINTZ, and SPINZ) 102-170 million years ago (MYA), before the split of the Neoaves and Eoaves. However, recombination continued in the second stratum (on Zp; UBAP2Z and ATP5A1Z) until after the divergence of extant avian orders, with Z and W diverging 58-85 MYA. Our data suggest that progressive and stepwise cessation of recombination is a general feature behind sex chromosome evolution.