Bengtsson B O, Goodfellow P N
Department of Genetics, Lund, Sweden.
Ann Hum Genet. 1987 Jan;51(1):57-64. doi: 10.1111/j.1469-1809.1987.tb00865.x.
Recent molecular analysis has proved the hypothesis that parts of the human sex chromosomes are homologous and can recombine in male meiosis. The biological consequences of this recombination have been investigated by considering the joint effect of neutral mutation and random genetic drift on a locus that is closely linked to the non-homologous segments of the sex chromosomes, but which recombines with them in an appreciable frequency. Our model predicts that, in the absence of selection, allelic differentiation between genes carried on the X and on the Y chromosomes will develop only if the recombination rate is of the same order of magnitude as the mutation rate or smaller. Similarly, a mutation favourable in males but disadvantageous in females will increase in frequency on the Y chromosomes, while remaining rare on the X chromosomes, only if the recombination rate is smaller than the fitness advantage of the mutation. The X and Y chromosomes are, thus, not expected to show any genetic differentiation for almost all of their homologous parts. Divergence will occur only for loci that very rarely recombine between the sex chromosomes.
人类性染色体的部分区域是同源的，并且在男性减数分裂过程中能够发生重组。通过考虑中性突变和随机遗传漂变对一个与性染色体非同源片段紧密连锁但又以可观频率与其发生重组的基因座的联合效应，对这种重组的生物学后果进行了研究。我们的模型预测，在没有选择的情况下，只有当重组率与突变率处于同一数量级或更低时，X染色体和Y染色体上携带的基因之间的等位基因分化才会出现。同样，只有当重组率小于突变的适合度优势时，一种对男性有利但对女性不利的突变才会在Y染色体上频率增加，而在X染色体上仍保持罕见。因此，对于X和Y染色体几乎所有的同源部分，预计不会表现出任何遗传分化。只有对于性染色体之间极少发生重组的基因座才会出现分化。
