Department of Biosciences, University of Helsinki, Helsinki, Finland.
PLoS One. 2011;6(10):e25362. doi: 10.1371/journal.pone.0025362. Epub 2011 Oct 10.
The heterogametic sex chromosomes (i.e. mammalian Y and avian W) do not usually recombine with the homogametic sex chromosomes which is known to lead into rapid degeneration of Y and W due to accumulation of deleterious mutations. On the other hand, some 96% of amphibian species have homomorphic, i.e. non-degenerate Y chromosomes. Nicolas Perrin's fountain-of-youth hypothesis states that this is a result of recombination between X and Y chromosomes in sex-reversed individuals. In this study, I model the consequences of such recombination for the dynamics of a deleterious mutation occurring in Y chromosomes. As expected, even relatively low levels of sex reversal help to purge deleterious mutations. However, the population-dynamic consequences of this depend on the type of selection that operates on the population undergoing sex reversal. Under fecundity selection, sex reversal can be beneficial for some parameter values, whereas under survival selection, it seems to be always harmful.
性染色体异型（即哺乳动物的 Y 和鸟类的 W）通常不会与同型性染色体重组，这导致 Y 和 W 由于有害突变的积累而迅速退化。另一方面，约 96%的两栖动物物种具有同形的，即非退化的 Y 染色体。Nicolas Perrin 的青春之泉假说指出，这是性反转个体中 X 和 Y 染色体之间重组的结果。在这项研究中，我模拟了这种重组对 Y 染色体上发生的有害突变动态的影响。正如预期的那样，即使是相对较低水平的性反转也有助于清除有害突变。然而，这种情况的种群动态后果取决于进行性反转的种群所经历的选择类型。在繁殖力选择下，性反转对某些参数值是有利的，而在生存选择下，它似乎总是有害的。
