UCL Genetics Institute, Department of Genetics, Evolution and Environment, University College London, London, UK.
Mol Ecol. 2019 Apr;28(8):1863-1865. doi: 10.1111/mec.15064. Epub 2019 May 5.
Under XY sex determination, the Y chromosome is only inherited via males, whereas the X chromosome is predominantly found in females. Thus, it is favourable when alleles with high male fitness become associated with the Y chromosome and when alleles with high female fitness become associated with the X chromosome. These favourable associations can be strengthened through linkage. Rearrangements, such as inversions and sex chromosome-autosome fusions, can increase linkage and thereby become favoured (Charlesworth, 2017). In a From the Cover article in this issue of Molecular Ecology, Toups, Rodrigues, Perrin, and Kirkpatrick (2019) present the first genomic analysis of a sex chromosome reciprocal translocation, a particularly dramatic chromosomal rearrangement that modifies linkage with the sex chromosome. As a result of reciprocal translocation, one studied population of the common frog (Rana temporaria, Figure 1) displays a remarkable sex-determining system in which there are two physically unlinked sex chromosomes that are exclusively cotransmitted (Figure 2a).
在 XY 性别决定中，Y 染色体仅通过男性遗传，而 X 染色体主要存在于女性中。因此，当具有高雄性适合度的等位基因与 Y 染色体相关联，当具有高雌性适合度的等位基因与 X 染色体相关联时，这是有利的。这些有利的关联可以通过连锁来加强。重排，如倒位和性染色体-常染色体融合，可以增加连锁，从而变得有利（Charlesworth，2017）。在本期《分子生态学》的一篇封面文章中，Toups、Rodrigues、Perrin 和 Kirkpatrick（2019）首次对性染色体相互易位进行了基因组分析，这是一种特别剧烈的染色体重排，改变了与性染色体的连锁。由于相互易位，研究人员对普通青蛙（Rana temporaria，图 1）的一个种群进行了研究，发现了一种显著的性别决定系统，其中有两条物理上不连锁的性染色体，它们是完全连锁传递的（图 2a）。
