Laboratoire Biométrie et Biologie Evolutive, CNRS / Univ. Lyon 1, Villeurbanne, France.
Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom.
Elife. 2020 Nov 18;9:e63650. doi: 10.7554/eLife.63650.
Sex chromosomes are typically comprised of a non-recombining region and a recombining pseudoautosomal region. Accurately quantifying the relative size of these regions is critical for sex-chromosome biology both from a functional and evolutionary perspective. The evolution of the pseudoautosomal boundary (PAB) is well documented in haplorrhines (apes and monkeys) but not in strepsirrhines (lemurs and lorises). Here, we studied the PAB of seven species representing the main strepsirrhine lineages by sequencing a male and a female genome in each species and using sex differences in coverage to identify the PAB. We found that during primate evolution, the PAB has remained unchanged in strepsirrhines whereas several recombination suppression events moved the PAB and shortened the pseudoautosomal region in haplorrhines. Strepsirrhines are well known to have much lower sexual dimorphism than haplorrhines. We suggest that mutations with antagonistic effects between males and females have driven recombination suppression and PAB evolution in haplorrhines.
性染色体通常由一个非重组区域和一个重组假常染色体区域组成。准确量化这些区域的相对大小对于从功能和进化角度理解性染色体生物学至关重要。假常染色体边界（PAB）在有胎盘类（猿猴）中的进化得到了很好的记录，但在无胎盘类（狐猴和懒猴）中却没有。在这里，我们通过对每个物种的一雄一雌基因组进行测序，研究了代表主要无胎盘类谱系的七个物种的 PAB，并利用覆盖度的性别差异来识别 PAB。我们发现，在灵长类动物进化过程中，PAB 在无胎盘类中保持不变，而在有胎盘类中，几个重组抑制事件移动了 PAB 并缩短了假常染色体区域。众所周知，无胎盘类的性二态性比有胎盘类低得多。我们认为，雄性和雌性之间具有拮抗作用的突变驱动了有胎盘类的重组抑制和 PAB 进化。
