Theodosiou L, McMillan W O, Puebla O
Max-Planck-Institute for Evolutionary Biology, Research Group for Community Dynamics, August-Thienemann-Straße 2, 24306 Plön, Germany.
Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panamá, República de Panamá.
Proc Biol Sci. 2016 Dec 14;283(1844). doi: 10.1098/rspb.2016.1821.
When there is no recombination (achiasmy) in one sex, it is in the heterogametic one. This observation is so consistent that it constitutes one of the few patterns in biology that may be regarded as a 'rule' and Haldane (Haldane 1922 J. Genet. 12, 101-109. (doi:10.1007/BF02983075)) proposed that it might be driven by selection against recombination in the sex chromosomes. Yet differences in recombination rates between the sexes (heterochiasmy) have also been reported in hermaphroditic species that lack sex chromosomes. In plants-the vast majority of which are hermaphroditic-selection at the haploid stage has been proposed to drive heterochiasmy. Yet few data are available for hermaphroditic animals, and barely any for hermaphroditic vertebrates. Here, we leverage reciprocal crosses between two black hamlets (Hypoplectrus nigricans, Serranidae), simultaneously hermaphroditic reef fishes from the wider Caribbean, to generate high-density egg- and sperm-specific linkage maps for each parent. We find globally higher recombination rates in the eggs, with dramatically pronounced heterochiasmy at the chromosome peripheries. We suggest that this pattern may be due to female meiotic drive, and that this process may be an important source of heterochiasmy in animals. We also identify a large non-recombining region that may play a role in speciation and local adaptation in Hypoplectrus.
当某一性别不存在重组（无交叉现象）时，该性别为异配性别。这一观察结果极为一致，构成了生物学中少数可被视为“规律”的模式之一，霍尔丹（Haldane，1922年，《遗传学杂志》12卷，101 - 109页。（doi:10.1007/BF02983075））提出，这可能是由对性染色体重组的选择所驱动。然而，在缺乏性染色体的雌雄同体物种中，也报道了两性之间重组率的差异（异交叉现象）。在植物中——绝大多数植物是雌雄同体——有人提出单倍体阶段的选择会驱动异交叉现象。然而，关于雌雄同体动物的数据很少，而关于雌雄同体脊椎动物的数据几乎没有。在这里，我们利用两种黑哈姆雷特鱼（黑拟花鮨，鮨科）之间的正反交，这两种鱼是来自更广阔加勒比地区的同时具有雌雄两性生殖功能的珊瑚礁鱼类，为每个亲本生成高密度的卵子特异性和精子特异性连锁图谱。我们发现卵子的重组率总体上更高，在染色体周边存在显著的异交叉现象。我们认为这种模式可能是由于雌性减数分裂驱动，并且这一过程可能是动物异交叉现象的一个重要来源。我们还确定了一个可能在拟花鮨属的物种形成和局部适应中起作用的大的非重组区域。
