Abstract：
Molluscs have undergone many transitions between separate sexes and hermaphroditism, which is of interest in studying the evolution of sex determination and differentiation. Here, we combined multi-locus genotypes obtained from restriction site-associated DNA (RAD) sequencing with anatomical observations of the gonads of three deep-sea hydrothermal vent gastropods of the genus Alviniconcha living in the southwest Pacific. We found that all three species (Alviniconcha boucheti, Alviniconcha strummeri, and Alviniconcha kojimai) share the same male-heterogametic XY sex-determination system but that the gonads of XX A. kojimai individuals are invaded by a variable proportion of male reproductive tissue. The identification of Y-specific RAD loci (found only in A. boucheti) and the phylogenetic analysis of three sex-linked loci shared by all species suggested that X-Y recombination has evolved differently within each species. This situation of three species showing variation in gonadal development around a common sex-determination system provides new insights into the reproductive mode of poorly known deep-sea species and opens up an opportunity to study the evolution of recombination suppression on sex chromosomes and its association with mixed or transitory sexual systems.
摘要：
软体动物经历了许多不同性别和雌雄同体之间的转变，这对研究性别决定和分化的进化很有意义。在这里，我们将从RAD测序获得的多位点基因型与性腺的解剖观察相结合，以研究居住在西南太平洋的Alviniconcha属的三种深海热液喷口腹足类。我们发现这三个物种(A.Boucheti,A.strummeri,和A.kojimai)共享相同的男性-异性恋XY性别决定系统，但是XXA.kojimai个体的性腺受到不同比例的男性生殖组织的侵袭。Y特异性RAD基因座的鉴定（仅在A.boucheti中发现）和所有物种共有的三个性别相关基因座的系统发育分析表明，X-Y重组在每个物种中的进化方式不同。三种物种在共同的性别决定系统周围的性腺发育变化的情况为人们对鲜为人知的深海物种的生殖模式提供了新的见解，并为研究性染色体上重组抑制的进化及其与混合或暂时性性系统的关联提供了机会。
