Data from: Dmrt1 polymorphism covaries with sex-determination patterns in Rana temporaria

Patterns of sex-chromosome differentiation and gonadal development have been shown to vary among populations of Rana temporaria along a latitudinal transect in Sweden. Frogs from the northern-boreal population of Ammarnäs displayed well-differentiated X and Y haplotypes, early gonadal differentiation, and a perfect match between phenotypic and genotypic sex. In contrast, no differentiated Y haplotypes could be detected in the southern population of Tvedöra, where juveniles furthermore showed delayed gonadal differentiation. Here, we show that Dmrt1, a gene that plays a key role in sex determination and sexual development across all metazoans, displays significant sex differentiation in Tvedöra, with a Y-specific haplotype distinct from Ammarnäs. The differential segment is not only much shorter in Tvedöra than in Ammarnäs, it is also less differentiated and associates with both delayed gonadal differentiation and imperfect match between phenotypic and genotypic sex. Whereas Tvedöra juveniles with a local Y haplotype tend to ultimately develop as males, those without it may nevertheless become functional XX males, but with strongly female-biased progeny. Our findings suggest that the variance in patterns of sex determination documented in common frogs might result from a genetic polymorphism within a small genomic region that contains Dmrt1. They also substantiate the view that recurrent convergences of sex determination toward a limited set of chromosome pairs may result from the co-option of small genomic regions that harbor key genes from the sex-determination pathway.瑞典境内沿纬度样带（latitudinal transect）分布的普通林蛙（Rana temporaria）不同种群间，其性染色体分化（sex-chromosome differentiation）与性腺发育（gonadal development）模式已被证实存在显著差异。来自北部寒温带种群阿马奈斯（Ammarnäs）的林蛙，其X、Y单倍型（haplotypes）分化清晰，性腺分化启动较早，且表型性别（phenotypic sex）与基因型性别（genotypic sex）完全一致。与之形成鲜明对比的是，南部特韦德拉（Tvedöra）种群未检测到分化的Y单倍型，该种群的幼体还表现出性腺发育延迟的特征。本研究显示，在所有后生动物（metazoans）的性别决定（sex determination）与性腺发育过程中发挥关键作用的Dmrt1基因（Dmrt1），在特韦德拉种群中存在显著的性别分化，其Y特异性单倍型与阿马奈斯种群的存在差异。特韦德拉种群中性别染色体的差异区段不仅比阿马奈斯种群短得多，分化程度也更低，且该区段与性腺发育延迟以及表型性别与基因型性别不完全匹配均存在关联。携带本地Y单倍型的特韦德拉幼体最终通常会发育为雄性个体，而未携带该单倍型的个体虽仍可能成为具有正常功能的XX型雄性，但其所产后代会呈现强烈的雌性偏向性。本研究结果表明，普通林蛙中已记录的性别决定模式差异，可能源于包含Dmrt1基因的小型基因组区域内的遗传多态性（genetic polymorphism）。同时，本研究也佐证了如下观点：性别决定系统反复趋同演化（recurrent convergences of sex determination）至有限的几对染色体（chromosome pairs），可能源于对携带性别决定通路（sex-determination pathway）关键基因的小型基因组区域的共招募（co-option）。