Data from: Sex-specific estimates of dispersal show female philopatry and male dispersal in a promiscuous amphibian, the alpine salamander (Salamandra atra)

Amphibians display wide variations in life-history traits and life cycles that should prove useful to explore the evolution of sex-biased dispersal, but quantitative data on sex-specific dispersal patterns are scarce. Here we focused on Salamandra atra, an endemic alpine species showing peculiar life-history traits. Strictly terrestrial and viviparous, the species has a promiscuous mating system and females reproduce only every three to four years. In the present study, we provide quantitative estimates of asymmetries in male vs female dispersal using both field-based (mark-recapture) and genetic approaches (detection of sex-biased dispersal and estimates of migration rates based on the contrast in genetic structure across sexes and age classes). Our results revealed a high level of gene flow among populations, which stems exclusively from male dispersal. We hypothesize that philopatric females benefit from being familiar with their natal area for the acquisition and defence of an appropriate shelter, while male dispersal has been secondarily favoured by inbreeding avoidance. Together with other studies on amphibians, our results indicate that a species' mating system alone is a poor predictor of sex-linked differences in dispersal, in particular for promiscuous species. Further studies should focus more directly on the proximate forces that favour or limit dispersal to refine our understanding of the evolution of sex-biased dispersal in animals.

两栖类具有多样的生活史特征与生活周期，有望为探索性偏扩散（sex-biased dispersal）的演化机制提供理想研究载体，但目前针对性别特异性扩散模式的定量数据仍十分稀缺。本研究聚焦于阿尔卑斯蝾螈（Salamandra atra）——一种特有的高山物种，其生活史特征颇为独特：该物种为严格陆生的胎生物种，交配制度混杂，且雌性每3至4年才繁殖一次。本研究综合利用野外标记重捕法（mark-recapture）与遗传分析手段，对雌雄个体间的扩散不对称性进行定量评估；其中遗传分析涵盖性偏扩散检测，以及基于不同性别与年龄组的遗传结构差异估算迁移率。研究结果显示，种群间存在高水平的基因交流，且该基因交流完全由雄性扩散介导。我们推测，具有恋巢性的雌性因熟悉出生地，可更高效地获取并守护适宜的栖息场所；而雄性扩散则因近交回避的选择压力得到进一步强化。结合其他两栖类相关研究，本研究结果表明，仅依靠物种的交配制度难以准确预测其扩散行为的性别差异，对于混杂交配物种而言尤其如此。未来研究应更直接地聚焦于调控扩散行为的近因因素，以此深化我们对动物性偏扩散演化机制的认知。