Data from: Molecular phenotyping of maternally mediated parallel adaptive divergence within Rana arvalis and Rana temporaria

When similar selection acts on the same traits in multiple species or populations, parallel evolution can result in similar phenotypic changes, yet the underlying molecular architecture of parallel phenotypic divergence can be variable. Maternal effects can influence evolution at ecological time scales and facilitate local adaptation, but their contribution to parallel adaptive divergence is unclear. In this study, we i) tested for variation in embryonic acid tolerance in a common garden experiment and ii) used molecular phenotyping of egg coats to investigate the molecular basis of maternally mediated parallel adaptive divergence in two amphibian species (Rana arvalis and R. temporaria). Our results on three R. arvalis and two R. temporaria populations show that adaptive divergence in embryonic acid tolerance is mediated via maternally derived egg coats in both species. We find extensive polymorphism in egg jelly coat glycoproteins within both species and that acid tolerant clutches have more negatively charged egg jelly – indicating that the glycosylation status of the jelly coat proteins is under divergent selection in acidified environments, likely due to its impact on jelly water balance. Overall, these data provide evidence for parallel mechanisms of adaptive divergence in two species. Our study highlights the importance of studying intraspecific molecular variation in egg coats and, specifically their glycoproteins, to increase understanding of underlying forces maintaining variation in jelly coats.当多个物种或种群的同一性状受到相似选择压力作用时，可引发平行演化（parallel evolution），产生相似的表型变化（phenotypic changes）；但平行表型分化的潜在分子架构（molecular architecture）往往存在变异。母体效应（maternal effects）可在生态时间尺度（ecological time scales）上影响演化进程，并促进本地适应（local adaptation），但其对平行适应性分化（parallel adaptive divergence）的贡献尚不明确。本研究通过两项实验展开探究：其一，借助同质园实验（common garden experiment）检测胚胎耐酸性（embryonic acid tolerance）的变异；其二，通过卵胶膜（egg coats）的分子表型分析（molecular phenotyping），解析两种两栖动物——沼泽蛙（Rana arvalis）与林蛙（Rana temporaria）——中母体介导的平行适应性分化的分子基础。我们针对3个沼泽蛙种群与2个林蛙种群的研究结果表明，两种物种的胚胎耐酸性适应性分化均由母体来源的卵胶膜所介导。研究发现，两种物种的卵胶糖蛋白（glycoproteins）均存在广泛的多态性（polymorphism），且耐酸性卵团（clutches）的卵胶携带更多负电荷（negatively charged）——这提示胶膜蛋白的糖基化状态（glycosylation status）在酸化环境中受到歧化选择（divergent selection），这可能与其对卵胶水平衡（water balance）的影响相关。综上，本研究数据为两个物种的适应性分化存在平行演化机制提供了实证支持。本研究同时强调，对卵胶膜的种内分子变异（intraspecific molecular variation）——尤其是其糖蛋白组分——开展研究，有助于深化我们对维持卵胶膜变异的内在驱动力的认知。