Terrestrial reproduction as an adaptation to steep terrain in African toads

How evolutionary novelties evolve is a major question in evolutionary biology. It is widely accepted that changes in environmental conditions shift the position of selective optima, and advancements in phylogenetic comparative approaches allow the rigorous testing of such correlated transitions. A longstanding question in vertebrate biology has been the evolution of terrestrial life histories in amphibians and here, by investigating African bufonids, we test whether terrestrial modes of reproduction have evolved as adaptations to particular abiotic habitat parameters. We reconstruct and date the most complete species-level molecular phylogeny and estimate ancestral states for reproductive modes. By correlating continuous habitat measurements from remote sensing data and locality records with life-history transitions, we discover that terrestrial modes of reproduction, including viviparity evolved multiple times in this group, most often directly from fully aquatic modes. Terrestrial mod...进化新特征如何演化，是进化生物学领域的核心议题之一。学界普遍认为，环境条件的改变会推动选择最适点（selective optima）的位移，而系统发育比较方法的进步则为这类关联演化转变的严谨检验提供了支撑。脊椎动物生物学中长期存在的经典问题之一，便是两栖动物陆生生活史的演化历程。为此，本研究以非洲蟾蜍科（Bufonidae）类群为研究对象，探讨陆生繁殖模式是否为针对特定非生物生境参数的适应性演化结果。我们构建了当前最完整的物种级分子系统发育树，并完成了其年代标定，同时估算了繁殖模式的祖先状态。通过将遥感数据与分布记录获取的连续生境参数与生活史转变进行关联分析，本研究发现：该类群的陆生繁殖模式（包括胎生（viviparity））曾多次独立演化，且多数情况下直接由完全水生的繁殖模式演化而来。陆生模式……