Data from: Species tree of a recent radiation: the subfamily Delphininae (Cetacea, Mammalia)

Lineages undergoing rapid radiations provide exceptional opportunities for studying speciation and adaptation, but also represent a challenge for molecular systematics because retention of ancestral polymorphisms and the occurrence of hybridization can obscure relationships among lineages. Dolphins in the subfamily Delphininae are one such case. Non-monophyly, rapid speciation events, and discordance between morphological and molecular characters have made the inference of phylogenetic relationships within this subfamily very difficult. Here we approach this problem by applying multiple methods intended to estimate species trees using a multi-gene dataset for the Delphininae (Sousa, Sotalia, Stenella, Tursiops, Delphinus and Lagenodelphis). Incongruent gene trees obtained indicate that incomplete lineage sorting and possibly hybridization are confounding the inference of species history in this group. Nonetheless, using coalescent-based methods, we have been able to extract an underlying species-tree signal from divergent histories of independent genes that supports relationships based on morphology. This is the first time a molecular study provides support for such relationships. This study further illustrates how methods of species-tree inference can be very sensitive both to the characteristics of the dataset and the evolutionary processes affecting the evolution of the group under study.

经历快速辐射演化的支系为物种形成与适应性演化的研究提供了绝佳契机，但同时也给分子系统学研究带来了挑战——祖先多态性的保留与杂交事件的发生，往往会模糊支系间的系统发育关系。海豚亚科（Delphininae）的海豚类群便是这类典型案例。该类群存在非单系性、快速物种形成事件，且形态学与分子性状间存在演化冲突，这使得推断该亚科内部的系统发育关系极具难度。本研究针对海豚亚科（Delphininae，包含驼海豚属（Sousa）、土库海豚属（Sotalia）、细吻海豚属（Stenella）、宽吻海豚属（Tursiops）、真海豚属（Delphinus）以及弗氏海豚属（Lagenodelphis））的多基因数据集，采用多种旨在推断物种树的分析方法以解决这一难题。研究得到的不一致基因树结果表明，不完全谱系分选或与杂交一同干扰了该类群物种演化历史的推断。尽管如此，借助基于溯祖理论的分析方法，我们仍从独立基因的差异化演化历史中提取到了核心的物种树信号，该信号支持基于形态学得到的系统发育关系。这是首次有分子生物学研究为这类系统发育关系提供实证支持。本研究进一步阐明，物种树推断方法对数据集特征以及研究所涉类群的演化过程均具有高度敏感性。