Data from: Phylogeny and temporal diversification of the New World pond turtles (Emydidae)

We present a comprehensive multigene phylogeny and time tree for the turtle family Emydidae. Our phylogenetic analysis, based on 30 nuclear and four mitochondrial genes (23,330 total base pairs) sequenced for two individuals for each of the currently recognized species of the subfamily Emydinae and two species from each of the more species-rich Deirochelyinae genera, yielded a well-supported tree that provides an evolutionary framework for this well-studied clade and a basis for a stable taxonomy. We calibrated an emydid time tree using three well-vetted fossils, modeled uncertainty in fossil ages to reflect their accuracy in node dating, and extracted stem/crown ages of a number of key diversification events. We date the age of crown emydids at a relatively young 44 Ma, and the crown age of both contained subfamilies at roughly 30 Ma. One deirochelyine clade, which includes the genera Graptemys, Malaclemys, Pseudemys, and Trachemys and contains 11% of all turtle species, dates to 21 Ma just prior to the mid-Miocene climatic optimum, suggesting a potential causal link between warm, moist conditions and rapid species accumulation of these highly aquatic turtles. Both nuclear DNA data alone and in combination with mitochondrial DNA support the monophyly of an inclusive genus Emys containing the old world species orbicularis and trinacris and the new world blandingii, marmorata and pallida. Given that all members of this group were originally aligned in the genus Emys and that the age of the clade is roughly equal to other emydine genera, we strongly support a classification that places these five species in a single genus rather than the alternative three-genus scheme (Emys (orbicularis, trinacris), Actinemys (marmorata, pallida), Emydoidea (blandingii). The phylogeny and resulting time tree presented here provides a comprehensive foundation for future comparative analyses of the Emydidae that will shed light on the historical ecology and conservation prioritization of this diverse chelonian clade.

本研究针对泽龟科（Emydidae）构建了一套全面的多基因系统发育树与时间树。本研究的系统发育分析以30个核基因与4个线粒体基因为基础（总序列长度达23330个碱基对），共对泽龟亚科（Emydinae）所有当前已确认物种各采集2个个体，同时对物种更丰富的迪罗龟亚科（Deirochelyinae）各属各采集2个物种进行测序；最终得到了高支持度的系统发育树，为这一被广泛研究的演化支提供了演化框架，也为稳定的分类学体系奠定了基础。本研究利用3个经过严格验证的化石对泽龟科时间树进行定年校准，并通过模拟化石年代的不确定性以反映其在节点定年中的准确性，同时提取了多个关键物种分化事件的茎群/冠群分化时间。本研究测得泽龟科冠群的分化时间为相对较新的44百万年前（44 Ma），而两个现生亚科的冠群分化时间均约为30百万年前（30 Ma）。其中一个迪罗龟亚科演化支包含地图龟属（Graptemys）、菱斑龟属（Malaclemys）、锦龟属（Pseudemys）与滑龟属（Trachemys），涵盖了所有龟类物种的11%，其分化时间为中新世中期气候最适宜期之前的21百万年前（21 Ma），这提示温暖湿润的环境与这些高度水生的龟类的快速物种积累之间可能存在因果关联。无论是单独使用核DNA数据，还是将核DNA与线粒体DNA数据结合分析，均支持将包含旧世界物种欧泽龟（Emys orbicularis）、西西里泽龟（Emys trinacris）与新世界物种布氏泽龟（Emys blandingii）、大理石泽龟（Emys marmorata）、淡色泽龟（Emys pallida）的广义泽龟属（Emys）视为单系群。鉴于该类群的所有成员最初均被归入泽龟属（Emys），且该演化支的分化时间与其他泽龟亚科属类大致相当，本研究强烈支持将这五个物种归为单一属的分类方案，而非替代的三属划分体系（即泽龟属（Emys）包含欧泽龟与西西里泽龟，动胸龟属（Actinemys）包含大理石泽龟与淡色泽龟，布氏泽龟属（Emydoidea）仅包含布氏泽龟）。本研究构建的系统发育树与对应的时间树，为未来针对泽龟科的比较分析提供了全面的基础，这些分析将有助于阐明这一多样的龟类演化支的历史生态学特征，并为其保护优先级划分提供依据。