Museum of Zoology, Senckenberg Natural History Collections Dresden, 01109 Dresden, Germany.
Grupo Biodiversidad y Conservación Genética, Instituto de Genética, Universidad Nacional de Colombia, Bogotá, Colombia; Estación de Biología Tropical Roberto Franco (EBTRF), Universidad Nacional de Colombia, Villavicencio, Colombia.
Mol Phylogenet Evol. 2024 Aug;197:108083. doi: 10.1016/j.ympev.2024.108083. Epub 2024 Apr 27.
Kinosternon is the most speciose genus of extant turtles, with 22 currently recognized species, distributed across large parts of the Americas. Most species have small distributions, but K. leucostomum and K. scorpioides range from Mexico to South America. Previous studies have found discordance between mitochondrial and nuclear phylogenies in some kinosternid groups, with the current taxonomy following the nuclear-based results. Herein, based on extended molecular, geographic, and taxonomic sampling, we explore the phylogeographic structure and taxonomic limits for K. leucostomum and the K. scorpioides group and present a fossil-calibrated nuclear time tree for Kinosternon. Our results reveal contrasting differentiation patterns for the K. scorpioides group and K. leucostomum, despite overlapping distributions. Kinosternon leucostomum shows only shallow geographic divergence, whereas the K. scorpioides group is polyphyletic with up to 10 distinct taxa, some of them undescribed. We support the elevation of K. s. albogulare and K. s. cruentatum to species level. Given the deep divergence within the genus Kinosternon, we propose the recognition of three subgenera, Kinosternon, Cryptochelys and Thyrosternum, and the abandonment of the group-based classification, at least for the K. leucostomum and K. scorpioides groups. Our results show an initial split in Kinosternon that gave rise to two main radiations, one Nearctic and one mainly Neotropical. Most speciation events in Kinosternon occurred during the Quaternary and we hypothesize that they were mediated by both climatic and geological events. Additionally, our data imply that at least three South American colonizations occurred, two in the K. leucostomum group, and one in the K. scorpioides group. Additionally, we hypothesize that discordance between mitochondrial and nuclear phylogenetic signal is due to mitochondrial capture from an extinct kinosternine lineage.
鳖是现存龟鳖目中物种最丰富的属，目前有 22 种，分布于美洲的大部分地区。大多数物种的分布范围较小，但 K. leucostomum 和 K. scorpioides 的分布范围从墨西哥延伸到南美洲。先前的研究发现，在一些鳖科群体中，线粒体和核系统发育之间存在不一致性，目前的分类学结果遵循核系统发育的结果。在此，我们基于扩展的分子、地理和分类学采样，探索了 K. leucostomum 和 K. scorpioides 组的系统地理结构和分类学界限，并为鳖科提供了一个化石校准的核时间树。我们的研究结果揭示了 K. scorpioides 组和 K. leucostomum 的分化模式截然不同，尽管它们的分布范围重叠。K. leucostomum 仅显示出浅层的地理分化，而 K. scorpioides 组则是多系的，有多达 10 个不同的分类单元，其中一些尚未被描述。我们支持将 K. s. albogulare 和 K. s. cruentatum 提升为独立物种。鉴于鳖属内部的深度分化，我们建议将该属分为三个亚属，即 Kinosternon、Cryptochelys 和 Thyrosternum，并放弃基于群体的分类，至少对于 K. leucostomum 和 K. scorpioides 组。我们的研究结果表明，鳖属发生了一次早期分化，产生了两个主要的辐射分支，一个是近北极的，另一个主要是新热带的。鳖属的大多数物种形成事件发生在第四纪，我们假设它们是由气候和地质事件共同介导的。此外，我们的数据表明，至少发生了三次南美殖民事件，其中两次发生在 K. leucostomum 组，一次发生在 K. scorpioides 组。此外，我们假设线粒体和核系统发育信号之间的不一致是由于来自一个已灭绝的鳖科谱系的线粒体捕获造成的。
