MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Science, Fudan University, Songhu Road 2005, Shanghai, China.
College of Marine and Environmental Sciences, James Cook University, Townsville, Qld 4811, Australia.
Mol Phylogenet Evol. 2022 Jun;171:107457. doi: 10.1016/j.ympev.2022.107457. Epub 2022 Mar 26.
The biogeography and molecular phylogeny of invertebrate zooplankton populations from inland saline waters remains under-explored in the Eastern Palearctic, especially the Qinghai-Tibetan Plateau. Here, we surveyed the diversity of the Brachionus plicatilis Müller, 1786 species complex from inland saline waters across China. We compared morphometrics with DNA taxonomy (using two genetic markers: the mitochondrial cytochrome c oxidase subunit I (COI) gene and the nuclear internal transcribed spacer (ITS-1)). Our phylogenies based on the sequences of ITS-1 recognized two distinct clades (i.e. two species: B. plicatilis sensu stricto (s.s.) and B. asplanchnoidis) in China. We detected two mitochondrial clades within B. plicatilis s.s and one within B. asplanchnoidis across China, consistent with the three morphogroups present. One of these three clades was novel and restricted to the Qinghai-Tibetan Plateau, where it exhibited evidence of recent expansion across the region. The new mitochondrial clade fell within B. plicatilis s.s. but was sister to all other mitochondrial sequences of that species, suggesting a period of isolation from other populations. Moreover, significant morphological differences were identified: B. plicatilis s.s. from the Qinghai-Tibetan Plateau had a larger lorica length and width than did members of this species from lowland China. Our data demonstrate the successful adaptation of this species complex to the harsh environment of the Qinghai-Tibetan Plateau.
内陆盐水无脊椎动物浮游动物种群的生物地理学和分子系统发育在东亚，尤其是青藏高原，仍未得到充分探索。在这里，我们调查了中国内陆盐水水域中褶皱臂尾轮虫复合体的多样性。我们将形态计量学与 DNA 分类学（使用两个遗传标记：线粒体细胞色素 c 氧化酶亚基 I（COI）基因和核内转录间隔区（ITS-1））进行了比较。我们基于 ITS-1 序列构建的系统发育树识别出中国存在两个截然不同的分支（即两个物种：褶皱臂尾轮虫 s.s. 和等尾轮虫）。我们在中国内陆盐水水域的褶皱臂尾轮虫 s.s.中检测到两个线粒体分支，在等尾轮虫中检测到一个分支，与存在的三个形态群相对应。这三个分支中的一个是新的，仅局限于青藏高原，在该地区存在近期扩张的证据。新的线粒体分支属于褶皱臂尾轮虫 s.s.，但与该物种的所有其他线粒体序列为姐妹关系，表明其与其他种群存在隔离期。此外，还发现了显著的形态差异：青藏高原的褶皱臂尾轮虫 s.s.的壳长和壳宽均大于中国低地的该物种成员。我们的数据表明，该物种复合体成功适应了青藏高原恶劣的环境。
