Schuchert Peter
Natural History Museum of Geneva, Route de Malagnou 1, CH-1208 Geneva, Switzerland.
Mol Phylogenet Evol. 2014 Jul;76:1-9. doi: 10.1016/j.ympev.2014.02.020. Epub 2014 Mar 3.
The marine hydroid Plumularia setacea has a near-cosmopolitan distribution. As in other sessile invertebrates with limited dispersal abilities, the wide distribution could also be a taxonomic artefact and the species might in fact be a complex of sibling species. To investigate this, a set of worldwide samples of P. setacea and several closely related species was examined using the mitochondrial markers 16S and COI, as well as the nuclear marker ITS. The results suggest an even higher degree of genetic diversity than expected. Almost all sampled regions had only private haplotypes and the resulting trees split into a multitude of geographically delimited lineages, this both for the mitochondrial and nuclear markers. In the framework of a genealogical species concept, these lineages would qualify as cryptic species. Using alternative species concepts, the results could be reconciled with traditional taxonomy by regarding P. setacea as a single species with an extensive population subdivision. A rapid molecular clock, limited dispersal abilities, and localized clonal propagation are likely the factors that explain the high but dispersed genetic diversity within this species.
海螅纲的刚毛羽螅分布几乎遍及全球。与其他扩散能力有限的固着无脊椎动物一样，这种广泛分布也可能是分类学假象，该物种实际上可能是一个姐妹种复合体。为了对此进行研究，我们使用线粒体标记16S和COI以及核标记ITS对一组来自全球的刚毛羽螅样本和几个近缘物种进行了检测。结果表明，其遗传多样性程度甚至高于预期。几乎所有采样区域都只有私有单倍型，由此产生的系统发育树分成了许多地理上界定的谱系，线粒体和核标记均是如此。在谱系物种概念的框架下，这些谱系可被视为隐存种。使用其他物种概念，通过将刚毛羽螅视为一个具有广泛种群细分的单一物种，这些结果可以与传统分类学相协调。快速分子钟、有限的扩散能力和局部克隆繁殖可能是解释该物种内高但分散的遗传多样性的因素。
