Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada; Biodiversity Institute of Ontario & Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada(1).
Departamento de Biodiversidad y Biología Experimental, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, 4to Piso, C 1428 EHA, Buenos Aires, Argentina.
Mol Phylogenet Evol. 2018 Aug;125:232-242. doi: 10.1016/j.ympev.2018.03.004. Epub 2018 Mar 12.
Ancient lakes are renowned for their exceptional diversity of endemic species. As model systems for the study of sympatric speciation, it is necessary to understand whether a given hypothesized species flock is of monophyletic or polyphyletic origin. Here, we present the first molecular characterization of the Hyalella (Crustacea: Amphipoda) species complex of Lake Titicaca, using COI and 28S DNA sequences, including samples from the connected Small and Large Lakes that comprise Lake Titicaca as well as from a broader survey of southern South American sites. At least five evolutionarily distant lineages are present within Lake Titicaca, which were estimated to have diverged from one another 12-20 MYA. These major lineages are dispersed throughout the broader South American Hyalella phylogeny, with each lineage representing at least one independent colonization of the lake. Moreover, complex genetic relationships are revealed between Lake Titicaca individuals and those from surrounding water bodies, which may be explained by repeated dispersal into and out of the lake, combined with parallel intralacustrine diversification within two separate clades. Although further work in deeper waters will be required to determine the number of species present and modes of diversification, our results strongly indicate that this amphipod species cloud is polyphyletic with a complex geographic history.
古老的湖泊以其独特的特有物种多样性而闻名。作为同域物种形成的研究模型系统，有必要了解给定的假定物种群是单系起源还是多系起源。在这里，我们使用 COI 和 28S DNA 序列，首次对的的喀喀湖（Crustacea：Amphipoda）Hyalella 物种复合体进行了分子特征描述，包括来自连接的小湖和大湖的样本，这些湖泊构成了的的喀喀湖，以及对南美南部更广泛地点的调查。在的的喀喀湖中存在至少五个进化上相距甚远的谱系，它们彼此之间的分化时间估计为 12-20 百万年前。这些主要谱系分布在更广泛的南美 Hyalella 系统发育中，每个谱系都代表了对该湖的至少一次独立殖民。此外，还揭示了来自湖泊的个体与来自周围水体的个体之间复杂的遗传关系，这可能是由于多次进出湖泊的扩散，以及两个独立分支内的平行湖泊内多样化所致。尽管需要在更深的水域进行进一步的研究，以确定存在的物种数量和多样化模式，但我们的结果强烈表明，这种片脚类动物云是多系起源的，具有复杂的地理历史。
