Gouskov Alexandre, Vorburger Christoph
Eawag, Aquatic Ecology Department, Überlandstrasse 133, P.O.Box 611, 8600, Dübendorf, Switzerland.
Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, 8092, Zürich, Switzerland.
BMC Evol Biol. 2016 Sep 9;16(1):185. doi: 10.1186/s12862-016-0750-9.
Distributions of European fish species were shaped by glaciations and the geological history of river networks until human activities partially abrogated the restrictions of biogeographical regions. The nearby origins of the Rhine, Rhone, Danube and Po rivers in the Swiss Alps allow the examination of historical and human-influenced patterns in fish genetic structure over a small geographic scale. We investigated these patterns in the widespread European chub (Squalius cephalus) from the Rhone, Rhine and Danube catchments and its proposed southern sister species Italian chub (Squalius squalus) from the Po catchment.
A phylogenetic tree constructed from mitochondrial Cytochrome b and COI sequences was consistent with earlier work in that it showed a separation of European chub and Italian chub, which was also reflected in microsatellite allele frequencies, morphological traits and shape differences quantified by geometric morphometrics. A new finding was that the predominant mitochondrial haplotype of European chub from the Rhine and Rhone catchments was also discovered in some individuals from Swiss populations of the Italian chub, presumably as a result of human translocation. Consistent with postglacial recolonizations from multiple refugia along the major rivers, the nuclear genetic structure of the European chub largely reflected drainage structure, but it was modified by watershed crossings between Rhine and Rhone near Lake Geneva as well as between Danube and Rhine near Lake Constance.
Our study adds new insights into the cyprinid colonization history of central Europe by showing that multiple processes shaped the distribution of different chub lineages around the Swiss Alps. Interestingly, we find evidence that cross-catchment migration has been mediated by unusual geological events such as drainage captures or watershed crossings facilitated by retreating glaciers, as well as evidence that human transport has interfered with the historical distribution of these fish (European chub haplotypes present in the Italian chub). The desirable preservation of evolutionarily distinct lineages will thus require the prevention of further translocations.
欧洲鱼类物种的分布受到冰川作用和河网地质历史的影响，直到人类活动部分消除了生物地理区域的限制。瑞士阿尔卑斯山中莱茵河、罗纳河、多瑙河和波河的源头相近，这使得我们能够在小地理尺度上研究鱼类遗传结构中的历史和人类影响模式。我们调查了罗纳河、莱茵河和多瑙河流域广泛分布的欧洲圆腹雅罗鱼（Squalius cephalus）以及波河流域其假定的南部姐妹物种意大利圆腹雅罗鱼（Squalius squalus）的这些模式。
由线粒体细胞色素b和COI序列构建的系统发育树与早期研究一致，显示欧洲圆腹雅罗鱼和意大利圆腹雅罗鱼相互分离，这也反映在微卫星等位基因频率、形态特征以及通过几何形态计量学量化的形状差异上。一个新发现是，在意大利圆腹雅罗鱼的瑞士种群的一些个体中也发现了莱茵河和罗纳河流域欧洲圆腹雅罗鱼的主要线粒体单倍型，这可能是人类迁移的结果。与沿着主要河流从多个避难所进行的冰期后重新定殖一致，欧洲圆腹雅罗鱼的核遗传结构在很大程度上反映了排水结构，但在日内瓦湖附近莱茵河和罗纳河之间以及康斯坦茨湖附近多瑙河和莱茵河之间的分水岭交叉处受到了改变。
我们的研究通过表明多种过程塑造了瑞士阿尔卑斯山周围不同圆腹雅罗鱼谱系的分布，为中欧鲤科鱼类的定殖历史增添了新的见解。有趣的是，我们发现有证据表明跨流域迁移是由不寻常的地质事件介导的，如排水捕获或冰川消退促成的分水岭交叉，以及人类运输干扰了这些鱼类历史分布的证据（意大利圆腹雅罗鱼中存在欧洲圆腹雅罗鱼单倍型）。因此，要保护进化上不同的谱系，就需要防止进一步的迁移。
