Previšić Ana, Gelemanović Andrea, Urbanič Gorazd, Ternjej Ivančica
Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000 Zagreb, Croatia.
School of Medicine, University of Split, Šoltanska 2, 21000 Split, Croatia.
Mol Phylogenet Evol. 2016 Jul;100:124-134. doi: 10.1016/j.ympev.2016.04.010. Epub 2016 Apr 7.
We use mitochondrial (mtCOI) and nuclear (nH3) sequence data to investigate differentiation of Eudiaptomus hadzici, a freshwater copepod endemic to the Western Balkans. E. hadzici has a disjunct distribution and morphological differences were observed at regional scale. In the current study 6 out of 7 known populations are included. We applied several species delimiting approaches, distance based methods (K2P p-distance and Automatic Barcode Gap Discovery, ABGD) using the mtCOI, Bayesian phylogeny and the Bayesian method implemented in bPTP and BPP programs using the concatenated sequences of both genes. Phylogenetic and species delimitation analyses all suggest that the nominal species E. hadzici consists of four isolated, cryptic evolutionary lineages in the Western Balkans. Each of the four lineages inhabits a single lake or a group of lakes in close proximity. They exhibit major differences in secondary sexual characters, e.g. right antennule in males. Denticulation of spine on 13th segment is substantially distinct among the four lineages, having different number and shape of tooth-like protrusions. Gene flow and dispersal are restricted to very small spatial scale, but with local differences, implying that diverse historical and contemporary processes are operating at small spatial scales in E. hadzici. In order to further examine spatial and temporal diversification patterns, we constructed a dated species tree analysis using (*)BEAST. Due to lack of reliable calibration points and taxa specific evolutionary rates, two evolutionary rates were applied and the faster one (2.6% myr) seems more plausible considering the geological history of the region. The divergence of E. hadzici lineages is dated from Early Miocene onwards with geographically close lineages diverging more recently, Late Miocene to Pleistocene and Pleistocene, respectively. Overall, our findings shed light on cryptic genetic complexity of endemics in one of European biodiversity hotspots. Moreover, this study represents one further example of integrative taxonomy, linking DNA methodology and classical taxonomy based on morphology. Therefore, it lays groundwork for future taxonomy and biogeography of freshwater microcrustaceans in the region.
我们利用线粒体（mtCOI）和核基因（nH3）序列数据，对西巴尔干地区特有的淡水桡足类动物哈氏真镖水蚤（Eudiaptomus hadzici）的分化情况展开研究。哈氏真镖水蚤分布间断，且在区域尺度上观察到形态差异。在本研究中，纳入了已知的7个种群中的6个。我们应用了多种物种界定方法，包括基于线粒体细胞色素氧化酶亚基I（mtCOI）序列的基于距离的方法（K2P遗传距离和自动条形码间隙发现法，ABGD）、贝叶斯系统发育分析，以及使用两个基因的串联序列，在bPTP和BPP程序中实现的贝叶斯方法。系统发育和物种界定分析均表明，名义上的哈氏真镖水蚤物种在西巴尔干地区由四个孤立的、隐秘的进化谱系组成。这四个谱系中的每一个都栖息在一个单独的湖泊或一组相邻的湖泊中。它们在第二性征上表现出重大差异，例如雄性的右触角。四个谱系中第13节上的刺的齿状结构有很大不同，齿状突起的数量和形状各异。基因流动和扩散仅限于非常小的空间尺度，但存在局部差异，这意味着不同的历史和当代过程在哈氏真镖水蚤的小空间尺度上发挥作用。为了进一步研究空间和时间上的多样化模式，我们使用（*）BEAST构建了一个带时间的物种树分析。由于缺乏可靠的校准点和特定分类群的进化速率，我们应用了两种进化速率，考虑到该地区的地质历史，较快的一种（2.6% 百万年）似乎更合理。哈氏真镖水蚤谱系的分化始于中新世早期，地理上相邻的谱系分化时间更近，分别为晚中新世至更新世和更新世。总体而言，我们的研究结果揭示了欧洲生物多样性热点地区之一特有物种的隐秘遗传复杂性。此外，本研究是整合分类学的又一个例子，将DNA方法与基于形态学的经典分类学联系起来。因此，它为该地区淡水微型甲壳类动物未来的分类学和生物地理学奠定了基础。
