Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12/16, 90-237 Łódź, Poland.
Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Braga, Portugal; Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Portugal.
Mol Phylogenet Evol. 2019 Mar;132:53-66. doi: 10.1016/j.ympev.2018.11.013. Epub 2018 Nov 24.
Amphipods of the genus Gammarus are a vital component of macrozoobenthic communities in European inland and coastal, marine and brackish waters of the Mediterranean and the Black Sea. Exceptional levels of cryptic diversity have been revealed for several widespread freshwater Gammarus species in Europe. No comprehensive assessment has yet been made for brackishwater counterparts, such as Gammarus aequicauda and G. insensibilis, which are among the most widely dispersed members of the so-called "G. locusta group" in the Mediterranean and in the Black Sea. Here we probe the diversity of these morphospecies examining the partitioning of mtDNA and nDNA across multiple populations along their distribution range and discuss it within the regional paleogeographic framework. We gathered molecular data from a collection of 166 individuals of G. aequicauda and G. insensibilis from 47 locations along their distribution range in the Mediterranean including the Black Sea. They were amplified for both mitochondrial COI and 16S rRNA as well as the nuclear 28S rRNA. All five MOTU delimitation methods (ABGD, BIN, bPTP, GMYC single and multiple threshold models) applied revealed deep divergence between Black Sea and Mediterranean populations in both G. aequicauda and G. insensibilis. There were eight distinct MOTUs delimited for G. aequicauda (6-18% K2P) and 4 MOTUs for G. insensibilis (4-14% K2P). No sympatric MOTUs were detected throughout their distribution range. Multimarker time-calibrated phylogeny indicated that divergence of both G. aequicauda and G. insensibilis species complexes started already in the late Oligocene/early Miocene with the split between clades inhabiting eastern and western part of the Mediterranean occurring in both species at the similar time. Our results indicate a high cryptic diversity within Mediterranean brackishwater Gammarus, similar to that observed for freshwater counterparts. Moreover, the phylogenetic history combined with the current geographic distribution indicate that the evolution of both studied Gammarus morphogroups has been strongly connected with the geological events in the Mediterranean Basin and it reflect the turbulent history of the area.
欧洲内陆和沿海、地中海和黑海的咸水水域的大型底栖动物群落中，端足目属的片脚类动物是一个重要组成部分。在欧洲，一些分布广泛的淡水十足目种类中，已经揭示出了非凡的隐种多样性。然而，对于像欧洲盐水端足目属的 Gammarus aequicauda 和 Gammarus insensibilis 等广泛分布的种类，还没有进行全面的评估，它们是所谓的“G. locusta 组”在地中海和黑海地区分布最广的成员之一。在这里，我们通过检查 mtDNA 和 nDNA 在其分布范围内的多个种群中的分布情况，来探究这些形态种的多样性，并在区域古地理框架内对其进行讨论。我们从地中海包括黑海在内的 47 个地点收集了 166 只 G. aequicauda 和 G. insensibilis 的个体的分子数据。我们对它们的线粒体 COI 和 16S rRNA 以及核 28S rRNA 进行了扩增。应用的所有五种 MOTU 界定方法（ABGD、BIN、bPTP、GMYC 单阈值和多阈值模型）都揭示了黑海中的种群和地中海种群之间的深度分化。在 G. aequicauda 和 G. insensibilis 中，界定了 8 个不同的 MOTU（6-18% K2P）和 4 个 MOTU（4-14% K2P）。在它们的整个分布范围内没有发现同域的 MOTU。多标记时间校准的系统发育表明，G. aequicauda 和 G. insensibilis 种复合体的分化始于晚始新世/早中新世，栖息在东地中海和西地中海的进化枝在两个物种中的分化时间相似。我们的研究结果表明，地中海盐水端足目属的隐种多样性很高，与淡水端足目属的情况相似。此外，系统发育历史与当前的地理分布相结合表明，这两个研究的端足目形态群的进化与地中海盆地的地质事件密切相关，反映了该地区动荡的历史。
