Departamento de Biología and Centro de Investigaciones Científicas Avanzadas (CICA), Universidade da Coruña, A Coruña, Spain.
Instituto Mediterráneo de Estudios Avanzados (IMEDEA), Consejo Superior de Investigaciones Científicas (CSIC) and Universitat de les Illes Balears, Esporles, Spain.
PLoS One. 2020 Aug 18;15(8):e0237037. doi: 10.1371/journal.pone.0237037. eCollection 2020.
The genus Palaemon comprises worldwide marine and freshwater shrimps and prawns, and some of them are ecologically or commercially important species. Palaemon is not currently a monophyletic group, so phylogenetics and systematics are constantly changing. Species crypticism has been pointed out in several Palaemon species, being the clearest evidence in the European rockpool shrimp P. elegans. Here we sequenced and described seven European Palaemon mitochondrial genomes. The mitochondrial protein-coding genes were used, along with those of three other Palaemon species, to perform mitogenome phylogenetic analyses to clarify the evolutionary relationships within the genus, and particularly to shed light on the cryptic species found within P. elegans. The Messinian Salinity Crisis (5.3-5.9 Ma, late Miocene) was proposed to be the origin of this cryptic species and it was used as aged constraint for calibration analysis. We provide the largest and the first time-calibrated mitogenome phylogeny of the genus Palaemon and mitogenome substitution rate was estimated (1.59% per million years) in Decapoda for the first time. Our results highlighted the need for future systematics changes in Palaemon and crypticism in P. elegans was confirmed. Mitochondrial genome and cox1 (1.41%) substitution rate estimates matched those published elsewhere, arguing that the Messinian Salinity Crisis was a plausible event driving the split between P. elegans and its cryptic species. Molecular dating suggested that Pleistocene glaciations were likely involved in the differentiation between the Atlantic and Mediterranean populations of P. elegans. On the contrary, the divergence between the Atlantic and Mediterranean populations of the common littoral shrimp P. serratus was greater and dated to be much older (4.5-12.3 Ma, Plio-Miocene), so we considered that they could represent two separated species. Therefore, species crypticism in the genus Palaemon seems to be a common phenomenon.
Palaemon 属包括世界范围内的海洋和淡水虾和对虾，其中一些是具有生态或商业重要性的物种。 Palaemon 目前不是一个单系群，因此系统发育和系统学不断变化。在几个 Palaemon 物种中已经指出了物种隐密性，这在欧洲岩石池虾 P. elegans 中是最明显的证据。在这里，我们对七种欧洲 Palaemon 线粒体基因组进行了测序和描述。使用线粒体蛋白质编码基因，以及其他三种 Palaemon 物种的基因，进行了线粒体基因组系统发育分析，以阐明属内的进化关系，特别是阐明在 P. elegans 中发现的隐密物种。有人提出，墨西拿盐度危机（530-590 万年，中新世晚期）是这种隐密物种的起源，并将其用作校准分析的年龄约束。我们提供了 Palaemon 属的最大和首次时间校准的线粒体基因组系统发育，并且首次估计了十足目动物的线粒体基因组替换率（每百万年 1.59%）。我们的结果强调了 Palaemon 未来系统发育变化的必要性，并确认了 P. elegans 的隐密性。线粒体基因组和 cox1（1.41%）替换率的估计与其他地方发表的数据相匹配，这表明墨西拿盐度危机是驱动 P. elegans 与其隐密物种分裂的一个合理事件。分子年代测定表明，更新世冰川作用可能参与了 P. elegans 的大西洋和地中海种群之间的分化。相反，常见的沿海虾 P. serratus 的大西洋和地中海种群之间的分歧更大，并且可以追溯到更早的时期（450-1230 万年，上新世-中新世），因此我们认为它们可能代表两个独立的物种。因此， Palaemon 属中的物种隐密性似乎是一种常见现象。
