We assessed the presence of independent evolving lineages of the trahira, Hoplias malabaricus, one of the few freshwater fish species having wide distribution in the Neotropics which is the region with the highest global diversity of freshwater fish. To achieve that goal, 58 mitochondrial sequences of cytochrome c oxidase subunit I (COI; DNA barcoding) were generated from collected samples and 85 obtained from public databases, which were analyzed in comparison to chromosomal and geological data. The magnitude of genetic diversity found among different sampling sites was greater than 2%. Molecular species delimitation methods indicated the existence of a least four distinct lineages. The recognised cytotypes did not form monophyletic groups, suggesting that the karyotypic macrostructure could be a homoplastic character. The haplotype relationships suggested secondary contacts between the ecoregions of Northern and Northeastern Brazil that were shaped by coastal routes between adjacent watersheds during the Pleistocene epoch and probable exchanges of their ichthyofaunas. Our results indicated that multiple factors have driven the diversification of H. malabaricus, from ancient geological events linked to the reactivation of tectonic faults to more recent occurrences related to eustatic changes in ocean levels. Ultimately, the magnitude of its genetic diversity suggests the necessity of revising its taxonomic status.

中文翻译：

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DNA 条形码揭示了新热带淡水 trahiras 的系统学和进化

我们评估了 trahira，Hoplias malabaricus 的独立进化谱系的存在，这是在新热带地区广泛分布的少数淡水鱼类之一，该地区是全球淡水鱼多样性最高的地区。为了实现这一目标，从收集的样本中生成了 58 个细胞色素 c 氧化酶亚基 I（COI；DNA 条形码）的线粒体序列，并从公共数据库中获取了 85 个，并与染色体和地质数据进行了比较分析。不同采样点间发现的遗传多样性幅度大于2%。分子物种定界方法表明存在至少四个不同的谱系。识别的细胞型没有形成单系群，表明核型宏观结构可能是同质性的。单倍型关系表明巴西北部和东北部生态区之间存在次要接触，这些接触是由更新世时期相邻流域之间的沿海路线以及它们的鱼群可能的交换所形成的。我们的研究结果表明，多种因素推动了 H. malabaricus 的多样化，从与构造断层重新激活有关的古代地质事件到与海平面变化有关的最近发生的事件。最终，其遗传多样性的规模表明有必要修改其分类地位。我们的研究结果表明，多种因素推动了 H. malabaricus 的多样化，从与构造断层重新激活有关的古代地质事件到与海平面变化有关的最近发生的事件。最终，其遗传多样性的规模表明有必要修改其分类地位。我们的研究结果表明，多种因素推动了 H. malabaricus 的多样化，从与构造断层重新激活有关的古代地质事件到与海平面变化有关的最近发生的事件。最终，其遗传多样性的规模表明有必要修改其分类地位。