Wang Fenglin, Jia Chenghao, Gao Tianxiang, Guo Xingle, Zhang Xiumei
Fisheries College, Zhejiang Ocean University, Zhoushan 316022, China.
School of Marine Sciences, Ningbo University, Ningbo 315211, China.
Animals (Basel). 2025 Jan 2;15(1):81. doi: 10.3390/ani15010081.
Species of the family Echeneidae are renowned for their capacity to adhere to various hosts using a sucking disc. This study aimed to examine the mitochondrial genome characteristics of three fish species (, , and ) within the family Echeneidae and determine their phylogenetic relationships. The findings revealed that the mitochondrial genome lengths of the three species were 16,611 bp, 16,648 bp, and 16,623 bp, respectively, containing 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and a D-loop region. Most PCGs utilized ATG as the initiation codon, while only used the GTG as the initiation codon. Additionally, seven genes employed incomplete termination codons (T and TA). The majority of PCGs in the three species displayed negative AT-skew and GC-skew values, with the GC-skew amplitude being greater than the AT-skew. The Ka/Ks ratios of the 13 PCGs did not exceed 1, demonstrating these species had been subjected to purification selection. Furthermore, only (GCT) lacked the D arm, while other tRNAs exhibited a typical cloverleaf secondary structure. Bayesian inference (BI) and maximum likelihood (ML) methods were utilized to construct a phylogenetic tree of the three species based on the 13 PCGs. was identified as a distinct group, while and were classified as sister taxa. This study contributes to the mitochondrial genome database of the family Echeneidae and provides a solid foundation for further systematic classification research in this fish group.
䲟科物种以其利用吸盘附着在各种宿主上的能力而闻名。本研究旨在研究䲟科三种鱼类（、和）的线粒体基因组特征，并确定它们的系统发育关系。研究结果显示，这三种物种的线粒体基因组长度分别为16,611 bp、16,648 bp和16,623 bp，包含13个蛋白质编码基因（PCGs）、22个转运RNA基因（tRNAs）、两个核糖体RNA基因（rRNAs）和一个D环区域。大多数PCGs以ATG作为起始密码子，而只有以GTG作为起始密码子。此外，七个基因使用不完全终止密码子（T和TA）。这三种物种中的大多数PCGs显示出负的AT偏斜和GC偏斜值，GC偏斜幅度大于AT偏斜。13个PCGs的Ka/Ks比值均不超过1，表明这些物种受到了纯化选择。此外，只有（GCT）缺乏D臂，而其他tRNAs呈现出典型的三叶草二级结构。基于13个PCGs，利用贝叶斯推断（BI）和最大似然（ML）方法构建了这三种物种的系统发育树。被确定为一个独特的类群，而和被归类为姊妹分类单元。本研究为䲟科线粒体基因组数据库做出了贡献，并为该鱼类群体的进一步系统分类研究提供了坚实的基础。
