The Complete Mitochondrial Genome of Schistura fasciolata: Phylogenetic and Evolutionary Implications within Tribe Nemacheilini

Background: The mitochondrial genome is widely used to understand the phylogeny and evolution of fish. This study aims to deepen the understanding of the mitochondrial genome of Schistura fasciolata and the evolutionary implications within Nemacheilini. Methods: This study utilized high-throughput sequencing technology and bioinformatics analysis to investigate the mitochondrial genome of the Schistura fasciolata. The aim was to reveal its structural or compositional characteristics, phylogenetic location and evolutionary rate. Result: We conducted a comprehensive sequence analysis of the complete mitochondrial genome of S. fasciolata, in which it contains 16,570 base pairs (bp) including 37 genes, i.e., 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs) and two ribosomal RNA genes (rRNAs). The base composition analysis indicated an A+T content of 56.51% and a G+C content of 43.49%. Phylogenetic analysis based on the 13 PCGs revealed extensive polyphyly within Nemacheilini. Furthermore, accelerated evolution in ND4, ND5 and CYTB genes were observed in Homatula and Troglonectes, suggesting an adaptation to specific environmental conditions. This study provides critical insights into the phylogeny and adaptive evolution within Nemacheilini.