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 tribe Nemacheilini. This study aims to deepen the understanding of the mitochondrial genome of Schistura fasciolata, and the evolutionary implications within Nemacheilini. Methods and Results: We conducted a comprehensive sequence analysis of the complete mitochondrial genome of Schistura fasciolata, which is comprised of 16,570 base pairs including 37 genes: 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 evolutionary rates in ND4, ND5, and CYTB genes were observed in Homatula and Troglonectes, suggesting an adaptation to specific environmental conditions. Conclusions: The mitochondrial genome analysis of S. fasciolata provides critical insights into the phylogeny and adaptive evolution within Nemacheilini. Our findings underscore the complex evolutionary dynamics within the tribe, with distinct evolutionary trajectories observed in mitochondrial genes among different genera.