DefinePK

Abstract

ABSTRACT Mitochondrial DNA is the most reliable tool in species classification, genetic diversity, and phylogeny of fish studies. In this study, two new mitochondrial genomes in the genus Corydoras (Callichthyidae) were determined, specifically C. hastatus and C. cruziensis. Comparative and phylogenetic analyses were conducted using our data and those of 12 other mitochondrial genomes from Corydoras. The nucleotide diversity and genetic distance among the protein-coding genes of the Corydoras mitochondrial genomes showed that the most conserved gene was COII. Analysis of the selection pressures on each gene showed that COI was associated with the strongest purifying selection. The Corydoras mitochondrial genomes had similar AT and GC contents, AT and GC skew, genetic distances, nucleotide diversity, number of codons, and Ka/Ks values, supporting concerted evolution within this genus. The resulting phylogenetic relationship supports a sister-group relationship between C. hastatus and C. pygmaeus and between C. cruziensis and (C. rabauti + C. aeneus). The complete mitochondrial genomes of C. hastatus and C. cruziensis provide valuable resources for future studies on the molecular phylogeny and population genetics of Callichthyidae.