# Comparative mitogenomics and phylogenetic implications of Dawkinsia apsara and Dawkinsia denisonii (Cypriniformes, Cyprinidae)

## TL;DR

This study compares the mitochondrial genomes of two fish species, Dawkinsia apsara and Dawkinsia denisonii, to clarify their evolutionary relationships and resolve classification issues.

## Contribution

The first complete mitochondrial genome of Dawkinsia apsara is sequenced, providing new phylogenetic insights into the Dawkinsia genus.

## Key findings

- The mitochondrial genomes of D. apsara and D. denisonii show similar nucleotide composition but differ in control region structure.
- Phylogenetic analysis confirms the monophyly of the genus Dawkinsia and improves resolution compared to prior studies.
- Structural variations in the control region, including tandem repeats, are revealed between closely related species.

## Abstract

The classification of the Puntius-Dawkinsia complex has long been controversial due to overlapping morphological characteristics and inconsistent phylogenetic tree topology based on short mtDNA fragments. In order to better clarify the species relationship within the genus Dawkinsia, the complete mitochondrial genome of Dawkinsia
apsara was determined for the first time, and the mitochondrial genome of Dawkinsia
denisonii was newly sequenced independently for comparative analysis. The results showed that the nucleotide composition of mtDNA of D.
apsara (16,470 bp) and D.
denisonii (16,900 bp) was similar. The total AT content of the two fish species was 58.9% and 58.2%, respectively. RSCU and amino acid composition showed that A/T-ending synonymous codons, and Leu was the most abundant amino acid. However, there are significant differences in the length and structure of the control region between the two species, especially in the tandem repeats and conserved structural units. The phylogenetic tree constructed based on ML and BI methods strongly supported the monophyly of genus Dawkinsia. The Dawkinsia
denisonii was clustered with D.
chalakkudiensis within the genus, followed by D.
tambraparniei and D.
apsara, and obtained a higher phylogenetic resolution than previous studies between Dawkinsia and its related genera such as Pethia and Puntius. This study provides the first complete mitochondrial genome of D.
apsara, reveals the structural variations in the genome, particularly within the control regions, among the closely related species of Dawkinsia, enriches the phylogenetic data of the genus Dawkinsia, and provides new mitochondrial genome-scale evidence for the long-controversial Puntius-Dawkinsia complex.