# Comparative Mitogenomics of Channa pyrophthalmus Unveils Orogeny-Driven Speciation and Lineage-Specific Adaptive Evolution in Snakeheads

## TL;DR

The Fire and Ice Snakehead's mitochondrial genome reveals it split from relatives 7 million years ago due to mountain uplift and evolved conservatively in its mountain stream habitat.

## Contribution

This study provides the first complete mitochondrial genome of Channa pyrophthalmus and links geological events to lineage-specific adaptive evolution in snakeheads.

## Key findings

- C. pyrophthalmus diverged from C. gachua around 7.1 million years ago, coinciding with the uplift of the Indo-Burman Ranges.
- The Fire and Ice Snakehead shows conservative evolution with purifying selection, contrasting with positive selection in giant snakehead lineages.
- Mitochondrial structural variation in the control region and accelerated evolution in ATP8 correlate with ecological and body size diversification.

## Abstract

Snakeheads are iconic freshwater predatory fishes in Asia, but their classification is often difficult due to similar appearances. Recently, a new species, the Fire and Ice Snakehead (Channa pyrophthalmus), was discovered in the Tenasserim Region of Myanmar. In this study, we decoded its complete mitochondrial genome to understand its evolutionary history. Our analysis confirms that this species is genetically distinct and split from its closest relatives approximately 7 million years ago, likely isolated by ancient mountains. Interestingly, unlike the widespread Striped Snakehead (Channa striata) which evolved rapidly to adapt to diverse environments, the Fire and Ice Snakehead shows a conservative evolutionary strategy, maintaining a stable genome suited to its specific mountain stream habitat. This study highlights the importance of the Tenasserim region as a biodiversity shelter and provides genetic tools for identifying and protecting this unique fish.

Snakeheads of the genus Channa display remarkable diversity in body size and ecology, yet evolutionary relationships within several species complexes remain unresolved. Channa pyrophthalmus, a recently described dwarf species endemic to Myanmar, represents a key lineage for investigating allopatric diversification in freshwater fishes. Here, we report the first complete mitochondrial genome of C. pyrophthalmus and perform comparative mitogenomic analyses across 18 Channa species. Phylogenetic analyses based on mitochondrial protein-coding genes robustly place C. pyrophthalmus as the sister lineage to C. gachua sensu stricto, supporting recent taxonomic revisions. While mitochondrial coding regions are highly conserved across the genus, the control region exhibits pronounced lineage-specific structural variation driven by tandem repeats. Divergence-time estimation dates the split between C. pyrophthalmus and C. gachua to ∼7.1 Ma (Late Miocene), a timeline congruent with the Late Miocene accelerated uplift of the Indo-Burman Ranges. Selection analyses reveal contrasting evolutionary regimes: pervasive purifying selection characterizes the dwarf lineage, whereas episodic positive selection on ND5 marks the ancestral lineage of giant snakeheads, indicating adaptive shifts in mitochondrial bioenergetics. Additionally, accelerated evolution in ATP8 was detected in rheophilic lineages. Together, these findings link geological vicariance and mitochondrial metabolic evolution to body size diversification in Channa.