International Journal of Aquaculture, 2025, Vol.15, No.3, 99-115 http://www.aquapublisher.com/index.php/ija 113 improves the credibility of taxonomy. On the other hand, mitochondrial variation also provides clues for studying species adaptability. Although its direct impact is limited, through the mitochondrial differences of different lineages, we can infer some possible ways for species to adapt to the environment and point out the direction for further functional research. For example, the molecular basis behind traits such as cold tolerance of black snakehead and disease resistance of spot snakehead can be inferred through lineage-specific mutations. Mitochondrial DNA as a maternal genetic marker can also help reveal population historical dynamics, such as glacial refuges and expansion routes. In the phylogeographic study of the genus Snakehead, the unique haplotypes in different regions and their phylogenetic positions provide evidence for reconstructing the history of species diffusion. For example, the haplotype diversity of the northern lineage of Channa argus is low and concentrated, suggesting that it may have experienced a rapid expansion after the glacial bottleneck; while the haplotype differentiation of Channa argus in Southeast Asia is deep, indicating that the region may be its long-term evolutionary center. These inferences all rely on the maternal genetic information recorded by mitochondrial variation. It can be said that mitochondrial genome variation is an indispensable part of the study of the phylogeny and evolution of the genus Snakehead. However, it should also be recognized that it is not omnipotent. In some recent events of rapid differentiation, mitochondria may have incomplete sequencing problems; for hybrid species, it can only reflect the history of the maternal side. Therefore, when using mitochondrial variation to analyze systematic relationships, we need to interpret it with caution and try to combine nuclear gene data to obtain a more comprehensive perspective. Although the mitochondrial genome provides a lot of useful information, the methods and data based on this study also have certain limitations. First, mitochondrial DNA only represents maternal inheritance and cannot reflect processes such as paternal gene flow and recombination. This may be misleading in some hybridization or gene penetration situations. For example, if two snakehead species have hybridized, mitochondria may only show a monophyletic relationship and mask the complex history of gene exchange. Therefore, the mitochondrial phylogenetic tree alone may not be able to fully reveal the species evolutionary network. In the genus Snakehead, although no new lineages formed by interspecific hybridization have been clearly reported, it does not rule out that there has been gene exchange in history, especially in geographical intersection areas. Solving this problem requires the introduction of nuclear genome markers (such as SNPs, nuclear gene sequences, etc.) for auxiliary verification. Secondly, the existing data coverage is still incomplete. There are dozens of species in the genus Snakehead, but sequencing studies are mainly focused on a few species with high economic value or wide distribution. Many rare species and newly described species lack genome data. For example, the mitochondrial genomes of several new species discovered in Myanmar in recent years have not yet been published. These gaps limit our understanding of the full picture of the genus Snakehead and cause species sampling bias in phylogenetic analysis. In the future, it is necessary to further determine the mitochondrial genomes of all known species in the genus Snakehead and conduct research on suspected cryptic species to improve the phylogenetic tree. In addition, the population-level sampling within some species is also insufficient. For example, in the complex lineage of the broad-headed Channa, there are few representative samples from different regions, and key lineage branches may be missed. Increasing population sampling will help depict the fine-scale phylogenetic geographical structure. On the technical level, mitochondrial genome analysis itself also has sources of error. For example, PCR amplification sequencing may produce errors, and there are difficulties in aligning sequences in tandem repeat regions. These need to be improved through higher-quality sequencing (such as third-generation sequencing to directly obtain complete circular sequences) and more optimized bioinformatics methods. Molecular clock calibration relies heavily on fossil records and evolutionary rate assumptions, and node ages may differ significantly under different assumptions. Therefore, we should be cautious about the inference of evolutionary time, and combine multiple genes and calibration points for cross-validation when necessary. Looking to the future, the phylogenetic and evolutionary research of the genus Snakehead is expected to achieve more in-depth results driven by the integration of genomics and ecological methods. On the one hand, the application of metagenomics and comparative genomics will enable us to go beyond mitochondria and understand
RkJQdWJsaXNoZXIy MjQ4ODYzNA==