International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.3, 144-152 http://ecoevopublisher.com/index.php/ijmec 145 Modern phylogenetic studies, combining mitochondrial DNA, nuclear gene sequences, and biogeographic data, supplemented by molecular clock estimates, have successfully reconstructed the evolutionary trajectory of Chinese snakehead fish (Britz et al., 2020; Prazhnikov, 2023). The introduction of whole-genome sequencing has provided a new approach for analyzing the genetic characteristics of key species. Furthermore, the continuous accumulation of multi-omics data is driving in-depth systematic studies of the mechanisms of adaptive evolution (Ou et al., 2021; Han et al., 2025). Certain functional genes have undergone rapid evolution in expression regulation, and this change is highly correlated with their unique ecological habits (Laskar et al., 2023). This study will systematically review multiple dimensions of research on the genus Blackfish, evaluate species diversity patterns and taxonomic controversies, analyze the main progress in molecular phylogenetic reconstruction, and explore the role of geological events in shaping lineage differentiation; At the same time, focusing on genomics research results, analyzing the genetic basis of key traits such as hypoxia adaptation and immune evolution; And compare the convergent adaptation cases of different ecological types of species. This study constructs a comprehensive framework for the adaptive evolution of the blackfish genus, providing a theoretical basis for subsequent conservation biology and evolutionary research. 2 Overview and Current Taxonomic Status of the Genus Channa 2.1 Species diversity and geographic distribution of the genus Channa The species diversity of the blackfish genus is high, and it is distributed in tropical, subtropical, and temperate regions of Asia. The geographical distribution range of each species varies greatly (Britz et al., 2020; Zhou et al., 2022). Traditional taxonomy has recorded about 35 species of Channa fish based on morphological characteristics, but in recent years, with the deepening of investigations in remote areas and the application of molecular identification methods, a large number of new species have been discovered and described, bringing the total number of species to around 50 (Britz et al., 2020; Htoo et al., 2025). For example, in Southeast Asia and South Asia, multiple new species have been announced in recent years: four new species of the Channa genus have been discovered in the Western Ghats Mountains of India (Praveenraj et al., 2019); New dwarf Channa spp. species have also been discovered in the border areas of Yunnan, China and Myanmar (Zhang et al., 2024). The natural distribution of Channa is concentrated in three major geographical regions: East Asia, Southeast Asia, and South Asia. There are several well-known species distributed in East Asia, such as the Channa argus in northeastern China and eastern Russia, as well as the Channa asiatica in southern China. Southeast Asia is the region with the richest species of snakehead fish. Large species such as Channa micropeltes, Channa marulius and Channa striata widely inhabit the Péninsule Indochine and the Malay Islands (Figure 1). A new species, Channa shingon, has been discovered in the surrounding areas of Yunnan and Myanmar (Britz et al., 2020; Htoo et al., 2025). There are also numerous endemic species in South Asia, such as the Channa Stewart in northeastern India and the Channa kelaartii in Sri Lanka (Praveenraj et al., 2020). The eastern foothills of the Himalayas are particularly rich in small and narrowly distributed species, making it a biodiversity hotspot for black fish. About 40% of the species in the snakehead genus are only distributed in this area. In contrast, the three species of snakehead in Africa belong to the Parachanna genus, which diverged from the Asian snakehead genus in ancient times (late Paleozoic to early Cenozoic). From the distribution range, they are completely isolated from the Asian snakehead genus (Britz et al., 2020). 2.2 Controversies and issues in taxonomy and nomenclature Snakehead species are remarkably similar in appearance, posing a long-standing challenge to their classification and identification (Praveenraj et al., 2020; Htoo et al., 2025). Researchers generally rely on body coloration and morphological features to distinguish snakeheads, but this method can be less accurate when these features overlap between species. Some "new species" named based on their morphology were found to be invalid after genetic testing and should be incorporated into existing species. For example, the recently described dwarf species C. shingon in the Channa genus in Myanmar was initially confused with its closely related species C. rubricacia, but its validity was later determined by combining morphology and COI sequences (Zhang et al., 2024). For
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