International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.3, 144-152 http://ecoevopublisher.com/index.php/ijmec 149 4.4 Genetic changes in behavioral and niche adaptation Blackfish show many differences in their behavior and ecological roles. Some are more aggressive about their territory. Others differ in how they reproduce or in their daily activity patterns. These differences seem to be linked to changes in their genes over time. The evolution of snakehead fish has formed a series of unique genetic characteristics, which have become important driving forces for its adaptation to the environment: for example, genes related to perception and behavioral regulation have undergone significant mutations, giving it advantages in foraging efficiency and intraspecific communication. In the adaptation to exercise and survival, muscle and stress-related genes (such as FoxO pathway genes) also undergo adaptive changes. These changes enable snakehead fish to move on land and cope with harsh environmental conditions (Ou et al., 2021; Townley et al., 2022). Subsequent research can systematically analyze the genetic basis of ecological adaptation strategies of different black fish species by integrating comparative genomics and transcriptomics methods, combined with behavioral ecology experiments. Cross analysis of multiple omics data is expected to reveal the complex interactions between genotype phenotype environment. 5 Comparative and Convergent Case Studies of Adaptive Evolution 5.1 Comparative analysis with other air-breathing fishes As a fish species capable of air respiration, the adaptation mechanism of the Blackfish genus to terrestrial respiration is similar to that of other fish species that have independently evolved respiratory organs (Jiang et al., 2016). Climbing sea bass (such as Anabas testudinius) and fighting fish, which have similar functions to black fish, also have auxiliary respiratory structures and can directly breathe air in hypoxic environments (Goodrich et al., 2020). Although these distant groups have different anatomical structures (climbing loaches are labyrinthine organs on their gills, while lungfish evolved from swim bladder to lungs, etc.), similar evolutionary characteristics often appear in molecular adaptation (Ou et al., 2021). For example, they all improve oxygen supply to auxiliary respiratory organs by enhancing the HIF-1 α signaling pathway and promoting angiogenesis pathway (Laskar et al., 2023). At the genetic level, some gene modules with similar patterns or functions experience similar selection pressure in air breathing fish. For example, the mucin gene responsible for maintaining a moist environment during respiration is highly expressed in both the intestinal tract of loaches and the gill organs of black fish to avoid tissue dryness (Laskar et al., 2023). For example, neurotransmitter genes that regulate respiratory rhythms show positive selection signs in both lungfish and blackfish, indicating their importance in periodic respiratory behavior (Rüber et al., 2020). 5.2 Genomic adaptation differences among Snakehead ecotypes Genomic adaptive differences exist among different snakehead ecotypes, but current research is only beginning to explore them. Genomic adaptations and divergence often occur between highland and lowland, and between river and swamp-dwelling snakeheads, specifically in response to their respective environments. Genomic resources for snakehead (C. argus) provide a foundation for studying adaptive mutations between different ecological types, such as highland and lowland, and aquatic and swamp-dwelling habitats (Xu et al., 2017). Research by Ou et al. (2021) revealed that snakehead fish (Canna argus) have a stronger response to low-temperature stress than snakehead fish (Canna maculatus): they rapidly activate cold shock proteins and metabolic regulatory genes during cooling, thus better adapting to cold waters. Scientists recently found Channa harcourt butleri fish in remote parts of eastern India (Prazdnikov, 2023). This discovery shows how being separated by geography helps create new fish species. Studies comparing chromosomes found big differences between Channa fish species. For example, C. gachua and C. stewartii have very different chromosome patterns (Figure 2). These differences probably show how each species adapted to their environment in unique ways. Geographical differences significantly influence the evolutionary paths of Channa fish. Under prolonged isolation, populations gradually undergo adaptive changes to cope with diverse aquatic environments. Just as in captivity, targeted breeding can lead to faster growth rates and enhanced disease resistance in snakehead fish within a short period of time (Cao et al., 2021).
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