Comparative Genome Analysis Reveals the Genomic Basis of Semi-Aquatic Adaptation in American Mink (Neovison vison)

Simple Summary In nature, every animal lives in its suitable environment to support life and reproduction. Due to survival pressure, the ancient ancestors of land animals changed from living in water to living on land through a long time of evolution. But as more and more animals live on land, the pressure to survive increases, and some animals continue to evolve and re-enter the water. Species evolved from water to land, fins became limbs, and re-entering organisms evolved webbing, all in an effort to better adapt to their environment. The American mink's life is extremely dependent on the water environment, but its external changes are less pronounced than those of other water-dependent animals. Since the limited external changes are not sufficient to indicate that the American mink is a semi-aquatic mammal, we can explore the evidence of aquatic adaptation at the molecular level. Through comparative genomic analysis, we obtained that American mink has certain adaptive evolution to aquatic environment in olfactory, coagulation, immunity and other aspects. The results of this study have important reference significance for exploring biological evolution and species conservation. Although the American mink is extremely dependent on water and has evolved a range of aquatic characteristics, its structural adaptation to water is still less obvious than that of other typical semi-aquatic mammals, such as otters. Therefore, many scholars consider it not to be a semi-aquatic mammal. In order to make the point that minks are semi-aquatic mammals more convincing, we provide evidence at the micro (genome)-level. In particular, we used the genomes of the American mink and 13 mammalian species to reconstruct their evolutionary history, identified genes that affect aquatic adaptation, and examined the evolution of aquatic adaptation. By analyzing unique gene families, the expansion and contraction of gene families, and positive selection genes, we found that the American mink genome has evolved specifically for aquatic adaptation. In particular, we found that the main adaptive characteristics of the American mink include the external structural characteristics of bone and hair development, as well as the internal physiological characteristics of immunity, olfaction, coagulation, lipid metabolism, energy metabolism, and nitrogen metabolism. We also observed that the genomic characteristics of the American mink are similar to those of other aquatic and semi-aquatic mammals. This not only provides solid genomic evidence for the idea that minks are semi-aquatic mammals, but also leads to a clearer understanding of semi-aquatic species. At the same time, this study also provides a reference for the protection and utilization of the American mink.