Factors limiting the spread of middle- and low-altitude fishes to the Qinghai-Tibet plateau

The distribution pattern of species is determined by the environment and their adaptability to environment. Qinghai-Tibet Plateau has become a natural laboratory for studying adaptive evolution due its extreme environmental characteristics such as low temperature, oxygen, high salinity ultraviolet radiation (UVR). Fish are sensitive stress, so they ideal materials high-altitude adaptation animals. Previous studies have mainly focused on plateau species, but reasons why plain cannot spread been ignored. In this study, stress experiments histological were used compare tolerance six Barbini fishes (family: Cyprinidae) distributed at different altitudes regions UVR. Results showed that factors was closely related main habitats. fish Gymnocypris eckloni had strong all factors, while other five from middle could not adapt single or multiple with significant interspecific differences. Among these middle- low-altitude common UVR, suggesting factor lacking altitude areas, plays an important role. Moreover, during uplift Plateau, Schizothorax disappeared plateau. We speculate caused intolerance increasingly environment, especially salinity.