Cave animals evolve distinct troglomorphic characters in perpetual darkness,most commonly,the reduction of eyesight,pigmentation,pineal organ,and scales,countered by augmented chemoreceptors,mechanoreceptors,and lipid storage.The most extensive investigation of the evolution of troglodyte traits in cavefish comes from investigations of the Mexican tetra Astyanax mexicanus.In cave Astyanax,lens apoptosis associated with over-expression of sonic hedgehog(shh)induces eye degeneration.Although troglodyte features evolved independently many times in cavefish,we do not yet know whether independent evolution of these characters involves common genetic mechanisms.The freshwater teleost genus Sinocyclocheilus(Cypriniformes: Cyprinidae)is endemic to the karst region of the east Yungui Plateau and northwest Guangxi in southwestern China.The genus includes many surface-dwelling species and at least 10 cave dwelling species with different degrees of eye degeneration.The research on a variety of cave-animal models is necessary to understand whether independent evolutionary lineages utilize related molecular genetic mechanisms,or if evolution can achieve similar results by different mechanisms.