Non-native carp of the genus Cyprinus in Lake Xingyun, China, as revealed by morphology and mitochondrial DNA analysis

Abstract

Lake Xingyun is a major body of water in Yunnan Province, China. Previous investigations suggested that the lake contained native populations of carp of the genus Cyprinus, but it is believed that these native populations disappeared due to overfishing. However, one or more Cyprinus species are currently abundant in Lake Xingyun but their identity and origin are unclear. To determine if the existing Cyprinus population is indeed non-native, we compared the morphologies of fish (n = 62) recently captured (2007) to museum preserved Cyprinus collected in the lake in the 1960s. In addition, we conducted mitochondrial DNA analyses of Cyprinus (n = 65) recently taken from the lake and found 28 haplotypes. The genetics of the lake’s sample were compared to Cyprinus from a wide range of other locations within and outside China. Together with previously published Japanese and Eurasian haplotypes, phylogenetic analysis demonstrated 28 haplotypes and these were classified into five different units. One of the five units included 16 closely related haplotypes that formed a monophyletic group apart from the Eurasian clade. Given their monophyly that included 3 native carp haplotypes, haplotypes from this unit were thought to originate from the native strain of Lake Xingyun. Furthermore, combining this with result from morphological analysis, it was concluded that these haplotypes were likely hybrid carp. Conversely, haplotypes from the other 4 units nested into the Eurasian clade. Their phylogenetic affinities to Eurasian lineages indicated that these haplotypes were domesticated strains introduced from other parts of China, Vietnam and Europe. These conclusions were supported by historical records on introduction. This study revealed that almost all carp from current Lake Xingyun may be originated from hybrid strains and domesticated strains introduced from Eurasia.