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.

Hybridization between Native Barbless Carp (Cyprinus pellegrini) and Introduced Common Carp (C. carpio) in Xingyun Lake, China

“…There are two reasons causing the difference between our and Yang et al (2011)' results. The lower sampling intensity in the study of Yang et al (2011) possibly resulted in absence of pure barbless carp in collection, and pure barbless carp may have become sparser in 2007 than in 2003 as a result of further hybridization and introgression. Based on the recommendations of Dowling and Childs (1992) and Allendorf et al (2001), hybridized populations should be protected to avoid the complete loss of the native species if pure native populations have become extinct or very rare.…”

“…In the introgressed population, only relatively few individuals were identified as barbless carp both morphologically and genetically, suggesting that barbless carp may be in danger of genetic extinction. It is noteworthy that Yang et al (2011) did not find the existence of any pure barbless carp in a total of 62 individuals of Cyprinus captured from Xingyun Lake in 2007. There are two reasons causing the difference between our and Yang et al (2011)' results.…”

“…It is noteworthy that Yang et al (2011) did not find the existence of any pure barbless carp in a total of 62 individuals of Cyprinus captured from Xingyun Lake in 2007. There are two reasons causing the difference between our and Yang et al (2011)' results. The lower sampling intensity in the study of Yang et al (2011) possibly resulted in absence of pure barbless carp in collection, and pure barbless carp may have become sparser in 2007 than in 2003 as a result of further hybridization and introgression.…”

“…Artificial F1 hybrids between barbless and common carp have been proved to be viable and able to successfully reach maturity with a normal development of gonads Zhang et al, 1979). Tang (2008) and Yang et al (2011) documented the occurrence of hybridization between barbless and common carp in Xingyun Lake based on morphological and mtDNA data. This study further revealed the extent and pattern of hybridization between the two species based on morphological and nuclear microsatellite data from a larger number of individuals, and provided valuable information with regards to conservation and management strategies for native barbless carp.…”

Introduction and use of non‐native species for aquaculture in China: status, risks and management solutions

“…Similarly, almost all carps from Lake Xingyun in Yunnan province are inter‐specific hybrids, as revealed by both morphological and genetic surveys (Yang et al . ). ‘Pure'native species do not exist in the wild, that is, species extinction genetically, the worst consequence caused by aquaculture‐mediated hybridization.…”