Genetic diversity and population structure of Kichulchoia multifasciata in South Korea

Abstract

Kichulchoia multifasciata, a small-sized loach (Family Cobitidae) inhabiting only the Nakdong River on the Korean Peninsula, is generally found around well-oxygenated minor tributaries. Despite the scarcity, this species is not yet a legally protected species in South Korea, and the spatial pattern of genetic diversity, which is essential to create management strategies, has never been studied. In this study, three mitochondrial loci and ten microsatellites were used to analyze the genetic diversity and the structure among eight K. multifasciata populations collected from different tributaries. K. multifasciata populations showed a high level of mitochondrial variability, with above 0.9 of average haplotype diversity in all three loci analyzed. A substantial microsatellite polymorphism was also found. Weak genetic structuring among populations and isolation by distance were clearly revealed in both mitochondrial and microsatellite data, indicating the high levels of gene flow among the tributaries. However, a few of the populations exhibited a genetic signature that they have experienced the historical size decline. Our data suggest that unequal gene flow might be one of the causes; nevertheless, the possibility of effective population size reduction by other factors could not be completely excluded. Our genetic evidence can be the critical information needed to protect the populations from the genetic erosion in the Nakdong River that has been destroyed and fragmented with increasing anthropogenic interferences.