Genetic Variation in Two Phenotypical Populations of Corbicula fluminea in Hongze Lake

Abstract:

In order to better manage and protect the genetic resources of Corbicula fluminea in Hongze Lake, molecular marker (mitochondrial cytochrome oxidase subunit I gene sequence, COI) and morphometric parameters (wet weight, shell length, width and height) were used to investigate the differences in genetic diversity and morphological characteristics of two populations with different morphology in color: black and yellow. Morphological analysis showed that the morphological parameters were significantly different between two populations. Using PCR amplification and sequencing, 614 bp of COI sequences were obtained. The base composition of COI sequences were very similar between black and yellow populations, in which the A+T content was higher than the G+C content. Seven haplotypes were found among 28 black individuals; the haplotype and nucleotide diversity were 0.794 and 0.04274, respectively. In parallel, 5 haplotypes were found among 30 yellow individuals, with the haplotype and nucleotide diversity being 0.607 and 0.02825, respectively. The genetic distance varied between 0.002 and 0.091 among all the COI haplotypes. Molecular phylogenetic trees were constructed using neighbor- joining and maximum parsimony, suggested that the COI gene haplotypes clustered into two clades. Analysis of molecular variance (AMOVA) based on COI sequences suggested that 78.26% variation occurred within the population, and a lower percentage of 21.74% variation occurred between two populations, and there was significant genetic differentiation in both populations (Fst=0.21736, P<0.01). The present results suggested that black and yellow C.fluminea populations in Hongze Lake should be protected and managed as two independent units in genetic resource.