Comparative Studies on the Molecular Genetic Diversities among Haliotis discus hannai,H.discus discus and Their Hybrids

The hybrid (H. discus hannai♀× H. discus discus♂) shows strong heterosis in both growth and survival rates during aquaculture. In order to better understand the genetic basis of heterosis, AFLP markers are adopted to compare the genetic diversities of the two parents and their hybrids. Six primer combinations reveal 552 loci, among which 88 loci show significant difference between the two parent populations (P<0.01). Analysis of molecular variance (AMOVA) indicates the genetic variance between them is significantly different (P<0.001). Thus there should be genetic basis of heterosis for their hybrids. In contrast to parents, more loci with lower frequency are amplified in hybrids than those in parents, whereas the loci with 0% and 100% frequency are less in hybrids than those in parents. Moreover, the genetic diversities of hybrids increase since the similarity indexes are lower and heterozygosities are higher in hybrids than those in parents. In addition, the genetic distances between reciprocal F1s and H. discus discus are both smaller than those between reciprocal F1s H. discus hannai.