Studies On Population Genetic Characteristic Of Spotted Seal (Phoca Largha) In Liaodong Gulf

Spotted seal (Phoca largha), one of the Second-class Protected Endangered Animals in China, is the only pinniped animal naturally bred in China seas. Liaodong Gulf of Bohai Sea is the most southern one of the eight breeding concentrations of spotted seals around the world. To know population genetic characteristic of spotted seal in Liaodong Gulf and protecting spotted seals better, molecular genetic characteristic was investigated using AFLP, SSR and partial mitochondrial DNA control region sequences. The results are as follows:The results of genetic diversity analysis using AFLP markers showed that a total of 241 reproducible bands amplified with seven AFLP primer combinations were obtained from 43 individuals. The percentage of polymorphic loci (P) ranged from 80.45 % to 95.85 % within the three populations and the overall percentage of polymorphic loci was 99.59 %. Shannon information index (I) ranged from 0.3817 to 0.4716. The genetic distance among the three populations was 0.1742 to 0.4023. All the three populations were clustered by UPGMA method and each individual was clustered by NTSYS software according to the genetic distance, but no obvious difference was found. No significant differences were found in the samples of the three years. Genetic diversity of spotted seals in Liaodong Gulf was moderate.The results of genetic diversity analysis using microsatellite markers showed that the average number of effective alleles (2~4). The number of average effective alleles and the expected heterozygosity was 3.19 and 0.69 (P2005), 3.37 and 0.73 (P2006), and 3.46 and 0.70 (P2007) respectively. There wasn't obvious genetic variation among the samples of the three years. Compared with other endangered mammals which suffered severe bottleneck effect (expected heterozygosity: 0.15~0.62), spotted seals from Liaodong Gulf were at a relative higher level.A pair of specific primers was designed according to spotted seal from Alaska (AM181031). A total of 159 sequences were obtained from seven spotted seals mtDNA control region about 1 kb upstream CSB-3 using PCR technique and DNA clone sequencing technique and 146 haplotypes (GenBank No. FJ008723~FJ008868) were determined after alignment analysis. The number of haplotypes (heteroplasmy) accounted for 91.82 % of the total sequences. The main cause of heteroplasmy is the existence of five kinds of tandom repeat motifs (GTACACAC, GTACAC, GTAC and GCACAC, GCAC) and their different repeat times. Heteroplasmy was detected among different individuals, different tissues of the same individual, and even in the same tissue of the same individual.The results of this study clarified the genetic diversity and genetic variation characteristic of spotted seal population in Liaodong Gulf, and would provide useful basic data for the conservation and management of Liaodong Gulf spotted seal colony.