Population Genetic Structure And Kinship Identification For Captive Population Of Finless Porpoises (Neophocaena Phocaenoides) Based On Microsatellite DNA Markers

This thesis includes three chapters:1. The characteristics and application of microsatellite DNA markers was reviewed.2. Four microsatellite loci were applied to investigate the population structure and genetic diversity of three finless porpoise (Neophocaena phocaenoides) populations in Chinese waters. Eighty-two samples were analyzed in the study, including 42 from the South China Sea population, 21 from the Yellow Sea population, and 19 from the Yangtze River population, respectively. The Yellow Sea population and the Yangtze River population, having the mean expected heterozygosity (HE) of 0.65 and 0.57 respectively, showed relatively high level of genetic diversity, whereas the South China Sea population had a relatively low one (He=0.36). There was a significant level of overall population structure in Chinese finless porpoises (Fst=0.1187, Rst=0.2303), however the structure was found mainly between either the Yangtze River population (FST=0.1366, RST=0.3168) or the Yellow Sea population (FST=0.1088, RST=0.2155) and the South China Sea population. Compared with the above-mentioned high level of genetic structure, the differentiation between the Yangtze River population and the Yellow Sea population was quite low (Fst=0.0349, RST=0.0808). it was also found that the allele frequency distributions did not vary between the Yangtze River and Yellow Sea populations for three of the four microsatellite loci examined. The present analysis, in combination with the previous mitochondrial DNA analyses, suggests an obvious migration and gene flow between the Yellow Sea and Yangtze River populations. Considering the important role of gene flow in the conservation and maintenance of genetic diversity in endangeredspecies, some conservation measures should be taken urgently to protect the Yangtze River estuary and adjacent waters in order to ensure the possible gene flow between the Yangtze and marine finless porpoises. Of course, some further studies are also needed in the near future to reveal the population genetic structure of this species more detailedly.3. Nine microsatellite loci were used to detect the possible kinship relationship of two newborn finless porpoises with other 19 individuals from a breeding population in a semi-natural waters in Tongling, Anhui Province. The parenthood of one newborn was successfully determined, whereas the parental origin of another individual was unresolved. The present study can be used to provide useful measures for the pedigree determination and genetic management of captive cetacean populations.