The Genetic Diversity Of Duck Populations And Study On Mitochondrial DNA D-loop Of Domestic Mallard Duck

The thesis consists of two parts.(1) The genetic diversity of duck populations.In this study, we investigated the genetic diversity and phylogenetic relationship of thirteen duck populations among three countries (Cambodia, Laos and Egypt)by employing the genetic polymorphisms of 18 microsatellites. The key indicators are the number of alleles, average effective numbers of alleles (Ne),average rates of heterozygosity of each population,polymorphism information content (PIC), mean expect heterozygosity (He), mean observed heterozygosity (Ho) and genetic distances (Ds). The results showed that the thirteen populations have a high average PIC (0.5762), He (0.6528) and Ho (0.4049). The test of Hardy-Weinberg equilibrium showed disequilibrium in thirteen populations. The F-statistic analysis results showed the range of FST was from 0.062 (APH08) to 0.285 (CAUD27). The mean Fst was 0.144. Phylogenetic analysis revealed that Cambodia duck (CKC, CSR, COD, CKP and CRK) was clustered in one group, Egypt duck (EAG, EAF and ESH) was clustered in one group, while the Laos duck was clustered in one group (LLG, LOD, LXK, LVC and LCP). The phylogenetic relationships among different populations were in accordance with their breeding history and distribution. Our data suggested that the 18 microsatellite loci were effective markers for analysis of genetic relationships among duck populations.(2)The study on mitochondrial DNA D-loop of domestic Mallard duck.In this study, a total of four pairs of primers located in different D-loop portions were used to amplify and sequence the partial D-loop fragment from definite domestic Mallard and Muscovy ducks together with domestic duck samples of unknown species of origin. Intensive sequencing profiles identified a homoplasmic D-loop in domestic Muscovy ducks but'heteroplasmic'mtDNA D-loop fragments in domestic Mallard ducks. The results supported the presence of Numts in blood samples of domestic Mallard duck. This phenomenon has not been recognized or reported before and it can certainly confound the application of D-loop sequence as a molecular marker to genetic study of domestic Mallard duck. Further investigation on tissue specificity of the Numts and establishment of specific primers to generate the true D-loop sequences are warranted for an accurate genetic characterization and species identification of domestic ducks.