| Centuries-old history , antiquity civilization and ecosystem along the Changjiang-Huai River incubate and cultivate many eminent and unique indigenous water bird breeds jointly. In order to develop inspect and control of genetic quality and offer basis for protect and utilization of indigenous duck breeds, microsatellite markers and the mitochondrial D-loop sequence were used to analyze the genetic characteristics, zoogeography, origin, systematic evolution biogeographic distribution pattern and evolution of 8 domestic duck breeds(Gaoyou, Caohu, Huainan, Mianyang, Jingjiang, Enshi, Weishang and Youxian sheldrake) along the Changjiang-Huai River was carried out. Egg character of Gaoyou sheldrake was investigated at the same time.1. Twenty-eight microsatellite markers with medium or high polymorphisms were selected to detect genetic diversity and genetic structure. According to the allele frequencies of 28 microsatellite sites, genetic parameters for each breed and genetic distances between breeds were calculated. UPGMA and NJ tree were completed respectively for analysis of genetic relationship among duck breeds. The results showed that 26 of 28 microsatellite sites were highly polymorphic, so the 28 markers were effective markers for analysis of genetic diversity. The discrepancy of 8 domestic duck breeds'heterozygosities was not distinct(0.551~0.606). The highest was the Weishang sheldrake(0.606), following the Enshi, Jingjiang and Mianyang sheldrake. The lowest was the Youxian sheldrake(0.551).The mean polymorphic information contents (PIC) of 8 domestic duck breeds were 0.481~0.524. The highest was Enshi sheldrake(0.524), and the lowest was the the Youxian sheldrake(0.481).The results implied that the genetic diversity of the 3 duck breeds in Hubei province were quite abundant, genetic diversity of Youxian sheldrake was the lowest among 8 duck breeds.The 8 duck breeds were divided into 2 clusters. Mianyang (egg type), Jingjiang(egg type), Enshi(egg type), and Caohu sheldrake(egg-meat type), were first cluster: Mianyang, Jingjiang and Enshi sheldrake were grouped firstly, then Caohu sheldrake was grouped with them, Huainan(egg type), Weishang(egg type), Youxian(egg type) and Gaoyou sheldrake(egg-meat type) were the second cluster: Huainan, Weishang, and Youxian sheldrake were grouped firstly, and then Gaoyou sheldrake was grouped with them. The cluster was consistent with the geographical distributing, breeding history and ecological type. There was not distinct difference between UPGMA and NJ methods or different genetic distances.There was marked genetic differentiation among 8 duck breeds by microsatellite marker research, 25% of the total genetic variation came from breed differences. The mean FIS (The fixation indices of individuals relative to its subpopulations) was–0.434, inbreeding was not significant by test.2. The mitochondrial D-loop of 106 samples collected from 9 breeds of domestic ducks were sequenced. There were 34 polymorphic sites (5.1% in total analyzed sites) found due to the transition, transversion, insertion and deletion. 31 haplotypes were identified. The major haplotype was A7. The haplotype diversity (Hd) and average nucleotide diversity (Pi) were 0.798% and 0.28%, respectively. Hd of Jingjiang shelduck was the highest among 9 duck breeds, and Hd of Wendeng black duck was lowest. The results showed the genetic diversity of mitochondrial DNA in breeds at middle reaches of Changjiang River was bigger than that at the lower reaches of Changjiang River. A unconspicuous negative correlation was observed between the estimated level of gene flow(Nm) and the geographic distance among breeds. Phylogenetic tree analysis demonstrated that no geographic clustering was observed, haplotypes were shared among geographic populations and an interwoven distribution pattern was presented.Phylogenetic analysis of the 31 haplotypes identified that there was only one distinct maternal lineage in domestic duck breeds and revealed that no evidence of contribution of Anas zonorhyncha to the maternal origin of domestic duck breeds.3. Although different absolute value of genetic distances, the relationship of genetic distances among breeds by two different methods was similar or close by the comparison of two different marker methods. The difference in genetic differentiation on two markers was probably related to the character and purpose of different marker.4. The equilibrium of high intensive artificial selection and natural selection resulted in the trait of Gaoyou duck's double-yolk egg. The fitness of double-yolk egg trait was analyzed by population genetics for the first time one the basis of special environment and natural geography. The results showed that the double-yolk egg trait fitness was 8.23 time as the normal egg trait fitness at artificial selection during the year 2000 to 2002.5. Two Dra I recognition sites of Prolactin(PRL) gene intron 1 of Gaoyou duck were detected by PCR-RFLP and DNA sequencing, but only one polymorphism was found for the first time. A T/C mutation at the position of the 1326 bp of the PRL gene was found by DNA sequencing The least square analysis showed that the BB ducks had significant egg weight at the age 30 weeks than AB ducks (P<0.01), the double-yolk percentage of the AB ducks was much higher than that of BB ducks (P<0.05) in double-yolk ducks, but there was not significant difference in egg number, longest clutch days and the body weight at first egg among 3 genotypes.
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