Study On The Genetic Diversity Of The MtDNA Partial Sequences And Its Evolution For The Main Chinese Domestic Duck

In the present paper, we determined the mitochondrial DNA sequence523bp of the high variableⅠD-loop regions (mtDNA HVS-Ⅰ) for 265 domesticand wild ducks. We also sequenced 546bp mitochondrial DNA of Cyt-b for 27ducks; D-loop region (mtDNA HVS-Ⅰ) for 56 individuals muskducks. Analyzingthis data together with the same sequence part available in Genbank byneighbor joining and network etc, we can draw some conclusion as follow:1. The average length of the Chinese domestic and wild duck mtDNA d-loopwere 522.9 bp, the percent of A+T was 48.6% and G+C was 51.4%, respectively.The content of A+T was slightly lower than that of G+C.2. There were 28 mutation sites in mtDNA d-loop partial sequences ofthe 525 bp length, it was 5.3% of the sequenced length; the singletonpolymorphic and Parsimony-informative sites were 14 and 14, respectively.The mutation motif includes transversion, transition, insertion anddeletion.3. The genetic diversity of the Chinese domestic and wild duck mtDNAd-loop was low. The average nueleotide difference was 1.099 amongbreeds/populations, the average nucleotide diversity amongbreeds/populations was 0.00214±0.00018 and the range of the haplotypediversity among breeds/populations was 0.133±0.112～0.752±0.0764. The average content of T, C, A and G in the 546 bp mtDNA Cyt B among10 Chinese domestic and wild duck population were 23.0%,37.7%,26.2%and 13.0%. The percent of A+T was 49.2% and G+C was 50.8%, respectively.The predominance codon for the first, second and third bases were C, T and C respectively. 181 amino acides were code in this segment and it contained20 kinds of amino acids, Cys was the least and only had 0.55% while Leu wasthe higest contents and reach to 19.89%.5. There were 7 haplotypes were determined in the 546 bp mtDNA Cyt Bamong 10 Chinese domestic and wild duck population. The haplotype diversitywas 0.504±0.114 and the average nucleotide diversity was 0.00155±0.00054,respectively. There were 7 mutation sites, 4 of them were the third codonsite and 3 of them were the first codon sites. 4 mutation sites weretransversion and 3 mutation sites were transition sites, respectively. Thepercentage of transversion was higher than the reports before, thenon-synoymy substitutaion reach to 42.9%.6. There was biggish bias for the synonymy codon in the 546 bp mtDNACyt B among 10 Chinese domestic and wild duck population.7. The Anas platyrhynchos in China was origin from haplogroup A basedon the report of Kulikova et al (2004, 2005). The Chinese domestic duckorigin from the Anas platyrhynchos and the Anas poecilorhynho also had somegene introgress into domestic duck. The genetic diversity of Chinesedomestic duck was low and only had single maternal mtDNA origin.8. The Chinese Cairina moschata had low genetic diversity. There were11mutation sites in mtDNA d-loop partial sequences of the 549 bp length;the singleton polymorphic and Parsimony-informative sites were 7 and 4,respectively. 10 haplotypes were determined and haplotype H3 was thedominant haplotype and occurred 33 times. The haplotype diversity was0.631±0.068 and the average nucleotide diversity was 0.00245±0.00043,respectively.