Chinese Silkies Genetic Diversity And The Origin Of Chicken Research

In the present paper, we determined the mitochondrial DNA sequence 539bp of the high variable I D-loop regions(mtDNA HVS-I) for 243 domestic fowls (19 were Wugu (or black-bone chicken) and 8 non-wugu breeds/races) and 38 red jungle fowls (Gallus. Gallus. spadiceus and Gallus. Gallus. jabouillei). We also sequenced 289bp mitochondrial DNA of Cyt-b for 5 red jungle fowls; D-loop region (mtDNA HVS-I)for 19 individuals Guinea fowl and 18 individuals mule chickens (Guinea fowl $ x Wugu chickens^ ) respectively; mtDNA HVS- II of D-loop region for 34 individuals of domestic fowls and red jungle fowls in 690bp and the MC1R code gene in 945 bp. Analyzing this data together with the same sequence part available in genbank by neighbor joining and network etc, we can draw some conclusion as follow:1. There were 23 mutation sites in mtDNA HVS-I of 66 individuals among 8 populations; it could be divided into 14 haplotypes. The result suggested that Silkies had several maternal ancestors. It was the result of long artificial selection in different place.2. There were 39 mutation sites in mtDNA HVS-I of 124 individuals; it could be divided into 34 haplotypes. The normal feather Wugu chickens also had a lot of maternal ancestors; the result showed that at least six populations of red jungle fowl contributed to the gene pool of the domestic fowls.3. Silkies were the mutation type of nomal feather Wugu chicken for it had more haplotypes and shared the major haplotypes with silkies.4. The sub-species of G. g. spadcieus and G. g. jabouillee in China were at the same clade with the G. g. gallus in and around the Thailand area, but were in difference clade with G. g. bankiva in Java island, so our result support the opinion that red jungle fowl could be classified as mainland type and island type.5. There were 66 mutation sites in mtDNA HVS-I of 314 domestic fowls and 62 red jungle fowls, it could be divided into 79 haplotypes, these haplotypes belong to nine clades. So, All the domestic fowl shared the same maternal ancestor of red jungle fowl and were domesticated several times independently in different places.6. In our studying, the mtDNA HVS-I and the mtDAN HVS- II showed the same result, so, it was suitable , high efficiency and economical to choose mtDNA HVS-I as a marker studying for the genetic divergence and evolution of species.7. There were 10 mute sites in the MC1R gene in 945 bp code region of the domestic fowls and red jungle fowls in all 34 individuals, in these mute sites, the 28th, 69th, 159th, 637th point mute sites were synonymous mutes, while the 10th 71th,92th, 2135h, 215th, 307th sites were amino acid mutation sites, among them , 71th, 213th, 215th, 307th were hybrid sites. We couldn't see the line-relationship of the mute sites and the feather color types; maybe MC1R was just one major but not only silky feather color functional gene, the feather color maybe controlled by several genes.8. There were length differences when using the same primer to amplify the mtDNA HVS-1 of black normal feather Wugu chickens and Guinea fowl. The PCR production sequence length of them were 539bp and 498bp respectively, the same region sequence of mule chicken were the same as Guinea fowl or black normal feather Wugu chickens. So, it suggested that the mule chickens were the progeny of Guinea fowl and the black normal feather Wugu chicken.