In the present study we studied the genetic structure of five Chinese sheep populations of Hu sheep, Tong sheep, Small-tailed Han sheep, Tan sheep, and Wadi （WD） sheep using 15 microsatellite loci. The results showed that the FIT, FST, and FIS statistics computed for the complete dataset had the following values, 0.523±0.140, 0.363±0.131 and 0.263±0.092, respectively. All loci were significantly contributed to the genetic differentiation among population （P0.001）. There is no relationship between the scatter of pairwise FST geographical distance points as geographical distance increases between the five populations. Membership probabilities and genetic structure of sheep populations were estimated when K=2, the populations were classified into Hu, Tong, Han and WD, and Tan sheep group. However, when K=3, the populations were classified into Hu and Tong, Han and WD, and Tan sheep group. The findings supported the previous literatures that these populations are originated on different time stages from the primogenitor population and communicated genetically with each other by natural and artificial selection in different ecological environment.
SUN WeiCHANG HongMusa Hussein HassanLIAO Xin-junCHU Ming-xingKija James
This study is based on the Tong sheep obtained by the random sampling method of typical colonies in the central area of Baishui County in Shaanxi Province, China. An investigation was undertaken to clarify the gene constitution of blood protein and nonprotein types of Tong sheep. Twelve genetic markers were examined by starch-gel electrophoresis and cellulose acetate electrophoresis. Polymorphism in Tong sheep was found at the following 10 loci, transferrin （Tf）, alkaline phosphatase （Alp）, leucine aminopeptidase （Lap）, arylesterase （Ary-Es）, hemoglobin-β （Hb-β）, X-protein （X-p）, carbonic anhydrase （CA）, catalase （Cat）, malate dehydrogenase （MDH）, and lysine （Ly）, whereas, albumin （A1） and postalbumin （Po） loci were monomorphic. Genetic approach degree method and phylogenetic relationship clustering method were used to judge the origin and phylogenetic status of Tong sheep. Results from both methods maintained that Tong sheep belonged to the ＂Mongolia group＂, and Mongolia sheep was the origin of Tong sheep. This was also supported by the history of Tong sheep breeding. Compared to the phylogenetic relationship clustering method, the genetic approach degree method was more reliable for the extraction from East and South of Central Asia, and was more effective in reflecting the breeding course of Tong sheep.
