Origin, Genetic Diversity And Conservation Of Chinese Sheep Populaions

To investigate the origin, genetic structure and genetic relationship of Chinese sheep, Tan sheep, Sunite sheep, Diqing sheep, Gangba sheep, Langkazi sheep, Yuxi fat-tailed sheep, Inner Mongolian semi-fine sheep, Alety sheep, Duolang sheep, Fat-tailed han sheep, Jinzhong sheep and multi-horned Mongolian sheep were studied by using mtDNA. Polymorphism of fragment of ND5 gene were detected by PCR-SSCP. Complete sequence of control region and Cytb gene were sequenced, and NJ tree and UPGMA tree of sheep were constructed. Network analysis and population expansion were carried out.29 microsatellite markers were selected to study the genetic variance of 16 Chinese sheep populations. Heterozygosity, the number of alleles, coefficient of gene differentiation, genetic distance were calculated. The dendgram were constructed based on genetic distance. Marginal diversity method was applied to set the priority of conservation. Based on the analysis of extinction probability, contribution rate and conservation potency, the optimal fund allocation were made. The conclusions were as follows:1,3 haplotype groups were detected by PCR-SSCP, and haplotype A is dominant in Chinese sheep populations.2,D-loop sequences of 114 individuals from 15 populations shared 105 haplotypes, which were clustered into 4 lineages based on phylogenetic analysis. Lineage D was a novel lineage in the present study. The result suggested that Chinese sheep derived from three independent maternal ancestors at least. And it support Mofolon had closely relationship with Chinese domestic sheep. Network analysis, Fu's test and mismatch distribution implied three lineages(A,B and C) of Chinese sheep ever experienced population expansion possibly.3,Complete Cytb gene of 42 individuals were sequenced, and which shared 40 haplotypes. The 4 lineages were found according to phylogenetic analysis.4,The result showed there were large genetic distance between multi-horned sheep and common domestic sheep.5,It showed there were abundant genetic diversity in Chinese sheep populations according to analysis using mircosatellite DNA markers. The mean PIC and heterzygosity of 16 populations were 0.698 and 0.74 respectively.6,The NJ dendgram based on D_A distance showed there were 4 groups in 16 sheep populations, which were generally agreement with the breeding history and distribution.7,Based on conservation potency, the conservation priorities of sheep populations were as follows: .Lanzhou fat-tailed sheep, Yuxi fat-tailed sheep, Langkazi sheep, Gangba sheep, Diqing sheep, Sunite sheep, fat-tailed sheep, Hanzhong sheep, Tan sheep, Guide black-fur sheep, Yuxi fat-tailed sheep, Duolang sheep and Tengchong sheep.8,We evaluated the effectiveness of different models to gain the maximal expected diversity and optimal fund allocation. Model A proved to be optimum for allocation of all the funds.Lanzhou fat-tailed sheep gained 33% of the funds, followed by Hanzhong sheep(18%), Guide black-fur sheep (12%), Yuxi fat-tailed sheep (11%), Duolang sheep(8%), Tengchong (6%), and Tan sheep gained 3%.