Analysis Of Genetic Diversity In 13 Sheep Breeds

The genetic diversity of thirteen sheep breeds, including ten native breeds in China and three introduced breeds, were analyzed by using 11 microsatellite DNA markers which recommended by FAO and ISAG. A total of 725 genotypes were detected and amplified products were analyzed based on ABI3100-Avant auto gene sequenator and fluorescence multiplex PCR. By calculating the alleles frequency, peculiar allele, heterozygosity(H), polymorphism information content (PIC), effective number of alleles(Ne), Nei's genetic distance(DA) and Nei's standard genetic distance(DS) among cattle breeds and constructing dendrogram as well as NJ method to analyze the genetic variability and genetic relationship between sheep breeds. The results were as follows:1. A total of 151 alleles were detected from fifteen microsatellite loci, and the average number was 13.7. The most allele number was 23 for OARFCB304, the least was 9 for OARAE129 and SRCRSP9, and other loci were from 10 to 20 in eleven microsatellite loci. In thirteen sheep breeds, the mean allele number was from 5 to 9, the most was Bashibai, and the least was Tengchong, Suffolk, Texel and Poll Dorset. The genetic diversity of thirteen sheep breeds was plentiful and the genetic variation was relatively great.2. A total of 23 peculiar alleles were found in thirteen sheep breeds, and other sheep breeds had a peculiar allele at least in one microsatellite loci except Yuxi Fat-Tailed, Suffolk and Texel, and the most was 5 for Weining and Bashibai. The frequency of peculiar allele was lower at eleven microsatellite loci in thirteen sheep breeds, the alleles frequency of OARFCB304 in the 157 bp (0.10) for Cele Black were the highest.3. At eleven loci the PIC was from 0.468 to 0.668 and the heterozygosity was from 0.452 to 0.635 and the Ne was from 1.000 to 11.765 in thirteen sheep breeds. In 11 microsatllite loci of the study, three were middly polymorphism loci, and eight were highly polymorphic,that could be used to the analysis of genetic diversity in sheep.4. The genetic distance between ten native sheep breeds and three introduced breeds was larger. The genetic distance among native breeds was small relatively (DA= 0.070~0.206, DS=0.041~0.244),thereinto, it was smallest between Zhaotong and Weining breeds(DA=0.070, DS=0.041),and it was biggest between 3 introduced and native breeds(DA=0.183~0.327, DS=0.167~0.567). 5. Thirteen sheep breeds were clustered into four groups based on the NJ tree. The first group includes Weining, Zhaotong, Hanzhong, Diqing; the second group includes Yuxi Fat-Tailed, Taihang Fur, Sishui Fur, Bashibai,Cele Black; the third group includes Tengchong; The forth group consists of foreign breeds including Poll Dorset, Suffolk and Texel.