Analysis of genetic polymorphism and genetic distance among four sheep populations

Abstract

The genomes of 4 sheep populations {Yuanqu white Tan sheep (YWT), Baozhongchang white Tan sheep (BWT), black Tan sheep (BT) and small-tailed Han sheep (Han)} were screened using 10 microsatellite DNA markers to estimate the genetic diversities and genetic distances among these populations. Small-tailed Han sheep was the reference group. About 167 alleles were detected at 10 loci in 4 populations. The average observed and expected heterozygosity ranged from 0.1771 to 0.4576 and from 0.8294 to 0.9083, respectively in 10 loci. The expected heterozygosity of each population was much higher than the observed heterozygosity. The mean polymorphism information content (PIC) value of populations ranged from 0.7723 to 0.7946. The coefficient of gene differentiation (Fst) between populations was high (8.93%). The percentage of inbreeding coefficient for all populations (Fit) was 67.4%, while within breeds (Fis) it was 64.2%. Constructing four dendrograms based on D_A and D_C genetic distance using UPGMA and NJ method, it was shown that the relationship between two white Tan sheep populations was the closest, then between white Tan sheep population and black Tan  sheep population, small-tailed Han sheep population was the farthest when compared with other three populations.

Key words: Sheep, microsatellite DNA, genetic polymorphism, genetic distance.