Genetic relationships between native sheep breeds in Nigeria based on microsatellite DNA polymorphisms.

Abstract

Genetic relationship among Nigeria's breeds of sheep and their crosses was studied using microsatellite DNA polymorphisms. DNA samples extracted from four Nigeria's breeds of sheep (West African Dwarf, the Balami, Uda and Yankassa) and their crosses were analysed using 30 microsatellite markers for diversity studies. Twenty of the markers were amplified by the sheep genome. Nineteen of the loci were polymorphic and were used to calculate genetic distances (Ds) between the breeds based on allele frequencies of the microsatellite. The phylogenetic relationships between the breeds were similarly estimated.

With the total number of loci studied, 285 alleles were generated and a high degree of heterozygosity was recorded, (0.57 to 0.72) a relatively high degree of reliability could be placed on the tree topology with the relationship between breeds portraying a closer relationship between the Yankassa and Uda (Ds 0.356). The genetic distance (Ds) was 0.432, 0.534 and 0.665 between the West African Dwarf and the Yankassa, Uda and Balami respectively also indicating a closer relationship between the Yankassa and the WAD compared to the basically Northern breeds (Uda and Balami). This further confirms the evolutionary divergence of the breeds which makes them distinct entities.

The data suggests that microsatellite DNA markers are very useful tools for studying the genetic relationships among these sheep breeds. The highly polymorphic alleles could thus be exploited in breed improvement and development.

Keywords: Sheep. Microsatellite DNA. Polymorphisms. Genetic Distance.