Genetic characterization of Southern African sheep breeds using DNA markers

[摘要] Merino sheep are an important resource for South Afric an farmers, providingmeat and wool and thus an important income source. Indigenous and locallydeveloped breeds are an important asset for many reasons, but particularly because,over time, they have developed unique combinations of adaptive traits to respond tothe pressures of the local environment. To be able to distinguish between breeds forconservation and utilization purposes, the genetic variability, population structure andphylogenetic relationships were determined. Seven different Merino genotypes weresampled. These included the Dormer, SA Merino, SA Mutton Merino, Landsheep,Letelle, Dohne and Afrino. The indigenous and locally developed breeds comprisedof the Damara, Pedi, Blinkhaar Ronderib Afrikaner, Blackhead Persian, BlackheadSpeckled Persian, Redhead Persian, Redhead Speckled Persian, Zulu, NamaquaAfrikaner, Karakul, Swazi, Van Rooy and Dorper.The Merino, indigenous and locally developed breeds were assessed for geneticdiversity using 24 microsatellites. Different statistical analyses were performed todetermine the genetic variation, genetic relationships and genetic differentiation of thebreeds.The SA Merino showed a high number of very distinct alleles. This studyconfirmed a higher variability of the SA Merino when compared with the otherbreeds. The genetic distance between the SA Merino and SA Mutton Merino, bothfine wool breeds, was high indicating that these two breeds are relatively distant fromeach other. The Afrino known to have 25% SA Merino, 25% Ronderib Afrikaner and50% SA Mutton Merino, indicated a closer relationship with the SA Mutton Merino.This result confirmed the development of the breed. From the phylogenetic analysisbetween the seven Merino genotypes, when compared to the other estimates obtainedin the study, it was evident that the Merino genotypes in South Africa have morewithin breed variation than between breed variation.The genetic distance estimates observed for the indigenous fat-tailed breeds wererelatively high indicating that even between these breeds genetic differences exist. Asexpected, a smaller genetic distance between the Persian varieties was observed.Genetic distances between the developed breeds supported their ancestral development. The results of the indigenous and locally developed breeds present thefirst study of the genetic characterization of these breeds using microsatellite markersin South Africa.Southern Africa is hosting a very large sheep (Merino, indigenous and locallydeveloped) genetic resource. Adapted to the agricultural production systems of thecontinent, it represents a unique resource that has great potential for furtherdevelopment of its productivity.

[发布机构] University of the Free State