Genetic diversity and spatial structure of indigenous sheep population of Benin revealed by microsatellite markers

Abstract

This study investigated the genetic variability existing within the indigenous sheep population of Benin. Hair samples from 681 unrelated sheep collected across the 10 phytogeographic zones of Benin were genotyped using a set of 12 microsatellite markers. Genetic diversity indices, Bayesian ancestral admixture model, Self-Organizing Map (SOM), and Discriminant Analysis of Principal Components (DAPC), were performed to assess both the genetic diversity and spatial structure of the population under study. The polymorphism information content (PIC) recorded for each microsatellite marker used was greater than 0.50 with an average value of 0.70. The average number of alleles (12.17) and heterozygosity values (He = 0.73; Ho = 0.68) obtained suggest high genetic diversity within the Beninese sheep population. The population genetic structure analysis revealed two ancestral sheep populations in Benin, namely, the Djallonké and Sahelian sheep. Furthermore, SOM and DAPC identified four clusters of sheep within the 10 phytogeographic zones, including two Djallonké and two Sahelian subpopulations with some admixture. Djallonké sheep were predominant in the humid zones of southern Benin, with one subpopulation mainly present in the Pobè and Oueme Valley zones, and the second in Coastal, Plateau, and Zou zones. The latter subpopulation seemed the most admixed, with a mean Djallonké ancestral proportion of 86.15%. Sahelian sheep were predominant in the phytogeographic zones of northern Benin. Sheep from the driest North zone consisted the first Sahelian subpopulation and had a higher Sahelian ancestry proportion (89.81%) compared to the second subpopulation (69.29%) that most consisted of sheep from the other phytogeographic zones of the North.