Genetic Structure and Differentiation Among African Bos Taurus Cattle Breeds

Abstract

African taurine cattle populations are widely distributed in humid and sub-humid zones of West and Central Africa. We assessed the genetic structure and differentiation within and across 8 African Bos taurus populations: 4 N’Dama populations (N’Dama, N’Dama1, N’Dama2, N’Dama3), Lagunaire, Lagune, Somba, and Baoule. A total of 38k autosomal SNPs were used for principal component analyses (PCA), estimation of pairwise FST values and within population heterozygosity (FIS), and neighbour-joining (NJ) tree construction. The first PC clearly differentiated Lagune and Lagunaire from N’Dama; PC2 separated Lagunaire, Lagune and one N’Dama population from the rest of taurine breeds; and PC3 separated N’Dama3 from Somba and Baoule. Estimates of pairwise FST values among the majority of populations ranged from 0.03 to 0.149, indicating low to moderate genetic differentiations, while a high genetic divergence between N’Dama3 and Lagune (FST =0.178), and N’Dama3 and Lagunaire (FST =0.168) was observed. No genetic subdivision was found between N’Dama and N’Dama1, and Lagune and Lagunaire. A higher heterozygosity (FIS value from -0.011 to 0.025) was found in N’Dama, N’Dama1, N’Dama2, Lagune, Lagunaire, and Baoule breeds. The NJ tree clearly separated Lagune and Lagunaire as well as Somba and Baoule with a 100% and around 31% bootstrap value, respectively, from the other taurine populations. We highlighted that African taurine populations are diverse and genetic differences between sampling locations exists even within a breed. Therefore, choice of an African taurine breed to anchor African indigenous breeds should be carefully considered.