Haplotype diversity and mechanisms of evolutionary divergence of the Georgian Mountain Breed of Bos taurus, exhibiting conjointly patterns of admixture populations, introgression, as well as possible parallel versus convergent evolution

Abstract

An in-depth understanding of the biodiversity of Bos taurus is highly important to tackling global food security challenges partially via deciphering and preserving local breeds that demonstrate their potential to adapt to the growing global warming worldwide. In this study, we elucidate the population structures and mechanisms of evolutionary divergence of the Georgian Mountain Breed (GMB) of cow and its genetically most closely related conspecifics worldwide. We performed the sequencing and evolutionary analyses of the specific mitochondrial DNA (mtDNA) region involving cytb, two tRNAs-encoding genetic loci, and the D-loop of the GMB populations from the Khevsureti and Adjara regions of Georgia. A large panel of different evolutionary algorithms, implemented in the MEGA11 and DnaSP software packages, were applied in these analyses. A total of 25 haplotypes were determined among 82 individuals of GMB, belonging predominantly to the haplogroups T (T3, T1, T2, T4) or Q (Q1). 10 hitherto unique haplotypes, exhibited by singletons (SNGTs), could be also determined in the GMB populations from the above regions. In the maximum likelihood evolutionary analysis, a specific SNGT appeared to be most closely related to the Bos indicus sub-haplogroup I1a. The haplotype diversity (0.997), nucleotide diversity (0.00636), and the overall mean distance within their populations (0.01) were higher for GMB as compared to these estimates (0.930, 0.00482, and 0.00) calculated for its genetically most closely related conspecifics respectively. It is suggested that the evolution of the GMB populations has been driven via introgression, as well as by parallel and/or possible convergent evolution.