P5004 Identification of signatures of selection and assessing the diversity of East African Shorthorn Zebu mitochondrial DNA

Abstract

The mitochondrial DNA (mtDNA) is an important genetic marker commonly used to study the evolution of the bovidae family. The availability of the full bovine mtDNA sequence has further cleared the domestication process of this species. Moreover, given the importance of the mitochondria in cell energy production, mtDNA is expected to be a target of natural selection. In this study we have compared the full mtDNA sequences of indigenous East African Shorthorn Zebu cattle (EASZ) with cattle breeds from Europe, Africa and Asia to evaluate the extent of EASZ mtDNA genetic diversity and identify signatures of selection within African cattle mtDNA. Our results indicated that the EASZ mtDNA sequences are all of the taurine type and members of T1a, T1b and T1b1 sub-haplogroups. Nineteen taurine-zebu non-synonymous variants were detected, but none seem to be associated with a selective advantage for taurine mtDNA. Based on ω ratio analyses, purifying selection is the main selection pressure targeting EASZ mtDNA with less selective constrains at the ATP6 and ATP8 genes. Interestingly, within African cattle, we identified a positive selection signal in the Cox-2 gene in the T1b/T1b1 sub-haplogroups, together the most common sub-haplogroups on the continent. This may indicate a probable advantage for these sub-haplogroups in Africa.

© American Society of Animal Science 2016