Genome-wide signature of positive selection in Ethiopian indigenous and European beef cattle breeds

Background

Despite the availability of genome-wide SNPs to uncover the origin and divergence of Ethiopian cattle population, knowledge regarding their genetic adaptability and divergence remain limited. To investigate signature of selection, three Ethiopian cattle breeds were genotyped with 80 K SNP array and three European beef cattle breeds were also used for comparison purposes.

Results

Across Ethiopian cattle populations, the mean observed and expected heterozygosity were 0.403 and 0.400, respectively, and for European beef cattle breeds observed and expected heterozygosity were 0.25 and 0.26 respectively. PCA and NJ-tree grouped the study cattle according to their breed group with close clustering of Ethiopian cattle breeds. The top 1% values were considered to delimit genomic regions under positive selection. Some of the candidate genes involved in biological processes and pathways linked to meat quality attributes. Furthermore, some of the candidate genes associated with tropical adaptation like heat tolerance and resistance to disease.

Conclusion

The genetic divergence of Ethiopian breeds from European beef breeds coincides with existing knowledge that European cattle breeds considered in this study are artificially selected for beef traits, while Ethiopian indigenous breeds are naturally selected.