Genomic adaptation of Mediterranean and Alpine local cattle breeds to the climate variables

Abstract. – Adaptive ability of livestock to climate variations is a factor of first importance in the context of global climate change. Domestic species such as cattle represent attractive biological models to characterize the genetic basis of short domestication history. Local cattle breeds are valuable genetic resources to decipher the molecular mechanisms of cattle adaptation to their specific environments. Using newly generated dense SNP genotyping data, we assessed the structuring of genetic diversity of 21 Mediterranean and 24 Alpine cattle breeds and performed genome‐wide association analyses with covariables discriminating the different Mediterranean and Alpine climate subtypes. This provided insights into both the demographic and adaptive histories. A detailed functional annotation of genes surrounding variants associated with climate variations highlighted several biological functions involved in Mediterranean and Alpine climate adaptation such as thermotolerance, UV protection, pathogen resistance or metabolism with strong candidate genes identified. Accordingly, our results suggest that main selective pressures affecting cattle in Mediterranean and Alpine area may have been related to variation in heat and UV exposure, in food resources availability and in exposure to pathogens. Taken together, our results highlight the genetic uniqueness of local Mediterranean and Alpine cattle breeds and strongly support conservation of these populations.