Molecular consequences of animal breeding.

The phenotypic diversity in domestic animals provides a unique opportunity to study genotype-phenotype relationships. The identification of causal mutations provides an insight into what types of mutations have contributed to phenotypic evolution in domestic animals. Whole genome sequencing has revealed that fixation of null alleles that inactivate genes, which are essential under natural conditions but disadvantageous on the farm, has not been a common mechanism for genetic adaptation in domestic animals. Numerous examples have been revealed where structural changes cause specific phenotypic effects by altering transcriptional regulation. An emerging feature is also the evolution of alleles by the accumulation of several consecutive mutations which affect gene function.