The dog was the first domesticated animal, with its origins tracing back at least 15,000 years. Over millennia, selective pressures from domestication and modern breed formation have profoundly shaped the canine genome, leading to today’s extraordinary morphological diversity. Dogs have served humans as hunting partners, guards, companions, and now as key models in scientific and medical research.
This study investigated three genetic systems – mitochondrial DNA (maternal inheritance), the Y chromosome (paternal inheritance), and autosomal chromosomes (biparental) – to understand how domestication and selective breeding influenced dogs’ genetic variation. The results show that domestication caused a relaxation of selective constraint in the mitochondrial genome, allowing more rapid accumulation of nonsynonymous mutations. These changes may have implications for health and disease susceptibility in dogs.
Furthermore, the process of breed creation introduced strong genetic structuring, often driven by an unequal contribution of breeding males and females. In particular, the use of a few popular sires combined with many dams has produced disruptive selection pressures within breeds, fragmenting genetic variation. This increased linkage disequilibrium enhances the suitability of dogs as models for identifying and mapping traits and diseases, both in veterinary and human medicine.
Overall, the findings emphasize that while domestication reduced some natural constraints, selective breeding has intensified genetic fragmentation. Together, these processes have transformed dogs into valuable resources for advancing our understanding of complex genetic diseases.
Source: Björnerfeldt, S., Hailer, F., Nord, M., & Vilà, C. (2007). Disruptive selection within dog breeds. Biology.
