Dog Breeding and Evolution

Dog Breeding and Evolution

Artificial selection by humans played the biggest role in shaping today’s dog breeds. Dog breeding was based on a desired temperament and specific skills, such as hunting, shepherding, guarding, work and company. As a result of artificial selection, dogs are the most phenotypically diverse mammal species presently known.

Although it gave us a great number of different dog breeds, each with unique traits, human selection caused a severe bottleneck within the domesticated dog population, causing a high frequency of inherited disorders among dogs. Most of these inherited disorders are autosomal recessive, meaning two copies (alleles) of disorder-causing genes are needed for the dog to be affected. If a dog possesses one copy of the causative gene, it will not develop symptoms of the disorder, meaning the mutation can be passed on for many generations without being observed. As the domestication of dogs caused the bottleneck, specific disease-causing variants became more frequent and inbreeding is no longer the only cause of inherited disorders among dogs.

DNA tests have been developed in order to detect the presence of disease-causing alleles, and have become a powerful tool in maintaining a healthy dog population and successful breeding programmes. Since many diseases develop later in life, after a dog’s sexual maturation, in adittion to a high frequency of dogs possessing one copy of causative genes without developing disease symptoms, breeding based on phenotypical selection is not sufficient in obtaining healthy cubs. DNA tests enable molecular selection and are the only method to ensure wanted traits among puppies without unpleasant surprises.

The following video explains the connection between dog evolution and the wide range of dog breeds we know today, as well as a growing number of genetic disorders among them.

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References

Marsden CD, Ortega-Del Vecchyo D, O’Brien DP, et al. Bottlenecks and selective sweeps during domestication have increased deleterious genetic variation in dogs. Proceedings of the National Academy of Sciences of the United States of America. 2016;113(1):152-157. doi:10.1073/pnas.1512501113.