The domestication of dogs may have inadvertently caused harmful genetic changes, a UCLA-led study suggests. Domesticating dogs from gray wolves more than 15,000 years ago involved artificial selection and inbreeding, but the effects of these processes on dog genomes have been little-studied.

UCLA researchers analyzed the complete genome sequences of 19 wolves; 25 wild dogs from 10 different countries; and 46 domesticated dogs from 34 different breeds. They found that domestication may have led to a rise in the number of harmful genetic changes in dogs, likely as a result of temporary reductions in population size known as bottlenecks. 

"Population bottlenecks tied to domestication, rather than recent inbreeding, likely led to an increased frequency of deleterious genetic variations in dogs," said Kirk Lohmueller, senior author of the research and assistant professor of ecology and evolutionary biology in the UCLA College. 

"Our research suggests that such variants may have piggybacked onto positively selected regions, which were also enriched in disease-related genes," Lohmueller said. "Thus, the use of small populations artificially bred for desired traits, such as smaller body size or coat color, may have led to an accumulation of harmful genetic variations in dogs."