C. Marsden et al. (2015) analyzed 90 whole-genome sequences from breed dogs, village dogs, and gray wolves to evaluate the genetic consequences of domestication. The findings reveal that dogs carry, on average, a 2–3% higher genetic load of harmful mutations compared to wolves.
The study attributes this increase to population bottlenecks during domestication and the effects of artificial selection for breed-defining traits. Unlike recent inbreeding, which had less impact, these long-term processes reduced the efficiency of natural selection, allowing deleterious variants to persist. Regions of the genome affected by selective sweeps were enriched with amino acid–altering variants and disease-associated genes.
These results provide the first quantitative estimates of the cost of domestication in terms of genetic health. The study questions the continued reliance on rigid breed standards—a practice inherited from Victorian breeding traditions—that may perpetuate harmful mutations. Instead, it emphasizes the importance of maintaining large population sizes and reconsidering selective practices to protect the health of both common and endangered breeds.
This work not only deepens our understanding of dog evolution but also highlights the welfare challenges posed by current breeding systems, urging a reevaluation of conservation and selective breeding policies.
Source: Marsden, C., Vecchyo, D. O.-D., O’Brien, D., Taylor, J. F., Ramírez, O., Vilà, C., Marquès-Bonet, T., Schnabel, R., Wayne, R., & Lohmueller, K. (2015). Bottlenecks and selective sweeps during domestication have increased deleterious genetic variation in dogs. Proceedings of the National Academy of Sciences, 113, 152–157. https://doi.org/10.1073/pnas.1512501113
