Labrador Retrievers are one of the most widely used working breeds, serving as guide dogs for the visually impaired or as sniffer dogs in law enforcement and biosecurity. Each role demands very different sensory capacities—guide dogs require a more subdued olfactory drive, while sniffer dogs benefit from highly acute scent detection abilities.
In a study published in Genetics Research, Yang and colleagues (2022) examined how artificial selection has acted on the genetics underlying these traits. Researchers analyzed 26 SNPs, two deletions, and two insertions across seven olfactory receptor (OR) genes in Chinese-bred Labrador populations trained as either sniffer or guide dogs. The results revealed statistically significant allele differences between the two groups, with candidate SNPs emerging as strong indicators of working-specific traits.
Interestingly, the study found relatively low levels of polymorphism across loci and limited linkage disequilibrium, suggesting that selective breeding over just a few decades has already driven detectable genetic divergence within the breed. Hardy–Weinberg equilibrium tests revealed higher ratios of disequilibrium in these working populations, consistent with the impact of purpose-driven selection.
The findings highlight how even in a short evolutionary timescale, human-guided breeding can alter the genetic architecture of sensory systems in dogs. By targeting olfactory receptor alleles, breeders have effectively shaped Labradors into distinct working lineages optimized for either scent detection or guiding humans, underscoring the powerful role of artificial selection in canine evolution.
Source: Yang, M., Han-Zhang, G., Geng, G.-J., Fu-Wang, Liu, C.-W., & Jian-Liu. (2022). Artificial Selection Drives SNPs of Olfactory Receptor Genes into Different Working Traits in Labrador Retrievers. Genetics Research, 2022. Published February 2, 2022.
