The Genetic Architecture of Behavior in the German Shepherd Dog

Studying canine behavioral genetics could provide important insights for dog breeding and for understanding both canine and human behavior. To identify genetic determinants of behavior in German Shepherd Dogs, we used a cohort of 373 dogs to search for genome-wide associations with behavioral variables and personality traits measured by the Dog Mentality Assessment (DMA), a standardized dog behavior evaluation widely used in Sweden. Multidimensional scaling using genetic data revealed two clusters identified by merits as working and show sub-populations differing in most of their DMA scores. These behavioral differences were strongly correlated with BOLDNESS-a higher-order trait considered a measure of the shyness-boldness personality continuum in dogs. A region with highest allele frequency differences between sub-populations was found on CFA24: 23.5-25.5 Mb containing genes for coat color specification and previously reported candidate regions of selection. The strongest association signals were found for traits/behavioral variables correlating with BOLDNESS as, for example, on CFA1 within a region encompassing the TCF4 gene for which, in humans, multiple associations with neuroticism (a reverse equivalent in humans of BOLDNESS in dogs) were reported. Signals of association were found in regions containing genes with important roles in the nervous system and associations with comparable personality traits, such as neuroticism, in humans. Our results indicate that within-breed selection in GSDs has had an effect on the shyness-boldness personality continuum, with working dogs scoring higher in all aspects of BOLDNESS-being more playful, prone to chase after toys, curious, fearless and socially interested in strangers compared with show dogs.