Signatures of Positive Selection in the Dog Genome

Strong artificial selection for form and function has led to the astounding variability in morphology and behavior in purebred dogs. Diversifying selection among breeds, coupled with purifying selection within breeds, simplifies efforts to identify genetic associations in dogs, but despite successful mapping of over a dozen morphological trait loci, no positively selected behavior loci have yet been found.

We used raw genotype data from 158 dog breeds to find genomic regions showing high haplotype differentiation across breeds indicative of classical selective sweeps from positive selection. We identify 72 loci showing signatures of positive selection. These regions overlap most of the known body size and coat type loci, as well as identify dozens of additional regions warranting further investigation. Using breed average breed phenotypes for morphological and behavioral characteristics, we find novel morphological and behavioral associations with some regions. While artificial selection for dozens of morphological characteristics in dogs has clearly proceeded through selective sweeps, we find little evidence that selection for behavior has generally produced similar sweep signatures.