From Proceedings of the Royal Society B:
Evan L. MacLean†, Noah Snyder-Mackler†, Bridgett M. vonHoldt and James A. Serpell
Published:02 October 2019 https://doi.org/10.1098/rspb.2019.0716
Variation across dog breeds presents a unique opportunity to investigate the evolution and biological basis of complex behavioural traits. We integrated behavioural data from more than 14 000 dogs from 101 breeds with breed-averaged genotypic data (n = 5697 dogs) from over 100 000 loci in the dog genome. We found high levels of among-breed heritability for 14 behavioural traits (the proportion of trait variance attributable to genetic similarity among breeds). We next identified 131 single nucleotide polymorphisms associated with breed differences in behaviour, which were found in genes that are highly expressed in the brain and enriched for neurobiological functions and developmental processes, suggesting that they may be functionally associated with behavioural differences. Our results shed light on the heritability and genetic architecture of complex behavioural traits and identify dogs as a powerful model in which to address these questions.
From Science News:
Using data from over 14,000 dogs described in C-BARQ, the researchers gave each breed a score for 14 different behaviors, and then searched for overall genetic similarities among breeds that had similar scores. For traits such as aggression toward strangers, trainability and chasing, the researchers found that genes contribute 60 to 70 percent of behavioral variation among breeds. Poodles and border collies, for example, had higher trainability scores, while Chihuahuas and dachshunds had higher aggression toward strangers.
Energy level and fearfulness showed a smaller genetic contribution, about 50 percent, suggesting that differences in environment or training play an equally important role in shaping those behaviors.
I’d be interested in seeing studies of how much variation there is among individuals of a single breed. My impression is that animals are more individualist, even eccentric than one might theorize.
It’s what I might call the Lewontin Question: how much diversity is there within a group versus across groups? People tend to have a hard time thinking about this question, being inclined to all or nothing answers, when the glass is almost inevitably part full and part empty.