Border collies are highly trainable, greyhounds love to chase, and German shepherds make good guard dogs. According to a study of 101 dog breeds, while the environment plays a role, traits like these are highly heritable. The work identifies 131 genetic variants associated with breed differences in behavior.
The researchers recognized that if a dog breed is associated with a particular behavior that distinguishes it from other breeds, it might be easier to detect the genetic variants contributing to that behavior if you compared that breed’s genome to a host of others.
The researchers used behavior data from C-BARQ, short for Canine Behavioral Assessment and Research Questionnaire, a survey that more than 50,000 dog owners have filled out about their pets. C-BARQ returns a result on 14 behavioral “factors” about each dog surveyed, giving a measure of traits such as stranger-directed aggression, excitability, energy level, and predatory chasing drive.
For this study, the researchers pulled 14,020 of those entries that included information about pure-bred dogs. To look for associations with genetics, they borrowed data from two earlier studies, together representing 5,697 dogs, for which 172,000 points in the genome had been sequenced.
They found that about half of the variation in the 14 measured behaviors across breeds could be attributed to genetics — a greater proportion than previous studies have found.
Taking advantage of their vast pool of genomic data, the researchers looked for genetic variants associated with breed differences in the 14 C-BARQ traits. They found 131 variants tightly linked to these behaviors. Some were located in genes that have been implicated in influencing behavior, including in humans. But many were unknown and provide fodder for future study.
As a final step, the team looked to see where the genes in which key variants appeared were expressed in the body. Their analysis showed the genes were much more likely to be expressed in the brain than in other tissues in the body.
Overview of findings
◊ The majority of breeding that humans have done with dogs has been to elicit particular behaviors.
◊ Some of the behaviors that help characterize breeds — a drive to chase or aggression toward strangers — are associated with distinct genetic differences between them.
◊ Traits with the highest rates of heritability — in other words, those that seemed to be most influenced by genetic factors rather than environmental ones — were behaviors such as trainability, predatory chasing, stranger-directed aggression, and attention seeking. For these traits, genetics explained 60 to 70 percent of variation across breeds.
“These are exactly the types of traits that have been selected for in particular breeds of dogs. So for trainability, you’re thinking of breeds like border collies that have to respond to human signals to accomplish complicated tasks; for chasing behavior you can think of something like a greyhound, which is innately predisposed to chase anything that runs; and for stranger-directed aggression you might focus on some of the guard dog breeds that are highly protective and tend to respond in a hostile way to unfamiliar people.”
-Dr. James A. Serpell, researcher, University of Pennsylvania
As a final note the researchers caution that genetic tendencies isn’t everything; environment and training still have a very, very strong effect on dogs’ behaviors.
Journal Reference: Evan L. MacLean, Noah Snyder-Mackler, Bridgett M. vonHoldt, James A. Serpell. Highly heritable and functionally relevant breed differences in dog behaviour. Proceedings of the Royal Society B: Biological Sciences, 2019; 286 (1912): 20190716 DOI: 10.1098/rspb.2019.0716