The Behavioral Genetics of Dogs
That much of dog behavior has genetic underpinnings is patently obvious. Differences in temperament and ability among breeds are well known. These diffferences are generally associated with the purposes for which the breed was created. This brief summary, which is typical of how dog breeds are classified, suggests some of the traits that have been subject to selection.
In general, dog breeds that are recognized by groups like the American Kennel Club (AKC) "breed true". This means that pairing any male and any female in the breed will result in pups with the breed-specific characteristics. If you think about this, you'll recognize that the only way to accomplish "breeding true" is through reduction of genetic variation. Any one breed of dogs will have less genetic variation within the breed than you find if you look across all dogs. At some point, breeding of this sort will eliminate most or all of the additive genetic variation in the breed, at least for some traits. At the point at which the additive genetic variation has been exhausted, no further "improvement" of the breed is possible even through carefully designed pairings.
Thinking about how heritability is calculated, it follows that within any dog breed you would expect to find low heritabilities, particularly for the traits which are thought to characterize the breed. Does this mean that the traits do not have a genetic underpinning? No--not at all. It simply means that further attempts to select for the trait will be futile. Following this line of reasoning, you would expect to observe higher heritabilities for traits (including, of course, behavioral traits) if you include a variety of dog breeds in a study, and lower heritabilities if you focus on only one dog breed.
Most measures of heritabiilties of dog behavioral traits are from studies of single breeds. Ruefenacht et al (2002), for example, found heritabilities of 0.24, or less, for personality traits of German Shepherds, and present a large table summarizing heritabilities for behavioral traits in dogs. Nearly all of the studies were performed within breeds (the alternative would be to do controlled matings between breeds). Generally heritabilities for behavioral traits range from 0 to 0.25. A wide range of behaviors have been measured, such as "willingness", fighting the leash, hare tracking, and "obedience".
These studies relate to two other interesting areas of dog behavior:
Ruefenacht S, Gebhardt-Henrich S, Miyake T, Gaillard C 2002 A behaviour test on German Shepherd dogs: heritability of seven different traits APPLIED ANIMAL BEHAVIOUR SCIENCE 79 (2): 113-132
Wilsson E, Sundgren PE 1997 The use of a behaviour test for selection of dogs for service and breeding .2. Heritability for tested parameters and effect of selection based on service dog characteristics APPLIED ANIMAL BEHAVIOUR SCIENCE 54 (2-3): 235-241
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