JB: So trying to “conserve” diversity, for instance, by not strictly adhering to a DNA test result, doesn’t make much sense to you?
MN: There’s nothing more important to the survival and adaptability of a species than genetic diversity. What I’m saying is that it seems incongruous to hold adherence to DNA testing to a different standard when the gene pools of these breeds have been closed and breeders are striving for conformation to a standard. I’m not sure I’m aware of a single instance where dogs have been brought in to add new “blood” to a breed.
JB: You said that in many cases, even when breeds are crossed with a dissimilar breed, it doesn’t take too long to re-establish the breed’s classic look and behavior. Why is that so?
MN: Most breed-defining traits are shared by multiple related breeds. For example, I would predict that the genes for pointing behavior are common to perhaps a dozen or more pointing breeds. So one could resurrect a breed by bringing together the right combination of genes from related breeds. This won’t always work because there are some characteristics that truly are unique, such as polydactyly in the Lundehund.
What makes breed development rapid is that most selected traits are tied to genes of big effect. So instead of moving a hundred genes of small effect through selective breeding, one only needs to move two or three. I’m speculating on this last part. We don’t entirely know this, but it’s a reasonable guess.