A 4-generation pedigree is an inaccurate measure of genetic diversity.
Updated: Jun 7, 2019
Let's continue our examination of the lack of meaning of a 4 generation pedigree when it comes to assessing the genetic diversity of a curly coated retriever. (If you haven't read our first post in the series, scroll down.)
We have a few curly coated retriever breeders extolling the virtues of their breeding by claiming increased genetic diversity because the breedings do not have any common ancestors in 3 or 4 generation pedigrees. Unfortunately, examining a 3 or 4 generation pedigree to ascertain genetic diversity simply doesn't work. Some other breeders are using ancestor loss percentage to claim greater than average genetic diversity in their breedings but, again, examining a 3 or 4 generation pedigree does not accurately assess ancestor loss.
A few other breeders believe if they just import a curly coated retriever and breed it to one of their stock, they will have increased the genetic diversity of the breed.
Let's look at the pedigree data of one of these curly coated retrievers which are supposed to be more genetically diverse than average to explain the fallacy of using 3 or 4 generations to evaluate inbreeding percentages and ancestor loss.
WOW! A Zero % Inbreeding Coefficient?
Check out the above pedigree data. Using 4 generations for calculation, the data indicates no common ancestors for four generations, an inbreeding coefficient of ZERO, and no ancestor loss.
Seems like a genetically diverse dog, doesn't it? Unfortunately, this dog actually is probably one of the LEAST genetically diverse curly coated retrievers one could find. (We can't really determine genetic diversity by pedigree analysis alone, but using pedigree data, we can refute the notion of some breeders that calculating inbreeding coefficients and ancestor loss is an accurate diversity measure.)
Why is this curly, which shows a ZERO percent inbreeding coefficient in 4 generations NOT a genetically diverse dog? Look at the pedigree data for 10 generations of the same dog and look at the ancestor loss.
Above You See the 10 Generation Pedigree Analysis for a Curly Coated Retriever Purported to be Genetically Diverse and Essentially an "Outcross".
You can see, according to the pedigree data, this curly coated retriever is essentially in the same genetic bottleneck most of our curlies are floating in. This curly goes back to Darelyn Rifleman 68 times in 10 generations.
In a 10 generation pedigree, there could be a maximum of 2046 UNIQUE ancestors. This curly coated retriever, claimed to be genetically diverse, actually has only 387 ancestors in 10 generations. An ancestor loss of more than 81 percent!!!!!
Darelyn Rifleman was a wonderful dog! I was the first U.S. breeder to try to breed to his brother, Falco, when Falco moved to the states. But we as curly coated retriever breeders must understand that probably 99.9 percent of all curly coated retrievers living today have either Rifleman or his brother Reveller in their pedigree. And most curlies trace back to these two dogs 50 or 70 or 100 times in just 10 generations.
Curly coated retriever breeders need to understand how to assess inbreeding and using 4 generation pedigrees is not the way.
I hope curly coated retriever breeders recognize that a few generations of pedigree analysis gives very little useful information regarding inbreeding and diversity.
I will reiterate: I am EXTREMELY supportive of breeding for genetic diversity but I am not supportive of breeders making claims of such when the data doesn't support the claims.
Breeders need to be half artist and half scientist now days (well, I think that was always true). If you breed for genetic diversity, good for you. But please understand how to assess that diversity.
THE BEAUTIFUL UK CH. DARELYN RIFLEMAN