NEMDA maintains an online database of pedigrees for the Entlebucher Mountain Dog.
The pedigrees not only contain information about dogs and their ancestors, but also include several calculated values:
Coefficient of Inbreeding (COI)
This percentage is calculated using the mathematical formula developed by evolutionary geneticist, Sewall Wright. Included in the online pedigrees are the calculations based on 5, 10, and 20 generations. COI is used to predict the likelihood that an offspring will inherit two copies of the same allele (gene). The more inbreeding occurring in a pedigree, the higher the COI.
Why is that important? Wright recognized that inbreeding produces two effects:
- “First, a decline in all elements of vigor, as weight, fertility, vitality, etc., and second, an increase in uniformity within the inbred stock, correlated with which is an increase in prepotency in outside crosses… The best explanation of the decrease in vigor is dependent on the view that Mendelian factors unfavorable to vigor in any respect are more frequently recessive than dominant, a situation which is the logical consequence of the two propositions that mutations are more likely to injure than improve the complex adjustments within an organism and that injurious dominant mutations will be relatively promptly weeded out, leaving the recessive ones to accumulate, especially if they happen to be linked with favorable dominant factors.” (Wright 1921)
Wright was thinking that since we know inbreeding has two consequences that matter to a breeder, one positive (uniformity and prepotency) and one negative (loss of vigor and fertility), it would be useful to be able to calculate the degree of inbreeding of an animal because it would make these effects more predictable. This was important because these two effects were at odds with each other; breeders could increase predictability and uniformity by inbreeding, but not without also having detrimental effects on an animal’s health and fertility. Breeders couldn’t just keep inbreeding and inbreeding …. with each incremental improvement in uniformity and homozygosity, there would be a price to pay in health, vitality, and reproductive performance, traits that are collectively referred to as “fitness”. The short-term gain in consistency from inbreeding was paid for by a longer-term penalty in viability.2
Ancestor Loss Coefficient (AVK)
This is a ratio of the number of unique relatives existing in a pedigree to the number of possible relatives. AVK_10 is calculated over 10 generations. In 10 generations, a dog could have as many as 2046 unique ancestors. In genealogy, AVK, also referred to as pedigree collapse, describes how reproduction between two individuals who share an ancestor causes the number of distinct ancestors in the family tree of their offspring to be smaller than it could otherwise be.
This is the number of unique ancestors found in a particular dog’s 10 generation pedigree. Recall that in 10 generations, a dog could have as many as 2046 unique ancestors.
1 READING PEDIGREES, A LOST ART? by Barbara J. Andrews, Publisher, Hall Of Fame Breeder
2 Wright’s Coefficient of Inbreeding by Carol Beuchat, PhD; Scientific Director, Institute of Canine Biology and Visiting Scholar, Division of Genetics, Genomics, and Development, Dept of Molecular and Cell Biology, University of California Berkeley
3 Inbreeding and Diversity by Fred Lanting, retired American Kennel Club judge, currently active United Kennel Club all breed judge and handler.