dog foot print and dna diagram

Essays on Dog Genetic Diversity

Inspired by conversations hosted by Jemima Harrison

The purpose of this website is to host essays and information about maintaining viable populations of healthy pure bred dogs

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copyright © 2009 by Dr Susan Thorpe-Vargus

Appendix 3: Some Quantative Aspects of Genetics

The Additive Relationship is the most commonly used measure of relationship. It is a measure of the fraction of genes shared by two animals and thus is an indication of how reliable one of the relative's records will be in predicting the genetic value of the other animal. The Coefficient of Inbreeding [or Inbreeding Coefficient or COI] of an animal is calculated as one-half the Additive Relationship between the parents." (p199, "Genetics for the Animal Sciences," LD Van Vleck, EJ Polak, EAB Altenacu, 1987)

Additive Relationship is twice the Coancestry (which is also called the coefficient of kinship or kinship coefficientor coefficient of consanguinity), "The coancestry of any two individuals is identical with the inbreeding coefficient of their progeny if they were mated. Thus the coancestry of two individuals is the probability that two gametes taken at random, one from each, carry alleles that are identical by descent." (p85, "Intro. to Quantitative Genetics," Falconer & Mackay, 4th Ed., 1996)

The important difference between the COI and the coancestry (one-half the  additive relationship) is that one, the COI, refers to the individual animal. The coancestry refers to the genetic similarity between two animals.

A bitch "Jacki" might have a high COI. A dog "Jessie" might have a high COI. But the coancestry of Jacki and Jessie might still be low or even zero. If this is the case, then both Jacki and Jessie are inbred (in fact, the entire breed line might be inbred), but there is still significant genetic diversity in the breed line if Jacki and Jessie have a low coancestry.

Continuing - If Jacki and Jessie have high COIs, they are prone to all the problems associated with inbreeding. If the average COI for the breed line is high, then the whole breed line is inbred and is likely to suffer the consequences as reflected in rates of hereditary defectives, increased puppy mortality, and reduced longevity. Yet, a low average coancestry for the breed line implies that there is a lot of latent genetic diversity in that same breed line. If so, the breed line can be salvaged by the appropriate choice of mates.

So when you discuss the genetic health of a single animal, consider its COI. When you discuss the latent genetic health of a breed (or a breed line), consider the average coancestry. To compare coancestry figures be certain that they are computed to the same depths of pedigrees(that is to the same number of generations). This is also the case when comparing the COI on different dogs.

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Articles at

Blogs Discussion Controversies in Dog Breeding

Jemima Harrison

Pedigree Dogs Exposed - The Blog

Border Wars

A Border Collie Manifesto

Desert Windhounds

A Bitter Cynoanarchist Rages On

Carol Fowler

Dog Breed Health

Interactive Genetics Tools Websites

Online COI Generator by Henk Meijers

Online COI Calculator

Academic Genetics Tutorials/Courses/Resources Online

Online Mendelian Inheritance in Animals (OMIA) OMIA

Understanding Gene Loss in successive generations An Interactive Academic Site on "Gene Dropping" at University of Montana

BIOL 4312: Genetics

GENUPComputer aided learning for quantitative genetics.
Although a Windows application Bonnie Dalzell has been able to run it under Ubuntu Linux from my desktop.

Design Of Crossbreeding Programs

A tactical approach to the design of crossbreeding programs.

Applied Animal and Plant Breeding

Cultivar Crazy - Preserving the Genetic Heritage of Plants

Applied Animal and Plant Breeding

Fitness and Viability of Small Populations
by Nina Pekkala

The Effects of Genetic Drift, Inbreeding, and Interpopulation Hybridization experimental study involving Drosophila (fruit flies)

Authoritative Inherited Diseases in Dogs Sites

Inherited Diseases in Dogs

Inherited Diseases in Dogs (IDID)

Canine Inherited Disorders Database

Canine Inherited Disorders Database

Inherited Disorders in Animals

List of Inherited Disorders in Animals (LIDA)

Canine Health Registries and Organizations

VMDB Veterinary Medical Database
The Veterinary Medical Database (VMDB) compiles patient encounter data from nearly all North American veterinary medical databases.

CERFCanine Eye Registration Foundation

CHIC) Canine Health Information Center

OFAOrthopedic Foundation for Animals

CERF Canine Eye Registration Foundation

APGAW: Associate Parliamentary Group For Animal Welfare
[Great Britain]

A Healthier Future for Pedigree Dogs

Canine Genetics Sites

The Hounds of Claybrook

Closed Registries, Genetics, and Inbreeding Depression


Canine Genetics Resources

Canine Diversity Website Homepage

Canine Diversity Homepage

A series of articles concerning the genetics of selection, inbreeding, inheritance of congenital defects.

Canine Inherited Disorders Database

CID Database

Sue Ann Bowling:

Animal Genetics Pages

To Breed or Not to Breed

All 4 essays by Susan Thorpe-Vargas Ph.D., John Cargill MA, MBA, MS, and D. Caroline Coile, Ph.D

The Genetic Cul-De-Sac

Dogs As An Endangered Species

Breed Related Sites

Borzoi Heritate Borzoi Pedigree Collection

Borzoi Pedigrees

Cesky Terriers

Cesky Terriers

The Dalmation Heritage Project

Project to breed Dalmations with normal uric acid metabolism

Author's Sites in no particular order:

John Burchard

Tepe Gawra Salukis

Jim Seltzer

Willowind Dalmations

Jeffery Bragg

Seppala Siberian Sleddogs

Dorothea Penizek

Clarmorris Parson Russell Terriers

Bonnie Dalzell

Borzoi Information Site

Academic Articles on Inbreeding, Fitness and Population Genetics

Fitness and Viability of Small Populations

by Nina Pekkala

The Effects of Genetic Drift, Inbreeding, and Interpopulation Hybridization experimental study involving Drosophila (fruit flies)