The Institute of Canine Biology
  • HOME
  • Blog
  • Courses
    • COI BootCamp (FREE!)
    • Basic Population Genetics (FREE)
    • The Science of Canine Husbandry
    • Managing Genetics For the Future >
      • Syllabus - Managing Genetics for the Future
    • The Biology of Dogs (Open Reg )
    • DNA For Dog Breeders >
      • Syllabus - DNA for Dog Breeders
      • Open Reg - DNA For Dog Breeders
    • Understanding Hip & Elbow Dysplasia >
      • Open Reg - Understanding Hip & Elbow Dysplasia
    • Genetics of Behavior & Performance >
      • Syllabus - Genetics Behavior & Performance
      • Open Reg - Genetics of Behavior & Performance (Open Reg)
    • Strategies for Preservation Breeding >
      • Open Reg - Strategies for Preservation Breeding
    • Group Discounts
    • MORE FREE COURSES >
      • Quickie Genetics (Free!)
      • Heredity & Genetics (Free!)
      • Useful Genetics (Free!)
      • Basic Genetics Videos
  • Breed Preservation
    • Breed Status
    • Breeding for the future >
      • BFF Breed Groups
    • The "Elevator Pitch"
    • What's in the Gene Pool?
    • The Pox of Popular Sires
    • What population genetics can tell us about a breed
    • What population genetics can tell you...Tollers & Heelers
    • How to use kinship data
    • Using EBVs to breed better dogs >
      • How population size affects inbreeding
      • EBV Examples
    • How to read a dendrogram
    • Global Pedigree Project >
      • The Database
    • Finding the genes without DNA
    • How to read a heat map
  • Health Data
    • Bloat (Purdue Study)
    • Body Condition Score >
      • % Dysplastic vs BCS
    • Breed Comparions
    • Cancer
    • Cardiac
    • Cataracts
    • Caesareans
    • Deafness
    • Degenerative Myelopathy
    • Elbow Dysplasia
    • Epilepsy
    • Genetic Diversity
    • Genetic Diversity (MyDogDNA)
    • Hip Dysplasia >
      • Hip Dysplasia (Hou et al 2013)
    • Inbreeding Effects
    • Inbreeding (Gubbels)
    • Inbreeding (Dreger)
    • Lifespan
    • Litter size
    • Metabolic
    • mtDNA
    • Orthopedic
    • Mode of Inheritance
    • Patella Luxation
    • Thyroid
    • Portosystemic shunt
    • Purebred vs Mixed (UC Davis)
    • Purebred vs Mixed Breed (Bonnett)
    • Spay & Neuter Effects
    • Calboli et al 2008
    • Hodgman (1963)
    • Scott & Fuller (1965)
    • Stockard: Purebred crosses
    • Summers (2011)
  • Projects
    • How To Interpret Breed Analyses
    • Afghan Hound
    • More details about the Toller study
    • Belgian Tervuren >
      • Belgian Terv p2
      • Belgians- why population size matters
    • Bernese Mountain Dog
    • Boxer
    • Brussels Griffon
    • Bullmastiff
    • Canaan Dog >
      • Canaan analyses
    • Cesky Terrier >
      • Cesky genetic history
    • Chinook
    • Curly-coated Retriever
    • Doberman
    • Entelbucher Mountain Dog
    • Flatcoat Retriever
    • French Bulldog
    • German Shorthair
    • Golden Retriever >
      • Golden Retriever Pedigree Charts
    • Irish Water Spaniel >
      • IWS (6 Nov 17)
    • Labrador Retriever
    • Manchester Terrier
    • Mongolian Bankhar >
      • Research Updates
      • Bankhar 1
    • Norwegian Lundehund
    • Plummer Terrier
    • Otterhound
    • Portuguese Water Dog >
      • Portuguese Water Dog (pt 2)
    • Ridgeback
    • Schipperke
    • Standard Poodle >
      • The Problem With Poodles
      • 3poodle pedigree charts
      • 3Poodle Wycliff dogs
      • Poodle Genetics
    • Tibetan Spaniel
    • Tibetan Mastiff
    • West Highland White Terrier
    • Whippet
    • Wirehaired Pointing Griffons
    • UK KC Graphs >
      • UK KC Breed Status
      • UK Groups
      • KC Gundogs
      • KC Hounds
      • KC Terriers >
        • Terriers (select breeds)
      • KC Pastoral
      • KC Toys
      • KC Working
      • KC Utility
      • Australian KC
    • Breed outcrossing programs
  • Resources
    • Genetics Databases
    • Stud Books >
      • American Kennel Club stud books
      • Field Dog stud books
      • The Kennel Club (UK)
    • Learn
    • Videos about dog genetics
    • The Amazing Things Dogs Do! (videos) >
      • Livestock Management
      • Livestock guarding
      • Transportation, exploration, racing
      • Conservation & wildlife management
      • Detection Dogs
      • Medicine & Research
      • Entertainment
      • AKC/CHF Podcasts
    • Read & Watch
    • Bookshelf
  • Preventing Uterine Inertia

A DNA Primer for Dog Breeders. Genetic Diversity: Inbreeding (Fis)

6/21/2018

 
By Carol Beuchat PhD
Sewell Wright, who first formulated the method for estimating inbreeding from pedigrees (hence, "Wright's Coefficient of Inbreeding"), also described another way of assessing inbreeding using something called a "fixation index", or Fis.

In a large, genetically diverse population in which mating is random, you would expect inbreeding to occur only rarely because the probability of two related individuals mating is low. If we were to find that there was a higher level of inbreeding in this population than what would be expected just by chance, that would be evidence of non-random mating of related individuals; i.e., preferential inbreeding.
If we know the allele frequencies of a particular marker in the population, we can estimate the genotypes to expect under random mating. These would be predicted by the "Hardy-Weinberg Equation" (p^2 + 2pq + q^2), where p and q are the frequencies of the two alleles for the marker of interest. We can use the Hardy-Weinberg equation to predict genotype frequencies under random mating in a population. If we measure the actual genotype frequencies and find them to be different than expected based on H-W, then we know that mating has not been random.
We can use this tool to detect non-random mating using Wright's fixation index, Fis. Animals in a population with a level of inbreeding higher than expected based on H-W will have a positive Fis statistic. Animals that are outbred relative to what is expected under H-W will have a negative F statistic. An Fis of zero indicates a level of inbreeding equal to the expected value based on allele frequencies in the populaion.

In a nutshell, a positive Fis indicates inbreeding; a negative Fis indicates avoidance of inbreeding.
We can use our thousands of SNP markers to estimate Wright's Fis statistic for a population of individuals in a breed. The graphs below show the distribution of inbreeding coefficients (Fis) in Boxers and Irish Wolfhounds. For both breeds, there is "excess homozygosity" - a higher incidence of homozygosity on average than you would expect to see in a randomly breeding population. In both breeds, breeders are preferentially mating dogs that are more related than average in the population to produce higher levels of inbreeding.

Picture
Picture
 
These data show that better choices when selecting breeding pairs could slow the rate of increase in inbreeding in both breeds and also lower the risk of genetic disorders caused by recessive mutations. 

To learn more about the genetics of dogs, check out
ICB's online courses

***************************************

Visit our Facebook Groups

ICB Institute of Canine Biology
...the latest canine news and research

ICB Breeding for the Future
...the science of animal breeding


Comments are closed.

    Archives

    January 2025
    November 2022
    July 2022
    May 2022
    April 2022
    March 2022
    February 2022
    November 2021
    October 2021
    December 2020
    January 2020
    August 2019
    July 2019
    June 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    October 2017
    August 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    September 2016
    August 2016
    July 2016
    June 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    February 2014
    December 2013
    October 2013
    September 2013
    July 2013
    March 2013
    July 2012
    April 2012

    Categories

    All
    Behavior
    Border-collie
    Herding

Blog

News


About Us

Contact Us








Copyright © 2012-2017 Institute of Canine Biology
Picture
Picture