Brakes of Genetic Improvement Flashcards
What is inbreeding?
The mating of individuals more closely related than average for the population
What are the effects of inbreeding on a population?
Increase homozygous genotypes, decrease heterozygous genotypes
What is inbreeding depression?
The reduced fitness in a given population as a result of breeding of related individuals?
What is heterosis?
The improved or increased function of any biological quality in a hybrid offspring
What is the inbreeding coefficient?
The level of inbreeding in an individual, the probability that both alleles at a single locus are identical by descent
F = (1/2) ^ (n+1)
What are some of the inherited disorders in dogs?
Blindness and joint deformities (GSD & golden retrievers), bleeding disorders (English springer spaniel), deafness (Dalmatian), range of eye problems (English springer spaniel, Labrador retriever, miniature schnauzer)
What methods are employed to reduce inbreeding?
Deliberately choose less related individuals, use more than one male from each selected full sib family, use selected parents only once, use factorial mating designs
How can single gene disorders be tested for in dogs?
Clinical screening, biochemical testing, DNA testing
Why is selecting against homozygous, clinically effected animals not efficient?
As the population frequency of recessive allele falls more mutant alleles are driven into heterozygote carriers, these carriers cannot be detected
How can biochemical analysis be used to detect a mutation of the gene encoding phosphofruktinase K (PFK), important for metabolism?
PFK can be measured in red blood cells
Homozygous normal dog – expected level of PFK
Homozygous affected dog – undetectable levels of PFK
Heterozygous carrier – level intermediate between homozygous normal and affected
When following a breeding programme what individuals should not be mated?
Untested x untested, carriers x untested, carriers x affected
