Quantitative genetics Flashcards
What is quantitative genetics?
Inheritance of quantitative (measurable traits)
E.g. milk yield - most of these traits are of economic interest
Are quantitative genetics affected by one or several genes?
Several genes at different loci
What should be considered when thinking about quantitative genetics?
Most traits are also affected by non-genetic factors e.g. environmental effects
What conditions are presumed when using the Hardy-Weinberg equilibrium?
Large random mating population
No mutation, migration or selection
Genes and genotype frequencies are complement
Genetic improvement of a trait requires variability. What are sources of genetic variation?
Differences in gene frequency
Segregation of genes
Recombination
Mutation
What is the equation for Variation in a population? (Vp)
Vp = variation in genetics (Vg) + environment (Ve)
What is heritability?
Estimating the degree of variation in a phenotype that is due to genetic variation
What do genetic correlations measure?
Direction and strength of association between genetic merit for 2 traits
What is pleiotropy?
Genes affecting more than one trait
Closely linked genes can affect 2 traits
What are predictive breeding values?
Genetic merit of an animal
Predicted from animals own performance and its relatives
What factors affect genetic gain?
Selection intensity - % of population excluded from matings Heritability/genetic variation of the trait (higher = better) Generation intervals (shorter = higher genetic gain)
What is inbreeding?
The mating of individuals that are related to each other by ancestry
What does inbreeding lead to?
Pairs of genes that originated from a single gene in a previous generation
Causes increased frequency of undesirable recessive genes and decreased performance
What is the correlation coefficient measured between?
-1 and 1
What is line breeding?
Mating close relatives (dramatic inbreeding!)
Some success but high risk
