Heritability Flashcards
how do you select phenotype
phenotype = genotype + environment
genotype: additive effects, dominance deviation, epstatic stress
environment: feeding, housing, stress and health
what is the goal of the animal breeder
change phenotype
improve environment
change genotype of breeding stalk
what is polygenic inheritance
many gene influencing one trait
3 or more genes = polygenic
- coat colour in cattle
head shape in horses
litter size in cats
eggs laid/day in chickens
herding ability in dogs
what is a interactive effects
two or more loci interact on one trait
E locus = extension, melanocortin 1 recotor (MC1R)
pigment - D locus - diluter
what is epistasis
masking
hypostasis - masked - gene for albinism
tyrosinase is epistatic gene - TYR takes away coat pigment and eye pigment from all parts of the body
how is heritability measured
measures strength of the relationship between performance and breeding value of a specific trait in a population
what is narrow sense heritability
ignores gene interaction such as dwarfism on height
not ideal - but expresses the reliabilityy of the phenotypic value as a guilde tp the breeding value
what is heritability estimate
based on how much relative resemble each other (compared to non relatives
varies (somewhat) with populationand environemnatal circumstanes
what has high heritability
growth
what has medium heritability
function and behaviour
what has low heirability
fertility and stamina
what is repeatability?
- correlation of several measurements from a single animal
measures environment variation within a single genotype
