Heritability Flashcards
phenotype=
genotype + environment
what contributes to genotype
-additive effects
-non additive effects
-dominance deviation
-epistatic effects
what contributes to the environment
-feed
-housing
-stress
-health
what is the goal of animal breeder
-change phenotype
-improve environment
-change genotype of breeding stock
what is polygenic inheritance
-many genes influence one trait
-when greater then or equal to 3 genes = polygentic
what things does polygenic inheritance influence
-coat color in cattle
-head shape in horses
-litter size in cats
eggs laid’day in chickens
-herding ability in dogs
interactive effects
-two or more loci “interact” on once trait
-ie
-E locus=extention
-black ED>wildtypeE+>red e
-D locus= “diluter”
-dark DD, medium Dd, dilute dd
-but dilute black still has black on nose
epistasis vs hypostatis
-epi= masking
-hypo- masked
additive effects example in diary cattle
-LLLlll average lactational yield~1800L
-LLLLLL ~2200L
-llllll ~14000L
-but still influenced by food, age, mastisis
-slow genetic progress
additive effects example height in dogs
-HHHHHH=tall (66cm)
-hhhhhh=short (60cm)
ie each H allele about 1 cm
-but influeced by nutrition, environment, health
-but there can be gene interaction
-HHHhhh= moderate
-HHHhhh + aa+ dwarf
heritability
broad sense heritability
genetic variance/phenotypic varience
narrow sense heritability
-additive genetic variance/phenotypic variance
-measures strength of the relationship between performance and breeding value for a specific trait in a population
-ignores gene interactions (ie dawrf on height)
-not ideal
-but expresses the reliabilty of the phenotypic value as a guid to breeding value
heritability estimate
-based on how much relatives resemble each other (compared to non rel)
-varies (somewhat) with population and environmental circumstances
regression (r)
-correlation coefficent (r) is slope of the line
-can be pos or neg
