Genetic Model for Quantitative Traits Flashcards
what are simply inherited traits?
affected by one or few genes, phenotypes placed into categories
give 3 examples of simply inherited traits
coat color, presence of horns, certain genetic defects
how do environmental factors affect simply inherited traits?
very little
what are polygenic traits?
affected by many genes (no gene having an overriding effect), generally described in numbers, typically quantitative or continuous in their expression
what is an exception to polygenic traits?
dystocia; it is effected by many genes, but is placed into categories like simply inherited traits, from 1-3 with 3 requiring the most assistance
are polygenic traits effected by the environment?
yes, very
what is the most basic model for quantitative traits?
P = mew + G + E
what is genotypic value?
the overall effect of all the genes carried by the animal (singly and in combination) on the phenotype of the animal for the trait, not directly measurable
what two values is genotypic value (G) the sume of?
breeding value (BV) and gene combination value (GCV)
what is breeding value also called?
additive genetic value
what is breeding value?
the part of the genotype that can be transmitted from parents to offspring, the sum of the effects of individual genes independent of the effects of dominance and epistasis, considered as a parental value
what must be done before selecting animals to be parents?
their breeding values must be estimated and the best BV must be chosen to get the best result
how much of their genes can an animal pass to their offspring? and can it be predicted?
1/2 and it’s random
what is used to rank animals genetically?
progeny difference and transmitting ability
what are the predicted values of PD and TA called?
expected progeny difference (EPD) and predicted transmitting ability (PTA)