Quantitative Genetics Flashcards
How do you determine the number of polyalleles?
1/4^n where n # of alleles.
2n+1 = total number of phenotypes
n= number of additive loci
What is the difference between broad and narrow sense heritablity?
broad sense heritability is the contribution of the genotypic variance to the total phenotypic variance, assumes genotype by environment variance is negligible.
Narrow sense heritability is the proportion of phenotypic variance due to the additive genotypic variance, helps assess the selectibility of a trait for breeding/ artificial selection
How do twins help examine genotypic versus environmental variance
For identical twins, phenotypic variance equals environment variance, and there is no genotypic variance.
For fraternal twins, phenotypic differences represent both environmental variance and half the genotypic variance
Helps determine broad sense heritability
What does a difference in concordance mean?
The difference in concordance( agreement) for a given trait in identical versus fraternal twins suggests whether there is a strong genetic component involved in the determination of the trait.
What are meristic traits
polygenic traits in which the phenotype is recorded by counting whole numbers
What are threshold traits
polygenic and often multifactorial, but have a small number of phenotypic classes
How does multifactor hypothesis relate to grain color in wheat
Adding more additive alleles increases intensity of hot pink
What do additive alleles do?
They contribute to a single quantitative character
What is heritability
The proportion of total phenotypic variation in a population due to genetic factors
What are the components of phenotypic variance
Genotypic variance, environmental variance,, genotype by environment interaction variance
What is genotypic variance partitioned into
additive variance, dominane variance, interactive variance
What Is realized heritability
Estimates the potential for artificial selection to be successful.
