W6L1 multi factorial inheritance

Question 1

Genetic basis of continuous traits

Answer 1

• Segregation of multiple genes
• Assortment of phenotype depends on allele frequency
• Dominance is not complete: difference in effect size

Question 2

What does quantitative genetics focuses primarily on

Answer 2

• Quantitative Genetics focuses primarily on the genes inducing variation rather than those fundamental to a function.
• Since it relies mostly on naturally occurring variation, this perspective helps considering genetic variation the way nature “sees” and acts upon it.

Question 3

What is genetic effect

Answer 3

• Each genetic factor controlling a trait can be seen as independent elementary block: a genetic effect.
• All these genetic effects add-up to “build” the genetic value of a genotype which is a linear model of decomposition of the genetic effects.
• The genetic effects a genotype transmits to the next generation is called genetic value which factors the allele frequency together with the genetic effect.

Question 4

What is genetic variation

Answer 4

• The amount of trait variation explained by genetic factors is called genetic variance.

Question 5

Requirement for H-W equilibrium

Answer 5

• Panmixia (= mating randomly)
• Isolated population (no migration) of infinite size (no drift)
• With no mutation and evolving neutrally (no selection)

Question 6

Linear Model for the decomposition of a trait

Answer 6

Question 7

What is additive and dominance effect

Answer 7

o (A): How much each allele is summed up as an elementary block.
o (D): Depends on the between two alleles: how much heterozygous genotype deviates from expected
.

Question 8

Working out additive and dominance genetic effects

Answer 8

u is the midpoint value, a and -a is the deviation from the mid point for homozygous while d is deviation from heterozygousity

Question 9

What are variation introduced genetic background

Answer 9

• Epistasis
• Genetic x Environment Interactions
  -reaction norms are differences in genotype across environmental environment or genetic background

Question 10

The genetic value of a population calculation

Answer 10

P = µ + A+ D + E
The genetic value is the expected (~average) value of a genotype relative to the mean of the population.
E[μG] = p2a + 2pqd + q2(-a)

Question 11

genetic variance

Answer 11

The genetic variance σ2G measures the proportion of a specific trait that is genetically determined for a specific population in a specific environment.

Question 12

General formula of the genetic variation

Answer 12