3. Extensions to Mendelian Inheritance

Which of the following terms describes an interaction between two genes?

Polygenic traits are controlled through which of the following ways.

Polygenic traits are usually continuous traits?

Which of the following traits would you expect to be inherited as quantitative traits?

Coat color in dogs

For the traits listed in the previous problem, which do you think are likely to be multifactorial traits, with phenotypes that are influenced by genes and environment? Identify two environmental factors that might play a role in phenotypic variation of the traits you identified.

Compare and contrast broad sense heritability and narrow sense heritability, giving an example of each measurement and identifying how the measurement is used.

In a cross of two pure-breeding lines of tomatoes producing different fruit sizes, the variance in grams (g) of fruit weight in the F₁ is 2.25 g and the variance among the F₂ is 5.40 g. Determine the genetic and environmental variance (VG and VE) for the trait and the broad sense heritability of the trait.

Describe the difference between continuous phenotypic variation and discontinuous variation. Explain how polygenic inheritance could be the basis of a trait showing continuous phenotypic variation. Explain how polygenic inheritance can be the basis of a threshold trait.

Calculate the mean, variance, and standard deviation for a sample of turkeys weighed at 8 weeks of age that have the following weights in ounces:

161, 172, 155, 173, 149, 177, 156, 174, 158, 162, 171, 181.

Provide a definition and an example for each of the following terms:

Threshold trait

Provide a definition and an example for each of the following terms:

Quantitative trait locus

Provide a definition and an example for each of the following terms:

Polygenic inheritance