Lecture 2: Quantitative Genetics 1 Flashcards Preview

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Flashcards in Lecture 2: Quantitative Genetics 1 Deck (11):
1

Define 'quantitative genetics'.

The study of the genetic and environmental components of traits that vary continuously.

2

Define 'qualitative traits' and give examples.

Difference between phenotypes of two individuals can be explained by the difference in genotype at a small number of loci i.e. 1 or two e.g. blood groups, cat coat colour, colour vision.

3

Define 'quantitative traits' and give examples.

Phenotypic difference between individuals is due to difference in genotype at a large number of loci e.g. weight, height.

4

What is the phenotypic variance dependent on?

Phenotypic variance = genetic variance + environmental variance.

5

What is genetic variance dependent on?

Genetic variance = additive genetic variance + dominance genetic variance + epistatic genetic variation.

6

What are the problems with predicting the evolution of quantitative traits?

- Dominance
- epistasis
- environmental effects.

7

Define 'heritability' and give its equation.

A measure of the degree of resemblance between relatives. H squared = additive genetic variance/ phenotypic variance. OR H squared = additive genetic variance/ (genetic variance + environmental variance).

8

What is the 'breeder's equation'?

R = h(squared) x S
R = response to selection
h = heritability
S = selection differential.

9

What is epistatic genetic variance?

Variation due to interactions among loci.

10

Define 'polygenetic inheritance'.

A trait is determined by a large number of different genes (resulting in high variation).

11

What is the midparent?

The mean of the mother and father values.