Flashcards in Lecture 4: Selection Deck (16):

1

## What would the heritability of a trait with no genetic variation be?

### 0.

2

## Define 'selection differential' (S).

### The selection differential is the difference of the base population mean and the mean of the selected parents.

3

## Define 'response to selection' (R).

### How much gain you make when mating the selected parents.

4

## Related response to selection and selection differential.

### R = h(squared) x S.

5

## Define 'phenotypic evolution'.

### Change in the mean or variance of a trait across generation due to changes in allele frequencies.

6

## Define 'fitness'.

### Relative transmission of alleles to the next generation.

7

## How can you measure directional selection?

### Linear regression.

8

## Define 'standardisation' (z-scores).

### Standardisation of phenotypic traits allows to interpret selection as a number of standard deviation from the mean.

9

## How do you calculate a z-score?

### The score minus the mean score, divided by the standard deviation.

10

## How can you measure non-linear selection?

### Quadratics.

11

## Does a positive quadratic represent destructive or stabilising non-linear selection?

### Destructive. (sad face)

12

## Does a negative quadratic represent destructive or stabilising non-linear selection?

### Stabilising. (smiley face)

13

## Define 'direct selection'.

###
Causal relationship between a

phenotypic trait and fitness.

14

## Define 'indirect selection'.

###
Covariance between a trait and fitness

caused by a phenotypic correlation between that trait

and another trait under direct selection.

15

## What is stabilising selection?

### Favours intermediate phenotype. There are no changes in the mean but a reduction in variance. It is expected to reduce genetic variation.

16