L28 Traits to Genes

Question 1

Traditional trait analysis in ecological genetics

Answer 1

see onenote

• focussed on morphological polymorphisms - discrete variation

Question 2

Examples of polymophisms

Answer 2

• peppered moth
• banding in snails
• coat colours

Question 3

Quantitative genetics

Answer 3

see onenote

• focussed on phenotypes with continuously distributed variation
• genetic basis of phenotype characterised by measuring related individuals or through direct selection

Question 4

Analyzing quantitative traits: components

Answer 4

see onenote

Question 5

Measuring adaptive genetic diversity

Answer 5

see onenote

Question 6

Vge

Answer 6

see onenote

VGE = how much the environment impacts each gene

Question 7

Measuring genetic diversity in quantitative traits

Answer 7

see onenote

• heritability
• broad-sense heritability
• narrow-sense heritability
• evolvability

Question 8

Evolvability

Answer 8

How much the trait will actually change when selection acts on it?

Traits that are crucial to survival are under very strong selection

Question 9

Heritability and evolvability

Answer 9

see onenote

Question 10

Heritability (evolvability) differences between quantitative traits

Answer 10

see onenote

• heritability differences depend on Ve
• depends on Va
• selection can decrease heritability - fitness traits often have low narrow-sense heritability

Question 11

Environment affects genetic parameters

Answer 11

see onenote

• h^2, Va, Ve are not constant, vary under different conditions
• in natural populations, often depends on stress levels

Good nutrition = high heritability
Low nutrition = low heritability
Environment affects heritability, heritability is not constant

Question 12

Heritability mapped against strength of natural selection

Answer 12

see onenote

• The higher the selection differential, the higher the strength of selection
• Strong selection, no heritable variation - when heritability is low, can’t respond to selection
• Weak selection, there is heritable variation

Question 13

Mutation, recombination and the environment

Answer 13

• recombination and mutation rate increases under stress
• in bacteria, evidence for specific mutational mechanism triggered under stress
• issue of whether these are adaptive responses or a consequences of a stressful condition

Question 14

E.coli stress response

Answer 14

E.coli stress response

• As you get more stressful environment, get more variability in bacteria
• Argues that it might be adaptive across generations