Selection- 3

Question 1

Constraints on what NS can do?

Answer 1

• Physical (physics)
• Pleiotropy (Gene influences multiple traits)
• Trade offs (trait has multiple functions)
• Linkage (Gene clusters)
• time frame
• past history
• No purpose to evolution (selection favours immediately beneficial changes)

Question 2

What other processes other than NS can cause evolution?

Answer 2

• Genetic drift
• Sexual selection
• Artificial

Question 3

Factors needed for NS?

Answer 3

• variation
• inheritance
• differential reproductive success
• (mutations)

Question 4

Difference between absolute and relative fitness?

Answer 4

relative: the avg number of offspring ‘relative to other individuals in the population’

Question 5

Overdominance?

Answer 5

Over dominance is heterozygote advantage e.g. heterozygote for SCA
The heterozygote is higher in fitness than both homozygotes

Question 6

What is frequency dependent selection?
Pos?
Neg?

Answer 6

The selective advantage of the trait depends on frequency of trit in the population.
fitness increase as trait frequency more common
fitness decrease as trait more common

Question 7

fishers sex ratio model is based on what type of selection?

Answer 7

negative frequency dependent selection

Question 8

genetic drift does what to genetic variation?

Answer 8

reduces

Question 9

neutral theory?

Answer 9

most dna is neutral with respect to fitness