Maintenance of Genetic Variation II

Question 1

What does this equation represent? Define each variable.

Answer 1

Frequency of allele V at equilibrium due to heterozygote advantage.
s = selection gradient against VV
t = selection gradient against LL
wVV = relative fitness of VV
wLL = relative fitness of LL

Question 2

Under heterozygote advantage, what does an s or t value of 1 indicate?

Answer 2

homozygote for respective allele is lethal

Question 3

Under heterozygote advantage, what does an s or t value of <1 indicate?

Answer 3

homozygote for allele has lower fitness than heterozygote

Question 4

Under heterozygote advantage, what does an s or t value of 0 indicate?

Answer 4

Homozygote has equal fitness as heterozygote

Question 5

What is GxE?

Answer 5

• GxE is when the fitness of different genotypes respond in different ways to environmental variation

Question 6

How does GxE maintain variation?

Answer 6

Via local adaptation

Question 7

When does local adaptation occur?

Answer 7

o Local adaptation occurs when GxE cause genotypes from one location to exhibit higher fitness in their native environment compared to genotypes from a foreign environment

Question 8

Is this figure indicative of GxE?

Answer 8

No.

Question 9

Is this graph indicative of GxE?

Answer 9

Yes

Question 10

Is this graph indicative of GxE? What does the intersection represent?

Answer 10

Yes
Point at which genetic variation can be maintained

Question 11

How does one experimentally test for local adaptation?

Answer 11

Question 12

What is phenotypic plasticity?

Answer 12

• Phenotypic plasticity is the ability of a genotype to change its phenotype in response to the environment

Question 13

What is adaptive phenotypic plasticity?

Answer 13

• Adaptive phenotypic plasticity refers to cases where individuals that alter their phenotype in response to the environment experience an increase in fitness

Question 14

What is non-adaptive phenotypic plasticity?

Answer 14

• Non-adaptive phenotypic plasticity occurs when a change in phenotype in response to the environment has no effect on or decreases fitness

Question 15

• Why do not all populations evolve to be phenotypically plastic to all environments?

Answer 15

o … A Jack of all trades is a master of none
o Plasticity often does not allow genotypes to maximize fitness as much as specializing on an environment via local adaptation