Natural Selection 2

Question 1

What is a trait called that is influenced by many genes?

Answer 1

A polygenic trait

Question 2

What type of variation is a polygenic trait?

Answer 2

Continuous/quantitative

Question 3

What branch of genetics is made up of studying polygenic traits?

Answer 3

Quantitative Genetics

Question 4

What is the difference between population genetics and quantitative genetics?

Answer 4

Population genetics deals with how genotypes effect phenotypes, and quantitative genetics studies how phenotypes affect genes

Question 5

What is the variance formula?

Answer 5

(sum((value - mean)^2))/n

Question 6

What is phenotypic plasticity?

Answer 6

The ability for a genotype to express more than one phenotype depending on its environment

Question 7

What are the 2 main contributors to phenotypic variation?

Answer 7

Phenotypic variation = Genetic variation + environmentally caused variation

Question 8

On a graph, what does Ve look like?

Answer 8

Variance from the environment give genotypic variance “wiggle room”

Question 9

What is broad sense heritability?

Answer 9

The proportion of phenotypic variation attributable to genetics

Question 10

How do we calculate broad sense heritability (H^2)?

Answer 10

H^2 =Vg/Vp = Vg/(Vg+Ve)

Question 11

What are the three portions of Vg?

Answer 11

Vg(genetic) = Va(additive) + Vd(dominance) + Vi(epistatic interactions)

Question 12

What are additive effects?

Answer 12

Alleles at a locus add up to affect trait value

Question 13

What is the difference between dominance and epistasis?

Answer 13

Dominance effect happens with masking in the same locus, but epistasis deals with the phenotypic expression of loci dependent on alleles at other loci as well

Question 14

What is the only type of heritability effect that can be passed down to offspring?

Answer 14

Additive heritability / narrow sense heritability (h^2)

Question 15

What is the formula for h^2?

Answer 15

h^2 = Va/Vp = Va/Ve+ Vg =Va/Va+Vi+Vd+Ve

Question 16

What type of heritability is used to measure evolution by natural selection?Why?

Answer 16

narrow sense heritability is the only variance that is passed down from parents to offspring

Question 17

Is heritability a trait of an individual or population?

Answer 17

Population

Question 18

Does a low heritability mean that traits do not vary?

Answer 18

No, it just means there is no additive variability

Question 19

What kind of graph is used to estimate heritability? What value on the graph represents heritability?

Answer 19

Parent-offspring regression (plot of values vs midpoint of parent values)

The slope of the line represents estimated heritability

Question 20

What type of interaction is responsible for Vg*e?

Answer 20

genotype-environment interactions

Question 21

How can you tell graphically when there is a Vg*e

Answer 21

There is a difference in slopes of heritability in different environments, some individuals will respond differently to different environments