Midterm: Phenotypic Variation and Heritability

Question 1

You observe a population of birds that are genetically identical regarding genes for height. Height differences are the result only of environmental effects.
Taller stature would be beneficial for feeding on taller plants. Can this population evolve by natural selection?

Answer 1

No. They are genetically identical.

Question 2

Evolution by natural selection can act ONLY on
________ characteristics

Answer 2

HERITABLE

Question 3

What is the equation for heritability?

Answer 3

H^2=Vg/Vp

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

Question 4

What is the highest number H^2 can be?

Answer 4

1

Question 5

What does H^2 indicate?

Answer 5

All phenotypic variation is due to genotypic variation

Question 6

Is it possible for a character to vary in a population and have a heritability of 0?

Answer 6

Yes

Question 7

Can one population of a species have h2 = 0 for a specific phenotype but in another population have h2 = 0.4 for that same phenotype?

Answer 7

Yes. This is because of environmental differences

Question 8

All individuals in a population have the exact same allele that codes for a given phenotype. Ve = 0 for this trait in this population. Given this information, what does h2 equal in this population?

Answer 8

0. No genetic variation means no phenotypic variability.
   Vg = 0, Ve + Vg = 0

Question 9

Assume h2 = 0.8 for human height in our class. Which of the following is accurate given this heritability?

Answer 9

80% of the variation in height in this class is explained by genetic variation

Question 10

Between Vp, Vg and Ve, which one does Natural Selection act on?

Answer 10

ONLY phenotypic variation from Vg (genetic variation)

Question 11

Define H2

Answer 11

piece of a population’s phenotypic variation that came from genotypic variation (Vg)

Question 12

Vp is ALWAYS from:

Answer 12

Vg and Ve

Question 13

H2 determines:

Answer 13

how strongly someone can respond to Natural Selection

ex: oaks very in the phenotype (Ve + Vg) for tanin concentration yet have same selective pressure (Ve= 0)

Question 14

The character “feather color” has a heritability of 0 in a population of crows. Given this information and your understanding of heritability, which of the following is correct?

A. Another population of crows may have a heritability of greater than 0 for feather color.
B. All individuals of this population may have identical alleles for feather color.
C. The phenotypic variation for feather color in the population with a heritability of 0 would be less than in a population with a heritability of more than 0.
D. Two of the above are correct.
E. All of the above are correct.

Answer 14

D. Two of the Above are correct

A and B