Exam 2

Question 1

The fact that the mtDNA of all living humans traces back to a single female ancestor is largelythe result of which evolutionary process?

Answer 1

genetic drift

Question 2

What is true about bipedalism in early hominids?

Answer 2

Bipedalism evolved before brain size and when the species was in woodlands.

Question 3

A gene locus has two alleles (A & B). If the three genotypes have the same phenotype:

Answer 3

All genotypes have relative fitness equal to 1.

Question 4

Low genetic effective population size (Ne) will:

Answer 4

Increase the impact of genetic drift.

Question 5

5. For genetic drift to have a strong impact on change in allele frequency at a gene locus which of the following must be true:

Answer 5

Natural selection must have little impact, gene flow must be low or absent, and the genetic effective population must be small.

Question 6

The impact of maternal environmental effects on offspring phenotype occurs as a result of:

Answer 6

The provisioning of the egg by the mother.

Question 7

F(A) vs. Generation graph: negative, exponential decay

Answer 7

The “A” allele is deleterious and has completely recessive effects on fitness.

Question 8

F(A) vs. Generation graph: reversed S shape

Answer 8

The “A” allele is deleterious with additive effects on fitness.

Question 9

F(A) vs. Generation graph: S, with a plateau at the top

Answer 9

The “A” allele is beneficial with completely dominant effects on fitness

Question 10

F(A) vs. Generation graph: S with plateau around the middle

Answer 10

AA > AB > BB

Question 11

F(A) vs. Generation graph: S, with a plateau at the top

Answer 11

AA > AB = BB

Question 12

F(A) vs. Generation graph: strong divergence of both alleles

Answer 12

BB > AA > AB

Question 13

What is correct about the impact of genetic drift and inbreeding on heterozygosity (H), polymorphism (P), and allelic richness (A) in a population:

Answer 13

Genetic drift decreases H, P and A while inbreeding only decreases H.

Question 14

Dominant alleles usually occur at higher frequencies than do recessive alleles. Beneficial alleles are usually dominant. Dominant alleles are usually beneficial. An allele that confers high fitness will be at high frequency.

Answer 14

All four of these statements are false.

Question 15

After an experiment, two populations, M and N, have allele frequencies at 1:

Answer 15

This is a product of genetic drift and selection for M

Question 16

This mating behavior (Storz et al 2001) results in some males fathering many pups and other males failing to form harems and reproduce. This will have which of the following effects:

Answer 16

It will decrease effective population size because of the high variance in male family
size.

Question 17

Bees and elderflowers…

Answer 17

Negative frequency dependent selection because, fluctuating because high frequency tricksters are known to be deceptive.

Question 18

What could result in heterozygote deficiency?

Answer 18

Inbreeding or heterozygote disadvantage; also genetic drift

Question 19

Fst: Species X lives in small, isolated populations; very few individuals move among populations…

Answer 19

Expect FST to be high. These are small population that will be strongly impacted by genetic drift, which results in the loss of alleles and increased fixation and differentiation among populations. There is little gene flow to counteract drift, and the alleles are neutral so natural selection is not occurring.

Question 20

Species Y lives in small populations, and movement of individuals among populations is common…

Answer 20

Expect FST to be low to low/moderate. While the small populations may be strongly impacted by genetic drift the movement of individuals produces gene flow. Gene flow decreases the chance of fixation and differentiation by homogenizing populations. Gene flow will almost certainly offset most or all impacts of genetic drift.

Question 21

Species Z lives in large populations, and there is moderate movement of individuals among populations…

Answer 21

Expect FST to be very low. Genetic drift won’t have much impact in these large populations and gene flow will further decrease the chance for fixation and differentiation of populations.

Question 22

Explain the impact of gene flow and natural selection on the pattern of copper
tolerance at the mine site.

Answer 22

High selection for copper tolerance, but low prevalence because of gene flow.

Question 23

Explain the impact of gene flow and natural selection on the pattern of copper
tolerance at the 5 mile site.

Answer 23

Gene flow is acting counter to local adaptation.