Question 1

Which of the following statements about genetic drift is true?

Accepted Answer

A)  Inbreeding depression, bottleneck effects, and founder effects are all examples of genetic drift. 
B)  The effect of genetic drift on allele frequencies is equally strong in large and small populations. 
C)  Genetic drift can lead to an increase in the average fitness of a population. 
D)  Genetic drift is nonrandom. 
E)  Genetic drift is caused by migration of individuals into, and out of, a population.

Question 2

Which of the following is the most predictable outcome of increased gene flow between two populations?

Accepted Answer

A)  decreased genetic difference between the two populations 
B)  lower average fitness in both populations 
C)  increased genetic drift 
D)  higher average fitness in both populations 
E)  increased genetic difference between the two populations

Question 3

In some jacana species, males take care of the eggs and young, and females compete for territories and males aga one another. Female jacanas are significantly larger than males. Which of these statements would you predict to of this bird species?
1) Male jacana fitness is primarily limited by ability to take care of eggs and raise young.
2) Female jacana fitness is limited by the number of males with which a female mates.
3) Variation in reproductive success should be greater in male jacanas than in females.
4) Variation in reproductive success should be greater in female jacanas than in males.
5) Males and females have equal variation in reproductive success.

Accepted Answer

A)  1 and 3 
B)  2 and 4 
C)  1, 2, and 3 
D)  1, 2, and 4 
E)  5

Question 4

$\begin{array} { l c } 
\text { Aendtype } & \text { \#individuals } \
A _ { 1 } A _ { 1 } & 50 \
A _ { 1 } A _ { 2 } & 50 \
A _ { 2 } A _ { 2 } & 400
\end{array}$ Use the information in the table above for the next questions).
-Given the information about the number of individuals of specific genotypes in the table above, what can you infer?

Accepted Answer

A)  A2 is the dominant allele. 
B)  The relative amounts of each allele. 
C)  The phenotype of A1 is likely disadvantageous. 
D)  The phenotype of the individuals with each genotype.

Question 5

Researchers Helle et al., 2004) analyzed rates of twin births in the Sami population of Northern Scandinavia during the eighteenth and nineteenth centuries. They found that 1) a baby born from a singleton pregnancy was more likely to survive to adulthood than a baby born from a twin pregnancy, and 2) the average number of offspring raised to adulthood was higher for women who had twins than for those who never had twins. These data suggest that in this population, human twinning rate was

Accepted Answer

A)  under sexual selection. 
B)  undergoing genetic drift. 
C)  under stabilizing selection. 
D)  under directional selection. 
E)  under disruptive selection.

Question 6

For Galápagos marine iguanas, body size is not correlated with survival, but small iguanas can sprint faster than large iguanas. If a new predator species e.g., cats) that preferably catches and eats slower iguanas is introduced to the island, iguana body size is likely to in the absence of other factors; the iguanas would then be under selection.

Accepted Answer

A)  increase; directional 
B)  decrease; directional 
C)  stay the same; stabilizing 
D)  decrease; stabilizing 
E)  increase; disruptive

Question 7

An earthquake decimates a ground- squirrel population. The surviving population happens to have broader stripes on average than the initial population. If broadness of stripes is genetically determined, what effect has the ground- squirrel population experienced during the earthquake?

Accepted Answer

A)  gene flow 
B)  a founder event 
C)  directional selection 
D)  a genetic bottleneck 
E)  disruptive selection

Question 8

Use the following information when answering the corresponding questions).
Researchers studying a small milkweed population note that some plants produce a toxin and other plants do not. They ident gene responsible for toxin production. The dominant allele T) codes for an enzyme that makes the toxin, and the recessive all
t) codes for a nonfunctional enzyme that cannot produce the toxin. Heterozygotes produce an intermediate amount of toxin. The genotypes of all individuals in the population are determined see chart) and used to determine the actual allele frequencies in the population.
  Figure 23.1
-Refer to Figure 23.1. Is this population in Hardy- Weinberg equilibrium?

Accepted Answer

A)  yes 
B)  No; there are more heterozygotes than expected. 
C)  No; there are more homozygotes than expected. 
D)  More information is needed to answer this question.

Question 9

Suppose 64% of a remote mountain village can taste phenylthiocarbamide PTC) and must therefore have at least one copy of the dominant PTC taster allele. If this population conforms to Hardy- Weinberg expectations for this gene, what percentage of the population must be heterozygous for this trait?

Accepted Answer

A)  48% 
B)  16% 
C)  32% 
D)  60% 
E)  40%

Question 10

Three- spined stickleback fish Gasterosteus aculeatus) show substantial heritable variation in gill- raker length. Fish caught in open water tend to have longer gill rakers and eat different foods than those caught in shallower water. Longer gill rakers appear to function better for capturing open- water prey, while shorter gill rakers function better for capturing shallow- water prey. Which of the following types of selection is most likely to be found in a large lake open water in middle and shallow water around the sides) with a high density of these fish?

Accepted Answer

A)  stabilizing selection 
B)  sexual selection 
C)  disruptive selection 
D)  no selection 
E)  directional selection

Question 11

If an allele is found at a frequency of 0.8 in a population that is in Hardy- Weinberg equilibrium, and an individual is heterozygous for that allele, what is the probability they will pass on that allele to their offspring?

Accepted Answer

A)  0.2 
B)  0.64 
C)  0.8 
D)  0.5

Question 12

Figure 23.4
-Refer to Figure 23.4. Male reproductive success, measured as the number of offspring surviving to adulthood pupating), is found for two closely related beetle species and graphed above. Which of these statements would you expect to be true of sexual dimorphism in the two species?

Accepted Answer

A)  Species A should have greater sexual dimorphism than species B. 
B)  Species B should have greater sexual dimorphism than species A. 
C)  Species A and B should have about equal amounts of sexual dimorphism. 
D)  Neither species should show any sexual dimorphism.

Question 13

Use the following information when answering the corresponding questions).
Martin Wikelski and L. Michael Romero Body size, performance and fitness in Galápagos marine iguanas, Integrative and Comparative Biology 43 [2003]:376- 86) measured the snout- to- vent anus) length of Galápagos marine iguanas and observed the percent survival of different- sized animals. Figure 23.2 shows the log snout- vent length SVL, a measure of overall body size) plotted against the percent survival of these different size classes for males and females.
  Figure 23.2
-Examine the figure above. What type of selection for body size appears to be occurring in these marine iguanas?

Accepted Answer

A)  stabilizing selection 
B)  directional selection 
C)  sexual selection 
D)  disruptive selection

Question 14

Speller et al. 2010) analyzed turkey mitochondrial DNA haplotypes and reported that turkeys were domesticated by precontact native North American cultures in several independent events. Which of the following would be evidence of domestication of turkeys?

Accepted Answer

A)  Low genetic variation in turkey tissues found at settlement sites compared to wild turkey tissues. 
B)  Similar amounts of genetic variation in wild turkeys relative to turkey tissues found at the settlement sites. 
C)  High genetic variation in turkey tissues found at settlement sites compared to wild turkey tissues. 
D)  Low genetic variation in wild turkeys relative to turkey tissues found at the settlement sites.

Question 15

A beneficial point mutation occurs in a plant ovule, which is fertilized. The seed matures, falls to the ground, and starts to grow. Is the plant's population likely to show evolutionary change as a result of this mutation? Why or why not?

Accepted Answer

The answer of A beneficial point mutation occurs in a...

Question 16

In Kerr and Wright's experiment with 96 fruit- fly populations, only 4 males and 4 females bred in each generation. After 16 generations, 73% of their populations had only one allele present for the bristle morphology gene. Which of the following would you expect to occur if they allowed 10 males and 10 females to breed each in generation?

Accepted Answer

A)  More than 73% of the populations would have only one allele present. 
B)  About 73% of the populations would have only one allele for the bristle morphology gene. 
C)  Less than 73% of the populations would have only one allele present. 
D)  All of the populations would have only one allele present.

Question 17

Male turkeys have a snood, a flap of skin that hangs across their beak. Snood length is negatively correlated with parasite load e.g., males with longer snoods have fewer parasites), and females prefer to mate with long- snooded males. This is an example of

Accepted Answer

A)  sexual selection via male- male competition. 
B)  sexual selection via female choice. 
C)  a genetic marker. 
D)  the fundamental asymmetry of sex.

Question 18

Two frog populations same species) living in two neighboring lakes sing slightly different courtship songs. Predict what likely happens to the songs of the two frog populations after increased irrigation makes the land between the two lakes wetter. Females prefer loud frogs to quieter frogs, but do not distinguish between the two slightly different songs. Assume that courtship song differences have a genetic basis.

Accepted Answer

A)  The songs become more different from each other. 
B)  The songs become more similar to each other. 
C)  There is no change in the frog courtship songs of the two lakes.

Question 19

Use the following information when answering the corresponding questions).
In 1983, a population of dark- eyed junco birds became established on the campus of the University of California, San Diego UCSD), which is located many miles from the junco's normal habitat in the mixed- coniferous temperate forests in the mountains. Juncos have white outer tail feathers that the males display during aggressive interactions and during courtship displays. Males with more white in their tail are more likely to win aggressive interactions, and females prefer to mate with males with more white in their tails. Females have less white in their tails than males, and display it less often. Pamela J. Yeh. 2004. Rapid evolution of a sexually selected trait following population establishment in a novel habitat. Evolution 58[1]:166- 74.)
-Based on the information given above, which of the following types of selection was most likely initially involved in the evolution of white outer tail feathers in juncos?

Accepted Answer

A)  stabilizing selection 
B)  disruptive selection 
C)  sexual selection 
D)  directional selection

Question 20

Why doesn't inbreeding depression, by itself, cause evolution?

Accepted Answer

A)  It increases homozygosity. 
B)  It does not change the population's allele frequencies. 
C)  It decreases the population's average fitness. 
D)  It limits gene flow. 
E)  It violates the Hardy- Weinberg assumptions.

Exam 23: Evolutionary Processes