Deck 23: Evolutionary Processes

Question 1

Wikelski and Romero 2003) found that large marine iguanas had higher reproductive success than smaller iguanas did. However, the large iguanas were generally in poor body condition because they could not eat enough; at higher temperatures their foraging efficiency improved, allowing them to eat more. Thus, Wikelski and Romero hypothesize that iguana size will as global warming gradually increases air and water temperatures in the Galápagos Islands.

A) decrease
B) vary more
C) increase
D) stay the same

Answer 1

C

Question 2

-Which of the graphs above best represents the relationship between the intensity of directional selection and the genetic variation present within a population?

Answer 2

B

Question 3

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?

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.

Answer 3

No; there are more homozygotes than expected.

Question 4

For biologists studying a large flatworm population in the lab, which Hardy- Weinberg condition is most difficult to meet?

A) no gene flow
B) random mating
C) no genetic drift
D) no mutation
E) no selection

Question 5

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?

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

Question 6

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.)

-The UCSD campus male junco population tails are about 36% white, whereas the tails of males from nearby mountain populations are about 40- 45% white. The founding stock of UCSD birds was likely from the nearby mountain populations because some of those birds overwinter on the UCSD campus each year. Population sizes on the UCSD campus have been reasonably large, and there are significant habitat differences between the UCSD campus and the mountain coniferous forests; UCSD campus has a more open environment making birds more visible) and a lower junco density decreasing intraspecific competition) than that in the mountain forests. Given this information, which of the following evolutionary mechanisms do you think is most likely responsible for the difference between the UCSD and mountain populations?

A) gene flow
B) inbreeding
C) natural selection
D) mutation
E) genetic drift

Question 7

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.

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

Question 8

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant A₁) and recessive A₂) alleles according to the Hardy- Weinberg model?

A) fA₁) = 0.9700, fA₂) = 0.0300
B) fA₁) = 0.9997, fA₂) = 0.0003
C) fA₁) = 0.9604, fA₂) = 0.0392
D) fA₁) = 0.9800, fA₂) = 0.0200
E) fA₁) = 0.9600, fA₂) = 0.0400

Question 9

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.)
The UCSD campus male junco population tails were, on average, 36% white, whereas the tails of males from nearby mountain populations averaged 40-45% white. If this observed trait difference were due to a difference in the original colonizing population, it would be due to

A) a genetic bottleneck.
B) sexual selection.
C) sexual dimorphism.
D) disruptive selection.
E) founder effect.

Question 10

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?

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

Question 11

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?

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

Question 12

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid- 1700s. They do not marry with members outside their own immediate community. Today, the Dunkers are genetically unique and differ in gene frequencies, at many loci, from all other populations including those in their original homeland. Which of the following likely explains the genetic uniqueness of this population?

A) sexual selection and inbreeding depression
B) population bottleneck and Hardy- Weinberg equilibrium
C) mutation and natural selection
D) heterozygote advantage and stabilizing selection
E) founder effect and genetic drift

Question 13

Which of the following statements about genetic drift is true?

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 14

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?

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

Question 15

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?

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

Question 16

A biologist doing a long- term study on a wild spider population observes increased variation in silk thickness. She hypothesizes that the population is experiencing

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

Question 17

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
Based on whether the population in Figure 23.1 is in Hardy- Weinberg equilibrium, the researchers had already noted that negligible mutation and migration existed in this milkweed population, and the toxin does not affect the butterflies that pollinate these plants. Which of the following would be a logical conclusion about this milkweed population?

A) There is either directional selection or sexual selection.
B) There is either disruptive selection or inbreeding.
C) Genetic drift and selection are negligible.
D) There is either a heterozygote advantage or stabilizing selection.

Question 18

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

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

Question 19

For a biologist studying a small fish population in the lab, which Hardy- Weinberg condition is easiest to meet?

A) random mating
B) no gene flow
C) no selection
D) no genetic drift
E) no mutation

Question 20

Cystic fibrosis is a genetic disorder in homozygous recessives ff) that typically causes death in the early 30s. Over time, we would expect the f allele frequency to for this trait.

A) fluctuate
B) remain the same
C) decrease
D) increase

Question 21

Cystic fibrosis is a genetic disease caused by a recessive allele. The membrane protein involved in cystic fibrosis confers resistance to typhoid fever. Imagine that a drug- resistant form of typhoid fever becomes common worldwide, killing a significant proportion of the human population over a period of several decades. Which of the following would you expect to observe in the world population during this period?

A) decrease in the frequency of cystic fibrosis
B) no change in the frequency of cystic fibrosis
C) increase in the frequency of cystic fibrosis

Question 22

Mutation is the only evolutionary mechanism that

A) is more important in eukaryotes than in prokaryotes.
B) has no effect on genetic variation.
C) is not mentioned by the Hardy- Weinberg model.
D) can cause decreased fitness.
E) does little to change allele frequencies on its own.

Question 23

Which of the following is true?

A) Hardy- Weinberg considers an organism's entire genotype all genes).
B) Hardy- Weinberg can be used to examine only 1 gene at a time.
C) Hardy- Weinberg can be used to examine more than 1 gene at a time.

Question 24

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?

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 25

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

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

Question 26

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?

Question 27

Which sex typically has more extreme sex- selected characteristics: males or females? Why? Give an example.

Question 28

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?

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

Question 29

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.

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

Question 30

In a population of parrots on an island, there is considerable variation in beak size. Parrots with small, thick beaks can efficiently eat locusts insect), while birds with long, thin beaks can efficiently eat beetles. Both food types are available on the island. Which of the following types of selection, and effects on phenotypic variation would you expect to see?

A) Directional selection; phenotypic variation increases.
B) Directional selection; phenotypic variation decreases.
C) Disruptive selection; phenotypic variation is maintained.
D) Disruptive selection; phenotypic variation decreases.
E) Directional selection; phenotypic variation remains the same.

Question 31

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?

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 32

In 1986, a nuclear power accident in Chernobyl, USSR now the Ukraine), led to high radiation levels for miles surrounding the plant. The high levels of radiation caused elevated mutation rates in the surviving organisms, and evolutionary biologists have been studying rodent populations in the Chernobyl area ever since. Based on your understanding of evolutionary mechanisms, which of the following most likely occurred in the rodent populations following the accident?

A) Mutation caused the fixation of new alleles.
B) Mutation led to increased genetic variation.
C) Mutation caused genetic drift and decreased fitness.
D) Mutation by itself led to major changes in rodent physiology over time.

Question 33

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

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 34

Which of the following populations is most likely to be in Hardy-Weinberg equilibrium?

A) a culture of bacteria exposed to antibiotic
B) a small population of fish living in an aquarium
C) an isolated colony of bacteria in a lab under controlled conditions
D) a large population of mice living on an island with lots of food and no predators
E) a large flock of chickens on a farm, in which the farmer regularly adds new chickens from another farmer's flock

Question 35

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.

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 36

$\begin{array} { l c } \text { Aendtype } & \text { \#individuals } \\A _ { 1 } A _ { 1 } & 50 \\A _ { 1 } A _ { 2 } & 50 \\A _ { 2 } A _ { 2 } & 400\end{array}$ Use the information in the table above for the next questions).

-Given the information above, what is the frequency of the A₂ allele in this population?

A) 0.9
B) 0.8
C) 0.85
D) 0.75
E) 0.875

Question 37

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

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.

Question 38

$\begin{array} { l c } \text { Aendtype } & \text { \#individuals } \\A _ { 1 } A _ { 1 } & 50 \\A _ { 1 } A _ { 2 } & 50 \\A _ { 2 } A _ { 2 } & 400\end{array}$ Use the information in the table above for the next questions).

-Given the information above, what is the frequency of individuals with the A₁A₁ genotype?

A) 0.15
B) 0.1
C) 0.4
D) 0.3
E) 0.2

Question 39

Which of the following describes what we should expect when a population is in Hardy- Weinberg genetic equilibrium?

A) an asexually reproducing population that is not evolving
B) a sexually reproducing population that is increasing in size
C) a sexually reproducing population that is evolving.
D) a sexually reproducing population that is not evolving
E) an asexually reproducing population that is increasing in size

Question 40

$\begin{array} { l c } \text { Aendtype } & \text { \#individuals } \\A _ { 1 } A _ { 1 } & 50 \\A _ { 1 } A _ { 2 } & 50 \\A _ { 2 } A _ { 2 } & 400\end{array}$ 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?

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 41

Dark- eyed junco birds have white outer tail feathers that the males display during aggressive interactions and also during courtship displays. Males with more white in their tail are more likely to win aggressive interactions with other males, and females prefer to mate with males with more white in their tails. In the case of juncos, aggression fighting) by males is a type of selection; thus, we would expect that variation in reproductive success to be higher in and this species should exhibit _ sexual dimorphism.

A) intersexual; females; greater
B) intersexual; males; less
C) intrasexual; males; greater
D) intrasexual; females; greater
E) intrasexual; males; less

Question 42

Humans have domesticated a number of plants and animals. In the domestication process, a few individuals of a species are "captured" to have a starting population and then these are bred for many generations. This is an example of a and you would therefore predict that domesticated organisms would show .

A) bottleneck effect; many useful adaptations for surviving floods
B) bottleneck effect; little genetic variation
C) founder effect; a lot of genetic variation
D) gene flow; speciation
E) founder effect; little genetic variation

Question 43

Consider the following two scenarios: 1) A flash- flood sweeps through an area and random lemmings are killed, resulting in a change in lemming phenotype in subsequent generations; 2) A flash- flood sweeps through an area and some lemmings are able to survive because they are able to hold their breath longer than other lemmings, resulting in a change in lemming phenotype in subsequent generations. What are the primary differences between the two scenarios?

A) Scenario 1 represents natural selection, while Scenario 2 represents genetic drift.
B) Both scenarios represent genetic drift.
C) Both scenarios represent natural selection.
D) Scenario 1 represents genetic drift, while Scenario 2 represents natural selection.

Question 44

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?

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 45

Which of the following is true with respect to natural selection and genetic drift?

A) Both natural selection and genetic drift increase variation.
B) Both natural selection and genetic drift have strong effects on large populations.
C) Both natural selection and genetic drift change the frequencies of alleles.
D) Both natural selection and genetic drift increase the average fitness of a population.
E) Both natural selection and genetic drift are random processes.

Question 46

How do the founder effect and the immigration aspect of gene flow differ for the cheetah Acinonyx jubatus)?

A) Both gene flow and founder effect involve cheetahs moving into an area where there is no established cheetah population.
B) Gene flow involves cheetahs moving into an area with an established cheetah population, whereas founder effect involves cheetahs colonizing an area where there is no established cheetah population but where there might be populations of other species).
C) Both gene flow and founder effect involve cheetahs moving into established populations of cheetahs.
D) Gene flow involves cheetahs moving into an area with an established population of another species e.g., lions), whereas founder effect involves cheetahs moving into an area where there is an established cheetah population.

Question 47

A hurricane sweeps across the southern tip of Florida, killing salamanders randomly. Salamander colour is genetic, and, after the storm, scientists notice that the frequency of yellow- brown salamanders and
Green- brown salamanders has changed significantly. This is an example of a _ and we would predict that 20 generations after the storm the population would show .

A) bottleneck effect; little genetic variation
B) founder effect; speciation
C) founder effect; little genetic variation
D) bottleneck effect; many useful adaptations to surviving floods
E) founder effect; a lot of genetic variation

Question 48

Which of the following best describes the effect of the migration of individuals into a population?

A) Migration of individuals into a population generally causes the recipient population to diverge so much that it becomes a new species.
B) Migration of individuals into a population generally causes no change in the genetic variability within the recipient population because it is a case of artificial selection.
C) Migration of individuals into a population generally decreases the genetic variability within the recipient population.
D) Migration of individuals into a population generally increases the genetic variability within the donor population.
E) Migration of individuals into a population generally increases the genetic variability within the recipient population.