Test Prep for AP® Courses

41.

Prior to 1800 in England, the typical moth of the species Biston betularia (peppered moth) had a light pattern. Dark colored moths were rare. By the late nineteenth century, the light-colored moths were rare, and the moths with dark patterns were abundant.


 
The cause of this change was hypothesized to be selective predation by birds (Tutt, 1896). During the industrial revolution, soot and other wastes from industrial processes killed tree lichens and darkened tree trunks. Thus, prior to the pollution of the industrial revolution, dark moths stood out on light-colored trees and were vulnerable to predators. With the rise of pollution, however, the coloring of moths vulnerable to predators changed to light.

 
Which of the following aspects of Darwin’s theory of evolution does the story of the peppered moth most clearly illustrate?
  1. There is competition for resources in an overbred population.
  2. There is great variability among members of a population.
  3. There is differential reproduction of individuals with favorable traits.
  4. The majority of characteristics of organisms are inherited.
42.

Prior to 1800 in England, the typical moth of the species Biston betularia (peppered moth) had a light pattern. Dark colored moths were rare. By the late nineteenth century, the light-colored moths were rare, and the moths with dark patterns were abundant.


 
The cause of this change was hypothesized to be selective predation by birds (Tutt, 1896). During the industrial revolution, soot and other wastes from industrial processes killed tree lichens and darkened tree trunks. Thus, prior to the pollution of the industrial revolution, dark moths stood out on light-colored trees and were vulnerable to predators. With the rise of pollution, however, the coloring of moths vulnerable to predators changed to light.

 
In the late 1900s, England cleaned up its air, and pollution decreased. The bark of trees went from dark to light.

 
Which of the following outcomes to the populations of peppered moth would you expect given this environmental change?
  1. an increase in the number of dark moths and a decrease in the number of light moths
  2. an increase in the number of moths overall
  3. an approximately equal number of light moths and dark moths
  4. an increase in the number of light moths and a decrease in the number of dark moths
43.

Prior to 1800 in England, the typical moth of the species Biston betularia (peppered moth) had a light pattern. Dark colored moths were rare. By the late nineteenth century, the light-colored moths were rare, and the moths with dark patterns were abundant.


 
The cause of this change was hypothesized to be selective predation by birds (Tutt, 1896). During the industrial revolution, soot and other wastes from industrial processes killed tree lichens and darkened tree trunks. Thus, prior to the pollution of the industrial revolution, dark moths stood out on light-colored trees and were vulnerable to predators. With the rise of pollution, however, the coloring of moths vulnerable to predators changed to light.

 
Commonly used in biology text books, the peppered moth is a classic example of evolutionary change in action. The example describes changes in a population’s allele frequencies-a small scale change, evolutionarily speaking. The presence of both light and dark forms within the gene pool is demonstrated by the story, but the peppered moth stays a peppered moth.

 
Which scenario, if it were to occur, would be a model for large scale evolutionary change?
  1. Conditions change such that the dark form of the moth is favored and the light form is diminished in the population due to predation. Conditions change again, the dark form is vulnerable, and the light form returns to prevalence.
  2. Conditions change such that the dark form of the moth is favored and the light form is eradicated in the population due to predation. Conditions change again, the dark form is vulnerable, and the dark form is eradicated due to predation.
  3. Conditions change such that dark form of the moth is favored and the light form is diminished in the population due to predation. Conditions change again, and both forms have equal prevalence.
  4. Conditions change such that dark form of the moth is favored and the light form is eradicated in the population due to predation. Conditions change again, the dark form is vulnerable. It develops an adaptation that shields it from predation.
44.
Given your understanding of evolutionary theory and the relationship between evolution and the genetic makeup of populations, which statement is false?
  1. Homologous characteristics that have evolved more recently are shared only within smaller groups of organisms.
  2. The genetic code is a homologous characteristic shared by all species because they share a common ancestor in the deep past.
  3. DNA sequence data would likely support any evolutionary tree drawn from anatomical data sets.
  4. The degree of relatedness between groups of organisms is only sometimes reflected in the similarity of their DNA sequences.
45.
Each of the following observations comes from a different scientific discipline. Which is the best support for Darwin’s concept of descent with modification?
  1. Geologists provide evidence that earthquakes reshape life by causing mass extinctions.
  2. Botanists provide evidence that South American temperate plants have more in common with South American tropical plants than temperate plants from Europe.
  3. Zoologists provide evidence that fewer animal species live on islands than on nearby mainlands.
  4. Ecologists provide evidence that species diversity increases closer to the equator.
46.
Paleontologists have recovered a fossil for an organisms named Archaeopteryx. It has many features in common with reptiles, but, like birds, shows evidence of feathers. For what aspect of evolutionary theory does this piece of evidence suggest support?
  1. Modern species are distinct natural entities.
  2. Modern species are not currently evolving.
  3. Modern species share a common ancestor.
  4. Modern species have both convergent and divergent traits.
47.
Which of the following pieces of evidence illustrates evolution as an ongoing process?
  1. Some genes from the bacterium E. coli have sequences that are similar to genes found in humans.
  2. Marsupial mammals live in just a few places in the world today-Australia, South America, and part of North America.
  3. The fossil record shows that Rodhocetus, an aquatic mammal related to whales, had a type of ankle bone that is otherwise unique to a group of land animals.
  4. In the 1940s, infections by the bacterium Staphylococcus aureus could be treated with penicillin; today populations exist that are completely resistant.
48.
The process of mutation, which generates genetic variation, is random. Thus, life has evolved, and continues to evolve, randomly. Which statement is an appropriately evidence-based refinement of the above?
  1. The process of mutation, which generates genetic variation, is random. However, the process of natural selection, which results in adaptations like the fit between a flower and its pollinator, favors variants which are better able to survive and reproduce. Natural selection is not random, so the overall process of evolution is not random, either.
  2. The process of mutation, which generates genetic variation, is random. However, the process of migration, which results in gene flow between populations, also generates genetic variation. Migration is not random, so the overall process of evolution is not random, either.
  3. The process of mutation, which generates genetic variation, is random. However, the process of sexual reproduction, which also introduces genetic variance, is not random. Because sexual reproduction is not random, the overall process of evolution is not random, either.
  4. The process of mutation, which generates genetic variation, is random. Whether mutations have a positive, negative, or neutral effect in terms of selective advantage is also random. Mutations and their effects are random, so the overall process of evolution is random.
49.

The selective breeding of plants and animals that possess desired traits is a process called artificial selection. for example, broccoli, cabbage, and kale are all vegetables that have been selected from one species of wild mustard. How is artificial selection both similar to and different from Darwin’s conception of natural selection? Does artificial selection provide evidence for evolution by natural selection? Explain.

  1. Both artificial selection and natural selection are the differential reproduction of individual organisms with favored traits. In artificial selection, humans have actively modified plants and animals by selecting and breeding individuals with traits deemed desirable. In natural selection, the most successful individuals in a species are selected by the species to reproduce.
  2. Both artificial selection and natural selection are processes that result in better-adapted individuals within a species. In artificial selection, humans have actively modified plants and animals by selecting beneficial genes from other organisms and inserting them into the target organisms. In natural selection, natural processes such as mutations and viruses introduce new genes to a population.
  3. Both artificial selection and natural selection are processes that cause organisms to be better adapted over time. In artificial selection, humans have trained animals to be more successful in completing tasks that the humans want completed. In natural selection, organisms train the functions that they will need to survive and reproduce.
  4. Both artificial selection and natural selection are the differential reproduction of individual organisms with favored traits. In artificial selection, humans have actively modified plants and animals by selecting and breeding individuals with traits deemed desirable. In natural selection, individuals are selected naturally as its traits deem it more fit for survival and reproduction.
50.

Genes important in the embryonic development of animals have been relatively well conserved during evolution. This means they are more similar among different species than many other genes. What explains this genetic conservation across animal species?

  1. Changes in the genes that are important to embryonic development have been relatively minor because there are no selective pressures on an individual before it is born.
  2. Changes in the genes that are important to embryonic development have been relatively minor because not much time has elapsed since the divergence of the various animal taxa.
  3. Changes in the genes that are important to embryonic development have been relatively minor because early embryos are very fragile and even small mutations can result in death.
  4. Changes in the genes that are important to embryonic development have been relatively minor because mutational tweaking in the embryo has magnified consequences in the adult.
51.
The upper forelimbs of humans and cats have fairly similar structures. In contrast, the upper forelimbs of whales (their flippers) have bones with a different shape and proportion from both cats and humans. Interestingly, genetic data suggests that all three organisms have a common ancestor from about the same point in time. What is a likely explanation for these data?
  1. Cats and humans are more closely related to each other than either are to whales.
  2. The shape of the whale forelimb arose a result of disadvantageous mutations
  3. The whale flipper is an adaptive characteristic unique to its water environment.
  4. The whale flipper is a vestigial structure.
52.
Biogeography is the study of biological species as they relate to geographical space and geological time. The fossil record shows that dinosaurs originated about 200 to 250 million years ago. Would you expect the geographic distribution of early dinosaur fossils to be broad (on many continents) or narrow (on one or a few continents)? Explain.
  1. broad because dinosaurs originated before the breakup of Pangaea
  2. broad because some dinosaurs could fly between continents
  3. narrow because they went extinct too quickly to disperse very far
  4. narrow because they lived so long ago that the fossils have mostly broken down or disappeared
53.

The term microevolution describes evolution on its smallest scale: The change in allele frequencies in a population over generations. DDT is a pesticide that was widely in use in the United States from the 1940s until 1972. The table below summarizes a particular allele frequency in laboratory strains of the common fruit fly, Drosophila melanogaster.

  Strains Collected from Flies in the Wild in the 1930s Strains Collected from Flies in the Wild in the 1960s
Frequency of allele conferring DDT resistance 0% 40%
Table 18.1

Using this information, describe a model in which natural selection improved the match between D. mealanogaster and its environment through microevolution.

  1. DDT killed off a large proportion of the population, and the alleles present in the surviving fruit flies differed from those in the original population
  2. Mutations from the application of DDT caused the allele conferring DDT resistance to appear in the population.
  3. Female mosquitoes chose to mate with male mosquitoes that had the allele conferring DDT resistance because it would make their offspring more fit.
  4. The wide use of DDT meant that fruit flies with DDT resistance were more evolutionarily fit than their counterparts without DDT resistance.
54.

In 1795, a Scottish geologist named Charles Hutton suggested that Earth’s geologic features could be explained by gradual processes that were still operating. This was in direct contrast to other scientific thought at the time, which included well-accepted proposals that geologic layers were representative of catastrophic events caused by processes no longer operating in the present time. Hutton proposed geologic features as the result of slow and consistent change, such as valleys formed by rivers wearing through rock. Hutton’s ideas were incorporated in the work of Charles Lyell, a geologist working in Darwin’s time. Lyell advocated a principle called uniformitarianism, the consistency of mechanisms of change over time. In other words, Lyell argued that the same geologic processes operating in the present had operated in the past, and at the same rate.


 
The ideas of Hutton and Lyell influenced the work of Charles Darwin. How do Hutton’s and Lyell’s ideas connect to and provide support for Darwin’s theory of evolutionary change?
  1. The idea that the same processes that operate in the present also operated in the past, and at the same rate, supported Darwin’s hypothesis of natural selection because humans could select for desirable traits and produce change very rapidly, so natural selection would also be fast enough to produce the full range of diversity in living organisms.
  2. The idea that the same processes that operate in the present also operated in the past, and at the same rate, connects to Darwin’s hypothesis of natural selection because he had observed it happening in the present.
  3. The idea that geologic change is the result of slow, continuous processes rather than sudden, substantial change connects to Darwin’s support of gradualism rather than punctuated equilibrium as the process that guided evolution.
  4. The idea that geologic change is the result of slow, continuous processes rather than sudden, substantial change connects directly to Darwin’s hypothesis that, given enough time, slow and subtle processes could produce substantial biological change.
55.

The human immunodeficiency virus (HIV) reproduces very quickly. A single virus can replicate itself a billion times in one 24-hour period. In a hypothetical treatment situation, a patient’s HIV population consists entirely of drug-resistant viruses after just a few weeks of treatment. How can this treatment result best be explained? How does this explanation illustrate that evolution is an ongoing process?

  1. The resistant viruses passed their genes to the non-resistant viruses so that 100 percent of the viruses became resistant. This illustrates evolution as an ongoing process because the genes of the population changed in real time.
  2. The non-resistant viruses died, and the resistant ones survived and rapidly reproduced. This illustrates evolution as an ongoing process because the change in the HIV population is the result of natural selection.
  3. The viruses developed resistance to the drug after repeated exposure to it. This illustrates evolution as an ongoing process because the viruses were able to adapt to changing conditions.
  4. The drug-resistant viruses were more fit than their non-resistant counterparts to begin with, and over time they dominated the population. This illustrates evolution as an ongoing process because natural selection favored one phenotype over another.
56.

A friend says: “Natural selection is about the survival of the very fittest in a population. The fittest are those that are strongest, largest, fastest.”

Would you agree with that statement? What evidence from scientific disciplines can you offer to support your agreement or your disagreement?

  1. The statement is true. If an organism is not strong and fast, it will not survive long enough to reproduce and pass on its genes, and if it is not large and fitter than the other individuals around it then it will not be able to compete for a mate. Many seal species, for example, have only a single male who gets to mate. He must be the very fittest seal to win all the females.
  2. The very fittest organisms are not necessarily the ones that survive. Sometimes it is the least fit organisms that survive and reproduce. For example, in one generation the mice who are bad at foraging for seeds may reproduce prolifically and dominate the mice who are good at foraging. In this case, natural selection will select for the less-fit phenotype and spread it in the population.
  3. The definition of fitness is not correct. The strongest and fastest organisms are more fit than the weaker and slower ones, but large individuals are often at a disadvantage to smaller ones because they are easily spotted by predators. For example, a large rabbit will stick out on a field more than a small one and will get eaten by a hawk.
  4. What is meant by fittest is not necessarily strong, large, and fast. Fitness, as defined in evolutionary terms, has to do with survival and the reproduction of genetic material. For example, a small but showy male bird may be selected by female birds to reproduce, while a large but less colorful one is not.
57.

A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after seven days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained.

These two tables compare the results for dish A and dish B. Dish A was covered until day 7. At day 7, 12 seeds had germinated, and all of the seedlings had yellow leaves. The mean stem length below the first set of leaves was 8 millimeters. Dish A was then left uncovered until day 14. At day 14, 20 seeds had germinated. Fourteen of the seedlings had green leaves, and 6 had yellow leaves. The mean stem length below the first set of leaves was 9 millimeters. Dish B was left uncovered for the entire time. At day 7, 20 seeds had germinated. Fifteen of the seedlings had green leaves, and 5 of the seedlings had yellow leaves. The mean stem length below the first set of leaves was 3 millimeters. As of day 14, no change occurred in any of these characteristics.
Figure 18.27

Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled?

  1. the number of yellow-leaved seedlings in dish A on day 7
  2. the number of germinated seeds in dish A on days 7 and 14
  3. the death of all the yellow-leaved seedings
  4. the existence of yellow-leaved seedlings as well as green-leaved ones on day 14 in dish B
58.

A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after seven days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained.

These two tables compare the results for dish A and dish B. Dish A was covered until day 7. At day 7, 12 seeds had germinated, and all of the seedlings had yellow leaves. The mean stem length below the first set of leaves was 8 millimeters. Dish A was then left uncovered until day 14. At day 14, 20 seeds had germinated. Fourteen of the seedlings had green leaves, and 6 had yellow leaves. The mean stem length below the first set of leaves was 9 millimeters. Dish B was left uncovered for the entire time. At day 7, 20 seeds had germinated. Fifteen of the seedlings had green leaves, and 5 of the seedlings had yellow leaves. The mean stem length below the first set of leaves was 3 millimeters. As of day 14, no change occurred in any of these characteristics.
Figure 18.28

Which best describes the usefulness of the yellow-leaved phenotype as a variation subject to natural selection?

  1. The yellow-leaved phenotype can germinate in environments without light.
  2. The germination of the yellow-leaved phenotype is unaffected by light intensity.
  3. The germination of the yellow-leaved phenotype is accelerated as compared to the green-leaved phenotype.
  4. The yellow-leaved phenotype cannot germinate in environments with light.
59.

A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after seven days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained.

These two tables compare the results for dish A and dish B. Dish A was covered until day 7. At day 7, 12 seeds had germinated, and all of the seedlings had yellow leaves. The mean stem length below the first set of leaves was 8 millimeters. Dish A was then left uncovered until day 14. At day 14, 20 seeds had germinated. Fourteen of the seedlings had green leaves, and 6 had yellow leaves. The mean stem length below the first set of leaves was 9 millimeters. Dish B was left uncovered for the entire time. At day 7, 20 seeds had germinated. Fifteen of the seedlings had green leaves, and 5 of the seedlings had yellow leaves. The mean stem length below the first set of leaves was 3 millimeters. As of day 14, no change occurred in any of these characteristics.
Figure 18.29

Yellow-leaved seedlings are unable to convert light energy to chemical energy. Which observation is most likely to be made on day 21?

  1. a few yellow-leaved seedlings alive in dish A, but none in dish B
  2. a few yellow-leaved seedlings alive in dish B, but none in dish A
  3. no yellow-leaved seedlings alive in dish A or dish B
  4. a few yellow-leaved seedlings alive in dish A and dish B
60.
Populations of a nocturnal toad live along a long river. On the other side of a band of territory that is about 10 kilometers wide, there are populations of a toad that appear similar. Which of the following data would provide compelling evidence that the two populations represent different species?
  1. The populations of toads on the other side of the banded territory are not completely nocturnal.
  2. Fertile hybrid populations of toads are found between the two other populations.
  3. There appear to be some hybrid toads between the two populations, but they are few and frail.
  4. The two populations of toads enact very different mating behaviors.
61.
A group of students summarized information on five great extinction events. The students are sampling a site in search of fossils from the Devonian period. Based on the chart, which of the following would be the most reasonable plan for the students to follow?

The table shows five extinction events. The first extinction event took place at the end of the Ordovician period, 443 million years. Organisms greatly reduced or made extinct by this event include trilobites, brachiopods, echinoderms, and corals. The second extinction event took place at the end of the Devonian period, 354 million years. Organisms greatly reduced or made extinct by this event include marine families on tropical reefs, corals, brachiopods, and bivalves. The third extinction event took place at the end of the Permian period, 248 million years. Organisms greatly reduced or made extinct by this event include trilobites, mollusks brachiopods, and many vertebrates. The fourth extinction event took place at the end of the Triassic period, 206 million years. Organisms greatly reduced or made extinct by this event include mollusks, sponges, marine vertebrates, and large amphibians. The fifth extinction event took place at the end of the Cretaceous period, 65 million years. Organisms greatly reduced or made extinct by this event include ammonites, dinosaurs, brachiopods, bivalves, and echinoderms.

  1. searching horizontal rock layers in any class of rock and trying to find those that contain the greatest number of fossils
  2. collecting fossils from rock layers deposited prior to the Permian period that contain some early vertebrate bones
  3. looking in sedimentary layers next to bodies of water in order to find marine fossils of bivalves and trilobites
  4. using relative dating techniques to determine the geological ages of the fossils found so they can calculate the rate of speciation of early organisms
62.

Populations of a plant species have been found growing in the mountains at altitudes above 2,500 meters. Populations of a plant that appears similar, with slight differences, have been found in the same mountains at altitudes below 2,300 meters.

Describe a plan for collecting two kinds of data that could provide a direct answer to the question: Do the populations growing above 2,500 meters and the populations growing below 2,300 meters represent a single species?

  1. Scientists could take the genetic code of a plant from each altitude and determine whether the two sets of DNA are identical. They could also insert genes from one plant into the cells from the other and see if the cells survive
  2. Scientists could look in the fossil record to find the plants’ most recent common ancestor. They could also check the surrounding mountains to determine if the most recent common ancestor is still living.
  3. Scientists could breed the two groups in the same environment and observe whether, over several generations, they begin to look more similar. They could also switch the groups, growing the high-altitude plants at low altitude and the low-altitude plants at high altitude, and observe whether the former begin to look like lowaltitude plants and the latter begin to look like high-altitude plants.
  4. Scientists could collect seeds and test whether they might be cross-pollinated to produce fertile offspring. They could also investigate the area between 2,500 meters and 2,300 meters to see if fertile hybrid populations might be found living between the two other populations of plants.
63.

Populations of a plant species have been found growing in the mountains at altitudes above 2,500 meters. Populations of a plant that appears similar, with slight differences, have been found in the same mountains at altitudes below 2,300 meters.

Explain how the two types of data you suggested provide a direct answer to the question of whether speciation has taken place.

  1. If the plants become more similar when grown in the same environment, or if the high-altitude plants respond to low altitude in the same way that low-altitude plants have, and low-altitude plants respond to high altitude the same way that high-altitude plants have, then the two groups have the same underlying genetic structure and belong to one species.
  2. If the seeds from the plants can be cross fertilized and developed into fertile offspring, the two populations are not yet reproductively isolated and remain one species. If hybrid forms are found, the two populations are not reproductively isolated and hybrids are both viable and successful.
  3. If the genetic codes of the two plants are identical, then they must belong to the same species. Also, if genes transplanted between the plants function successfully, then the plants must be similar enough to each other to belong to the same species.
  4. If scientists are able to find the common ancestor of the two groups in the fossil record or in neighboring communities, then they can determine whether the plants have diverged into separate species or remain a single species.
64.

Assuming a population that has genetic variation and is under the influence of natural selection, place the following events in the order in which they would occur:

  • Genetic frequencies within the population change.
  • A change occurs in the population’s environment.
  • Phenotypic variations shift.
  • Individuals who are well-adapted leave more offspring than individuals who are poorly adapted.
  • Individuals who are poorly adapted do not survive at the same rate as individuals who are well adapted.
    1. A change occurs in the population’s environment.
    2. Individuals who are poorly adapted do not survive at the same rate as individuals who are well adapted.
    3. Individuals who are well-adapted leave more offspring than individuals who are poorly adapted.
    4. Genetic frequencies within the population change.
    5. Phenotypic variations shift.
    1. A change occurs in the population’s environment.
    2. Genetic frequencies within the population change.
    3. Phenotypic variations shift.
    4. Individuals who are poorly adapted do not survive at the same rate as individuals who are well adapted.
    5. Individuals who are well-adapted leave more offspring than individuals who are poorly adapted.
    1. Phenotypic variations shift.
    2. A change occurs in the population’s environment.
    3. Genetic frequencies within the population change.
    4. Individuals who are poorly adapted do not survive at the same rate as individuals who are well adapted.
    5. Individuals who are well-adapted leave more offspring than individuals who are poorly adapted.
    1. Individuals who are well-adapted leave more offspring than individuals who are poorly adapted.
    2. Individuals who are poorly adapted do not survive at the same rate as individuals who are well adapted.
    3. Phenotypic variations shift.
    4. Genetic frequencies within the population change.
    5. A change occurs in the population’s environment.
65.

A biologist studies a population of voles for 20 years. During almost the entire research period, the population stays between 50 and 75 individuals. Additionally, fewer than half of the voles born do not survive to reproduce, due to predation and competition for food. Then, in one generation, 80 percent of the voles born live to reproduce. The population increases to 110 individuals. What inferences about food and predation can you make for the singular generation in which 80 percent of offspring survived? What prediction can you make about the genetic and phenotypic variation of future populations for this group of voles?

  1. Either there was fewer food available or the degree of predation increased. The future generations of this group of voles should evidence fewer genetic variation.
  2. Either there was fewer food available or the degree of predation increased. The future generations of this group of voles should evidence greater genetic variation.
  3. Either there was more food available or the degree of predation decreased. The future generations of this group of voles should evidence less genetic variation.
  4. Either there was more food available or the degree of predation decreased. The future generations of this group of voles should evidence greater genetic variation.
66.
There are years of drought in a small, relatively isolated community. During the drought, small seeds with thin shells become rare. Large seeds with hard cases become increasingly common. The large, tough seeds are successfully eaten by birds with large and broad beaks. Assuming that the drought continues and the population of birds in the community stays isolated, what predictions for the population can you make under the influence of natural selection?
  1. The birds with small, thin beaks will grow larger, broader beaks to be able to eat the larger seeds. This will result in subsequent generations having a higher percentage of birds with large, broad beaks.
  2. There will be more birds with small, thin beaks dying and more birds with large, broad beaks surviving. Differential reproduction of birds with large, broad beaks will result in subsequent generations having a higher percentage of birds with large, broad beaks.
  3. The species will diverge into two species, one with small, thin beaks and one with large, broad beaks. The two species will then compete for resources.
  4. There will be neither phenotypic nor genotypic changes in the population.
67.
At one time, avian researchers in the Sulawesi region of Indonesia described the Flowerpecker populations on the mainland and the Wakatobi archipelago as one species. A recent reassessment of the Wakatobi populations resulted in the suggested reclassification of these populations as a distinct species, the Wakatobi Flowerpecker. Which of the following pieces of evidence, if true, would be cause for this reclassification?
  1. The populations have become dependent on the island food sources.
  2. The populations have become morphologically distinct from the mainland species.
  3. The populations have become adapted to the island habitat.
  4. The populations have become reproductively isolated from the mainland species.
68.
What pattern in the fossil record would you expect to see to support the model of gradual speciation? How would you expect this pattern to differ from a pattern in the fossil record that supports the model of punctuated equilibrium? Explain.
  1. In the case of gradual speciation, the fossil record would show only a few hybrid individuals, followed by individuals of the two distinct species. For the case of punctuated equilibrium, the fossil record would show many hybrid individuals persisting through several geological layers.
  2. In the case of gradual speciation, the fossil record would show the parent species in a single location, such that the newly diverged species remained in contact with each other. For the case of punctuated equilibrium, the fossil record would show a geographic divide within the parent species that caused it to diverge into multiple new species.
  3. In the case of gradual speciation, the fossil record would show many intermediate forms. For the case of punctuated equilibrium, the fossil record would show new forms that persist essentially unchanged through several geological layers, then disappear just as a new form appears.
  4. Gradual speciation would be undetectable in the fossil record. For the case of punctuated equilibrium, the fossil record would show a steady progression of distinct forms.
69.
Until recently, these three species of short-tailed pythons, Python curtus, Python brongersmai (middle), and Python breitensteini were considered one species. However, due to the different locations in which they are found, they have become three distinct species. What is this an example of?
  1. divergent evolution
  2. sympatric speciation
  3. allopatric speciation
  4. variation
70.
Consider two species of birds that diverged while separated geographically but resumed their contact before reproductive isolation was complete. Which describes the first step in what would happen over time if the two species mated extensively and their hybrid offspring survived and reproduced more poorly than offspring from intra-species matings?
  1. Natural selection would cause prezygotic barriers to reproduction between the parent species to strengthen over time.
  2. The production of unfit hybrids would increase and the speciation process would complete.
  3. The extensive mating between the species would continue to produce large numbers of hybrids.
  4. The gene pools of the parent species would fuse over time, reversing the speciation process.