Deck 22: Evolution by Natural Selection

Question 1

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

A) None of the organisms depicted by the tree ate the same foods.
B) Some of the organisms depicted by the tree had lived in different habitats.
C) The skeletal remains of the organisms depicted by the tree were incomplete (in other words, some bones were missing).
D) Transitional fossils had not been found.
E) Relationships between DNA sequences among the species did not match relationships between skeletal patterns.

Answer 1

E

Question 2

There is a population of beetles that typically have black wings. A scientist studying these beetles knows that their eggs hatch in early spring, the young insects grow through the late spring and summer, they lay eggs in the early fall, and they die in the early winter. Recently some beetles have been born with white wings. Early in life, the black- and white-winged beetles seem to be very similar in number of mating events, eggs laid, and survival rates, but shortly after laying their eggs, the white beetles die and there are only black-winged beetles during the late fall. Which of the following is a TRUE statement about the beetles?

A) White- and black-winged beetles have equal fitness.
B) Black-winged beetles have a higher fitness than white-winged beetles.
C) The number of baby white-winged beetles will decrease in frequency over time.
D) White wings are an adaptation.

Answer 2

A

Question 3

Which of the following most strongly supports the common origin of all life on Earth? All organisms ________.

A) require energy
B) use essentially the same genetic code
C) reproduce
D) show heritable variation
E) evolve

Answer 3

B

Question 4

The following question(s) refer to the accompanying figure, which shows an outcrop of sedimentary rock whose strata are labeled A-D.
If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata?

A) one stratum
B) two strata
C) three strata
D) four strata

Question 5

Many crustaceans (for example, lobsters, shrimp, and crayfish) use their tails to swim, but crabs have reduced tails that curl under their shells and are not used in swimming. This is an example of ________.

A) convergent evolution
B) a homologous structure
C) natural selection
D) a vestigial trait

Question 6

Use the following information and figure to answer the question(s) below.
Traditionally, whales and hippopotamuses have been classified in different orders, the Cetacea and the Artiodactyla, respectively. Recent molecular evidence, however, indicates that the whales' closest living relatives are the hippos. This has caused some zoologists to lump the two orders together into a single clade, the Cetartiodactyla. There is no consensus on whether the Cetartiodactyla should be accorded order status or superorder status. This is because it remains unclear whether the whale lineage diverged from the lineage leading to the hippos before or after the other members of the order Artiodactyla (pigs, camels, etc.) diverged (see the accompanying figure). The figure contrasts the "Within the artiodactyls" origin of the whale lineage with the "Without the artiodactyls" origin of the whale lineage.
One morphological feature of some modern cetaceans is a vestigial pelvic girdle. If it is determined that the cetacean lineage diverged from the artiodactyls' lineage after the divergence of pigs and other artiodactyla, then the vestigial pelvic girdle of cetaceans should be considered a shared ________.

A) ancestral character of the cetartiodactyls
B) derived character of the cetartiodactyls
C) ancestral character of the cetaceans
D) derived character of the cetaceans

Question 7

Darwin and Wallace's theory of evolution by natural selection was revolutionary because it ________.

A) was the first theory to refute the ideas of special creation
B) proved that individuals acclimated to their environment over time
C) dismissed the idea that species are constant and emphasized the importance of variation and change in populations
D) was the first time a biologist had proposed that species changed through time

Question 8

Given a population that contains genetic variation, what is the correct sequence of the following events under the influence of natural selection?
1) Well-adapted individuals leave more offspring than do poorly-adapted individuals.
2) A change occurs in the environment.
3) Genetic frequencies within the population change.
4) Poorly-adapted individuals have decreased survivorship.

A) 2 → 4 → 1 → 3
B) 4 → 2 → 1 → 3
C) 4 → 1 → 2 → 3
D) 4 → 2 → 3 → 1
E) 2 → 4 → 3 → 1

Question 9

Which of the pairs of plant structures below are homologous?

A) oak tree root and leaf
B) rose bush stem and flower
C) rose bush leaf and oak tree leaf
D) There are no homologous plant structures.

Question 10

About thirteen different species of finches inhabit the Galápagos Islands today, all descendants of a common ancestor from the South American mainland that arrived a few million years ago. Genetically, there are four distinct lineages, but the thirteen species are currently classified among three genera. The first lineage to diverge from the ancestral lineage was the warbler finch (genus Certhidea). Next to diverge was the vegetarian finch (genus Camarhynchus), followed by five tree finch species (also in genus Camarhynchus) and six ground finch species (genus Geospiza). If the six ground finch species have evolved most recently, then which of these is the most logical prediction?

A) They should be limited to the six islands that most recently emerged from the sea.
B) Their genomes should be more similar to each other than are the genomes of the five tree finch species.
C) They should share fewer anatomical homologies with each other than they share with the tree finches.
D) The chances of hybridization between two ground finch species should be less than the chances of hybridization between two tree finch species.

Question 11

Which piece of evidence supports the hypothesis shown in the "Within the artiodactyls" origin of the whale lineage, suggesting that the whale lineage diverged from the lineage leading to the hippos after the other members of the order Artiodactyla (pigs, camels, etc.) diverged?

A) A phylogeny of fossil cetaceans indicates that a gradual transition occurred between terrestrial forms and aquatic, whale-like forms.
B) DNA comparisons show that whales and hippos share more genetic sequences than whales share with other artiodactyls.
C) Some modern cetaceans have a vestigial pelvic girdle.
D) Whales arose from a terrestrial ancestor about 50 million years ago.
E) All artiodactyls other than whales share an unusual ankle bone called the astragalus.

Question 12

The following question(s) refer to the accompanying figure, which shows an outcrop of sedimentary rock whose strata are labeled A-D.
If x indicates the location of fossils of two closely related species, then fossils of their most recent common ancestor are most likely to occur in which stratum?

A) A
B) B
C) C
D) D

Question 13

The giant sloth described by Georges Cuvier suggests that ________.

A) organisms could not have originated by special creation
B) organisms could go extinct
C) the great flood or some other catastrophe caused the evolution of new species
D) the Earth is old enough for evolution to have occurred

Question 14

Similar gill pouches in embryos of a chick, human, and cat are an example of ________.

A) structural homology
B) developmental homology
C) genetic homology
D) the inheritance of acquired characters

Question 15

What must be TRUE of any organ described as vestigial?

A) It must be analogous to some feature in an ancestor.
B) It must be homologous to some feature in an ancestor.
C) It must be both homologous and analogous to some feature in an ancestor.
D) It need be neither homologous nor analogous to some feature in an ancestor.

Question 16

The same basic internal organs (kidneys, stomach, heart, lungs) are found in frogs, birds, snakes, and rodents. This is primarily an example of ________.

A) structural homology
B) developmental homology
C) genetic correlation
D) inheritance of acquired characteristics

Question 17

Which of the following, if discovered, could refute our current understanding of the pattern of evolution?

A) no fossils of soft-bodied animals
B) a modern bird having reptile-like scales on its legs
C) radioactive dating of rocks showing that rocks closer to the Earth's surface are younger than lower rock strata
D) diverse fossils of mammals in Precambrian rock

Question 18

Which of the following is the best modern definition of evolution?

A) descent with modification
B) change in the number of genes in a population over time
C) survival of the fittest
D) inheritance of acquired characters

Question 19

Fossils of Thrinaxodon, a species that lived during the Triassic period, have been found in both South Africa and Antarctica. Thrinaxodon had a reptile-like skeleton and laid eggs, but small depressions on the front of its skull suggest it had whiskers and, therefore, fur. Thrinaxodon may have been warm-blooded. The fossils of Thrinaxodon are consistent with the hypothesis that ________.

A) fossils found in a given area look like the modern species in that same area
B) the environment where it lived was very warm
C) mammals evolved from a reptilian ancestor
D) Antarctica and South Africa separated after Thrinaxodon went extinct

Question 20

Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, you notice that males with longer hair get more opportunities to mate and father more offspring. To test the hypothesis that having longer hair is adaptive in these males, you should ________.

A) test whether other traits in these males are also adaptive
B) look for evidence of hair in ancestors of tamarins
C) determine if hair length is heritable
D) test whether males with shaved heads are still able to mate

Question 21

Vestigial traits and neutral changes in DNA sequences are good examples of ________.

A) adaptation
B) acclimation
C) convergent traits
D) nonadaptive traits
E) none of the above

Question 22

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Instead, DDT is largely useless against many insects. Which of these would have prevented this evolution of DDT resistance in insect pests?

A) Larger doses of DDT should have been applied from the air, into water, and within the soil.
B) All habitats should have received applications of DDT at about the same time.
C) The frequency of DDT application should have been higher.
D) None of the insect pests would have genetic variations that resulted in DDT resistance.
E) DDT application should have been continual.

Question 23

Use the following information to answer the question below.
In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20 percent of the β hemoglobin alleles in the human gene pool.
The sickle-cell allele is pleiotropic (that is, it affects more than one phenotypic trait). Specifically, this allele affects oxygen delivery to tissues and affects one's susceptibility to malaria. Heterozygous individuals who have one normal and one sickle-cell allele have a phenotype that has both costs and benefits. The cost: Under conditions of low atmospheric oxygen availability, individuals heterozygous for this allele can experience life-threatening sickle-cell "crises." The benefit: Such individuals are less susceptible to malaria. Thus, pleiotropic genes/alleles reveal that ________.

A) new advantageous alleles do not arise on demand
B) evolution is limited by historical constraints
C) adaptations are often compromises
D) chance events can affect the evolutionary history of populations

Question 24

Researchers discovered that a new strain of bacteria that cause tuberculosis (M. tuberculosis) taken from a dead patient has a point mutation in the rpoB gene that codes for part of the RNA polymerase enzyme. This mutant form of RNA polymerase does not function as well as the more common form of RNA polymerase. A commonly used antibiotic called rifampin does not affect the mutant rpoB bacteria.
A researcher mixes M. tuberculosis with and without the rpoB mutation and adds the bacteria to cell cultures. Half the cell cultures contain only standard nutrients, while the other half of the cell cultures contain rifampin and the standard nutrients. After many cell generations, the researcher finds that ________.

A) very few M. tuberculosis in the standard nutrient cell cultures carry the rpoB gene mutation, but almost all of the M. tuberculosis in the cell cultures with rifampin carry the rpoB mutation
B) almost all M. tuberculosis in the standard nutrient cell cultures carry the rpoB gene mutation, but very few of the M. tuberculosis in the cell cultures with rifampin carry the rpoB mutation
C) very few M. tuberculosis in any of the cell cultures carry the rpoB gene mutation
D) almost all of the M. tuberculosis in both types of cell cultures carry the rpoB mutation
E) a mix of both M. tuberculosis strains thrive in the standard cell cultures, but no living bacteria can be found in the cell cultures that contain rifampin

Question 25

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is TRUE?

A) Each bird evolved a deeper, stronger beak as the drought persisted.
B) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.
C) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation.
D) The frequency of the strong-beak alleles increased in each bird as the drought persisted.

Question 26

Parasitic species tend to have simple morphologies. Which of the following statements best explains this observation?

A) Parasites evolved early, and this is why they have simple morphologies.
B) Parasites evolved simple morphologies in order to reproduce successfully in their hosts.
C) Simple morphologies convey some advantages in most parasites.
D) Parasites have simple morphologies to evade detection by their hosts.

Question 27

Biological fitness is best defined as

A) a heritable trait that increases the match of an individual to its environment.
B) variability in the population for a trait that increases survival.
C) the ability of an individual to produce offspring that survive and reproduce, relative to other individuals in the population.
D) competition among individuals for resources that allow them to have more offspring.
E) similar reproductive success among individuals in a population.

Question 28

If you say that a ground squirrel has greater evolutionary fitness than another ground squirrel in the same population, you mean that the animal

A) has a longer life.
B) is able to mate more frequently.
C) is able to dominate other squirrels to gain access to food.
D) has more offspring that survive and reproduce themselves.
E) All of the above statements are correct.

Question 29

Which of the following is a fitness trade-off (compromise)?

A) In some hornbill species, the male helps seal the female in a tree with her nest until the young are ready to fledge.
B) Hummingbirds are the best pollinators of certain flowers, but bees are the best pollinators for orchids.
C) The strong, thick beak of a woodpecker helps it find insects in trees.
D) Turtle shells provide protection but are heavy and burdensome when moving.

Question 30

The following question is based on information from Frank M. Frey, "Opposing Natural Selection from Herbivores and Pathogens May Maintain Floral-Color Variation in Claytonia virginica (Portulacaceae)," Evolution 58(11), 2004: 2426-37.
Claytonia virginica is a woodland spring herb with flowers that vary from white to pale pink to bright pink. Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical differences between the two), and plants experiencing severe herbivory are more likely to die. The bees that pollinate this plant also prefer pink to white flowers, so Claytonia with pink flowers have greater relative fruit set than Claytonia with white flowers. A researcher observes that the percentage of different flower colors remains stable in the study population from year to year. Given no other information, if the researcher removes all slugs from the study population, what do you expect to happen to the distribution of flower colors in the population over time?

A) The percentage of pink flowers should increase over time.
B) The percentage of white flowers should increase over time.
C) The distribution of flower colors should not change.
D) The distribution of flower colors should randomly fluctuate over time.

Question 31

A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these explanations best explains what happened?

A) The herbicide company lost its triazine formula and started selling poor-quality triazine.
B) Natural selection caused the pigweed to mutate, creating a new triazine-resistant species.
C) Triazine-resistant pigweed has less efficient photosynthesis metabolism.
D) Triazine-resistant weeds were more likely to survive and reproduce.

Question 32

After the drought of 1977, researchers hypothesized that on the Galápagos island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough T. cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?

A) evolution of yet larger, deeper beaks over time, until all birds have relatively large, deep beaks
B) evolution of smaller, pointier beaks over time, until all birds have relatively small, pointy beaks
C) increased variation in beak size and shape over time
D) no change in beak size and shape over time

Question 33

The following question(s) are based on information in Hopi E. Hoekstra, Kristen E. Drumm, and Michael W. Nachman, "Ecological Genetics of Adaptive Color Polymorphism in Pocket Mice: Geographic Variation in Selected and Neutral Genes," Evolution 58(6), 2004: 1329-41.
Refer to the figure above. In their investigation of natural selection on Mc1r alleles (the gene that determines coat color) in Arizona pocket mice, Hoekstra et al. determined the frequency of the D and d alleles in each population. They also determined the frequency of alleles for two neutral mitochondrial DNA genes (genes that do not affect and are not linked to coat color). Why did the researchers include the mitochondrial DNA genes as part of their experimental design?

A) Allele change for the neutral mitochondrial genes serves as an experimental group and gives information on any general background genetic difference among these populations.
B) Allele change for the neutral mitochondrial genes serves as a control and determines coat-color differences among these populations.
C) Allele change for the neutral mitochondrial genes serves as an experimental group and gives information on coat-color differences among these populations.
D) Allele change for the neutral mitochondrial genes serves as a control and gives information on any general background genetic difference among these populations.
E) None of the above answers applies.

Question 34

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, what would happen in environments that lack antibiotics?

A) These genes would be maintained in case the antibiotics appear.
B) These bacteria would be outcompeted and replaced by bacteria that have lost these genes.
C) These bacteria would try to make the cost worthwhile by locating and migrating to microenvironments where traces of antibiotics are present.
D) The number of genes conveying antibiotic resistance would increase in these bacteria.

Question 35

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do NOT seem to be optimally arranged because ________.

A) natural selection has not had sufficient time to create the optimal design in each case but will do so given enough time
B) in many cases, phenotype is determined by genotype and the environment
C) though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design
D) natural selection is generally limited to modifying structures that were present in previous generations and/or in previous species

Question 36

After the drought of 1977, researchers on the island of Daphne Major hypothesized that medium ground finches that had large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. If this hypothesis is correct, what would you expect to observe if a population of these medium ground finches colonizes a nearby island where T. cistoides is the most abundant food for the next 1000 years? Assume that (1) even the survivors of the 1977 drought sometimes had difficulty cracking the tough T. cistoides fruits and would eat other seeds when offered a choice; and (2) food availability is the primary limit on finch fitness on this new island.

A) evolution of yet larger, deeper beaks over time
B) evolution of smaller, pointier beaks over time
C) random fluctuations in beak size and shape
D) no change in beak size and shape

Question 37

The following question(s) are based on information in Hopi E. Hoekstra, Kristen E. Drumm, and Michael W. Nachman, "Ecological Genetics of Adaptive Color Polymorphism in Pocket Mice: Geographic Variation in Selected and Neutral Genes," Evolution 58(6), 2004: 1329-41.
The accompanying figure shows the distribution of pocket-mouse coat colors in several Arizona populations found either on light-colored granite substrate or on dark volcanic rock (dark substrate). The Melanocortin-1 receptor (Mc1r) alleles, D and d, differ by four amino acids. Mice with DD and Dd genotypes have dark coats, whereas mice with the dd genotype are light colored. What sort of genotype frequencies might you expect to find in the Xmas, Mid, and O'Neill populations?

A) Xmas-high DD frequency; Mid-high Dd frequency, O'Neill-high dd frequency
B) Xmas-high Dd frequency; Mid-high DD frequency, O'Neill-high dd frequency
C) Xmas-high Dd frequency; Mid-high dd frequency, O'Neill-high DD frequency
D) Xmas-high dd frequency; Mid-high Dd frequency, O'Neill-high DD frequency
E) Xmas-high dd frequency; Mid-high DD frequency, O'Neill-high Dd frequency

Question 38

Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

A) Natural selection cannot account for losses but accounts only for new structures and functions.
B) Natural selection accounts for these losses by the principle of use and disuse.
C) Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.
D) The ancestors of these organisms experienced harmful mutations that forced them to lose these structures.