Biology- Chapter 22; Evolution by Natural Selection

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

C) a vestigial trait

22. Evolution in a population of island iguanas can be caused by the following agent(s): A) gene flow. B) genetic drift. C) natural selection. D) All of the above can be agents. E) both natural selection and genetic drift.

D) All of the above can be agents.

65. The largest extinction, measured as a percentage of species that disappeared, occurred at the endof which geological period? A) Tertiary B) Cretaceous C) Silurian D) Permian E) Devonian

D) Permian

39. Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if TRUE, would be cause for this reclassification? A) The two forms are very similar in coloration. B) The two forms have many genes in common. C) The two forms have similar food requirements. D) The two forms interbreed often in nature, and their offspring have good survival and reproduction. E) The two forms live in similar habitats.

D) The two forms interbreed often in nature, and their offspring have good survival and reproduction.

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

D) Triazine-resistant weeds were more likely to survive and reproduce.

28. Which of the following statements best summarizes evolution by natural selection as it is viewed today? A) Evolution by natural selection is the differential survival and reproduction of the most-fit phenotypes. B) Evolution by natural selection is the descent of humans from the present-day great apes. C) Evolution by natural selection represents the result of selection for acquired characteristics. D) Evolution by natural selection is the production of adaptations that meet present and anticipated needs.

A) Evolution by natural selection is the differential survival and reproduction of the most-fit phenotypes.

66. How do mass extinctions differ from background extinctions? A) Mass extinctions cause a larger proportion of organisms to go extinct than background extinctions. B) Mass extinctions typically result from Hox gene mutations, and background extinctions typically result from changes in weather patterns. C) Mass extinctions occur over a longer period of time than background extinctions. D) Mass extinctions, but not background extinctions, are generally caused by competition.

A) Mass extinctions cause a larger proportion of organisms to go extinct than background extinctions.

40. should deep water shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp? A) They have been geographically isolated from each other for a longer time. B) Fresh water entering the ocean from the canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation. C) Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deepwater shrimp. D) The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp.

A) They have been geographically isolated from each other for a longer time.

58. Which of the following organisms would be most likely to fossilize? A) a common squirrel B) a rare worm C) a rare squirrel D) a common worm

A) a common squirrel

56. Some beetles and flies have antler-like structures on their heads, much like male deer do. The existence of antlers in beetle, fly, and deer species with strong male-male competition is an example of ________. A) convergent evolution B) a synapomorphy C) parsimony D) homology

A) convergent evolution

25. Cystic fibrosis is a genetic disorder in homozygous recessive (ff) humans that typically significantly reduces life expectancy. Over time, we would expect the f allele frequency to________ for this trait. A) decrease B) remain the same C) fluctuate D) increase

A) decrease

27. Currently, the only predators of Galápagos marine iguanas are Galápagos hawks. Iguana body size is not correlated with risk of hawk predation, although small iguanas can sprint faster than large iguanas. If predators (for example, cats) that preferentially catch and eat slower iguanas are introduced to the island, iguana body size is likely to ________ in the absence of other factors; the iguanas would then be under ________ selection. A) decrease; directional B) decrease; disruptive C) increase; directional D) increase; disruptive E) stay the same; stabilizing

A) decrease; directional

13. Similar gill pouches in embryos of a chick, human, and cat are an example of ________. A) developmental homology B) structural homology C) genetic homology D) the inheritance of acquired characters

A) developmental homology

45. Which of the following describes the most likely order of events in allopatric speciation? A) genetic isolation, genetic drift, divergence B) genetic drift, genetic isolation, divergence C) divergence, genetic drift, genetic isolation D) divergence, genetic isolation, genetic drift E) genetic isolation, divergence, genetic drift

A) genetic isolation, genetic drift, divergence

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

A) increased variation in beak size and shape over time

14. 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) genetic correlation C) developmental homology D) inheritance of acquired characteristics

A) structural homology

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

A) the ability of an individual to produce offspring that survive and reproduce, relative to other individuals in the population.

6. In the United States today, about half of the corn crop is genetically engineered with a protein that is toxic to corn borers, an insect pest of corn. Which of the following conditions would be necessary for evolution of resistance to the toxic protein to occur in the corn borer? A. The corn borer must have or generate (by mutation) heritable variation in resistance to the toxic protein. B. The resistant corn borers must survive better or reproduce more than non-resistant corn borers. C. The corn borers must experience unlimited success in their ability to survive or reproduce. D. The corn borers must experience no success in their ability to survive or reproduce. E. The corn borer must lack variation in resistance to the toxic protein.

A. The corn borer must have or generate (by mutation) heritable variation in resistance to the toxic protein.

67. Species in hot climates tend to _____ compared to species in cold climates. A.Have larger surface-to-volume ratios B.Be less colorful C.Experience less interspecific competition D.Have smaller surface-to-volume ratios E.Have less fear of humans

A.Have larger surface-to-volume ratios

59. Approximately how far back in time does the fossil record extend? A) 3.5 million years B) 3.5 billion years C) 5.0 billion years D) 5.0 million years

B) 3.5 billion years

42. Which of these habitats is likely to harbor the most recently diverged species? A) A4 and B4 B) A1 and B1 C) A2 and B2 D) A5 and B5 E) A3 and B3

B) A1 and B1

43. The Panama Canal was completed in 1914, and its depth is about 50 feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of thecanal? A) A5 and B5 B) A1 and B1 C) A3 and B3 D) either A1 and A2, or B1 and B2 E) A1A3 and B1B3 have equal likelihoods of harboring snapping shrimp species that canhybridize.

B) A1 and B1

23. 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 violates the Hardy Weinberg assumptions. D) It limits gene flow. E) It decreases the population's average fitness.

B) It does not change the population's allele frequencies.

3. The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data? A) whales are not properly classified as mammals B) Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy C) Genes mutate faster in whales than in humans or bats D) Forelimb evolution was adaptive in people and bats, but not in whales

B) Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy

47. Which of the following could be a vicariance event? A) Some insects get blown in a storm to a new mountain range, where they lay eggs. B) The level of water in a lake recedes, creating two lakes where there used to be one. C) Radiation near Chernobyl increases mutation rates, causing an increase in auto polyploidy. D) Global warming allows populations of mosquitoes to survive at higher elevations.

B) The level of water in a lake recedes, creating two lakes where there used to be one.

1. A group of small fish live in a lake with a uniformly light-brown sandy bottom. Most of the fish are light brown, but about 10% are mottled. This fish species is often prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction of what will happen to this fish population? A) The ratio of light brown to mottled will not change B) The proportion of mottled fish will increase over time. C) As the mottled fish are eaten, more mottled fish will be produced to fill the gap. D) There is no way to predict the result

B) The proportion of mottled fish will increase over time.

64. Whatever its ultimate cause(s), the Cambrian explosion is a prime example of ________. A) a large meteor impact B) adaptive radiation C) evolutionary stasis D) mass extinction

B) adaptive radiation

9. 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) dismissed the idea that species are constant and emphasized the importance of variation and change in populations C) proved that individuals acclimated to their environment over time D) was the first time a biologist had proposed that species changed through time

B) dismissed the idea that species are constant and emphasized the importance of variation and change in populations

29. Which of the following is most likely to produce an African butterfly species in the wild whose populations show two strikingly different color patterns? A) artificial selection B) disruptive selection C) sexual selection D) directional selection E) stabilizing selection

B) disruptive selection

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

B) evolution of yet larger, deeper beaks over time

61. Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception. A) vacant ecological niches B) genetic drift C) an adaptive radiation in a group of organisms (such as plants) that another group uses as food D) colonization of an isolated region that contains suitable habitat and few competitor species E) evolutionary innovation

B) genetic drift

26. 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 hypothesized that iguana size will________ as global warming gradually increases air and water temperatures in the Galápagos Islands. A) decrease B) increase C) stabilize around the mean body size D) remain unchanged (it is not clear that body size increases fitness)

B) increase

52. Phylogenetic trees constructed from evidence from molecular systematics are based on similarities in ________. A) biochemical pathways B) mutations to homologous genes C) the pattern of embryological development D) habitat and lifestyle choices E) morphology

B) mutations to homologous genes

30. Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. Which of the following terms best describes this situation? A) disruptive selection B) stabilizing selection C) artificial selection D) directional selection E) sexual selection

B) stabilizing selection

7. 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 incase 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

B) these bacteria would be outcompeted and replaced by bacteria that have lost these genes.

10. Which of the following most strongly supports the common origin of all life on Earth? All organisms ________. A) reproduce B) use essentially the same genetic code C) show heritable variation D) require energy E) evolve

B) use essentially the same genetic code

2. A farmer wishes to develop a strain of high-yield corn that is also resistant to drought. He has the following individuals from the current year's crop: Individual A—Yield: 179 bushels/acre; drought resistance: high Individual B—Yield: 220 bushels/acre; drought resistance: low Individual C—Yield: 185 bushels/acre; drought resistance: medium Individual D—Yield: 140 bushels/acre; drought resistance: high Individual E—Yield: 200 bushels/acre; drought resistance: medium Which of the following crosses would produce the highest corn yield with the highest resistance to drought? A. B and B B. A and E C. C and E D. A and B

B. A and E

69. Which term describes a trait that increases an individual's ability to survive in a particular environment? A. Fitness B. Adaptation C. Heritability D. Evolution

B. Adaptation

71. Which of the following statements is an accurate combination of postulates 3 and 4 of natural selection? A. Individuals experience uniform success in their ability to survive or reproduce. B. Individuals experience differential success in their ability to survive or reproduce. C. Individuals experience unlimited success in their ability to survive or reproduce. D. Individuals experience no success in their ability to survive or reproduce.

B. Individuals experience differential success in their ability to survive or reproduce.

41. In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4? A) either A3 or A5 B) A5 C) B4 D) A3 E) any species from any one of the side A habitats

C) B4

15. What must be TRUE of any organ described as vestigial? A) It need be neither homologous nor analogous to some feature in an ancestor. B) It must be both homologous and analogous to some feature in an ancestor. C) It must be homologous to some feature in an ancestor. D) It must be analogous to some feature in an ancestor.

C) It must be homologous to some feature in an ancestor.

54. Which of the following statements best describes the rationale for applying the principle of parsimony in constructing phylogenetic trees? A) The molecular clock validates the principle of parsimony. B) Parsimony allows the researcher to "root" the tree. C) Similarity due to common ancestry should be more common than similarity due to convergent evolution. D) The outgroup roots the tree, allowing the principle of parsimony to be applied.

C) Similarity due to common ancestry should be more common than similarity due to convergent evolution.

60. Upon being formed, oceanic islands, such as the Hawaiian Islands, should feature what characteristic, leading to which phenomenon? A) adaptive radiation, leading to founder effect B) mass extinctions, leading to bottleneck effect C) a variety of empty ecological niches, leading to adaptive radiation D) overcrowding, leading to rafting to nearby lands E) major evolutionary innovations, leading to rafting to nearby continents

C) a variety of empty ecological niches, leading to adaptive radiation

57. Ichthyosaurs, now extinct, were aquatic reptiles with dorsal fins and tails, similar to those offish. Their most recent ancestors were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are ________. A) adaptations to different environments B) adaptations to a common environment and homologous structures C) adaptations to a common environment and examples of convergent evolution D) homologous structures

C) adaptations to a common environment and examples of convergent evolution

44. Which process led to the formation of the species pairs of Pacific and Caribbean snapping shrimp? A) sympatric speciation by vicariance B) sympatric speciation by dispersal C) allopatric speciation by vicariance D) allopatric speciation by dispersal

C) allopatric speciation by vicariance

49. A hybrid zone is properly defined as ________. A) an area where the ranges of two closely related species overlap, but do not interbreed B) an area where members of two closely related species intermingle, but gene flow is prevented by prezygotic barriers C) an area where mating occurs between members of two closely related species, producing viable offspring D) a zone where sterile hybrids form, kept separate by postzygotic barriers

C) an area where mating occurs between members of two closely related species, producingviable offspring

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

C) determine if hair length is heritable

36. Two populations of birds with somewhat different coloration live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds. When birds from the two populations are brought together, they produce young whose appearance is intermediate between the two parents. These offspring will breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees. The two populations are ________. A) different species, under the biological species concept B) different species, under the phylogenetic species concept C) different subspecies, under the morphological species concept D) none of the above.

C) different subspecies, under the morphological species concept

31. Soon after the island of Hawaii rose above the sea surface (somewhat less than 1 million years ago) and organisms colonized the island, the evolution of life on this new island should have been most strongly influenced by ________. A) habitat differentiation B) a genetic bottleneck C) founder effects D) sexual selection

C) founder effects

48. Which of the following does NOT tend to promote speciation? A) natural selection B) the founder effect C) gene flow D) polyploidy E) disruptive selection

C) gene flow

35. Two populations of birds with somewhat different coloration live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds. When birds from the two populations are brought together, they produce young whose appearance is intermediate between the two parents. These offspring will breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees. What keeps the two populations separate? A) behavioral reproductive isolation B) lack of hybrid viability C) habitat isolation D) temporal reproductive isolation

C) habitat isolation

8. Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, which develop from similar embryonic tissues. These structural similarities are an example of _____. A) the evolution of similar appearance as a result of common function B) the evolution of common structure as a result of common function C) homology D) convergent evolution

C) homology

51. The approach to estimating phylogenetic trees is most like the approach of which speciesconcept? A) subspecies concept B) morphological species concept C) phylogenetic species concept D) biological species concept

C) phylogenetic species concept

24. When nonrandom mating occurs in a population so that individuals prefer to mate with similar individuals, allele frequencies should A) remain the same, at Hardy Weinberg equilibrium. B) change and heterozygotes will be overrepresented in the population. C) remain the same, but homozygotes will be overrepresented in the population. D) remain the same, but heterozygotes will be overrepresented in the population. E) change and homozygotes will be overrepresented in the population.

C) remain the same, but homozygotes will be overrepresented in the population.

53. Your professor wants you to construct a phylogenetic tree of orchids. She gives you tissue from seven orchid species and one lily. What is the most likely reason she gave you the lily? A) to see if the lily is a cryptic orchid species B) to demonstrate likely homoplasies C) to serve as an outgroup D) to see if the lily and the orchids show all the same shared derived characters(synapomorphies)

C) to serve as an outgroup

5. What happened in the soapberry bug population in central Florida when the bugs began to feed on smaller golden rain tree fruits? A. The length of each bug's beak gradually became shorter over time. B. Bugs developed short beaks, because they needed them to feed on the small fruits. C. Bugs with shorter beaks had more access to food, allowing them to produce more offspring.

C. Bugs with shorter beaks had more access to food, allowing them to produce more offspring.

4. Soapberry bugs use needlelike "beaks" to feed on seeds within the fruits of various plants. Bugs feed most successfully when their beak length matches the size of the fruit on which they are feeding. For 25 years, populations of soapberry bugs in central Florida have been feeding on small golden rain tree fruits that were introduced to the area, rather than on the larger native balloon vine fruits that serve as food for other soapberry bug populations. Beak lengths of soapberry bugs are variable, but the average beak length is shorter in soapberry bug populations that feed on golden rain tree fruits than in populations that feed on balloon vine fruits, as shown in the graph. How does natural selection act on beak length in soapberry bug populations? A. Natural selection increases beak length in soapberry bug populations. B. Natural selection decreases beak length in soapberry bug populations. C. The action of natural selection on beak length in soapberry bug populations varies with the environment.

C. The action of natural selection on beak length in soapberry bug populations varies with the environment.

70. Which of these lists contains the four postulates of natural selection? A. Uniform population, heritable traits, selection, differential survival or reproduction B. Variation in population, heritable variation, selection, unlimited survival and reproduction C. Variation in population, heritable variation, selection, differential survival or reproduction D. Variation in population, environmental variation, selection, differential survival or reproduction

C. Variation in population, heritable variation, selection, differential survival or reproduction

46. How are two different species most likely to evolve from one ancestral species? A) sympatrically, due to extensive inbreeding B) sympatrically, by a point mutation affecting morphology or behavior C) allopatrically, due to extensive inbreeding D) allopatrically, after the ancestral species has split into two populations

D) allopatrically, after the ancestral species has split into two populations

38. Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent? A) temporal isolation B) gametic isolation C) habitat isolation D) behavioral isolation

D) behavioral isolation

33. Which of the following is the most predictable outcome of increased gene flow between two populations? A) increased genetic difference between the two populations B) higher average fitness in both populations C) increased genetic drift D) decreased genetic difference between the two populations E) lower average fitness in both populations

D) decreased genetic difference between the two populations

37. What does the biological species concept use as the primary criterion for determining species boundaries? A) morphological similarity B) geographic isolation C) molecular (DNA, RNA, protein) similarity D) gene flow E) niche differences

D) gene flow

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

D) has more offspring that survive and reproduce themselves.

11. The giant sloth described by Georges Cuvier suggests that ________. A) organisms could not have originated by special creation B) the Earth is old enough for evolution to have occurred C) the great flood or some other catastrophe caused the evolution of new species D) organisms could go extinct

D) organisms could go extinct

68. In the Andes, at elevations of 12,000 feet, Darwin collected fossilized marine shells. The existence of marine shells at this altitude provided evidence that _____. A.Earth's surface does not change B.Geologic Processes occur at a rapid rate C.Marine organisms can survive at great elevation D.The deposit had been gradually uplifted to its present location E.Someone carried them from the oceans and left them on the mountains.

D. The deposit had been gradually uplifted to its present location

32. An earthquake decimates a ground-squirrel population, killing 98 percent of the squirrels. 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) disruptive selection D) directional selection E) a genetic bottleneck

E) a genetic bottleneck

62. All of the following events can trigger an adaptive radiation EXCEPT ________. A) the evolution of a new morphological feature B) Hox gene duplication events C) the colonization of a new habitat D) the extinction of competitors E) an unusual event splitting a habitat, such as a severe hurricane

E) an unusual event splitting a habitat, such as a severe hurricane

55. To apply parsimony to constructing a phylogenetic tree, ________. A) base phylogenetic trees only on the fossil record, as this provides the simplest explanation for evolution B) choose the tree in which the branch points are based on as many shared derived characters as possible C) choose the tree that assumes all evolutionary changes are equally probable D) choose the tree with the fewest branch points E) choose the tree that represents the fewest evolutionary changes, either in DNA sequences or morphology

E) choose the tree that represents the fewest evolutionary changes, either in DNA sequencesor morphology

50. In hybrid zones where reinforcement is occurring, you should see a decline in ________. A) speciation B) the genetic distinctness of two gene pools C) mutation rates D) hybrid sterility E) gene flow between distinct gene pools

E) gene flow between distinct gene pools

63. Which statement is most consistent with the hypothesis that the Cambrian explosion was causedby the rise of predator-prey relationships? The fossil record reveals an increased incidence of________. A) larger animals B) fern galls C) worm burrows D) organic material E) hard parts

E) hard parts

34. Mutation is the only evolutionary mechanism that ________. A) is more important in eukaryotes than in prokaryotes B) does little to change allele frequencies C) decreases fitness D) has no effect on genetic variation E) is the ultimate source of variation in natural populations

E) is the ultimate source of variation in natural populations

72. The wing of a bat is homologous to the _____ of a whale. A. Rib cage B. Baleen C. Blowhole D. Tail E. Flipper

E. Flipper