Chapter 24: The Origin of Species

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1

Use the following information to answer the question(s) below.

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.

1) What keeps the two populations separate?

A) temporal reproductive isolation

B) lack of hybrid viability

C) behavioral reproductive isolation

D) habitat isolation

D

2

Use the following information to answer the question(s) below.

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.

2) The two populations are _____.

A) different subspecies, under the morphological species concept

B) different species, under the biological species concept

C) different species, under the phylogenetic species concept

A

3

3) Three populations of crickets look very similar, but the males have courtship songs that sound different. What function would this difference in song likely serve if the populations came in contact?

A) a temporal reproductive isolating mechanism

B) a postzygotic isolating mechanism

C) a behavioral reproductive isolating mechanism

D) a gametic reproductive isolating mechanism

C

4

4) Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall. They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season. Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species?

A) They must have strong postzygotic isolating mechanisms to spend winter in such close proximity.

B) They must have strong prezygotic isolating mechanisms to spend winter in such close proximity.

C) Their winter habitat has no bearing on their degree of reproductive isolation.

D) Reinforcement must be occurring when they winter together.

C

5

5) The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-nineteenth century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species?

A) Yes, because natural selection has affected the frequency of the two different forms.

B) Yes, because they have completely different coloration.

C) Yes, because they are reproductively isolated based on habitat.

D) No.

D

6

Use the following information to answer the question(s) below.

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus, were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. (N. Knowlton, L. A. Weigt, L. A. Solorzano, D. K. Mills, and E. Bermingham. 1993. Divergence in proteins, mitochondrial DNA, and reproductive incompatibility across the Isthmus of Panama. Science 260:1629-32.)

6) Refer to the paragraph about the formation of the Isthmus of Panama. The sister populations on opposite sides of the isthmus are true species under which species concept?

A) the morphological species concept

B) the biological species concept

C) the phylogenetic species concept

D) the morpholoogical species, biological species, and phylogenetic species concepts

D

7

Use the following information to answer the question(s) below.

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus, were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. (N. Knowlton, L. A. Weigt, L. A. Solorzano, D. K. Mills, and E. Bermingham. 1993. Divergence in proteins, mitochondrial DNA, and reproductive incompatibility across the Isthmus of Panama. Science 260:1629-32.)

7) The common edible frog of Europe is a hybrid between two species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when they mate among themselves, they are rarely successful in producing offspring. What can you infer from this information?

A) Postzygotic isolation exists between the two frog species.

B) Prezygotic isolation exists between the two frog species.

C) These two species are likely in the process of fusing back into one species.

D) The hybrids form a separate species under the biological species concept.

A

8

8) The approach to estimating phylogenetic trees is most like the approach of which species concept?

A) morphological species concept

B) biological species concept

C) phylogenetic species concept

C

9

9) Macroevolution is _____.

A) the same as microevolution, but includes the origin of new species

B) evolution above the species level

C) defined as the evolution of microscopic organisms into organisms that can be seen with the naked eye

D) defined as a change in allele or gene frequency over the course of many generations

B

10

10) Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?

A) phylogenetic

B) ecological

C) biological

D) morphological

C

11

11) There is still some controversy among biologists about whether Neanderthals should be placed within the same species as modern humans or into a separate species of their own. Most DNA sequence data analyzed so far indicate that there was probably little or no gene flow between Neanderthals and Homo sapiens. Which species concept is most applicable in this example?

A) phylogenetic

B) ecological

C) morphological

D) biological

D

12

12) You are confronted with a box of preserved grasshoppers of various species that are new to science and have not been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use?

A) biological

B) phylogenetic

C) ecological

D) morphological

D

13

13) Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?

A) temporal isolation

B) behavioral isolation

C) habitat isolation

D) gametic isolation

C

14

14) Rank the following in order from most general to most specific:

  1. gametic isolation
  2. reproductive isolating mechanism
  3. sperm-egg incompatibility in sea urchins
  4. prezygotic isolating mechanism

A) 2, 3, 1, 4

B) 2, 4, 1, 3

C) 4, 1, 2, 3

D) 4, 2, 1, 3

B

15

15) Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. These two frog species separate by _____.

A) reduced hybrid viability

B) hybrid breakdown

C) reduced hybrid fertility

D) gametic isolation

A

16

16) The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of _____.

A) reduced hybrid viability

B) hybrid breakdown

C) reduced hybrid fertility

D) mechanical isolation

C

17

17) Dogs (Canis lupus familiaris) and gray wolves (Canis lupus) can interbreed to produce viable, fertile offspring. These species shared a common ancestor recently (in geologic time) and have a high degree of genetic similarity, although their anatomies vary widely. Judging from this evidence, which two species concepts are most likely to place dogs and wolves together into a single species?

A) ecological and morphological

B) ecological and phylogenetic

C) biological and morphological

D) biological and phylogenetic

D

18

18) Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species. These two juniper species are kept separate by _____.

A) habitat isolation

B) temporal isolation

C) gametic isolation

D) behavioral isolation

C

19

19) What does the biological species concept use as the primary criterion for determining species boundaries?

A) geographic isolation

B) niche differences

C) gene flow

D) morphological similarity

C

20

20) The largest unit within which gene flow can readily occur is _____.

A) a population

B) a species

C) the entire range of a genus

D) the hybrid zone

B

21

Use the following information to answer the question(s) below.

About 3 million years ago, the Isthmus of Panama (a narrow strip of land connecting North and South America) formed, dividing marine organisms into Pacific and Caribbean populations. Researchers have examined species of snapping shrimp on both sides of the isthmus. Based on the morphological species concept, there appeared to be seven pairs of species, with one species of each pair in the Pacific and the other in the Caribbean. The different species pairs live at somewhat different depths in the ocean. Using mitochondrial DNA sequences, the researchers estimated phylogenies and found that each of these species pairs, separated by the isthmus, were indeed each other's closest relatives. The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other, and any that did mate almost never produced fertile offspring. (N. Knowlton, L. A. Weigt, L. A. Solorzano, D. K. Mills, and E. Bermingham. 1993. Divergence in proteins, mitochondrial DNA, and reproductive incompatibility across the Isthmus of Panama. Science 260:1629-32.)

21) Refer to the paragraph about the formation of the Isthmus of Panama. If the isthmus formed gradually rather than suddenly, what pattern of genetic divergence would you expect to find in these species pairs?

A) similar percentages of difference in DNA sequence between all pairs of sister species

B) greater percentage of difference in DNA sequence between species that inhabit deep water than between species that inhabit shallow water

C) greater percentage of difference in DNA sequence between species that inhabit shallow water than between species that inhabit deep water

B

22

22) Which of the following describes the most likely order of events in allopatric speciation?

A) genetic drift, genetic isolation, divergence

B) genetic isolation, divergence, genetic drift

C) divergence, genetic drift, genetic isolation

D) genetic isolation, genetic drift, divergence

D

23

23) You want to study divergence of populations, and you need to maximize the rate of divergence to see results within the period of your grant funding. You will form a new population by taking some individuals from a source population and isolating them so the two populations cannot interbreed. What combination of characteristics would maximize your chance of seeing divergence in this study?

  1. Choose a random sample of individuals to form the new population.
  2. Choose individuals from one extreme to form the new population.
  3. Choose a species to study that produces many offspring.
  4. Choose a species to study that produces a few, large offspring.
  5. Place the new population in the same type of environment as the source population.
  6. Place the new population in a novel environment compared to that of the source population.

A) 1, 3, and 6

B) 1, 4, and 6

C) 2, 3, and 5

D) 2, 3, and 6

D

24

24) How are two different species most likely to evolve from one ancestral species?

A) sympatrically, by a point mutation affecting morphology or behavior

B) sympatrically, due to extensive inbreeding

C) allopatrically, due to extensive inbreeding

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

D

25

25) House finches were found only in western North America until 1939, when a few individuals were released in New York City. These individuals established a breeding population and gradually expanded their range. The western population also expanded its range somewhat eastward, and the two populations have recently come in contact. If the two forms were unable to interbreed when their expanding ranges met, it would be an example of _____.

A) prezygotic isolation

B) reinforcement

C) allopatric speciation

D) sympatric speciation

C

26

26) Most causes of speciation are relatively slow, in that they may take many generations to see changes, with the exception of _____.

A) polyploidy

B) reinforcement

C) colonization

D) natural selection

A

27

27) Two researchers experimentally formed tetraploid frogs by fertilizing diploid eggs from Rana porosa brevipoda with diploid sperm from Rana nigromaculata. When they mated these tetraploid frogs with each other, most of the offspring that survived to maturity were tetraploid, with chromosome sets of both diploid parent species. Based on these results, if this type of tetraploid formed in the wild, what would be the result? (Y. Kondo and A. Kashiwagi. 2004. Experimentally induced autotetraploidy and allotetraploidy in two Japanese pond frogs. Journal of Herpetology 38(3):381-92.)

A) The two parent species would interbreed and fuse into one species.

B) The two parent species would recognize each other as mates.

C) The tetraploids would be reproductively isolated from both parent species.

D) The tetraploids would be selected against.

C

28

28) A researcher notices that in a certain moth species, some females prefer to feed and lay eggs on domesticated solanaceous plants like potatoes and tomatoes. Other females prefer to feed and lay eggs on wild solanaceous plants like Datura. Both male and female moths primarily use scent to find these plants from afar. Females tend to mate where they feed, and the researcher finds a genetic basis for scent preference in these moths. Based on the above information, what might be occurring in this moth species?

A) divergence in sympatry

B) divergence due to habitat fragmentation

C) postzygotic isolation

D) polyploidization

A

29

29) Two species of tree frogs that live sympatrically in the northeastern United States differ in ploidy: Hyla chrysoscelis is diploid, and Hyla versicolor is tetraploid. The frogs are identical in appearance, but their mating calls, which females use to find mates, differ. Which difference most likely evolved first?

A) polyploidy

B) difference in mating calls

C) Polyploidy and different mating calls must have evolved at the same time.

A

30

30) In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In the western United States, pronghorns and cattle often associate with one another in the same open rangeland. Some of these fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood. The host mammal can be considered as the fleas' habitat. If this situation persists, and new species evolve, this would be an example of _____.

A) sympatric speciation and habitat isolation

B) sympatric speciation and temporal isolation

C) allopatric speciation and habitat isolation

D) allopatric speciation and gametic isolation

A

31

31) The difference between geographic isolation and habitat differentiation (isolation) is the _____.

A) relative locations of two populations as speciation occurs

B) speed (tempo) at which two populations undergo speciation

C) amount of genetic variation that occurs among two gene pools as speciation occurs

D) identity of the phylogenetic kingdom or domain in which these phenomena occur

A

32

32) Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species?

A) allopatric speciation and sexual selection

B) allopatric speciation and polyploidy

C) sympatric speciation and sexual selection

D) sympatric speciation and polyploidy

D

33

33) Beetle pollinators of a particular plant are attracted to its flowers' bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in this example, and what has driven it?

A) allopatric speciation; ecological isolation

B) sympatric speciation; habitat differentiation

C) allopatric speciation; behavioral isolation

D) sympatric speciation; allopolyploidy

B

34

Use the following description to answer the question(s) below.

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about two hundred miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about fourteen million years ago.

34) Using only the information provided in the paragraph, which of the following is the best initial hypothesis for how D. santomea descended from D. yakuba?

A) allopolyploidy

B) autopolyploidy

C) habitat differentiation

D) sexual selection

C

35

Use the following description to answer the question(s) below.

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

35) Which two of the following have operated to increase divergence between mosquitofish populations on Andros?

  1. improved gene flow
  2. bottleneck effect
  3. sexual selection
  4. founder effect
  5. natural selection

A) 1 and 3

B) 2 and 3

C) 2 and 4

D) 3 and 5

D

36
card image

Use the following description to answer the question(s) below.

In the ocean, on either side of the Isthmus of Panama, are thirty species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are fifteen species on the Pacific side and fifteen different species on the Atlantic side. The Isthmus of Panama started rising about ten million years ago. The oceans were completely separated by the isthmus about three million years ago.

In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest.

36) Why should deepwater 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) Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deepwater shrimp.

C) 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.

D) 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.

A

37
card image

37) In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?

A) A3

B) A5

C) B4

D) either A3 or A5

C

38
card image

38) Which of these habitats is likely to harbor the most recently diverged species?

A) A5

B) B4

C) A3

D) A1

D

39

39) Which habitats should harbor snapping shrimp species with the greatest degree of genetic divergence from each other?

A) A1 and A5

B) A1 and B5

C) A5 and B5

D) Both A1/A5 and B1/B5 should have the greatest, but equal amounts of, genetic divergence.

C

40

40) Which factor is most important for explaining why there are equal numbers of snapping shrimp species on either side of the isthmus?

A) the relative shortness of time they have been separated

B) the depth of the ocean

C) the number of actual depth habitats between the surface and the sea floor

D) the elevation of the isthmus above sea level

A

41

41) The Panama Canal was completed in 1914, and its depth is about fifty feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?

A) A5 and B5

B) A3 and B3

C) A1 and B1

D) A1-A3 and B1-B3 have equal likelihoods of harboring snapping shrimp species that can hybridize.

C

42

42) Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be _____.

A) 14

B) 16

C) 28

D) 56

C

43

43) A small number of birds arrive on an island from a neighboring larger island. This small population begins to adapt to the new food plants available on the island, and their beaks begin to change. About twice a year, one or two more birds from the neighboring island arrive. These new arrivals _____.

A) speed up the process of speciation

B) tend to promote adaptation to the new food plants

C) tend to retard adaptation to the new food plants

D) represent a colonizing event

C

44

44) Male frogs give calls that attract female frogs to approach and mate. Researchers examined mating calls of closely related tree frogs in South America. If reinforcement is occurring, what would you expect if you compare the calls of the two species in zones of sympatry versus zones of allopatry?

A) Calls would be about the same in both areas.

B) Calls would be more similar in areas of sympatry.

C) Calls would be more different in areas of sympatry.

C

45

45) Male frogs give calls that attract female frogs to approach and mate. Researchers examined mating calls of closely related but separate species of tree frogs in South America. What outcomes could possibly occur where the ranges of two species overlap?

I) The species will interbreed, eventually fusing over time.

II) A stable hybrid zone will form if hybrids are better adapted to the area of overlap than either parent species is.

III) Species will continue to diverge and be isolated by behavioral or genetic mechanisms.

A) I

B) II

C) III

D) I, II, and III

D

46

46) Reinforcement is most likely to occur when _____.

A) the environment is changing

B) hybrids have lower fitness than either parent population

C) prezygotic isolating mechanisms are in place

D) gene flow is low

B

47

47) The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and _____.

A) an increasing number of infertile hybrids is produced over the course of the next one hundred generations

B) no reproduction occurs in the hybrid zone

C) an increasing number of viable, fertile hybrids is produced over the course of the next one hundred generations

D) a decreasing number of viable, fertile hybrids is produced over the course of the next one hundred generations

C

48

48) 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 mating occurs between members of two closely related species, producing viable offspring

C) a zone where sterile hybrids form, kept separate by postzygotic barriers

D) an area where members of two closely related species intermingle, but gene flow is prevented by prezygotic barriers

B

49

49) In hybrid zones where reinforcement is occurring, we should see a decline in _____.

A) gene flow between distinct gene pools

B) speciation

C) the genetic distinctness of two gene pools

D) mutation rates

A

50

50) Other than predation by introduced Nile perch, the most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is _____.

A) reinforcement

B) fusion

C) stability

D) polyploidy

B

51

51) A narrow hybrid zone separates the toad species Bombina bombina and Bombina variegata. What is true of those alleles that are unique to the parental species?

A) Such alleles should be absent.

B) Their allele frequency should be nearly the same as the allele frequencies in toad populations distant from the hybrid zone.

C) The alleles' heterozygosity should be higher among the hybrid toads than in toad populations distant from the hybrid zone.

D) Their allele frequency on one edge of the hybrid zone should roughly equal their frequency on the opposite edge of the hybrid zone.

C

52

Use the following description to answer the question(s) below.

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands, and is also found on the African mainland, located about two hundred miles away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species). Sao Tomé rose from the Atlantic Ocean about fourteen million years ago.

52) The observation that island D. yakuba are more closely related to mainland D. yakuba than island D. yakuba are to D. santomea is best explained by proposing that D. santomea _____.

A) descended from a now-extinct, non-African fruit fly

B) arrived on the island before D. yakuba

C) descended from a single colony of D. yakuba, which had been introduced from elsewhere, with no subsequent colonization events

D) descended from an original colony of D. yakuba, of which there are no surviving members. The current island D. yakuba represent a second colonization event from elsewhere.

D

53

Use the following description to answer the question(s) below.

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

53) What is the best way to promote fusion between two related populations of mosquitofish, one of which lives in a predator-rich pond and the other of which lives in a predator-poor pond?

A) Build a canal linking the two ponds that permits free movement of mosquitofish, but not of predators.

B) Transfer only female mosquitofish from a predator-rich pond to a predator-poor pond.

C) Perform a reciprocal transfer of females between predator-rich and predator-poor ponds.

D) Remove predators from a predator-rich pond and transfer them to a predator-poor pond.

A

54

54) Suppose that a group of male pied flycatchers migrated from a region where there were no collared flycatchers to a region where both species were present. Assuming events like this are very rare, which of the following scenarios is LEAST likely?

A) Migrant pied males would produce fewer offspring than would resident pied males.

B) Pied females would rarely mate with collared males.

C) Migrant males would mate with collared females more often than with pied females.

D) The frequency of hybrid offspring would decrease.

D

55

The following questions refer to this hypothetical situation.

A female fly, full of fertilized eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species, each of which eats only a certain type of food. None of the species can fly and their balancing organs (halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. The ranges of all of the daughter species overlap.

55) Fly species W, found in a certain part of the island, produces fertile offspring with species Y. Species W does not produce fertile offspring with species X or Z. If no other species can hybridize, then which of the following statements about species W and Y are true?

I) Species W and Y have genomes that are still similar enough for successful meiosis to occur in hybrid flies.

II) Species W and Y have more genetic similarity with each other than either did with the other two species.

III) Species W and Y may fuse into a single species if their hybrids remain fertile over the course of many generations.

A) Only I is correct.

B) Only II is correct.

C) Only III is correct.

D) I, II, and III are correct.

D

56

56) According to the concept of punctuated equilibrium, the "sudden" appearance of a new species in the fossil record means that _____.

A) the species is now extinct

B) speciation occurred in one generation

C) speciation occurred rapidly in geologic time

D) the species will consequently have a relatively short existence, compared with other species

C

57

57) According to the concept of punctuated equilibrium, _____.

A) natural selection is unimportant as a mechanism of evolution

B) given enough time, most existing species will gradually give rise to new species

C) a new species accumulates most of its unique features as it comes into existence

D) evolution of new species features long periods during which changes are occurring, interspersed with short periods of equilibrium, or stasis

C

58

58) Speciation _____.

A) occurs at such a slow pace that no one has ever observed the emergence of new species

B) occurs only by the accumulation of small genetic changes over vast expanses of time

C) must begin with the geographic isolation of a small, frontier population

D) can involve changes to a single gene

D

59

59) According to the biological species concept, for speciation to occur, _____.

A) the number of chromosomes in the gene pool must change

B) changes to centromere location or chromosome size must occur within the gene pool

C) large numbers of genes that affect numerous phenotypic traits must change

D) at least one gene, affecting at least one phenotypic trait, must change

D

60
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60) Which conclusion can be drawn from this evolutionary tree?

A) A single clade (that is, a group of species that share a common ancestor) can include species that formed by gradualism and other species that formed by punctuated equilibrium.

B) A single clade (that is, a group of species that share a common ancestor) will either include species that formed by gradualism or species that formed by punctuated equilibrium.

C) Assuming that the tip of each line represents a species, there are five extant (that is, not extinct) species resulting from the earliest common ancestor.

D) Species X and Z best represent species that evolved by punctuated equilibrium.

A