1. 22
The Origin of Species

2. Cynotilapia afra, introduced at West Thumbi Island in Lake Malawi in the 1960s, has split into two genetically distinct populations, located at the north and south ends of the island. How can scientists determine whether these populations are now different species, according to the biological species concept?
See whether the two populations are morphologically different from each other: coloring, bone structure, and so on.
Determine whether captured individuals from the two different populations will mate and produce offspring in a laboratory fish tank.
Determine whether individuals from one population will interbreed with individuals from the other population when introduced into each other’s native habitats.
Answer: C
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3. Cynotilapia afra, introduced at West Thumbi Island in Lake Malawi in the 1960s, has split into two genetically distinct populations, located at the north and south ends of the island. How can scientists determine whether these populations are now different species, according to the biological species concept?
See whether the two populations are morphologically different from each other: coloring, bone structure, and so on.
Determine whether captured individuals from the two different populations will mate and produce offspring in a laboratory fish tank.
Determine whether individuals from one population will interbreed with individuals from the other population when introduced into each other’s native habitats.
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4. Cichlids in Lake Victoria are thought to have diversified from a relatively few species to 600 species in about 12,000 years (the last time the lake dried up). What is the best way to test this hypothesis?
Examine the fossil record in lake sediments.
Look for morphological characteristics shared among Lake Victoria species that are distinct from the species present in other lakes.
Look for genetic characteristics shared among Lake Victoria species that are distinct from species present in other lakes.
This is not a testable hypothesis.
Answer: C. A phylogenetic analysis should provide the most conclusive answer: The Lake Victoria species should form one or a few clades distinct from the clades in other African great lakes.
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5. Cichlids in Lake Victoria are thought to have diversified from a relatively few species to 600 species in about 12,000 years (the last time the lake dried up). What is the best way to test this hypothesis?
Examine the fossil record in lake sediments.
Look for morphological characteristics shared among Lake Victoria species that are distinct from the species present in other lakes.
Look for genetic characteristics shared among Lake Victoria species that are distinct from species present in other lakes.
This is not a testable hypothesis.
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6. In what type of environment is a scientist most likely to find examples of ongoing speciation?
areas that have a large range of altitudes, such as mountains and deep valleys
areas such as large plains that facilitate migration of animals
extreme physical environments that are marginal for supporting life
areas that are already species-rich
areas that have undergone recent environmental disturbance or change
Answer: E
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7. In what type of environment is a scientist most likely to find examples of ongoing speciation?
areas that have a large range of altitudes, such as mountains and deep valleys
areas such as large plains that facilitate migration of animals
extreme physical environments that are marginal for supporting life
areas that are already species-rich
areas that have undergone recent environmental disturbance or change
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8. Sea urchins are broadcast spawners: They release their gametes into the water without courtship. Which of these reproductive isolation mechanisms is most likely affecting sea urchins?
behavioral isolation or mechanical isolation
gametic isolation or temporal isolation
habitat isolation
Answer: B
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9. Sea urchins are broadcast spawners: They release their gametes into the water without courtship. Which of these reproductive isolation mechanisms is most likely affecting sea urchins?
behavioral isolation or mechanical isolation
gametic isolation or temporal isolation
habitat isolation
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10. You spot a sea snake while you are in a boat on the ocean and note how similar it looks to a snake that lives in central Illinois. However, you know that they are most likely separate species due to which of the following reproductive barriers?
behavioral isolation
gametic isolation
ecological/habitat isolation
temporal isolation
Answer: C. Snakes living in the ocean are most likely never going to come into contact with snakes living in the center of a continent.
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11. You spot a sea snake while you are in a boat on the ocean and note how similar it looks to a snake that lives in central Illinois. However, you know that they are most likely separate species due to which of the following reproductive barriers?
behavioral isolation
gametic isolation
ecological/habitat isolation
temporal isolation
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12. The century cactus flowers every 100 years
The century cactus flowers every 100 years. A similar cactus flowers every 50 years. If the 50-year-cactus pollen has the correct characteristics to fertilize the century cactus, which reproductive barrier will most likely be working against that possibility?
behavioral isolation
gametic isolation
ecological/habitat isolation
temporal isolation
Answer: D. They produce flowers on different schedules.
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13. The century cactus flowers every 100 years
The century cactus flowers every 100 years. A similar cactus flowers every 50 years. If the 50-year-cactus pollen has the correct characteristics to fertilize the century cactus, which reproductive barrier will most likely be working against that possibility?
behavioral isolation
gametic isolation
ecological/habitat isolation
temporal isolation
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14. Several species of amphibians are able to read and understand each other’s mating rituals, tend to be fertile at the same time, and are usually similar in size. However, when they attempt to mate, they never produce offspring. Which of the following barriers is most likely the cause of this?
behavioral isolation
gametic isolation
reduced hybrid fertility
hybrid breakdown
Answer: B. If they fail to create any offspring, gametic isolation would be the most likely cause. Options C and D are not correct because they refer to offspring that two separate species create. Option A is not correct because it was stated in the question that the mating rituals were working.
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15. Several species of amphibians are able to read and understand each other’s mating rituals, tend to be fertile at the same time, and are usually similar in size. However, when they attempt to mate, they never produce offspring. Which of the following barriers is most likely the cause of this?
behavioral isolation
gametic isolation
reduced hybrid fertility
hybrid breakdown
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16. The fossil record shows that species remain constant for long periods of time, but then speciation episodes occur rapidly. This is indicative of
gradualism.
punctuated equilibrium.
allopatric speciation.
sympatric speciation.
Answer: B. Punctuated equilibrium suggests that once the process of speciation begins, it can be completed relatively rapidly.
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17. The fossil record shows that species remain constant for long periods of time, but then speciation episodes occur rapidly. This is indicative of
gradualism.
punctuated equilibrium.
allopatric speciation.
sympatric speciation.
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18. When differentiating between two species of fish, you notice that one species stay near the surface and feed on floating algae, while the other species are bottom feeders. This is using the
morphological species concept.
ecological species concept.
phylogenetic species concept.
Answer: B. This is viewing species based on their ecological niche.
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19. When differentiating between two species of fish, you notice that one species stay near the surface and feed on floating algae, while the other species are bottom feeders. This is using the
morphological species concept.
ecological species concept.
phylogenetic species concept.
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20. Why is speciation a conceptual “bridge” between microevolution and macroevolution?
Speciation can be directly observed, whereas microevolution and macroevolution cannot.
Speciation links population-level phenomena to patterns of evolution above the species level.
Speciation leads to the tremendous diversity of life.
Answer: B
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21. Why is speciation a conceptual “bridge” between microevolution and macroevolution?
Speciation can be directly observed, whereas microevolution and macroevolution cannot.
Speciation links population-level phenomena to patterns of evolution above the species level.
Speciation leads to the tremendous diversity of life.
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22. Which aspect of population genetics is fundamental to the biological species concept?
mutation
selection
gene flow
genetic drift
Answer: C. This is a good question for transitioning between population genetics and speciation.
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23. Which aspect of population genetics is fundamental to the biological species concept?
mutation
selection
gene flow
genetic drift
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24. The most common means of identifying bacterial species is to use DNA sequencing of 16S rRNA genes. Which species concept is implicit in this approach?
biological species concept
morphological species concept
ecological species concept
phylogenetic species concept
Answer: D
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25. The most common means of identifying bacterial species is to use DNA sequencing of 16S rRNA genes. Which species concept is implicit in this approach?
biological species concept
morphological species concept
ecological species concept
phylogenetic species concept
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26. In a long-term evolution experiment using Escherichia coli, Richard Lenski and colleagues discovered a new strain that can use citrate as an energy source, whereas wild-type E. coli cannot. Some have claimed that this strain could be considered a new species. Such a claim would be based on what species concept?
biological species concept
morphological species concept
ecological species concept
phylogenetic species concept
Answer: C
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27. In a long-term evolution experiment using Escherichia coli, Richard Lenski and colleagues discovered a new strain that can use citrate as an energy source, whereas wild-type E. coli cannot. Some have claimed that this strain could be considered a new species. Such a claim would be based on what species concept?
biological species concept
morphological species concept
ecological species concept
phylogenetic species concept
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28. Enallagma ebrium and E. hageni are sister species of damselflies that occupy the same habitats. Males of each species will readily attempt to mate with the “wrong” females; however, incompatibility in secondary genital structures prevents interspecies hybridization. This is an example of what type of reproductive barrier?
temporal isolation
behavioral isolation
mechanical isolation
gametic isolation
Answer: C. There are lots of good images of damselfly secondary genitalia that one could include with this question.
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29. Enallagma ebrium and E. hageni are sister species of damselflies that occupy the same habitats. Males of each species will readily attempt to mate with the “wrong” females; however, incompatibility in secondary genital structures prevents interspecies hybridization. This is an example of what type of reproductive barrier?
temporal isolation
behavioral isolation
mechanical isolation
gametic isolation
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30. Ligers are the offspring of male lions and female tigers
Ligers are the offspring of male lions and female tigers. Most ligers die in utero or shortly after birth. Those that do survive are often sterile. Occasionally, ligers can produce live offspring, but those offspring are of poor health. How would you describe these facts in terms of reproductive barriers?
gametic isolation
reduced hybrid viability
reduced hybrid fertility
hybrid breakdown
Answer: B, C, D. This question allows for discussion of the inherent overlap and inter-relatedness of these three concepts.
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31. Ligers are the offspring of male lions and female tigers
Ligers are the offspring of male lions and female tigers. Most ligers die in utero or shortly after birth. Those that do survive are often sterile. Occasionally, ligers can produce live offspring, but those offspring are of poor health. How would you describe these facts in terms of reproductive barriers?
gametic isolation
reduced hybrid viability
reduced hybrid fertility
hybrid breakdown
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32. Which of the following phenomena could facilitate allopatric speciation?
founder effect
gene flow
allopolyploidy
hybrid zone
Answer: A
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33. Which of the following phenomena could facilitate allopatric speciation?
founder effect
gene flow
allopolyploidy
hybrid zone
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34. The marsh grass Spartina anglica is an allotetraploid species that originated in southern England around Its “parent” species are the European Spartina maritima, with a 2n = 60 karyotype, and the American Spartina alterniflora, with a 2n = 62 karyotype. How many chromosomes should Spartina anglica have?
either 30 or 31 61
122
244
Answer: C. This is a good example to lead into a discussion of the process of allopolyploidization.
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35. The marsh grass Spartina anglica is an allotetraploid species that originated in southern England around Its “parent” species are the European Spartina maritima, with a 2n = 60 karyotype, and the American Spartina alterniflora, with a 2n = 62 karyotype. How many chromosomes should Spartina anglica have?
either 30 or 31 61
122
244
© 2017 Pearson Education, Ltd.