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Scientists studying a group of related bird species on an island archipelago discover that these species are always more closely related to each other within an island than they are between any two islands.The most likely explanation for this result is that


A) each bird species evolved different adaptations in allopatry and then colonized the other islands.
B) one bird species colonized each island and then evolved into distinct species on that island through character displacement.
C) each bird species became reproductively isolated by living on a different island, then later colonized the other islands and acquired new adaptations.
D) many ancestral bird species colonized each island.

E) All of the above
F) B) and C)

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Courtship for Anolis lizards involves the male displaying a dewlap (skin under the throat area) that varies in appearance based upon the species.Lizards that are found in darker, more shaded environments will have dewlaps that are lighter in color because they are more noticeable by potential mates.Which of the following mechanisms best explains how speciation is at work in this example?


A) Postzygotic isolation
B) Reinforcement
C) Genetic drift
D) Natural selection

E) A) and B)
F) All of the above

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Males of many marsupial species have forked penises that are incompatible with the anatomy of female placental mammals.What type of isolating mechanism does this represent?


A) ecological isolation
B) temporal isolation
C) mechanical incompatibility
D) hybrid sterility

E) B) and D)
F) A) and D)

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Many male songbirds have very distinctive songs that are used to attract females.These songs are an example of a ________ isolating mechanism.


A) postzygotic, ecological
B) prezygotic, behavioral
C) prezygotic, temporal
D) postzygotic, mechanical

E) A) and B)
F) All of the above

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Due to character displacement, two closely related species may differ most morphologically when they


A) are allopatric.
B) are sympatric.
C) occupy the same niche.
D) occupy different niches.

E) None of the above
F) A) and C)

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If a new species is produced by the interbreeding of two members of distinct species, this would be __________ speciation achieved via _________.


A) allopatric; autopolyploidy
B) allopatric; allopolyploidy
C) sympatric; autopolyploidy
D) sympatric; allopolyploidy

E) All of the above
F) A) and D)

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D

According to the biological species concept, two groups of organisms that are unable to form fertile, viable hybrids are considered to be different


A) races.
B) species.
C) kingdoms.
D) hybrids.

E) A) and B)
F) A) and C)

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Evolution acts at the level of the


A) ecosystem.
B) population.
C) species.
D) community.

E) A) and B)
F) A) and C)

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Scientists observed that marine bryozoan fossils lack intermediate forms.This evidence supports which hypotheses? Check all that apply.__X__ Evolution occurs in spurts, alternating with long periods of little change._____ Evolution proceeds steadily, with gradual, incremental change in a given evolutionary line.__X__ There is variability in the rate of evolution._____ Evolution proceeds at a constant rate that is the same for all organisms.

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Reflect on Process
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Several species of sea urchins may inhabit the same tide pool and their reproductive periods overlap.Although they practice external fertilization, they seldom interbreed because eggs produce chemicals that are only attractive to sperm of their own species.This is an example of a _________ barrier that _______________.


A) prezygotic; causes geographic isolation
B) prezygotic; causes temporal isolation
C) prezygotic; prevents gamete fusion
D) postzygotic; prevents zygote fusion

E) A) and B)
F) A) and C)

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If two species are able to mate and produce an offspring which can mate with itself, but is unable to mate with either parent's species, it is an example of


A) allopatric speciation.
B) sympatric speciation via disruptive selection.
C) sympatric speciation via polyploidy.
D) a species cluster.

E) None of the above
F) B) and D)

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C

The __________ __________ model assumes that evolution occurs in spurts, between which there are long periods of stasis with little evolutionary change.

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punctuated equilibrium

Very rapid speciation occurred when cichlid fishes were isolated in Lake Victoria.Widespread extinction was dramatically seen when


A) artificial selection stopped.
B) predatory fish were added.
C) hybridization stopped.
D) fishing was prohibited.

E) All of the above
F) B) and C)

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Several new tetraploid species of a plant called salsify (Tragopogon) known as salsify have arisen in western North America.These new species each arose from a diploid species that went through the process of allopolyploidy.This mode of speciation is a type of ________ and it occurs _______.


A) allopatric speciation; almost instantaneously
B) allopatric speciation; very slowly
C) sympatric speciation; almost instantaneously
D) sympatric speciation; very slowly

E) All of the above
F) C) and D)

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Adaptive radiation is best described as the


A) existence of groups of closely related species recently evolved from a common ancestor.
B) existence of groups of distantly related species recently evolved from a common ancestor.
C) existence of groups of closely related species recently evolved from different ancestors through hybridization.
D) existence of individuals of closely related species that originated in different areas within diverse habitats, but that have rejoined as a single species.

E) A) and B)
F) A) and C)

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Choose the best cause and effect sequence for the process of speciation by natural selection.


A) Variation --> Selection --> Reproductive Isolation --> Mutation --> Speciation
B) Mutation --> Variation --> Selection --> Reproductive Isolation --> Speciation
C) Speciation --> Reproductive Isolation --> Selection --> Mutation --> Variation
D) Variation --> Reproductive Isolation --> Speciation --> Mutation --> Selection

E) All of the above
F) None of the above

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Two bird species have different mating calls, occupy different habitats in nature, and when they hybridize, the hybrids are infertile.Which isolating mechanisms maintain these species?


A) ecological isolation, behavioral isolation, and hybrid sterility
B) mechanical isolation, hybrid sterility, geographical isolation
C) ecological isolation, mechanical isolation, hybrid sterility
D) geographical isolation, temporal isolation, behavioral isolation

E) A) and B)
F) All of the above

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Reinforcement is most likely to drive the evolution of


A) prezygotic isolating mechanisms, because selection favors alleles that prevent hybridization.
B) postzygotic isolating mechanisms, because selection acts after the formation of hybrids.
C) prezygotic isolating mechanisms, because selection favors alleles that promote hybridization.
D) postzygotic isolating mechanisms, because hybrids have low fitness relative to the parents.

E) C) and D)
F) A) and C)

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Two populations that inhabit the same area but remain genetically distinct can best be called


A) species.
B) subspecies (races) .
C) polymorphic.
D) allopatric species.

E) B) and C)
F) None of the above

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The most common mechanism for sympatric speciation in plants is


A) polyploidy.
B) geographic isolation.
C) spontaneous mutation.
D) punctuated equilibrium.

E) A) and B)
F) A) and C)

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