BIO 148 Unit 7 Practice Exam
Questions and Correct Answers.
You encounter two birds living in the same tree. One is brightly colored; the other has a more
drab coloration. Other features of the two birds are very similar. Based on DNA sequence
analysis, the birds are in the same clade. The two birds’ mate and have fertile offspring. Which
of the following is the most likely to be true?
a. The birds are different species under the Biological Species Concept
b. The birds are different species under the Morphological Species Concept
c. The birds are different species under the Phylogenetic Species Concept
d. Color is a sexual dimorphic trait of the birds - Answer D; The most likely explanation is that
this is a male and female from the same species
Which of the following does NOT promote divergence between two populations?
a. founder effect
b. vicariance events
c. natural selection
d. gene flow - Answer D; Gene flow between two populations will make them more similar
Which of the following describes the most likely order of events in allopatric speciation if
genetic drift is the main mechanism responsible for changes in allele frequency over time?
a. geographic separation, genetic drift, reproductive isolation
b. reproductive isolation, geographic separation, genetic drift
c. genetic drift, geographic separation, reproductive isolation d. geographic separation,
reproductive isolation, genetic drift e. genetic drift, reproductive isolation, geographic isolation -
Answer A
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 interbreed often in nature, and their offspring survive and reproduce.
b. The two forms live in similar habitats.
c. The two forms have many genes in common.
d. The two forms have similar food requirements.
e. The two forms are very similar in coloration. - Answer A
, A species of sawflies feed, mate, and lay eggs on white pine trees. Within a single population, it
has been observed that some of these sawflies are starting to feed, mate, and lay eggs on red
pine trees in the same geographical area. After many generations, matings between flies that
live on white pines and flies that live on red pines produce offspring with low fitness. What is
the most likely explanation for the low fitness of the hybrid offspring? The population is in the
process of
a. Allopatric speciation
b. Sympatric speciation
c. Vicariance
d. Dispersal - Answer B; Since they are living in the same geographical area, this is an
example of divergence in sympatry
Rising sea levels flood an island such that only the tops of the mountains are now above sea
level. A large population of birds is now divided into multiple populations on each of the newly
formed islands. The birds cannot fly across the sea between islands. Warming temperatures
maintain the sea levels for thousands of years causing the bird populations to become separate
species. This is best described as...
a. isolation by dispersal
b. isolation by vicariance
c. a form of sympatric speciation
d. a form of speciation due to polyploidy
e. a form of speciation due to continued gene flow - Answer B; This is an example of physical
splitting of a habitat, or vicariance
Which of the following factors would contribute to speciation after two populations are created
from one by an allopatric mechanism?
a. One of the populations is small and genetic drift causes dramatic change in allele frequencies
in this population.
b. The two populations are exposed to different natural selection pressures.
c. Gene flow between the two populations is extensive.
d. A and B
e. A, B and C - Answer D; Both genetic drift and natural selection can result in divergence
between two populations
Leopard frogs and wood frogs are closely related species that maintain reproductive isolation
via different breeding periods; this is an example of _______ isolation mechanism. If fertilization
is made to occur in a laboratory, the resulting zygotes are not viable, which further maintains
the two as separate species as a result of this ______ isolation mechanism.
a. postzygotic; postzygotic
b. prezygotic; prezygotic
Questions and Correct Answers.
You encounter two birds living in the same tree. One is brightly colored; the other has a more
drab coloration. Other features of the two birds are very similar. Based on DNA sequence
analysis, the birds are in the same clade. The two birds’ mate and have fertile offspring. Which
of the following is the most likely to be true?
a. The birds are different species under the Biological Species Concept
b. The birds are different species under the Morphological Species Concept
c. The birds are different species under the Phylogenetic Species Concept
d. Color is a sexual dimorphic trait of the birds - Answer D; The most likely explanation is that
this is a male and female from the same species
Which of the following does NOT promote divergence between two populations?
a. founder effect
b. vicariance events
c. natural selection
d. gene flow - Answer D; Gene flow between two populations will make them more similar
Which of the following describes the most likely order of events in allopatric speciation if
genetic drift is the main mechanism responsible for changes in allele frequency over time?
a. geographic separation, genetic drift, reproductive isolation
b. reproductive isolation, geographic separation, genetic drift
c. genetic drift, geographic separation, reproductive isolation d. geographic separation,
reproductive isolation, genetic drift e. genetic drift, reproductive isolation, geographic isolation -
Answer A
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 interbreed often in nature, and their offspring survive and reproduce.
b. The two forms live in similar habitats.
c. The two forms have many genes in common.
d. The two forms have similar food requirements.
e. The two forms are very similar in coloration. - Answer A
, A species of sawflies feed, mate, and lay eggs on white pine trees. Within a single population, it
has been observed that some of these sawflies are starting to feed, mate, and lay eggs on red
pine trees in the same geographical area. After many generations, matings between flies that
live on white pines and flies that live on red pines produce offspring with low fitness. What is
the most likely explanation for the low fitness of the hybrid offspring? The population is in the
process of
a. Allopatric speciation
b. Sympatric speciation
c. Vicariance
d. Dispersal - Answer B; Since they are living in the same geographical area, this is an
example of divergence in sympatry
Rising sea levels flood an island such that only the tops of the mountains are now above sea
level. A large population of birds is now divided into multiple populations on each of the newly
formed islands. The birds cannot fly across the sea between islands. Warming temperatures
maintain the sea levels for thousands of years causing the bird populations to become separate
species. This is best described as...
a. isolation by dispersal
b. isolation by vicariance
c. a form of sympatric speciation
d. a form of speciation due to polyploidy
e. a form of speciation due to continued gene flow - Answer B; This is an example of physical
splitting of a habitat, or vicariance
Which of the following factors would contribute to speciation after two populations are created
from one by an allopatric mechanism?
a. One of the populations is small and genetic drift causes dramatic change in allele frequencies
in this population.
b. The two populations are exposed to different natural selection pressures.
c. Gene flow between the two populations is extensive.
d. A and B
e. A, B and C - Answer D; Both genetic drift and natural selection can result in divergence
between two populations
Leopard frogs and wood frogs are closely related species that maintain reproductive isolation
via different breeding periods; this is an example of _______ isolation mechanism. If fertilization
is made to occur in a laboratory, the resulting zygotes are not viable, which further maintains
the two as separate species as a result of this ______ isolation mechanism.
a. postzygotic; postzygotic
b. prezygotic; prezygotic
