Question 1

In hybrid zones where reinforcement is occurring, we should see a decline in ________.

Accepted Answer

A)  gene flow between distinct gene pools 
B)  speciation 
C)  the genetic distinctness of two gene pools 
D)  mutation rates 
A)  gene flow between distinct gene pools 
B)  speciation 
C)  the genetic distinctness of two gene pools 
D)  mutation rates

Question 2

A hybrid zone is properly defined as ________.

Accepted Answer

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 
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

Question 3

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.

Accepted Answer

A)  1, 3, and 6 
B)  1, 4, and 6 
C)  2, 3, and 5 
D)  2, 3, and 6 
A)  1, 3, and 6 
B)  1, 4, and 6 
C)  2, 3, and 5 
D)  2, 3, and 6

Question 4

How can reproductive barriers form sympatric populations while their members remain in the same geographic area?

Accepted Answer

A)  increased gene flow 
B)  polyploidy 
C)  decreased sexual selection 
D)  habitat sharing 
A)  increased gene flow 
B)  polyploidy 
C)  decreased sexual selection 
D)  habitat sharing

Question 5

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?

Accepted Answer

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)  These two species mate in different climates. 
D)  Reinforcement must be occurring when they winter together. 
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)  These two species mate in different climates. 
D)  Reinforcement must be occurring when they winter together.

Question 6

The largest unit within which gene flow can readily occur is ________.

Accepted Answer

A)  a population 
B)  a species 
C)  the entire range of a genus 
D)  the hybrid zone 
A)  a population 
B)  a species 
C)  the entire range of a genus 
D)  the hybrid zone

Question 7

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?

Accepted Answer

A)  polyploidy 
B)  difference in mating calls 
C)  habitat differentiation 
D)  Polyploidy and different mating calls must have evolved at the same time. 
A)  polyploidy 
B)  difference in mating calls 
C)  habitat differentiation 
D)  Polyploidy and different mating calls must have evolved at the same time.

Question 8

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 ________.

Accepted Answer

A)  habitat isolation 
B)  temporal isolation 
C)  gametic isolation 
D)  behavioral isolation 
A)  habitat isolation 
B)  temporal isolation 
C)  gametic isolation 
D)  behavioral isolation

Question 9

According to the punctuated equilibria model,

Accepted Answer

A)  given enough time, most existing species will branch gradually into new species. 
B)  most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species. 
C)  most evolution occurs in sympatric populations. 
D)  speciation is usually due to a single mutation. 
A)  given enough time, most existing species will branch gradually into new species. 
B)  most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species. 
C)  most evolution occurs in sympatric populations. 
D)  speciation is usually due to a single mutation.

Question 10

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?

Accepted Answer

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)  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.

Question 11

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

Accepted Answer

A)  reduced hybrid viability 
B)  hybrid breakdown 
C)  reduced hybrid fertility 
D)  mechanical isolation 
A)  reduced hybrid viability 
B)  hybrid breakdown 
C)  reduced hybrid fertility 
D)  mechanical isolation

Question 12

Which of the following factors would not contribute to allopatric speciation?

Accepted Answer

A)  The separated population is small, and genetic drift occurs. 
B)  The isolated population is exposed to different selection pressures than the ancestral population. 
C)  Different mutations begin to distinguish the gene pools of the separated populations. 
D)  Gene flow between the two populations is extensive. 
A)  The separated population is small, and genetic drift occurs. 
B)  The isolated population is exposed to different selection pressures than the ancestral population. 
C)  Different mutations begin to distinguish the gene pools of the separated populations. 
D)  Gene flow between the two populations is extensive.

Question 13

The question refers to the following evolutionary tree, in which the horizontal axis represents time (present time is on the far right), and the vertical axis represents morphological change.
 
Which conclusion can be drawn from this evolutionary tree?

Accepted Answer

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)  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.

Question 14

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 describing species relationship between modern humans and Neanderthals is most applicable in these observations?

Accepted Answer

A)  genetic 
B)  ecological 
C)  morphological 
D)  biological 
A)  genetic 
B)  ecological 
C)  morphological 
D)  biological

Question 15

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

Accepted Answer

A)  genetic 
B)  ecological 
C)  biological 
D)  morphological 
A)  genetic 
B)  ecological 
C)  biological 
D)  morphological

Question 16

Use the following description to answer the question.
In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.
In the 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.
 
Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?

Accepted Answer

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)  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.

Question 17

Use the following information to answer the question.
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?

Accepted Answer

A)  temporal reproductive isolation 
B)  lack of hybrid viability 
C)  behavior isolates reproductive activities 
D)  habitat isolation 
A)  temporal reproductive isolation 
B)  lack of hybrid viability 
C)  behavior isolates reproductive activities 
D)  habitat isolation

Question 18

The largest unit within which gene flow can readily occur is a

Accepted Answer

A)  population. 
B)  species. 
C)  genus. 
D)  hybrid. 
A)  population. 
B)  species. 
C)  genus. 
D)  hybrid.

Question 19

Use the following description to answer the question.
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.
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?

Accepted Answer

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)  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.

Question 20

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 ________.

Accepted Answer

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)  sympatric speciation and habitat isolation 
B)  sympatric speciation and temporal isolation 
C)  allopatric speciation and habitat isolation 
D)  allopatric speciation and gametic isolation

Exam 24: The Origin of Species

In hybrid zones where reinforcement is occurring, we should see a decline in ________.

A hybrid zone is properly defined as ________.

How can reproductive barriers form sympatric populations while their members remain in the same geographic area?

The largest unit within which gene flow can readily occur is ________.

According to the punctuated equilibria model,

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

Which of the following factors would not contribute to allopatric speciation?

The question refers to the following evolutionary tree, in which the horizontal axis represents time (present time is on the far right), and the vertical axis represents morphological change. Which conclusion can be drawn from this evolutionary tree?

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

The largest unit within which gene flow can readily occur is a

Evolution, the Themes of Biology, and Scientific Inquiry

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Vascular Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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