Question 1

Why is speciation by polyploidy more likely in plants than in animals?
A)Plant gametes can be produced from somatic cells that have undergone many rounds of mitosis.
B)Plant gametes lack postzygotic isolating mechanisms.
C)Plants are sessile and,therefore,are never prezygotically isolated to ensure reproduction.
D)Plants are sessile and cannot speciate via dispersal.
E)Plants lack the DNA repair enzymes that animals have.

Accepted Answer

Polyploidy, or having extra sets of chromosomes, can occur in plants when their somatic cells undergo multiple rounds of mitosis without cytokinesis, resulting in a cell with multiple sets of chromosomes. These cells can then develop into viable gametes, leading to the formation of a new species. This process is much less likely to occur in animals, as their somatic cells do not readily produce gametes.

Answer: D
 Plants are sessile, meaning they cannot move from one location to another. This makes it more difficult for them to disperse to new areas and for populations of the same species to become geographically isolated from one another. Polyploidy can create a mechanism for speciation within a population of plants that are unable to disperse to new areas.

Question 2

You want to study divergence of populations,and you need to maximize the rate of divergence in order 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
E)2,4,and 6

Accepted Answer

Choosing individuals from one extreme to form the new population (option 2) would increase the likelihood of rapid divergence. Additionally, choosing a species that produces a few, large offspring (option 4) would also help to speed up divergence as there would be fewer interruptions due to interbreeding. Finally, placing the new population in a novel environment compared to that of the source population (option 6) would help to accelerate divergence as different selection pressures may cause different adaptations in the two populations. Option 3 is not necessarily relevant to maximizing divergence, as producing many offspring does not drive fast evolutionary changes. Option 1 is also not ideal as randomly selecting individuals may not necessarily lead to extreme or divergent traits. Option 5 may slow divergence as the two populations may continue to face the same uniform selection pressures.

Question 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 prezygotic isolating mechanism
B)a postzygotic isolating mechanism
C)a behavioral reproductive isolating mechanism
D)a gametic reproductive isolating mechanism
E)two of the above

Accepted Answer

The difference in courtship songs would serve as a prezygotic isolating mechanism (A) and a behavioral reproductive isolating mechanism (C), preventing interbreeding by ensuring that females only mate with males of their own population.

Question 4

The theory of plate tectonics describes movement of plates of the Earth's crust through time.Which of the following can you deduce from what you learned in this chapter about plate tectonics?
A)The continental plates have stopped moving,so continents are now in their final locations.
B)Some other organisms must have speciation patterns similar to those of ratites due to plate tectonics.
C)All distributions of animals on land can be explained by vicariance events due to past plate movements.
D)None of the above statements is true.

Accepted Answer

Plate tectonics can lead to speciation patterns in organisms, similar to those observed in ratites, due to the separation and movement of land masses.

Question 5

Most causes of speciation are relatively slow,in that they may take many generations of organism to see changes,except _____.
A)polyploidy
B)vicariance
C)colonization
D)natural selection

Accepted Answer

Polyploidy is a relatively rapid form of speciation. It occurs when an organism has more than two sets of chromosomes, typically due to a failure in cell division during meiosis. The resulting offspring can be reproductively isolated from their parent species and may undergo rapid evolution, leading to speciation.

Question 6

The two populations are _____.
A)different subspecies,under the morphospecies concept
B)different species,under the biological species concept
C)different species,under the phylogenetic species concept
D)all of the above

Accepted Answer

The answer of The two populations are _____.
A)different subspecies,under the...

Question 7

There is an island in the middle of a large river that houses a large population of ants.Damming of the river causes the island to flood and only the highest points of the island are now above water.The ants cannot swim,so are now in multiple isolated populations.Which of the following best describes this event?
A)isolation by dispersal
B)isolation by vicariance
C)a form of sympatric speciation
D)only a rare development of polyploidy could lead to speciation in this case.
E)speciation will not occur in this case because of gene flow

Accepted Answer

The event can be best described as isolation by vicariance because the damming of the river caused the physical separation of the ant populations on the island, leading to their isolation from each other. Isolation by dispersal would occur if some of the ants moved to a different location, while sympatric speciation, polyploidy, and gene flow are not relevant in this scenario.

Question 8

What keeps the two populations separate?
A)temporal reproductive isolation
B)lack of hybrid viability
C)They are already separate species.
D)spatial reproductive isolation
E)behavioral reproductive isolation

Accepted Answer

Spatial reproductive isolation occurs when two populations are separated by physical barriers, preventing them from interbreeding.

Question 9

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)Yes,because they have completely different coloration and natural selection has affected the frequency of the two different forms.
E)No.

Accepted Answer

The two forms of moths should not be considered separate species as they are still capable of interbreeding and producing viable offspring. The differences between them are due to a single gene and are not significant enough to warrant separate species classification. Additionally, the changes in frequency of the two forms are a result of natural selection acting on the population, but do not necessarily indicate the emergence of separate species.

Question 10

Use the following information when answering the corresponding question(s).
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 morphospecies 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. )
-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 morphospecies concept
B)the biological species concept
C)the phylogenetic species concept
D)both the morphospecies and phylogenetic species concepts
E)the morphospecies,biological species,and phylogenetic species concepts

Accepted Answer

The answer of Use the following information when answering the...

Question 11

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.
E)Any of the above answers could be correct,depending on the environment.

Accepted Answer

The formation of tetraploid offspring with chromosome sets of both parent species would result in reproductive isolation from both parent species, as they would not be able to produce viable offspring with either diploid parent species. This is a common pattern in polyploid species, where the increased number of chromosomes can lead to hybrid infertility and result in the establishment of a new, reproductively isolated species. Therefore, options A, B, and D are not likely outcomes, and option E is not as likely because reproductive isolation is a common pattern in polyploid species, regardless of the environment.

Question 12

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
E)phylogenetically,due to heterozygote advantage in hybrids

Accepted Answer

Allopatric speciation, or speciation through geographic isolation, is the most common way for two different species to evolve from one ancestral species. This occurs when a population is separated by a physical barrier, such as a river or mountain range, and over time genetic drift, natural selection, and mutation cause the populations to become genetically distinct and eventually unable to interbreed. This process can take a long time, but it has been observed and documented in many different types of organisms.

Question 13

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 meet,what would this situation definitely illustrate?
A)prezygotic isolation
B)reinforcement
C)autopolyploidy
D)allopatric speciation
E)sympatric speciation

Accepted Answer

This situation would illustrate allopatric speciation, where two populations of the same species become geographically isolated, evolve independently, and eventually become unable to interbreed when they come into contact again.

Question 14

Which of the following does not tend to promote speciation?
A)the founder effect
B)gene flow
C)natural selection
D)polyploidy
E)disruptive selection

Accepted Answer

Gene flow involves the movement of genetic material from one population to another and tends to increase genetic similarity between populations, thereby hindering the development of genetic differences that could lead to speciation. The other choices (A, C, D, and E) tend to promote speciation in various ways. The founder effect can contribute to speciation by reducing genetic diversity in a newly established population, creating a genetic distinctiveness that could lead to further divergence. Natural selection can drive the evolution of new traits that increase the fitness of individuals in a particular environment, leading to the formation of new species. Polyploidy, a condition in which an organism has more than two sets of chromosomes, can lead to reproductive isolation and the formation of new species in plants. Disruptive selection can drive divergence in a population by favoring individuals at opposite ends of a trait spectrum, potentially leading to the formation of two separate populations that cannot interbreed.

Question 15

Figure 26.1 
 
-Refer to Figure 26.1.Which of the following forms a monophyletic group?
A)A,B,C,D
B)C and D
C)D,E,and F
D)E,F,and G
E)all of the above

Accepted Answer

The answer of Figure 26.1 
 
-Refer to Figure 26.1.Which...

Question 16

The snake family Typhlopidae consists of small,burrowing species with vestigial eyes.They are found in Australia,sub-Saharan Africa,India and some adjacent areas,and South America.What is the most likely explanation for this distribution?
A)rafting to the different continents from the point of origin on one of these continents
B)convergent evolution in the different regions
C)origin on Gondwana followed by continental drift and some range expansion
D)all of the above

Accepted Answer

The distribution of Typhlopidae across continents that were once part of Gondwana suggests that the family originated on the supercontinent. The populations were then separated due to continental drift and subsequently underwent range expansion to their current distribution. Rafting explains the long-distance distribution of some species but seems unlikely to be the only explanation for such widespread distribution. Convergent evolution may have led to similarities in form in different regions, but it cannot explain the global distribution of Typhlopidae. Therefore, the best choice is C.

Question 17

Use the following information when answering the corresponding question(s).
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 morphospecies 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. )
-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

Accepted Answer

If the isthmus formed gradually, species in deep water would have been separated first, leading to greater genetic divergence over time compared to those in shallow water.

Question 18

Which of the following could be a vicariance event for species in that habitat?
A)The level of water in a lake recedes,creating two lakes where there used to be one.
B)Some insects get blown in a storm to a new mountain range,where they lay eggs.
C)Radiation near Chernobyl increases mutation rate,causing an increase in autopolyploidy.
D)All of the above could be vicariance events for species in that habitat.

Accepted Answer

Vicariance events involve a physical splitting of a habitat, such as the separation of populations due to the formation of a new boundary, like a river or a mountain range. The receding of water in a lake can result in the formation of two separate lakes, which could lead to speciation of populations that were once connected.

B and C are not examples of vicariance events. B is an example of dispersal, where individuals move from their original range to a new one. C is an example of sympatric speciation, which can occur through mechanisms such as autopolyploidy, but does not involve a physical splitting of the habitat.

Question 19

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 in order to spend winter in such close proximity.
B)They must have strong prezygotic isolating mechanisms in order 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.
E)two of the above

Accepted Answer

The answer of Many songbirds breed in North America in...

Question 20

Use the following information when answering the corresponding question(s).
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 morphospecies 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. )
-Which of the following describes the most likely order of events in speciation?
A)genetic drift,genetic isolation,divergence
B)genetic isolation,divergence,genetic drift
C)divergence,genetic drift,genetic isolation
D)divergence,genetic isolation,genetic drift
E)genetic isolation,genetic drift,divergence

Accepted Answer

The most likely order of events in speciation is genetic isolation, followed by genetic drift, and then divergence. The formation of the Isthmus of Panama caused genetic isolation, allowing genetic drift to occur in the separated populations, leading to divergence over time.

Quiz 26: Speciation

Why is speciation by polyploidy more likely in plants than in animals?

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?

The theory of plate tectonics describes movement of plates of the Earth's crust through time.Which of the following can you deduce from what you learned in this chapter about plate tectonics?

Most causes of speciation are relatively slow,in that they may take many generations of organism to see changes,except _____.

The two populations are _____.

What keeps the two populations separate?

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

Which of the following does not tend to promote speciation?

Figure 26.1 -Refer to Figure 26.1.Which of the following forms a monophyletic group?

The snake family Typhlopidae consists of small,burrowing species with vestigial eyes.They are found in Australia,sub-Saharan Africa,India and some adjacent areas,and South America.What is the most likely explanation for this distribution?

Which of the following could be a vicariance event for species in that habitat?