Question 1

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)No,because there is no evidence that they are reproductively isolated.
D)Both A and B are correct.

Accepted Answer

The two forms of moth should not be considered separate species because there is no evidence that they are reproductively isolated. Reproductive isolation is a key component of defining separate species. Although natural selection has affected the frequency of the two forms, and they have different coloration, these alone are not enough to classify them as separate species.

Question 2

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 living in deeper water would have been separated earlier than those in shallow water because the rising land would first block the shallower areas, leading to a longer period of genetic divergence for deep-water species.

Question 3

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)All of the above answers are correct.

Accepted Answer

The formation of tetraploid frogs using gametes from two different diploid species suggests that the resulting tetraploids would be allopolyploid, meaning they have chromosomes sets from two different species. Allopolyploids often experience reproductive isolation from their diploid parent species, which would support choice C as the best answer. Choices A and B are unlikely because the parent species are still present and able to interbreed with each other. Choice D is also unlikely since the offspring were able to reach maturity in the experiment.

Question 4

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 answer of Which of the following describes the most...

Question 5

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 of...

Question 6

Which of the following statements explains why animals are less likely than plants to speciate by polyploidy?
A)Animals self-fertilize less often than plants,so diploid gametes are less likely to fuse.
B)Animals have better mechanisms for repairing chromosomes than plants have.
C)Animals are better at recognizing appropriate mates.
D)Animals are more mobile,so populations get separated far less often.

Accepted Answer

Polyploidy often occurs through self-fertilization, which is more common in plants than in animals. This makes it less likely for animals to speciate through polyploidy.

Question 7

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 A and C
E)all of the above

Accepted Answer

The answer of The sister populations on opposite sides of...

Question 8

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 illustrate?
A)vicariance
B)allopolyploidy
C)autopolyploidy
D)allopatric speciation
E)sympatric speciation

Accepted Answer

This situation illustrates allopatric speciation, where populations become reproductively isolated due to geographic barriers (in this case, distance), leading to the evolution of distinct species.

Question 9

What keeps the two populations separate?
A)temporal reproductive isolation
B)lack of hybrid viability
C)gametic barrier
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 10

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 prezygotic or postzygotic isolating mechanisms in order to spend winter in such close proximity.
B)The two species do not breed in the same area,so they are reproductively isolated by allopatry.
C)One of the species is probably polyploid,so they are reproductively isolated by genetic incompatibility.
D)Reinforcement must be occurring when they winter together.

Accepted Answer

The two species are reproductively isolated by allopatry because they breed in different geographical areas, which prevents them from interbreeding.

Question 11

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 snakes can be explained by their origins on the supercontinent Gondwana, which later split into the current continents where these species are found. This means they likely originated in a single location and then were distributed on the different continents through continental drift, and potentially some range expansion. Rafting and convergent evolution are less likely explanations for the distribution of this specific family of snakes.

Question 12

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 morphospecies...

Question 13

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 lack the DNA repair enzymes that animals have.
D)Plants are sessile and cannot speciate via dispersal.

Accepted Answer

Polyploidy involves a rare event of genome duplication, leading to the formation of gametes with doubled chromosome number. In plants, this is more likely because they are capable of producing gametes from somatic cells that have undergone many rounds of mitosis. In contrast, animal gametes are derived from primordial germ cells that undergo meiosis and do not generate somatic cells.

Answer: B
 Polyploidy can lead to reproductive isolation, but plants lack postzygotic isolating mechanisms. This makes it easier for polyploid plants to reproduce with each other and create a new, reproductively isolated species.

Answer: C and D are incorrect.
 There is no evidence to suggest that plants lack the DNA repair enzymes that animals have. Additionally, while plants are sessile, this is not the reason why polyploidy is more likely in plants than in animals.

Question 14

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)all of the above

Accepted Answer

The difference in courtship songs of the male crickets serves as a prezygotic isolating mechanism as it prevents interbreeding between the populations. This can lead to the formation of different species. A postzygotic isolating mechanism, on the other hand, would occur after mating and would result in infertility or reduced viability of hybrid offspring.

Question 15

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 autopolypolidy.
D)All of the above could be vicariance events for species in that habitat.

Accepted Answer

Vicariance events are usually associated with physical barriers that separate a once continuous population. In this scenario, the separation of a single lake into two separate lakes due to receding waters can create a physical barrier that separates the species living in that habitat.

Option B describes a scenario where species are dispersed, which is not a vicariance event. Option C describes a scenario of mutation, rather than physical separation, which is also not a vicariance event. Therefore, A is the best choice for a vicariance event.

Question 16

How are two different species most likely to evolve from one ancestral species?
A)sympatrically,by a point mutation affecting morphology or behavior
B)allopatrically,after the ancestral species has split into two populations
C)phylogenetically,due to heterozygote advantage in hybrids

Accepted Answer

The most common way for two different species to evolve from one ancestral species is through allopatric speciation, which occurs when a population of the ancestral species is split geographically and isolated from each other. Over time, different mutations and selective pressures can lead to genetic and phenotypic differences between the two groups, ultimately resulting in the evolution of separate species. Sympatric speciation through a point mutation affecting morphology or behavior is less common, and phylogenetic speciation through heterozygote advantage in hybrids is a theoretical concept that has not been observed in nature.

Question 17

When the Isthmus of Panama formed,a land bridge resulted between North and South America.What opportunities for colonization did this land bridge offer?
A)colonization of the newly arisen land by organisms from North and South America
B)colonization of North America by organisms from South America
C)colonization of South America by organisms from North America
D)both B and C
E)all of the above

Accepted Answer

The formation of the Isthmus of Panama allowed for the exchange of species between North and South America, enabling organisms from both continents to colonize new areas, including the newly formed land bridge itself.

Question 18

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 5
B)1,3,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 will create a population with a higher genetic variance, increasing the potential for divergence. Choosing a species that produces a few, large offspring allows for more genetic variation to be passed on to each offspring. Placing the new population in a novel environment compared to that of the source population will increase the likelihood of environmental pressures leading to divergence.

Question 19

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 can result in rapid speciation because it involves a sudden change in the number of chromosomes, which can lead to reproductive isolation and the creation of a new species in just one generation. The other options listed are typically slower processes that may take many generations to result in speciation.

Question 20

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

Accepted Answer

Gene flow tends to homogenize gene pools and reduce genetic differences between populations, thus making speciation less likely. The other options (founder effect, natural selection, polyploidy) are all capable of promoting speciation by introducing or enhancing genetic differences between populations.

Quiz 26: Speciation

If the isthmus formed gradually rather than suddenly,what pattern of genetic divergence would you expect to find in these species pairs?

Which of the following describes the most likely order of events in speciation?

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

Which of the following statements explains why animals are less likely than plants to speciate by polyploidy?

The sister populations on opposite sides of the isthmus are true species under which species concept?

What keeps the two populations separate?

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?

The two populations are

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?

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

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

When the Isthmus of Panama formed,a land bridge resulted between North and South America.What opportunities for colonization did this land bridge offer?

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

Which of the following does not tend to promote speciation?