Deck 26: Speciation

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.

Answer 1

C

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

Answer 2

B

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.

Answer 3

C

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

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

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.

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

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

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

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.

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

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.

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.

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

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.

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

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

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

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.

Question 20

Which of the following does not tend to promote speciation?

A)the founder effect
B)gene flow
C)natural selection
D)polyploidy

Question 21

Which of the following reproductive barriers would prevent a mating attempt?

A)behavioural isolation
B)mechanical isolation
C)hybrid sterility
D)gametic isolation
E)sexual selection

Question 22

A researcher notices that in a certain moth species,some females prefer to feed and lay eggs on domesticated solanaceous plants like potatoes and tomatoes.Other females prefer to feed and lay eggs on wild solanaceous plants like Datura.Both male and female moths primarily use scent to find these plants from afar.Females tend to mate where they feed,and the researcher finds a genetic basis for scent preference in these moths.Based on the above information,what might be occurring in this moth species?

A)divergence in sympatry
B)divergence due to vicariance
C)postzygotic isolation
D)polyploidization

Question 23

Which of the following reproductive barriers would prevent a hybrid zygote from developing into a viable,fertile adult?

A)behavioural isolation
B)gametic hybridization
C)mechanical isolation
D)hybrid sterility

Question 24

A species of groundhog spreads through an environmentally varying region surrounding a lake;the different populations,each in their own environments,accumulate habitat-specific morphological traits.Which of the following is this an example of?

A)Allopatric speciation
B)Sub-species
C)Species cluster
D)Founder effect

Question 25

You are studying lizards in the field.The range of the northern population,species 1,overlaps the range of the southern population,species 2.You find hybrids in the zone of overlap.What is happening?

A)Reinforcement is occurring.
B)The postzygotic isolating mechanisms aren't working.
C)Hybrids are best adapted to this region where overlap occurs.
D)There is not enough information to decide what is happening.

Question 26

Two species of tree frogs that live sympatrically in the northeastern United States differ in ploidy: Hyla chrysocelis 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?

A)polyploidy
B)difference in mating calls
C)A and B must have occurred at the same time.

Question 27

Imagine two North American ground cricket species that contact each other as the southern species moves northward during a period of global warming.These two species do not mate much,due to differences in their courtship songs.The northern cricket does not seem to tolerate the warmer temperatures well,but is limited in its ability to move north because it does not normally disperse much.Based on this information,which is the most likely outcome?

A)fusion of the populations
B)reinforcement
C)hybrid zone formation
D)extinction of one of the species
E)creation of a new species

Question 28

Which of the following is FALSE regarding speciation?

A)Once two groups have become physically isolated,natural selection deliberately isolates them reproductively.
B)Speciation can occur among individuals occupying the same geographic area.
C)Polyploidy leads to rapid speciation relative to allopatric speciation.
D)When populations come back into contact,a hybrid zone is where interbreeding may occur.

Question 29

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?

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 30

Male frogs give calls that attract female frogs to approach and mate.Researchers examined mating calls of closely related tree frogs in South America.What outcomes can occur where the ranges of two species overlap?

A)The species will interbreed,eventually fusing over time.
B)A stable hybrid zone will form if hybrids are better adapted to the area of overlap than either parent species is.
C)Species will continue to diverge and be isolated by behavioral or genetic mechanisms.
D)All of the above are possible outcomes.
E)None of the above are a possible outcome.

Question 31

A storm brings two formerly separated populations of beetles together.They look very similar.Under the biological species concept,which of the following would show that the two populations are different species?

A)One population breeds in spring,the other in fall.
B)Males of the two populations have different flight patterns in courtship.
C)When individuals from the two populations mate with each other in the laboratory,the eggs fail to hatch.
D)All of the above are correct.
E)None of the above are correct.

Question 32

A population of ground squirrels is separated by a glacier.Changes in which of the following would most likely result in reproductive isolation if the two populations came into contact several generations later?

A)A change in the fur colour of one group.
B)A change in the diet of one group.
C)A change in the gene encoding of a receptor on the egg-cell surface in one group.
D)A change in the alarm call of one group to warn of predators.

Question 33

Natural selection for traits that keep distinct populations from reproducing with each other is called reinforcement.When is reinforcement beneficial?

A)when populations would otherwise fuse over time
B)when hybrids have lower fitness than either parent population
C)when prezygotic isolating mechanisms are in place
D)when one population could be overwhelmed by the other
E)reinforcement is beneficial under all of the above conditions

Question 34

Six potential species of seaside sparrows were genetically analyzed to determine their phylogenetic relationships.DNA analysis revealed that there were only two monophyletic groups with individuals from three subspecies making up each group.The three Altantic coast subspecies formed one monophyletic group,while the three Gulf coast subspecies made up the other monophyletic group.If you could only save two subspecies of the seaside sparrows from extinction,would you choose two subspecies from the Atlantic coast,two from the Gulf coast,or one each from the Atlantic and Gulf coasts?

A)Save one each from the Atlantic and Gulf coasts to preserve more genetic diversity.
B)Save two subspecies from the Atlantic coast,as this coastline is longer and more likely to provide habitat for the birds.
C)Save two subspecies from the Gulf coast,as this area is much warmer and birds are more likely to survive.

Question 35

Which of the following is a disadvantage of the morphological species concept?

A)It cannot be used to evaluate fossils.
B)It is subjective in nature,with differences of opinion that cannot be resolved by data.
C)Two groups may use very similar resources,but be evolutionarily independent.
D)Reliable information exists only for a small number of organisms.

Question 36

If a plant species with 2n = 14 forms an allopolyploid with a plant species with 2n = 18,what would be the likely diploid (2n)number of the allopolyploid?

A)16
B)28
C)32
D)36

Question 37

Male frogs give calls that attract female frogs to approach and mate.Researchers examined mating calls of closely related tree frogs in South America.If reinforcement of prezygotic isolation is occurring,what would you expect if you compare the calls of the two species in zones of sympatry versus zones of allopatry?

A)Calls would be about the same in both areas.
B)Calls would be more similar in areas of sympatry.
C)Calls would be more different in areas of sympatry.
D)There is not enough information to decide what is happening.

Question 38

A small number of birds arrive on an island from a neighboring larger island.This small population begins to adapt to the new food plants available on the island,and their beaks begin to change.About twice a year,one or two more birds from the neighboring island arrive.What effect do these new arrivals have?

A)Their arrival speeds the process of speciation.
B)Their arrival tends to promote adaptation to the new food plants.
C)Their arrival tends to retard adaptation to the new food plants.
D)Their arrival represents a colonizing event.

Question 39

You are studying two populations of spiders of the Dolomedes genus,characterized by a light stripe down each side of the body.One population lives in a pond,while another nearby population lives in the trees.Which of the following species concept would you be using if you determined that these were two different species?

A)biological
B)morphospecies
C)phylogenetic
D)ecological

Question 40

Which of the following evolutionary processes is not acting when two groups of organisms are identified as different species according to the Biological Species Concept?

A)genetic drift
B)natural selection
C)mutation
D)gene flow
E)sexual selection

Question 41

Several stickleback species live in sympatry.These species exhibit morphological divergence as they each exploit either the benthic (bottom)or the limnetic (deeper,open-water)environment.Occasionally,the two kinds mate,resulting in hybrid offspring.Which of the following is a potential reason for maintenance of these two separate groups despite the occasional hybridization event?

A)Hybrids share traits of both species,and thus are specialized and able to hunt well in either environment.
B)Hybrids share traits of both species,and thus are able to attract mates of either species.
C)Hybrids share traits of both species,and thus are not specialized to either environment in terms of hunting.
D)Hybrids share traits of both species,and thus may not have specific traits to attract mates of either species.
E)Both A and B.
F)Both C and D.