learning curve chapter 15

In asexually reproducing organisms, _______ cause(s) an offspring to be genetically different from its parent.

a. genetic drift
b. mutation
c. directional selection
d. recombination
e. All of the above

b

The presence of pathogens tends to _______ the evolution of sexual reproduction because _______.

a. favor; pathogens disrupt Muller’s ratchet
b. disfavor; pathogens disrupt Muller’s ratchet
c. favor; populations require more genetic variation to evolve defenses against pathogens
d. disfavor; populations require more genetic variation to evolve defenses against pathogens
e. disfavor; populations do not need as much genetic variation to evolve against pathogens

c

A population of ocotillo plants has four alleles at the Dopa locus, with allelic frequencies of 0.38, 0.32, 0.19, and 0.11, and the genotype frequencies roughly consistent with the Hardy-Weinberg equilibrium. This is a description of the genetic _______ of the population.
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monomorphism

equilibrium

fitness

structure

ratchet

d

A gene family that codes for various hormone receptors has been accumulating nucleotide substitutions at a rate of 0.4 per million years. On average, there have been 60 substitutions between the common ancestor of this gene family and each of the various living forms of this gene. Based on these figures, this hormone receptor gene family likely originated _______ million years ago.
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15

24

75

150

300

d

Which phenomenon is most likely to lead to an increase in the rate that pseudogenes evolve?
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a. A decreased point mutation rate
b. More intense purifying selection
c. An increased rate of gene duplication
d. Less intense positive selection
e. A decreased rate of gene duplication

c

Whether a fly has white or red eyes is due to alleles at a single locus. It is thus a _______ or _______ trait.

a. quantitative; discrete
b. quantitative; continuous
c. qualitative; continuous
d. heritable; continuous
e. qualitative; discrete

e

Which statement about evolution is false?
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a. Natural selection is one of several mechanisms of evolution.

b. Populations, not individuals, evolve.

c. Genetic drift can change the genetic makeup of populations over time.

d.Nonrandom mating can change the genetic makeup of populations over time.

e. Evolution is goal-directed.

e

There are three isolated populations of orchids. Population A has had a constant size of about 40,000. Population B has had a constant size of about 14,000. Population C has had a constant size of about 300. We most expect to see an increase in the frequency of deleterious alleles in population _______, because this population would experience the _______ genetic drift.
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a. A; most

b. A; least

c. B; most

d. C; most

e. C; least

d

Which statement about positive selection is true?
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a. It can produce adaptations.

b. It involves the movement of gametes between populations.

c. It weeds out harmful variants.

d. It pertains only to artificial selection.

e. It involves random changes in allele frequencies.

a

If the frequency of the A3 allele of a creatine phosphatase locus in a population of lions is 0.4, how many copies of that allele should we expect to see in a population of 500 lions?
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100

200

400

500

600

400

Who besides Darwin deserves credit for formulating evolution by natural selection?
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Alfred Russel Wallace

Gregor Mendel

Jean-Baptiste Lamarck

James Watson

Thomas Hunt Morgan

a

Which statement best describes the difference between Darwin and Lamarck?
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a. Both Darwin and Lamarck presented convincing cases for the existence of evolution, but only Darwin made a convincing case for how it occurred.

b. Unlike Darwin, Lamarck did not accept evolution.

c. Darwin presented a convincing case for the fact that evolution had taken place; Lamarck did not.

d. Lamarck extended Darwin’s theories of evolution.

e. Both Darwin and Lamarck presented convincing evidence for how evolution occurred, but Darwin had better scientific connections, so the credit went to Darwin.

a

A normally asexual lineage experiences sexual reproduction, and as a result, the amount of genetic variation increases and deleterious mutations are purged from the lineage. This purging is a reversal of
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disruptive selection.

directional selection.

Muller’s ratchet.

heterozygote advantage.

trade-offs.

c

A missense substitution is the same as a _______ substitution.
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silent

nonsynonymous

coincident

parallel

synonymous

b

In a population of pitcher plants, 200 individuals are sampled for variation at a locus. Sixteen are heterozygous for the X1 allele, and four are homozygous for it. What is the frequency of the X1 allele?
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0.04

0.06

0.08

0.12

0.16

b

Suppose there are two alleles at a locus that is at Hardy-Weinberg equilibrium. If the frequency of one allele is r, what is the frequency of the heterozygotes?
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(1 – r)^2
2r × (1 – r)
r^2
r × (1 – r)
r^2 × (1 – r)

b

As the amount of lateral gene transfer in a taxon increases, it becomes _______ difficult to infer relationships among lineages within the taxon and _______ to infer species boundaries.
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less; there would be no effect on the ability

less; more difficult

more; more difficult

more; less difficult

less; less difficult

e

As the amount of lateral gene transfer in a taxon increases, it becomes _______ difficult to infer relationships among lineages within the taxon and _______ to infer species boundaries.
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less; there would be no effect on the ability

less; more difficult

more; more difficult

more; less difficult

less; less difficult

c

Suppose the size of a population of crickets is 1,500. According to genetic drift theory, what is the probability that a newly arisen neutral mutation will become fixed in this population?

1/3000

Suppose that the mutation rate per base pair for a genetic locus is 4 × 10-8, and that the locus contains 1,500 base pairs. What is the per-locus mutation rate?

6 x 10^-5

How does genetic drift compare to natural selection in its affects on a population?
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a. Both genetic drift and natural selection affect a population directly through environmental pressures.

b. The change in allele frequency by genetic drift is random, while change in allele frequency by natural selection is predictable.

c. The change in allele frequency by natural selection is random, while change in allele frequency by genetic drift is predictable.

d. Genetic drift only affects small populations, while natural selection only affects large populations.

e. Genetic drift only affects large populations, while natural selection affects all populations.

b

Suppose that the size of a population of midges is 20 million and that the mutation rate of a gene is 1.5 per million midges per generation. How many new mutations of this gene should appear in the next generation of the population?
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1.5

3

20

30

60

60

Which would most likely lead to a change in the genetic structure of a population?
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a. An increase of 1.1-fold in the reproductive success of all genotypes
b. A decrease of 20 percent in the reproductive success of all genotypes
c A 5 percent increase in the reproductive success of some genotypes, but a 5 percent decrease in the reproductive success of other genotypes
d. Either a or b
e. None of the above
None of the above

c

Researchers suspect that the gene FOXP2, which is involved in speech and cognition, has been under positive selection in the human lineage. Which evidence would provide the strongest support for such a claim?
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There is a higher rate of nonsynonymous substitutions than of synonymous ones.

There is a lower rate of nonsynonymous substitutions than of synonymous ones.

In addition to the gene FOXP2, there are several pseudogenes related to FOXP2.

The gene evolves following the molecular clock.

Neutral mutations tend to vanish from the population.

a

Which statement would best exemplify Lyell’s ideas that led Darwin to formulate his views on evolution?
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A catastrophic earthquake could almost instantaneously wipe out many species.

Large-scale volcanic eruptions can quickly alter the landscape.

Species of the temperate regions of South America are more similar to those of tropical South America than they are to temperate European species.

Coastline formation has occurred slowly enough to be almost imperceptible, but it can operate over vast spans of time, even many millions of years.

Species of the temperate regions of South America are more similar to temperate European species than they are to those of tropical South America.

d

Three different alleles (c1, c2, and c3) at the c locus exist in a hypothetical population of juniper trees. If the frequency of c1 is 0.3, the frequency of c2
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cannot be less than 0.3.

cannot be greater than 0.3.

is 0.7.

is 0.

cannot be greater than 0.7.

e

Mutations in the third position of codons are the least likely to affect the amino acid sequence. Mutations in the second position are most likely to change the amino acid sequence, while first-position mutations are intermediate. Based on what you know about molecular evolution, predict the relative rates of evolution for first-, second-, and third-position codon nucleotides from highest to lowest.
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First, second, third

First, third, second

Third, first, second

Third, second, first

Second, first, third

c

You discover a population of guppies and find it to be at Hardy-Weinberg equilibrium with respect to the S locus. Suppose there are two alleles at this locus, and the frequency of one of those alleles (the s allele) is 0.40. Of the individuals that carry at least one s allele, what fraction are homozygotes?
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1/8

1/6

1/4

1/3

1/2

c

The FY3 gene plays a role in immune responses in flies. In one population, there are two alleles, and the frequency of one allele is 0.80. If the population is at Hardy-Weinberg equilibrium, how many homozygotes for the most common allele should we observe in a sample of 250 individuals?
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10

40

80

120

160

160

Which statement about genomes is true?
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Genome size is dictated by the number of functional genes needed by an organism.

Most of the DNA in humans codes for proteins.

The variation in genome size between organisms is less than the variation in the number of genes in those organisms.

The variation in genome size between organisms is greater than the variation in the number of genes in those organisms.

Humans are the most complex of all organisms and require the largest genome.

d

The population size hypothesis for genome size proposes that _______ selection is _______ effective in large populations, and thus species with large populations should have _______ genomes than those with smaller populations.

positive; more; larger

positive; less; smaller

purifying; more; larger

purifying; more; smaller

purifying; less; larger

d

Which phenomenon is most likely to lead to an increase in the rate that pseudogenes evolve?

A decreased point mutation rate

More intense purifying selection

An increased rate of gene duplication

Less intense positive selection

A decreased rate of gene duplication

c

Suppose that in a population of 250,000 mice the mutation rate per base pair for a genetic locus is 4 × 10-8. The locus contains 1,500 base pairs. How many new mutations should we expect at this locus in each generation?
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3

10

15

20

30

30

Suppose a hard frost in southern Florida kills nearly all of a population of plants. Even though the plant population recovers in numbers after a couple of decades, the genetic variation within that population remains much reduced. What is the most likely cause of the diminished genetic variation?
a. Muller’s ratchet
b. founder effect
c. purifying selection
d. population bottleneck
e. gene flow

d

Which taxonomic category is next larger (more general) than an order?
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Family
Genus
Class
Phylum
Kingdom

c

Similar traits that arise independently in different lineages through convergent evolution are called
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homoplastic traits.
derived traits.
homologous traits.
synapomorphies.
ancestral traits.

a

Which statement about the taxonomic category of a family is false?
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Groups of families make up an order.
Families are comprised of groups of genera.
All families are equivalent in size.
The suffix -aceae denotes a plant family.
Many different species may be present in the same family.

c

Which is an important application of phylogenetic analysis in fighting infectious diseases?
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Determining when a pathogen first infected the human population
Tracing the different forms of the pathogen as it spreads through the human population
Documenting the animal host the pathogen used to move into the human population
Identifying when a new form of the pathogen emerges in the human population
All of the above

e

A biologist studying a bird species observes that females prefer males with bright plumage. The biologist selects a related bird species in which all males have dull plumage to compare to the first species. What evidence collected from this second species would support the idea that female preference for bright plumage evolved after the bright plumage trait in males evolved?
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When exposed to a robotic model of a male of their own species covered in bright plumage, females express interest in looking at the model.

When exposed to a live male of their own species, females express interest in looking at the male.

When exposed to two live males of the first species, females express more interest in looking at the male with bright plumage than dull plumage.

When exposed to two robotic models of males of their own species, one with bright plumage and the other dull, females express the same interest in looking at both models.

When exposed to a live male of the first species, females express no interest in looking at the male.

d

Any _______ trait can be used in a phylogenetic analysis.
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physical
biological
heritable
behavioral
observable

c

Which phrase describes an outgroup?
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A group of extinct organisms that gave rise to a group of living organisms

A reference group related to but not part of a group under study

A population living in an area distant from a population being examined

A group of organisms that lost derived traits as a result of evolutionary reversal

A control group of organisms having traits similar to an experimental group

b

Binomial nomenclature names an organism by
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genus name followed by species name.
family name followed by species name.
species name followed by genus name.
species name only.
species name followed by family name.

a

A group of species that consists of a common ancestor and all of its evolutionary descendants is called a
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population.

lineage.

clade.

taxon.

sister group.

c

Females of some bird species prefer computer-generated songs that are more complex than songs they normally hear from males during courtship. Such observations
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challenge the principle of parsimony.
support the principle of parsimony.
challenge the molecular clock hypothesis.
challenge the sensory exploitation hypothesis.
support the sensory exploitation hypothesis.

e

Why are frog calls generally more useful in phylogenetic analysis than bird songs?
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a. Bird songs tend to be more complicated than frog calls, and thus violate the principle of parsimony.
b. Bird songs contain less information than frog calls and cannot support accurate phylogenetic study.
c. Bird songs are more difficult to obtain during field studies than frog calls.
d. Bird songs tend to be culturally inherited, whereas frog calls tend to be genetically inherited.
e. Bird songs undergo more rapid evolutionary change than frog calls, which makes them more difficult to use in phylogenetics.

d

Which evidence below is consistent with the hypothesis that a group of related viruses infecting humans originated from a virus that infected one animal host?
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DNA sequences show that all of the human viruses form a unique clade.

All of the viruses within the group are pathogenic and cause host cell death.

Genes from the human viruses can be grouped into two distinct groups based on sequence comparisons.

A phylogenetic tree constructed from genetic data places human viruses in multiple places, interspersed with animal viruses.

Molecular data places several of the human viruses near the root of the phylogenetic tree.

a

Genes that code for enzymes responsible for cellular metabolism generally evolve very slowly. Thus, these genes would most likely be used to determine the evolutionary relationship between

a. single-celled organisms
b. closely related species
c. very distantly related organisms
d. extinct species
e. organisms with long life spans

c

Which represents a trait that cannot be applied to phylogenetic analysis?
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A duck’s instinctive behavior that is genetically determined
An extinct plant’s seed size determined from fossil evidence
A plant’s flower color that varies with soil acidity
A bacterium’s flagellar structure observed under the microscope
A frog’s tail that disappears during its development

c

why is phylogeny a useful basis for biological classification?
a. other methods cannot thoroughly and accurately classify all living things.

b. It provides a way for biologists to accurately distinguish organisms without error.

c. It is the only concept that provides a basis for distinguishing and grouping organisms.

d. It has a hierarchical framework for grouping organisms that can readily be adopted by biologists worldwide.

e. Both b and d

d

A monophyletic group contains
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a. species that have a single common characteristic.
b. all species in a single phylum.
c. an ancestor and all descendants of that ancestor.
d. all related organisms in a group, excluding their common ancestor.
e. an extinct species and all of its related living species.

c

Suppose a biologist has collected data indicating divergence times between pairs of closely related species. For each of these pairs, the biologist has also determined the number of nucleotide differences within a particular gene. The biologist plots the average rate of change on a graph with divergence time on the x axis and the number of nucleotide changes on the y axis. If the molecular clock hypothesis is valid, the plotted points will show a(n)

a. downward curve.
b. straight line with a positive slope.
c. upward curve.
d. straight line with a negative slope.
e. straight line with a slope of zero.

b

Which statement about the relatedness of organisms is true?

a. A relationship exists between any two organisms because they share a common ancestor.
b. Organisms living now cannot be related to extinct organisms that died out thousands of years ago.
c. Because they are physically separated, two organisms living in completely different parts of the world cannot be related.
d. All animals are related to one another but do not share a relationship with other living things, such as plants or bacteria.
e. For organisms to be related to one another, they must share similar physical traits.

a

Biologists have observed a similar change in several distantly related vertebrates. These organisms all decreased in size when they migrated from the mainland to different islands. The most likely explanation for this shared similarity is that the traits
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resulted from synapomorphy.
underwent evolutionary reversal.
arose by convergent evolution.
share the same ancestral genes.
evolved as homologous traits.

c

Whales and pigs diverged from a common ancestor about 80 million years ago. If a DNA sequence shows 24 nucleotide differences between whales and pigs, what is the rate of change per million years for this sequence? In your analysis, take into account that both the lineage that led to pigs and the lineage that led to whales underwent change after the split.
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0.15 changes per million years
0.24 changes per million years
0.30 changes per million years
0.48 changes per million years
0.60 changes per million years

a

Species A and B are sister species. Species C and D are also sister species. The lineage leading to species A and B diverged from the lineage leading to species C and D at node 1. Prior to node 1, the lineage leading to species E diverged from the lineage leading to species A, B, C, and D at node 2. Suppose a newly discovered species (Species F) was determined to be the sister species of Species E. Which group is monophyletic?
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Species D, E, and F
Species A, B, C, and D and their common ancestor at node 1
Species A, B, C, and E and their common ancestor at node 2
Species A, B, E, and F
Species A, B, and E and their common ancestor at node 2

b

Why are the bones making up bird and bat wings considered to be homologous, but the wings as a whole are not?

Bone traits are under much different selective pressures from the environment than wing traits.

The bones in birds and bats are similar in appearance, whereas the wing structures in these organisms are very different.

Bones have the same function in birds and bats, but because birds flap their wings and bats glide, the functions of their wings differ.

Bone traits existed in a common ancestor from long ago, while wing traits evolved after the bird and bat lineages split.

Bone traits are governed by fewer genetic elements than wing traits, which are more complex.

d

A phylogenetic analysis of a group of organisms can
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provide information about when specific traits evolved.
help pinpoint when a particular genetic mutation occurred.
allow biologists to make predictions about the relationship between traits and selective pressures.
identify the sequence of evolutionary change in a particular lineage.
All of the above

e

Which statement about traits and phylogeny is true?

All similar traits are evidence of relatedness.

All synapomorphies can be classified as either ancestral or derived traits, depending on the point of reference.

All shared traits are synapomorphies.

Some traits can appear to have different origins but evolved from a common ancestor through evolutionary reversal.

Homologous traits can arise through evolution from a common ancestor and through convergent evolution.

b

A few species of Drosophila have elaborate pigment patterns on their wings, although most do not. Which evidence could be used to support the hypothesis that these pigment patterns arose through convergent evolution in the species that display them?
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The same pigment patterns on wings are found in a variety of different clades of Drosophila.

Drosophila with pigment patterns on wings are shown to evolve faster than those without pigment patterns on wings.

Elaborate pigment patterns on wings are discovered to exist in a common ancestor of all Drosophila.

Drosophila species without pigment patterns on wings are shown to have the genes that produce pigment patterns on wings.

All species of Drosophila with pigment patterns on wings are found to exist in a single clade.

a

The globin gene of fish species A differs by ten amino acid substitutions from the globin gene of fish species B. Furthermore, biogeographical evidence has established that these two fish species diverged 5 million years ago. A third fish species (species C) differs from species A by 40 amino acid substitutions. Use the molecular clock hypothesis to estimate how long ago species A and C split from each other.
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5 million years
10 million years
20 million years
40 million years
50 million years

c

In 2013, a virus was isolated from a patient and its DNA sequenced. This DNA showed a 9 percent difference in base sequence from a sample of the same virus isolated from a different patient in 1983 and preserved in a storage freezer. If the total amount of base sequence difference among contemporary samples of this virus is 27 percent, what year did the virus most likely entered the human population, according to the molecular clock hypothesis?
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1890
1923
1938
1953
1983

b

Which is a prezygotic isolating mechanism?
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Low hybrid adult viability

Hybrid infertility

Low hybrid zone viability

Hybrid zones

Incompatibility between gametes

e

Which is an example of behavioral reproductive isolation?
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Cricket males of two closely related species use the same sounds to attract the same females.

Two species of moths feed and mate on the same plant species.

The mating call of a male frog attracts females of several closely related species.

Hummingbird females of one species ignore the elaborate mating flights of a closely related species.

Three closely related lily species have flowers that open in the afternoon.

d

The morphological species concept, used by Linnaeus to describe and name thousands of species, can be problematic because
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different species often have very different physical characteristics.

males and females within a species do not have identical chromosomes.

many organisms change in physical appearance as they age.

some species reproduce sexually, while others reproduce asexually.

many species change little over large geographic distances.

c

The morphological species concept classifies organisms in groups that
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are known to be genetically related.

look alike.

share a habitat.

change color.

live in the same region.

b

Which event is not likely to lead to allopatric speciation?
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Uplifting of the Rocky Mountains separating the mid-plains region from the West Coast

A lava flow separating a formerly contiguous forest into isolated patches

Sea level rise eliminating a land bridge between North and South America

A glacier receding, joining habitats that were previously separated

River erosion creating a canyon separating two sides of a plain

d

Two species of three-spined stickleback fish have been found together in five different lakes. The larger, bottom-dwelling species feeds on large prey close to shore. A surface-dwelling species feeds on small plankton in open water. DNA analysis shows that the two species in each lake are more closely related to each other than they are to any of the other species in the lakes. However, they are reproductively isolated. These two species are likely to have arisen due to
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autopolyploidy.
allopatric speciation.
polyploidy.
allopolyploidy.
sympatric speciation.

e

The vegetable we know as the potato resulted from naturally occurring genome doubling within one species. In other words, the potato has twice as many chromosomes as the ancestor it was derived from. The potato could therefore be described as being the result of the process known as
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autopolyploidy.
allopatric speciation.
hybrid sterility.
allopolyploidy.
hybridization.

a

Which is not an example of a prezygotic mechanism preventing hybridization?
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Differences in food preferences between two populations of snakes
Differences in the timing of breeding seasons of male frogs
Differences in courtship song between two populations of wrens
Structural differences between male external reproductive organs in different species of millipedes
Failure of meiosis in hybrids formed between two populations of insects

e

The Dobzhansky-Muller model of speciation can involve
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a single nucleotide.

a single gene.

a pair of genes.

chromosomal rearrangements.

Both c and d

e

Suppose a species begins diverging into two separate species and that the speciation process takes thousands of years to complete. As speciation occurs, the percentage of offspring produced as hybrids over the thousand-year time would begin at
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0 and gradually increase to 100.
0 and gradually increase to 50.
50 and gradually decline to 0.
100 and gradually decline to 0.
100 and gradually decline to 50.

d

In what way do prezygotic and postzygotic mechanisms of isolation differ?

No zygotes are formed when prezygotic mechanisms are operating, whereas zygotes are formed when postzygotic mechanisms are operating.

Zygotes may be formed when either mechanism is operating, but viable zygotes are only possible when prezygotic mechanisms are operating.

Zygotes may be formed when either mechanism is operating, but viable zygotes are only possible when postzygotic mechanisms are operating.

Zygotes are formed when prezygotic mechanisms are operating, whereas no zygotes are formed when postzygotic mechanisms are operating.

No zygotes are formed in prezygotic mechanisms because mating is inhibited, whereas no zygotes are formed in postzygotic mechanisms because of mechanical incompatibility between males and females.

a

Allopatric speciation would not result when a population becomes
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separated by a large lake.

separated into two distinct mating groups within the same geographic range.

separated by a desert.

geographically isolated by a range of mountains.

isolated on several islands as sea level rises.

b

In 1928, a Russian plant geneticist crossed cabbage (Brassica) with radish (Raphanus). Fusion of gametes produced mostly infertile hybrids, but a few fertile plants contained a complete set of cabbage (n = 9) and radish (n = 9) chromosomes (n = 18). Fusion of their gametes in turn produced fertile 36-chromosome plants with cabbage-like roots and radish-like leaves. These new plants could interbreed, but not with cabbage or radish ancestors. Production of this new species, which can also occur in nature, is called
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hybrid sterility.
autopolyploidy.
hybridization.
allopatric speciation.
allopolyploidy.

e

The biological species concept states that species arise when
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populations are isolated from each other geographically.
populations are isolated from each other reproductively.
populations are isolated from each other both geographically and reproductively.
groups of organisms from the same species are actually interbreeding.
two groups of organisms from the same species can exchange genes.

b

Two species of three-spined stickleback fish have been found together in five different lakes. The larger, bottom-dwelling species feeds on large prey close to shore. A surface-dwelling species feeds on small plankton in open water. DNA analysis shows that the two species in each lake are more closely related to each other than they are to any of the other species in the lake. Which prezygotic mechanism most likely allowed divergence of an ancestral species into these present-day species?
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Habitat isolation
Mechanical isolation
Temporal isolation
Allopatric speciation
Behavioral isolation

a

Tetraploid and diploid individuals that originated from the same species are typically
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able to produce fertile hybrid offspring.
not able to reproduce.
reproductively isolated from one another.
not possible.
not able to produce gametes.

c

According to the Dobzhansky-Muller model of speciation,
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two ancestral populations are assumed to merge into a single descendent population.

the same new allele becomes fixed at a gene locus in two distinct populations.

independent lineages can hybridize, but the hybrid offspring that result are inferior or may die.

descendent populations evolve independently, and new alleles arise and become fixed in each of the descendent lineages.

lineages become independent from one another as a result of genetic similarities.

c

How could you determine whether two groups of organisms that live in two different parts of the world were members of the same species, according to the biological species concept?
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Move individuals from their native habitat to the other group’s habitat to see if they adapt.

Move individuals from one group to the other to see if they are accepted by the other group’s members.

Compare their genomes to see if they are identical.

Test their ability to mate with one another.

Observe whether their physical features are the same.

d

Question Value: 35 points
+35pts
Exactly! The correct answer is:
they are the same species according to the biological species concept, and they are not reproductively isolated.
Challenge this Question
While studying colorful happy-face spiders on the Hawaiian islands of Oahu, Molokai, Maui, and Hawaii, you discover that populations on these islands share anatomical features but have a variety of patterns on their abdomens. You also discover that they share reproductive behaviors and can freely mate with one another, producing viable offspring. You can conclude that
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they are the same species according to the biological species concept, and they are reproductively isolated.

they are the same species according to the lineage species concept, and they are not reproductively isolated.

they are the same species according to the morphological species concept, and they are not reproductively isolated.

they are the same species according to the biological species concept, and they are not reproductively isolated.

they are the same species according to the morphological species concept, and they are reproductively isolated.

d

Reproductive isolation depends on genetic changes in separated populations that result in _______ allele combinations in hybrid offspring.
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incompatible
viable
fertile
lost
repeating

a

The morphology and natural history of a common and widely distributed butterfly was observed over 25 years in Costa Rica. Recent DNA barcoding (DNA sequence analysis) showed that what was once thought to be a single species is actually a group of 10 or more species. Though caterpillars of these species eat different food plants and have somewhat different habitat preferences than their adult forms, their morphological differences are subtle. This group of species would likely never have been identified as multiple species had it not been for considering which type of species concept?
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Lineage
Biological
Mayr
Morphological
Linnean

a

Which statement does not describe gametic isolation?
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A protein that assists in binding sperm to eggs is not recognized.

Sperm cannot penetrate an egg.

Gametes cannot successfully fuse into a zygote.

Hybrid zygotes fail to mature normally.

Gametes are chemically incompatible.

d

An X-linked gene produces spots on some platyfish. All platyfish have an autosomal repressor that inhibits the expression of the spot-producing gene. The closely related swordtail lacks both the spot-producing gene and the repressor. In backcrosses between these two species, some hybrids receive the spot-producing gene but not the repressor. These individuals can develop malignant tumors, because the expression of the spot-producing gene is not properly regulated. This appears to be an example of
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the Dobzhansky-Muller model of speciation.
polymorphism.
hybrids surviving just as well as nonhybrids.
an inability to hybridize.
meiosis.

a

Genetic divergence in a population is possible when
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there is divergence among alleles at different gene loci.
the criteria for the Dobzhansky-Muller model of speciation are fulfilled.
differences arise in centric fusion during meiosis.
there are lethal combinations of incompatible alleles.
All of the above

e

The graph shown in the figure compares the frequency ranges of male mating calls from two frog species in allopatry and in sympatry. Which statement is consistent with these data?
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Sympatric populations have experienced greater reinforcement of a prezygotic isolating mechanism than allopatric populations have.
Allopatric populations have experienced greater reinforcement of a prezygotic isolating mechanism than sympatric populations have.
Sympatric populations have experienced greater reinforcement of a postzygotic isolating mechanism than allopatric populations have.
Allopatric populations have experienced greater reinforcement of a postzygotic isolating mechanism than sympatric populations have.
Both sympatric and allopatric populations are evolving toward greater reinforcement of a prezygotic isolating mechanism.

a

Divergent centric fusions can be barriers to reproduction in first-generation hybrids because
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the fused chromosomes do not replicate correctly.
they change the mating behavior of the hybrids.

the hybrid organism cannot make sperm.
the fused sperm cannot fertilize an egg cell.
they increase the genetic divergence in the population.

c

What is the difference between a root and a node of a phylogenetic tree?
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A root represents living species that have undergone little or no evolutionary change, whereas a node represents living species that have undergone evolutionary change.

A root represents all living species, whereas a node represents a single species.

A root represents the earliest ancestor that all species have in common, whereas a node represents later ancestors that some species have in common.

A root represents an extinct species, whereas a node represents a living species.

A root is related to all species depicted in a tree, whereas a node is only related to species that emerge later in time.

c