Mastering Biology Assignment 5

Cattle breeders have improved the quality of meat over the years by which process?

a. artificial selection

b. directional selection

c. stabilizing selection

d. artificial selection and directional selection

e. artificial selection and stabilizing selection

d.

Sexual dimorphism is most often a result of ?
a. intersexual selection.

b. stabilizing selection.

c. artificial selection.

d. pansexual selection.

e. intrasexual selection.

a.

The Darwinian fitness of an individual is measured most directly by ?

a. the number of mates it attracts.

b. the number of "good genes" it possesses.

c. the number of its offspring that survive to reproduce.

d. its physical strength.

e. how long it lives.

c.

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA.

The outcome of the conflict between bacteria and bacteriophage at any point in time results from?

a. neutral variation.

b. genetic variation being preserved by diploidy.

c. evolutionary imbalance.

d. heterozygote advantage.

e. frequency-dependent selection.

e.

Natural selection is most nearly the same as ?

a. differential reproductive success.

b. genetic drift.

c. diploidy.

d. non-random mating.

e. gene flow.

a.

Each of the following has a better chance of influencing gene frequencies in small populations than in large populations, but which one most consistently requires a small population as a precondition for its occurrence?

a. Non-random mating

b. Gene flow

c. Mutation

d. Natural selection

e. Genetic drift

e.

Which of the following is a true statement concerning genetic variation?

a. It must be present in a population before natural selection can act upon the population.

b. It tends to be reduced by the processes involved when diploid organisms produce gametes.

c. It is created by the direct action of natural selection.

d. A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity.

e. It arises in response to changes in the environment.

a.

Which statement correctly describes the role of chance in evolution?

a. Evolutionary change proceeds by an accumulation of changes that occur by chance.

b. An allele that increases evolutionary fitness cannot be lost from a population by chance events.

c. The ultimate source of new alleles is mutation, random changes in the nucleotide sequences of an organism’s DNA

c.

sexual dimorphism was developing over time in these species

Adult male humans generally have deeper voices than do adult female humans, as the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females, and increasing larynx size in adult males, then _____.

a population’s gene frequency

Which of these can change via natural selection?

Each insect’s survival is strongly influenced by how resistant it is during a growing season.

A population of boll weevils (an insect that damages cotton crops) is subjected to aerial spraying of a pesticide repeatedly throughout the growing season. Which statement about pesticide resistance in boll weevils during the growing season is true?

mistakes in translation of structural genes.

In modern terminology, diversity is understood to be a result of genetic variation. Sources of variation for evolution include all of the following except _____.

a cline

An ecologist is able to correlate the darkness of leaves in a particular species of small plant with its exposure to sunlight: when plants grow on the forest floor under trees, their leaves are dark green; plants growing at the edge of the forest at the edge of the forest with intermediate levels of sunlight are moderately green; and plants growing in the open field next to the forest under maximum sunlight have leaves that are pale green.This observed difference in leaf color is an example of _____.

The phenotype observed in the open field study plot arose from parental alleles causing dark leaves.

The ecologist plants seeds produced from the forest-floor plants in the open field and she plants seeds from the open-field plants in the forest floor. After a sufficient period of growth, she observes that plants in the open-field study plot have dark leaves and plants in the forest-floor study plot have pale-green leaves. How should she interpret these results?

A, B, and C

Lake Jackson is a 6.2-square mile lake on the northwest side of Tallahassee that drains every twenty-five years or so. Two sinkholes open up and the water in the lake drains into the Florida aquifer, or water table. The fish and other organisms in the lake obviously perish, except for those that survive in a small isolated pool. Remarkably, the lake gradually fills again over a period of several years as a result of rain and plant and animal populations rebound.A population geneticist experimentally determined that the large-mouth bass population in Tallahassee’s Lake Jackson has a relatively high proportion of genes that are "fixed" in this population. As a result, this population would have relatively low ____.

Genetic drift

What mechanism might account for the relatively high proportion of genes that are "fixed" in the Lake Jackson bass population?

All new alleles are the result of nucleotide variability.

Which statement about variation is true?

The proportions of both types of homozygote should decrease & The population’s average heterozygosity should increase.

In a hypothetical population’s gene pool, an autosomal allele, which had previously been fixed, undergoes a mutation that introduces a new allele, one that is incompletely dominant to the original allele. Natural selection then causes stabilizing selection at this locus. Consequently, what should happen over the course of many generations?

Silent mutations

Which of the following explains why comparing the DNA sequences of homologous genes and not the amino-acid sequences of homologus proteins is a more accurate way of determining the evolutionary relatedness of different species?

B (look at picture)

Blue light is that portion of the visible spectrum that penetrates the deepest into bodies of water. Ultraviolet (UV) light, though, can penetrate even deeper. A gene within a population of marine fish that inhabits depths from 500 m to 1,000 m has an allele for a photopigment that is sensitive to UV light, and another allele for a photopigment that is sensitive to blue light. Which graph below best depicts the predicted distribution of these alleles if the fish that carry these alleles prefer to locate themselves where they can see best?

The two phenotypes are about equally adaptive under laboratory conditions.

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive phenotype, the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait has not changed over time?

0.50

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive phenotype, the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the estimated frequency of the dominant allele in the gene pool?

0.50

What proportion of the population is probably heterozygous for this trait?

cannot be determined from this information

What is the frequency of the recessive allele for a particular gene in a population of frogs that is in Hardy-Weinberg equilibrium if the frequency of the heterozygote genotype is 0.42?

0.25

Assume that all possible "ABO" blood phenotypes are present in a certain population that is in Hardy-Weinberg equilibrium with respect to this class of blood-type alleles. The frequency of the "IA" allele is 0.3 and the frequency of the IB allele is 0.2. What is the frequency of individuals with Type O blood in the population?

0.24

Assume that all possible "ABO" blood phenotypes are present in a certain population that is in Hardy-Weinberg equilibrium with respect to this class of blood-type alleles. The frequency of the "IA" allele is 0.3 and the frequency of the IB allele is 0.2. What is the frequency of individuals with Type B blood in this population?

0.60

A gene that is in Hardy-Weinberg equilibrium in the swallowtail butterfly population on St. George Island controls antennal length, whereby the long-antenna allele is completely dominant to the short-antenna allele. Of the 400 butterflies in this population, 256 butterflies have long antennae. What is the frequency of the recessive allele in this population?

A,B, & C

A forest fire kills most of the gopher tortoises in an area, and a population geneticist experimentally determines that the frequency of the recessive allele for shell thickness decreased from 0.67 before the fire to 0.21 after the fire. What has occurred?

populations

Gene flow is a concept best used to describe an exchange of alleles between _____.

natural selection

Which of these evolutionary agents is most consistent at causing populations to become better suited to their environments over the course of generations?

mate choice and intersexual selection

Sail-fin mollies (a small freshwater fish) prefer to mate with males that have long, colorful dorsal fins. Which of the following terms are appropriately applied to the situation described above?

directional selection

Sail-fin mollies (a small freshwater fish) prefer to mate with males that have long, colorful dorsal fins. The distribution of fin phenotypes in the males of this population would reflect _____.

relative fitness

If genetic variation is truly "neutral," then it should have no effect on _____.

disruptive selection

Which describes an African butterfly species that exists with similar frequency in two strikingly different color patterns?

artificial selection and directional selection

Southern farmers have produced a variety of corn that grows tall and bears large ears of corn despite the intense summer heat by which process?

living 2 years and producing six offspring with one mate

Which of the following examples reflects the highest evolutionary fitness?

stabilizing selection

What is true of the trait whose frequency distribution in a large population appears above? It has probably undergone _____.

directional selection and adaptation

If the curve shifts to the left or to the right, there is no gene flow, and the population size consequently increases over successive generations, then which of these is (are) probably occurring?

the body design of snakes is analgous feature that evolved multiple times by convergent evolution

What best explains why all snakes have a similar body design even though they are not all descended from a common ancestor?

the two forms interbreed in nature and their offspring survive and reproduce well

The myrtle warbler and Audubon’s warbler were once listed as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification?

biological

Beetle pollinators of a particular plant are attracted to its flowers’ bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, interbreeding is no longer possible between these two beetle variants. Based on this information, the two variants of beetles can be assigned to different species based on which species concept?

choices A,B, AND C

A pop’n. biologist obtains data indicating that the frequency of a particular recessive allele in a pop’n. previously in H/W equilibrium changed from 0.3 to 0.8. A possible explanation is _____.

bottom of diagram is oldest

Which stratum (A-D) should contain the greatest proportion of extinct organisms? _____

closest anscestor is closer to bottom

If "x" indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum? _____

Lamarck

Who believed that species could evolve by individuals striving to become better adapted to their environment generation after generation?

0.70

Let’s assume that the latest census of great blue herons that hang out by the FSU Reservation on Lake Bradford revealed a population of only 25 adult herons (so not likely to be in H/W equilibrium). For a gene that determines bill size, whereby the allele for stout bills is dominant to the allele for more slender bills, calculate the frequency of the recessive allele in this population if ten herons have slender bills and all other herons are heterozygous?

Which of these is a statement that Darwin would have rejected?
A) Environmental change plays a role in evolution.
B) The smallest entity that can evolve is an individual organism.
C) Individuals can acquire new characteristics as they respond to new environments or situations.
D) Inherited variation in a population is a necessary precondition for natural selection to operate.
E) Natural populations tend to produce more offspring than the environment can support.

b

Which definition of evolution would have been most foreign to Charles Darwin during his lifetime?
A) change in gene frequency in gene pools
B) descent with modification
C) the gradual change of a populationʹs heritable traits over generations
D) populations becoming better adapted to their environments over the course of generations
E) the appearance of new varieties and new species with the passage of time

a

About which of these did Darwin have a poor understanding?
A) that individuals in a population exhibit a good deal of variation
B) that much of the variation between individuals in a population is inherited
C) the factors that cause individuals in populations to struggle for survival
D) the sources of genetic variations among individuals
E) how a beneficial trait becomes more common in a population over the course of generations

d

If, on average, 46% of the loci in a speciesʹ gene pool are heterozygous, then the average homozygosity of the
species should be
A) 23%
B) 46%
C) 54%
D) 92%
E) There is not enough information to say

c

Which of these variables is likely to undergo the largest change in value as the result of a mutation that
introduces a brand-new allele into a populationʹs gene pool at a locus that had formerly been fixed?
A) Average heterozygosity
B) Nucleotide variability
C) Geographic variability
D) Average number of loci

a

Which of these is the smallest unit upon which natural selection directly acts?
A) a speciesʹ gene frequency
B) a populationʹs gene frequency
C) an individualʹs genome
D) an individualʹs genotype
E) an individualʹs phenotype

e

Which of these is the smallest unit that natural selection can change?
A) a speciesʹ gene frequency
B) a populationʹs gene frequency
C) an individualʹs genome
D) an individualʹs genotype
E) an individualʹs phenotype

b

Which of these evolutionary agents is most consistent at causing populations to become better suited to their
environments over the course of generations?
A) Mutation
B) Non-random mating
C) Gene flow
D) Natural selection
E) Genetic drift

d

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is
true?
A) Each bird evolved a deeper, stronger beak as the drought persisted.
B) Each bird developed a deeper, stronger beak as the drought persisted.
C) Each birdʹs survival was strongly influenced by the depth and strength of its beak as the drought
persisted.
D) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the
previous generation.
E) The frequency of the strong-beak alleles increased in each bird as the drought persisted.

c

Each of the following has a better chance of influencing gene frequencies in small populations than in large
populations, but which one most consistently requires a small population as a precondition for its occurrence?
A) Mutation
B) Non-random mating
C) Genetic drift
D) Natural selection
E) Gene flow

c

In modern terminology, diversity is understood to be a result of genetic variation. Sources of variation for
evolution include all of the following except
A) mistakes in translation of structural genes.
B) mistakes in DNA replication.
C) translocations and mistakes in meiosis.
D) recombination at fertilization.
E) recombination by crossing over in meiosis.

a

A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example
of
A) a cline.
B) a bottleneck.
C) relative fitness.
D) genetic drift.
E) geographic variation.

a

The higher the proportion of loci that are ʺfixedʺ in a population, the lower is that populationʹs
A) nucleotide variability.
B) genetic polyploidy.
C) average heterozygosity.
D) A, B, and C
E) A and C only

e

Which statement about variation is true?
A) All phenotypic variation is the result of genotypic variation.
B) All genetic variation produces phenotypic variation.
C) All nucleotide variability results in neutral variation.
D) All new alleles are the result of nucleotide variability.
E) All geographic variation results from the existence of clines.

d

In a hypothetical populationʹs gene pool, an autosomal gene, which had previously been fixed, undergoes a
mutation that introduces a new allele, one inherited according to incomplete dominance. Natural selection then
causes stabilizing selection at this locus. Consequently, what should happen over the course of many
generations?
A) The proportions of both types of homozygote should decrease.
B) The proportion of the population that is heterozygous at this locus should remain constant.
C) The populationʹs average heterozygosity should increase.
D) Both (A)and (B)
E) Both (A)and (C)

e

Rank the following 1-base point mutations (from most likely to least likely) with respect to their likelihood of
affecting the structure of the corresponding polypeptide:
1. insertion mutation deep within an intron
2. substitution mutation at the 3rd position of an exonic codon
3. substitution mutation at the 2nd position of an exonic codon
4. deletion mutation within the first exon of the gene
A) 1, 2, 3, 4
B) 4, 3, 2, 1
C) 2, 1, 4, 3
D) 3, 1, 4, 2
E) 2, 3, 1, 4

b

Sponges are known to contain a single Hox gene. Most invertebrates have a cluster of 10 similar Hox genes, all
located on the same chromosome. Most vertebrates have four such clusters of Hox genes, located on four
non-homologous chromosomes. The process responsible for the change in number of Hox genes from sponges
to invertebrates was most likely __________, whereas a different process that could have potentially
contributed to the clusterʹs presence on more than one chromosome was __________.
I. binary fission
II. translation
III. gene duplication
IV. non-disjunction
V. transcription
A) I, II
B) II, III
C) II, V
D) III, IV
E) III, V

d

HIVʹs genome of RNA includes code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a
DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection
by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for
antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act
against PR.
18) Which of these represents the treatment option that is most likely to avoid the production of drug -resistant
HIV (assuming no drug interactions or side effects)?
A) using a series of NAs, one at a time, and changed about once a week
B) using a single PI, but slowly increasing the dosage over the course of a week
C) using high doses of NA and a PI at the same time for a period not to exceed 1 day
D) using moderate doses of NA and of two different PIʹs at the same time for several months

d

Within the body of an HIV-infected individual who is being treated with a single NA, and whose HIV particles
are currently vulnerable to this NA, which of these situations can increase the virusʹ relative fitness?
1. mutations resulting in RTs with decreased rates of nucleotide mismatch
2. mutations resulting in RTs with increased rates of nucleotide mismatch
3. mutations resulting in RTs that have proofreading capability
A) 1 only
B) 2 only
C) 3 only
D) 1 and 3
E) 2 and 3

b

HIV has 9 genes in its RNA genome. Every HIV particle contains two RNA molecules, each molecule
containing all 9 genes. If, for some reason, the two RNA molecules within a single HIV particle do not have
identical sequences, then which of these terms can be applied due to the existence of the non-identical regions?
A) homozygous
B) gene variability
C) nucleotide variability
D) average heterozygosity
E) all except A

e

If two genes from one RNA molecule become detached and then, as a unit, get attached to one end of the other
RNA molecule within a single HIV particle, which of these is true?
A) There are now fewer genes within the viral particle.
B) There are now more genes within the viral particle.
C) A point substitution mutation has occurred in the retroviral genome.
D) The retroviral equivalent of crossing-over has occurred, no doubt resulting in a heightened positive
effect.
E) One of the RNA molecules has experienced gene duplication as the result of translocation.

e

The DNA polymerases of all cellular organisms have proofreading capability. This capability tends to reduce
the introduction of
A) extra genes by gene duplication events.
B) chromosomal translocation.
C) genetic variation by mutations.
D) proofreading capability into prokaryotes.

c

Which of these makes determining the evolutionary relatedness of different species based on the amino acid
sequence of homologous proteins generally less accurate than determinations of relatedness based on the
nucleotide sequences of homologous genes?
A) Silent mutations
B) Gene duplications
C) Translocation events that change gene sequences
D) Crossing-over
E) Independent assortment

a

Which is a true statement concerning genetic variation?
A) It is created by the direct action of natural selection.
B) It arises in response to changes in the environment.
C) It must be present in a population before natural selection can act upon the population.
D) It tends to be reduced by the processes involved when diploid organisms produce gametes.
E) A population that has a higher average heterozygosity has less genetic variation than one with a larger
average heterozygosity.

c

What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait
(aa) has not changed over time?
A) The population is undergoing genetic drift.
B) The two phenotypes are about equally adaptive under laboratory conditions.
C) The genotype AA is lethal.
D) There has been a high rate of mutation of allele A to allele a.
E) There has been sexual selection favoring allele a.

b

What is the estimated frequency of allele A in the gene pool?
A) 0.05
B) 0.25
C) 0.50
D) 0.75
E) 1.00

c

What proportion of the population is probably heterozygous (Aa) for this trait?
A) 0.05
B) 0.25
C) 0.50
D) 0.75
E) 1.00

c

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a
is 0.4. What is the percentage of the population that is homozygous for this allele?
A) 4
B) 16
C) 32
D) 36
E) 40

b

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is
0.1. What is the percentage of the population that is heterozygous for this allele?
A) 90
B) 81
C) 49
D) 18
E) 10

d

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is
0.2. What is the frequency of individuals with Aa genotype?
A) 0.20
B) 0.32
C) 0.42
D) 0.80
E) Genotype frequency cannot be determined from the information provided.

b

You sample a population of butterflies and find that 42% are heterozygous at a particular locus. What should
be the frequency of the recessive allele in this population?
A) 0.09
B) 0.30
C) 0.49
D) 0.70
E) Allele frequency cannot be determined from this information.

e

What is the frequency of the B allele?
A) 0.001
B) 0.002
C) 0.100
D) 0.400
E) 0.600

e

If there are 4,000 children born to this generation, how many would be expected to have AB blood under the
conditions of Hardy-Weinberg equilibrium?
A) 100
B) 960
C) 1,920
D) 2,000
E) 2,400

c

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36
purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the
value of q for this population?
A) 0.36
B) 0.60
C) 0.64
D) 0.75
E) 0.80

e

Which of these is closest to the allele frequency in the founding population?
A) 0.1 a, 0.9 A
B) 0.2 a, 0.8 A
C) 0.5 a, 0.5 A
D) 0.8 a, 0.2 A
E) 0.4 a, 0.6 A

a

If one assumes that Hardy-Weinberg equilibrium applies to the population of colonists on this planet, about
how many people will have attached earlobes when the planetʹs population reaches 10,000?
A) 100
B) 400
C) 800
D) 1,000
E) 10,000

a

If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite
different in the subsequent generations. This would be an example of
A) diploidy.
B) gene flow.
C) genetic drift.
D) disruptive selection.
E) stabilizing selection.

c

In which population is the frequency of the allele for brown feathers highest?
A) Population A.
B) Population B.
C) Population C.
D) They are all the same.
E) It is impossible to tell from the information given.

d

In which population would it be least likely that an accident would significantly alter the frequency of the
brown allele?
A) Population A.
B) Population B.
C) Population C.
D) They are all the same.
E) It is impossible to tell from the information given.

b

Which population is most likely to be subject to the bottleneck effect?
A) Population A.
B) Population B.
C) Population C.
D) They are all the same.
E) It is impossible to tell from the information given.

a

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture
bottle after each generation. After several generations, you notice that the viability of the flies has decreased
greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to
reverse this trend is to
A) cross your flies with flies from another lab.
B) reduce the number of flies that you transfer at each generation.
C) transfer only the largest flies.
D) change the temperature at which you rear the flies.
E) shock the flies with a brief treatment of heat or cold to make them more hardy.

a

If the frequency of a particular allele that is present in a small, isolated population of alpine plants decreases
due to a landslide that leaves an even smaller remnant of surviving plants bearing this allele, then what has
occurred?
A) a bottleneck
B) genetic drift
C) microevolution
D) A and B only
E) A, B, and C

e

If the original finches that had been blown over to the Galapagos from South America had already been
genetically different from the parental population of South American finches, even before adapting to the
Galapagos, this would have been an example of
A) genetic drift.
B) bottleneck effect.
C) founderʹs effect.
D) all three of these
E) both A and C

e

Over time, the movement of people on Earth has steadily increased. This has altered the course of human
evolution by increasing
A) non-random mating.
B) geographic isolation.
C) genetic drift.
D) mutations.
E) gene flow.

e

Gene flow is a concept best used to describe an exchange between
A) species.
B) males and females.
C) populations.
D) individuals.
E) chromosomes.

c

The outcome of the conflict between bacteria and bacteriophage at any point in time results from
A) frequency-dependent selection.
B) evolutionary imbalance.
C) heterozygote advantage.
D) neutral variation.
E) genetic variation being preserved by diploidy.

a

Natural selection is most nearly the same as
A) diploidy.
B) gene flow.
C) genetic drift.
D) non-random mating.
E) differential reproductive success.

e

Over the course of evolutionary time, what should occur?
A) Methylated DNA should become fixed in the gene pools of bacterial species.
B) Nonmethylated DNA should become fixed in the gene pools of bacteriophages.
C) Methylated DNA should become fixed in the gene pools of bacteriophages.
D) Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages,
with ratios that vary over time.
E) Both A and B are correct.

d

Arrange the following from most general (i.e., most inclusive) to most specific (i.e., least inclusive):
1. Natural selection
2. Microevolution
3. Intrasexual selection
4. Evolution
5. Sexual selection
A) 4, 1, 2, 3, 5
B) 4, 2, 1, 3, 5
C) 4, 2, 1, 5, 3
D) 1, 4, 2, 5, 3
E) 1, 2, 4, 5, 3

c

Sexual dimorphism is most often a result of
A) pansexual selection.
B) stabilizing selection.
C) intrasexual selection.
D) intersexual selection.
E) artificial selection.

d

During breeding season, one should expect female house finches to prefer to mate with males with the
brightest red feathers. Which of the following is true of this situation?
A) Alleles that promote more efficient acquisition of carotenoid-containing foods by males should increase
over the course of generations.
B) Alleles that promote more effective deposition of carotenoid pigments in the feathers of males should
increase over the course of generations.
C) There should be directional selection for bright red feathers in males.
D) All three of these.
E) Only B and C.

d

Which of the following terms are appropriately applied to the situation described in the previous question?
A) Sexual selection
B) Mate choice
C) Intersexual selection
D) All three of these
E) Only B and C

d

The situation as described in the paragraph above should select most directly against males that
A) are unable to distinguish food items that are red from those of other colors.
B) are older, but still healthy.
C) are capable of defending only moderately sized territories.
D) have slightly lower levels of testosterone during breeding season than have other males.
E) have no prior experience courting female house finches.

a

If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females, and
increasing larynx size in adult males, then
A) sexual dimorphism was developing over time in these species.
B) intrasexual selection seems to have occurred.
C) the ʺgood genesʺ hypothesis was refuted by these data.
D) stabilizing selection was occurring in these species concerning larynx size.
E) selection was acting more directly upon genotype than upon phenotype.

a

Which addition to the information in the paragraph above would make more than one of the answers listed in
the previous question correct?
A) If larynx size was also affected by the amount the larynx was used (i.e., the amount of vocalization).
B) If males prefer to mate with females possessing higher voices.
C) If females killed female offspring whose voices were too deep.
D) If the trend described above was seen in the fossil record of only one species of ape.

c

If one excludes the involvement of gender in the situation described in the paragraph above, then the pattern
that is apparent in the fossil record is most similar to one that should be expected from
A) pansexual selection.
B) directional selection.
C) disruptive selection.
D) stabilizing selection.
E) asexual selection.

c

The Darwinian fitness of an individual is measured most directly by
A) the number of its offspring that survive to reproduce.
B) the number of ʺgood genesʺ it possesses.
C) the number of mates it attracts.
D) its physical strength.
E) how long it lives.

a

When we say that an individual organism has a greater fitness than another individual, we specifically mean
that the organism
A) lives longer than others of its species.
B) competes for resources more successfully than others of its species.
C) mates more frequently than others of its species.
D) utilizes resources more efficiently than other species occupying similar niches.
E) leaves more viable offspring than others of its species.

e

Which of the following statements best summarizes evolution as it is viewed today?
A) It is goal-directed.
B) It represents the result of selection for acquired characteristics.
C) It is synonymous with the process of gene flow.
D) It is the descent of humans from the present-day great apes.
E) It is the differential survival and reproduction of the most-fit phenotypes.

e

If neutral variation is truly ʺneutral,ʺ then it should have no effect on
A) nucleotide diversity.
B) average heterozygosity.
C) our ability to measure the rate of evolution.
D) relative fitness.
E) gene diversity.

d

Which describes an African butterfly species that exists in two strikingly different color patterns?
A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

d

Which describes brightly colored peacocks mating more frequently than drab peacocks?
A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

e

Most Swiss starlings produce four to five eggs in each clutch. Those producing fewer or more than this have
reduced fitness. Which of the following terms best describes this?
A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

c

Fossil evidence indicates that horses have gradually increased in size over geologic time. Which of the
following terms best describes this?
A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

b

The average birth weight for human babies is about 3 kg. Which of the following terms best describes this?
A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

c

A certain species of land snail exists as either a cream color or a solid brown color. Intermediate individuals are
relatively rare. Which of the following terms best describes this?
A) artificial selection
B) directional selection
C) stabilizing selection
D) disruptive selection
E) sexual selection

d

Cattle breeders have improved the quality of meat over the years by which process?
A) artificial selection
B) directional selection
C) stabilizing selection
D) A and B
E) A and C

d

The recessive allele that causes phenylketonuria (PKU) is harmful, except when an infantʹs diet lacks the amino
acid, phenylalanine. What maintains the presence of this harmful allele in a populationʹs gene pool?
A) heterozygote advantage
B) stabilizing selection
C) diploidy
D) balancing selection

c

Mules are relatively long-lived and hardy organisms that cannot, generally speaking, perform successful
meiosis. Consequently, which statement about mules is true?
A) They have a relative evolutionary fitness of zero.
B) Their offspring have less genetic variation than the parents.
C) Mutations cannot occur in their genomes.
D) If crossing-over happens in mules, then it must be limited to prophase of mitosis.
E) When two mules interbreed, genetic recombination cannot occur by meiotic crossing over, but only by the
act of fertilization.

a

Heterozygote advantage should be most closely linked to which of the following?
A) sexual selection
B) stabilizing selection
C) random selection
D) directional selection
E) disruptive selection

b

In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds,
respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would
then operate on the finch population?
A) disruptive selection
B) directional selection
C) stabilizing selection
D) sexual selection
E) No selection would operate because the population is in Hardy-Weinberg equilibrium.

b

What is true of the trait whose frequency distribution in a large population appears above? It has probably
undergone
A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) random selection.

b

If the curve shifts to the left or to the right, there is no gene flow, and the population size consequently
increases over successive generations, then which of these is (are) probably occurring?
1. immigration or emigration
2. directional selection
3. adaptation
4. genetic drift
5. disruptive selection
A) 1 only
B) 4 only
C) 2 and 3
D) 4 and 5
E) 1, 2, and 3

c

Male satin bowerbirds adorn structures that they build, called ʺbowers,ʺ with parrot feathers, flowers, and
other bizarre ornaments in order to attract females. Females inspect the bowers and, if suitably impressed,
allow males to mate with them. The evolution of this male behavior is due to
A) frequency-dependent selection.
B) artificial selection.
C) sexual selection.
D) natural selection.
E) disruptive selection.

c

When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the
members of the minority sex often receive a greater proportion of care and resources from parents than do the
offspring of the majority sex. This is most clearly an example of
A) sexual selection.
B) disruptive selection.
C) balancing selection.
D) stabilizing selection.
E) frequency-dependent selection.

e

The same gene that causes various coat patterns in wild and domesticated cats also causes the cross -eyed
condition in these cats, the cross-eyed condition being slightly maladaptive. In a hypothetical environment, the
coat pattern that is associated with crossed eyes is highly adaptive, with the result that both the coat pattern
and the cross-eyed condition increase in a feline population over time. Which statement is supported by these
observations?
A) Evolution is progressive and tends toward a more perfect population.
B) Phenotype is often the result of compromise.
C) Natural selection reduces the frequency of maladaptive genes in populations over the course of time.
D) Polygenic inheritance is generally maladaptive, and should become less common in future generations.
E) In all environments, coat pattern is a more important survival factor than is eye-muscle tone.

b

A proficient engineer can easily design skeletal structures that are more functional than those currently found
in the forelimbs of such diverse mammals as horses, whales, and bats. That the actual forelimbs of these
mammals do not seem to be optimally arranged is because
A) natural selection has not had sufficient time to create the optimal design in each case, but will do so given
enough time.
B) natural selection operates in ways that are beyond the capability of the human mind to comprehend.
C) in many cases, phenotype is not merely determined by genotype, but by the environment as well.
D) though we may not consider the fit between the current skeletal arrangements and their functions
excellent, we should not doubt that natural selection ultimately produces the best design.
E) natural selection is generally limited to modifying structures that were present in previous generations
and in previous species.

e

There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to
be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and
tool-making capability. They reason that if these features are generally beneficial, then the apes should have
evolved them as well. Which of these provides the best argument against this misconception?
A) Advantageous alleles do not arise on demand.
B) A populationʹs evolution is limited by historical constraints.
C) Adaptations are often compromises.
D) Evolution can be influenced by environmental change.

a

A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in
the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of
the flies carry both A1 and A2?
A) 0.7
B) 0.49
C) 0.21
D) 0.42
E) 0.09

d

There are 40 individuals in population 1, all of which have genotype A1A1, and there are 25 individuals in
population 2, all of genotype A2A2. Assume that these populations are located far from one another and that
their environmental conditions are very similar. Based on the information given here, the observed genetic
variation is mostly likely an example of
A) genetic drift.
B) gene flow.
C) disruptive selection.
D) discrete variation.
E) directional selection.

a

Natural selection changes allele frequencies in populations because some __________ survive and reproduce
more successfully than others.
A) alleles
B) loci
C) gene pools
D) species
E) individuals

e

No two people are genetically identical, except for identical twins. The chief cause of genetic variation among
human individuals is
A) new mutations that occurred in the preceding generation.
B) the reshuffling of alleles in sexual reproduction.
C) genetic drift due to the small size of the population.
D) geographic variation within the population.
E) environmental effects.

b

Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings,
illustrating
A) the bottleneck effect.
B) stabilizing selection.
C) frequency-dependent selection.
D) neutral variation.
E) disruptive selection.

b

inter

between

intra

within

micro

small

gene duplication

Humans have an estimated 1,000 olfactory receptor genes. This is most likely a result of _________.

sexual reproduction

What provides the genetic variation found in plant and animal population?

directional selection

A plant population is found in an area that is becoming more arid. The average surface area of leaves has been decreasing over generations. This trend is an example of _______.

relative number of viable offspring

What describes an organism’s relative fitness?

individuals

Natural selection changes allele frequencies because some ______ survive and reproduce more successfully than others.

stabilizing selection

Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating ________

Pathogenic bacteria found in many hospitals are antibiotic resistant.

B. directional selection

Cattle breeders have improved the quality of meat over the years by which process?

c. stabilizing selection

The allele that causes phenylketonuria (PKU) is harmful, except when an infant’s diet lacks the amino acid, phenylalanine. What maintains the presence of this harmful allele in a population’s gene pool?

b. stabilizing selection

Mules are relatively long-lived and hardy organisms that cannot, generally speaking, perform successful meiosis. Which statement about mules is true?

a. They have a relative evolutionary fitness of zero.

Heterozygote advantage should be most closely linked to which of the following?

b. stabilizing selection

In equatorial Africa, all of the following factors contribute to keeping the sickle-cell allele at a high frequency in the population, except

E) frequency-dependent selection.

Which statement about variation is most true?

D) All new alleles are the result of nucleotide variability.

If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?

b. directional selection

What is true of the trait whose frequency distribution in a large population appears above? It has probably undergone

b. stabilizing selection.

If the unimodal distribution shown above becomes a bimodal distribution over time, then

B) a situation of balanced polymorphism may be produced.

If the curve shifts to the left or to the right, there is no gene flow, and the population size consequently increases over successive generations, then which of these is (are) probably occurring?

c. 2 and 3

Male satin bowerbirds adorn structures that they build, called "bowers," with parrot feathers, flowers, and other bizarre ornaments in order to attract females. Females inspect the bowers and, if suitably impressed, allow males to mate with them, after which they go off to nest by themselves. The evolution of this behavior is best described as due to

c. sexual selection.

In many animal species, mature males are much larger than mature females. This size difference can be attributed to

E) A, B, and C

Adult male vervet monkeys have red penises and blue scrotums. Males use their colorful genitalia in dominance displays wherein they compete with each other for access to females. The coloration of the male genitalia is best explained as the result of ____, and specifically of ____.

C) sexual selection; intrasexual selection

Which of the following is most likely to have been produced by sexual selection?

A) a male lion’s mane

When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of

e. frequency-dependent selection.

Female wasps, which are protected by the use of a painful stinger, often make their presence conspicuous by rapidly moving their usually long antennae. These wasps are often mimicked by flies with short antennae who give the appearance of rapidly moving long antennae by waving their forelegs in front of their bodies. Which of the following statements concerning this behavior is not consistent with current evolutionary theory?

D) Given enough time, these flies will develop longer antennae and become perfect mimics.

The same gene that causes various coat patterns in wild and domesticated cats also causes the cross-eyed condition in these cats, the cross-eyed condition being slightly maladaptive. In a hypothetical environment, the coat pattern that is associated with crossed eyes is highly adaptive, with the result that both the coat pattern and the cross-eyed condition increase in a feline population over time. Which statement is best supported by these observations?

b. Phenotype is often the result of compromise.

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. That the actual forelimbs of these mammals do not seem to be optimally arranged is because

e. natural selection is generally limited to modifying structures that were present in previous generations and in previous species.

Gene flow is a concept best used to describe an exchange between

c. populations.

Which of these is closest to the allele frequency in the founding population?

a. 0.1 a, 0.9 A

If one assumes that Hardy-Weinberg equilibrium applies to the population of colonists on this planet, about how many people will have attached earlobes when the planet’s population reaches 10,000?

a. 100

If four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This is an example of

c. genetic drift.

A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of

a. a cline.

Which of the following is one important evolutionary feature of the diploid condition?

D) Diploid organisms express less of their genetic variability than haploid organisms.

The outcome of the conflict between bacteria and bacteriophage at any point in time results from

a. frequency-dependent selection.

Over the course of evolutionary time, what should occur?

d. Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time.

The Darwinian fitness of an individual is measured by

a. the number of its offspring that survive to reproduce.

If a phenotypic polymorphism lacks a genetic component, then

B) natural selection cannot act upon it to make a population better adapted over the course of generations.

When we say that an individual organism has a greater fitness than another individual, we specifically mean
that the organism

e. leaves more viable offspring than others of its species.

Which of the following statements best summarizes evolution as it is viewed today?

e. It is the differential survival and reproduction of the most fit phenotypes.

The higher the proportion of loci that are "fixed" in a population, the lower is that population’s

D) A, B, and C

If neutral variation is truly "neutral," then it should have no effect on

d. relative fitness.

An African butterfly species exists in two strikingly different color patterns

D. disruptive selection

Brightly colored peacocks mate more frequently than do drab peacocks.

E. sexual selection

Most Swiss starlings produce four to five eggs in each clutch.

C. stabilizing selection

Fossil evidence indicates that horses have gradually increased in size over geologic time

B. directional selection

The average birth weight for human babies is about 3 kg.

C. stabilizing selection

A certain species of land snail exists as either a cream color or a solid brown color. Intermediate individuals are relatively rare.

D. disruptive selection

Which of the following is the best example of humans undergoing evolution, understood as "descent with modification"?

a. reduction in the amount and coarseness of body hair over millennia

Which statement best describes how the evolution of pesticide resistance occurs in a population of insects?

d. A number of genetically resistant pesticide survivors reproduce. The next generation of insects contains more genes from the survivors than it does from susceptible individuals.

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. What would need to be true for pest eradication efforts to have been successful in the long run?

d. All individual insects should have possessed genomes that made them susceptible to DDT.

Some members of a photosynthetic plant species are genetically resistant to an herbicide, while other members of the same species are not resistant to the herbicide. Maintaining resistance against the herbicide is metabolically expensive for the plants. Which combination of events should cause the most effective replacement of the non-herbicide-resistant strain of plants by the resistant strain?

d. 1, 3, and 6

If 3TC resistance is costly for HIV, then which plot (I-IV) best represents the response of a strain of 3TC-resistant HIV over time, if 3TC administration begins at the time indicated by the arrow?

c. III

Of the following anatomical structures, which is homologous to the wing of a bat?

e. arm of a human

If two modern organisms are distantly related in an evolutionary sense, then one should expect that

b. they should share fewer homologous structures than two more closely related organisms.

Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from the same embryonic tissues. How do biologists interpret these similarities?

d. A and C only

Human intestines are held in place by membranes called mesenteries. In bipedal humans, it would be logical for these mesenteries to be attached to the rib cage. Instead, they are attached to the backbone, as they are in quadrupedal mammals. Because of this arrangement, human mesenteries have a tendency to tear more often than mesenteries in other mammals, as frequently observed among truck drivers and jackhammer operators. The same evolutionary modification that causes increased susceptibility to torn mesenteries is responsible for

c. back and knee problems.

As adults, certain species of whales possess baleen instead of teeth. Baleen is used to filter the whales’ diet of planktonic animals from seawater. As embryos, baleen whales possess teeth, which are later replaced by baleen. The teeth of embryonic baleen whales are evidence that

c. baleen whales are descendants of toothed whales.

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

c. Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.

Which of the following pieces of evidence most strongly supports the common origin of all life on Earth?

b. All organisms use essentially the same genetic code.

What would be the best technique for determining the evolutionary relationships among several closely related species, each of which still contains living members?

e. DNA or RNA analysis

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

e. DNA sequence evidence fully disagreed with morphological evidence.

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would shed the most light on whether these structures are homologous or whether they are, instead, the result of convergent evolution?

b. The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.

Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails just as fish do, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are

e. B and C only

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that

a. island forms and mainland forms descended from common ancestors.

Monkeys of South and Central America have prehensile tails, meaning that their tails can be used to grasp objects. The tails of African and Asian monkeys are not prehensile. Which discipline is most likely to provide an explanation for how this difference in tails came about?

b. biogeography

The theory of evolution is most accurately described as

d. an overarching explanation, supported by much evidence, for how populations change over time.

An event that describes the idea of catastrophism

The sudden demise of the dinosaurs, and various other groups, by the impact of a large extraterrestrial body with Earth

the prevailing notion prior to the time of Lyell and Darwin

Earth is a few thousand years old, and populations are unchanging

During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." What decription is most likely to be helpful in correcting this student’s misconception?

Characteristics acquired during an organism’s life are generally not passed on through genes.

In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to ever-colder temperatures, would eventually give rise to ever more cold-tolerant winter wheat. Lysenko’s attempts in this regard were most in agreement with the ideas of…

Lamarck.

In Darwin’s thinking, the more closely related two different organisms are, the…

more recently they shared a common ancestor

Natural selection is not based on

individuals adapt to their environments and, thereby, evolve.

Natural selection is based on all of the following

genetic variation exists within populations. the best-adapted individuals tend to leave the most offspring. individuals who survive longer tend to leave more offspring than those who die young. populations tend to produce more individuals than the environment can support.

During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection?

More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.

Today, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run?

None of the individual insects should have possessed genomes that made them resistant to DDT.

Logically, what should have casted the most doubt on the relationships depicted by an evolutionary tree?

Relationships between DNA sequences among the species did not match relationships between skeletal patterns.

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution?

The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.

Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?

By proposing that humans, bats, and dolphins share a common ancestor

the smallest unit that natural selection can change?

a population’s gene frequency

What is a TRUE statement concerning genetic variation?

It must be present in a population before natural selection can act upon the population

You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown.
In which population would it be LEAST likely would alter the frequency of the brown allele?

Population B.

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to…

cross your flies with flies from another lab

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing the chance of…

gene flow

Describe an African butterfly species that exists in two strikingly different color patterns within the same population?

diversifying (disruptive) selection

What describes brightly colored peacocks mating more frequently than drab peacocks?

sexual selection

Most Swiss starlings produce four to five eggs in each clutch. Those producing fewer or more than this have reduced fitness. What term best describes this?

stabilizing selection

Fossil evidence indicates that horses have gradually increased in size over geologic time. What term best describes this?

directional selection

Mules are relatively long-lived and hardy organisms that cannot, generally speaking, perform successful meiosis. Consequently, what is true statement about mules?

They have a relative evolutionary fitness of zero

the fossil record.

Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes), was Cuvier’s attempt to explain the existence of

The sudden demise of the dinosaurs, and various other groups, by the impact of a large extraterrestrial body with Earth

Which of the events described below agrees with the idea of catastrophism?

D

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Surface A x B C D Figure 22.1 Which stratum should contain the greatest proportion of extinct organisms?

C

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Surface A x B C D Figure 22.1 If "x" indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum?

Cuvier

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Surface A x B C D Figure 22.1 Who would have proposed that the boundaries between each stratum mark the occurrence of different localized floods?

Hutton and Lyell

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Surface A x B C D Figure 22.1 Which pair would have been likely to agree that strata such as those depicted here were deposited gradually over long periods of time by subtle mechanisms that are still at work?

a mechanism for evolution that was supported by evidence.

Charles Darwin was the first person to propose

All variation between individuals is due only to environmental factors.

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

individuals adapt to their environments and, thereby, evolve.

Natural selection is based on all of the following except

2 4 1 3

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection? 1. Well-adapted individuals leave more offspring than do poorly adapted individuals. 2. A change occurs in the environment. 3. Genetic frequencies within the population change. 4. Poorly adapted individuals have decreased survivorship.

Subsequent generations of a population should have greater proportions of individuals that possess traits better suited for success in unchanging environments.

Which of the following statements is an inference of natural selection?

an overarching explanation, supported by much evidence, for how populations change over time.

The theory of evolution is most accurately described as