Deck 15: Processes of Evolution

Question 1

Which evolutionary process creates new genetic variation?

A) Natural selection
B) Genetic drift
C) Mutation
D) Nonrandom mating
E) None of the above

Answer 1

C

Question 2

Natural selection can be defined as

A) chance variations in traits.
B) the potential for all species to increase rapidly in number.
C) the processes that lead individuals to resemble their parents.
D) the differential survival and reproduction of individuals.
E) the immutability of species.

Answer 2

D

Question 3

Which statement about mutations is true?

A) Most mutations are either deleterious or advantageous.
B) Mutations are random with respect to the adaptive needs of organisms.
C) The effects of a mutation are constant;whether a mutation is deleterious or beneficial cannot be influenced by environmental conditions.
D) Only rarely does an individual human carry a new mutation in his or her genome.
E) Mutations alone result in adaptation.

Answer 3

B

Question 4

Migration of moths is most likely to lead to

A) mutation.
B) genetic drift.
C) gene flow.
D) adaptation.
E) a population bottleneck.

Question 5

Why do most scientists and historians give Darwin more credit than Wallace regarding their contributions to evolutionary theory?

A) Darwin provided more extensive evidence in support of evolution.
B) Only Darwin provided a mechanism for evolution.
C) Wallace did not write his ideas down.
D) Wallace did not accept natural selection.
E) Alphabetical order;Darwin comes before Wallace.

Question 6

Use the following to answer questions :
A cricket has a diploid genome of 1.2 billion base pairs.Assume that there are about 200,000 individuals in the population and that the mutation rate is one per 100 million base pairs.
About how many new mutations will occur in each generation of the population of crickets?

A) 1.2
B) 12
C) 200,000
D) 1 million
E) 2.4 million

Question 7

Which statement about evolution is false?

A) Individuals evolve.
B) Evolution is possible in the absence of natural selection.
C) Developmental change occurs within an individual.
D) Evolutionary change requires genetic change.
E) Natural selection has been demonstrated to be an important process of evolution.

Question 8

The artificial selection experiments with bristle numbers in Drosophila illustrate which generality?

A) In such experiments,it is difficult to obtain individuals with traits that fall outside the range found in the original population.
B) Populations often contain considerable genetic variation upon which selection can operate.
C) Such experiments usually take thousands of generations to achieve their results.
D) Mutations occur to suit the needs of the population.
E) Mutations are random with respect to the adaptive needs of organisms.

Question 9

What is the maximum number of alleles that a given human adult (with 23 pairs of chromosomes)can have at any particular genetic locus?

A) 1
B) 2
C) 23
D) 46
E) There is no maximum number.

Question 10

Darwin's breeding of pigeons

A) showed that breeding can produce a great deal of variation in traits.
B) provided him with a mechanism of heredity.
C) provided insight on the rate of new mutations.
D) showed that most populations have little genetic variability.
E) led him to conclude that individuals evolve.

Question 11

Use the following to answer questions :
A cricket has a diploid genome of 1.2 billion base pairs.Assume that there are about 200,000 individuals in the population and that the mutation rate is one per 100 million base pairs.
On average,how many new mutations will occur in an individual cricket?

A) 0.002
B) 1.2
C) 2
D) 12
E) 2.4 million

Question 12

A small population of sawflies that was once connected to a larger one but is now isolated is no longer experiencing

A) enhanced genetic drift.
B) gene flow.
C) reproductive isolation.
D) natural selection.
E) genotypic equilibrium.

Question 13

Suppose you are a researcher in an influenza lab and your team has uncovered four strains that have evolved changes from last year's influenza virus.Strain A has evolved four changes in its surface proteins and three changes in its interior proteins.Strain B has evolved two changes in its surface proteins and seven changes in its interior proteins.Strain C has evolved six changes in its surface proteins and none in its interior proteins.Strain D has evolved only a single change in its surface proteins and none in its interior proteins.Assuming that all other factors are equal,which strain is most likely to be infectious?

A) Strain A
B) Strain B
C) Strain C
D) Strain D
E) All of the strains are equally likely to be infectious.

Question 14

Although Darwin's voyage aboard the HMS Beagle took him around the world,most of his observations on natural history were made on the continent of _______ and its nearby islands.

A) Europe
B) North America
C) South America
D) Asia
E) Africa

Question 15

Darwin published The Origin of Species

A) before 1840.
B) between 1841 and 1880.
C) between 1881 and 1920.
D) between 1921 and 1960.
E) after 1960.

Question 16

Which vegetable is most likely to be produced from wild mustard,Brassica oleracea,given continued selection for larger stems and flowers?

A) Kale
B) Brussels sprouts
C) Broccoli
D) Cabbage
E) Cauliflower

Question 17

Which is not an example of adaptation?

A) A plant population that is very resistant to drought due to the action of natural selection
B) The process by which a plant population became drought resistant
C) The increased ability (above baseline)of an individual plant to withstand further drought after it has received a heat shock,which causes the expression of specific proteins that enable more efficient use of water
D) A zebra that runs quickly to evade lions
E) A lion that runs quickly in order to catch zebra prey

Question 18

Which statement about Darwin is true?

A) Even as a youth,Darwin recognized that life evolves.
B) Darwin published his observations about evolution soon after the HMS Beagle arrived in England.
C) Darwin recognized that animals on the Galápagos Islands were all identical to those on the mainland.
D) Darwin had a keen interest in geology.
E) Darwin was the first to present evidence for evolution.

Question 19

Which statement about the 1918-1919 influenza pandemic is false?

A) Compared with most flu viruses,the virus of the pandemic hit young adults particularly hard.
B) There were more deaths from this virus than there were combat deaths in World War I.
C) The virus often triggered an especially intense reaction in the immune system.
D) The virus was the product of evolution.
E) All of the above are true;none is false.

Question 20

Which vegetable is most likely to be produced from wild mustard,Brassica oleracea,given continued selection for larger flower clusters?

A) Kale
B) Brussels sprouts
C) Broccoli
D) Cabbage
E) Cauliflower

Question 21

In a hypothetical population of tree swallows,18 individuals are homozygous for the c4 allele,22 individuals are heterozygous for the allele,and 10 individuals lack the allele.What is the frequency of the c4 allele?

A) 0.29
B) 0.36
C) 0.40
D) 0.58
E) 0.80

Question 22

What was Darwin's explanation for the evolution of bright colors and other apparently useless (and potentially deleterious)but conspicuous characters in males of many species?

A) Stabilizing selection
B) Genetic drift
C) Sexual selection
D) Disruptive selection
E) Gene flow

Question 23

Malte Andersson's study of widowbirds demonstrated that

A) females prefer males with unaltered tails.
B) the preferences of females change according to the season.
C) sexually selected traits have no benefits or costs to survivorship.
D) long tails help males compete against other males.
E) females prefer males with longer-than-average tails.

Question 24

Three different alleles (b1,b2,and b3)at the b locus exist in a hypothetical population of juniper trees.If the frequency of b1 is 0.4,what can be said about the frequency of b3?

A) It cannot be less than 0.4.
B) It is 0.6.
C) It is 0.4.
D) It is 0.
E) Insufficient information is given to answer the question.

Question 25

Use the following to answer questions :
Suppose you have a population of flour beetles with 1,000 individuals.Normally the beetles are red;however,this population is polymorphic for a mutant autosomal body color,black,designated by bb.Red is dominant to black,so BB and Bb genotypes are red.Assume the population is at Hardy-Weinberg equilibrium,with equal frequencies of the two alleles.
What would be the expected frequencies of the homozygous dominant,heterozygous,and homozygous recessive (in that order)after 100 generations,assuming that no selection or other evolutionary processes are operating?

A) 0.75;0.20;0.05
B) 0.25;0.5;0.25
C) 0.33;0.33;0.33
D) All red,because it is the natural color
E) All black,because all red alleles would mutate to black

Question 26

Which is not a condition that must be met for a population to be at Hardy-Weinberg equilibrium?

A) Absence of gene flow
B) Absence of differential survival among genotypes
C) Random mating of individuals with respect to genotype
D) Absence of genetic drift that would cause chance fluctuations of allele frequencies
E) Small population size

Question 27

A fairly large population of sparrows has a much greater than expected proportion of heterozygotes at many loci.Which explanation is most plausible?

A) Mating preference for individuals of different genotypes
B) Mating preferences for individuals of the same genotypes
C) A strong population bottleneck
D) Genetic drift
E) Mutation

Question 28

Use the following to answer questions :
Suppose you have a population of flour beetles with 1,000 individuals.Normally the beetles are red;however,this population is polymorphic for a mutant autosomal body color,black,designated by bb.Red is dominant to black,so BB and Bb genotypes are red.Assume the population is at Hardy-Weinberg equilibrium,with equal frequencies of the two alleles.
What would be the expected frequencies of the red and black phenotypes?

A) 0.25 red;0.75 black
B) 0.5 red;0.5 black
C) 0.75 red;0.25 black
D) All red
E) All black

Question 29

Which statement about allele frequencies is true?

A) It is possible to have a negative allele frequency.
B) Allele frequencies can be greater than 1 in some populations.
C) The sum of all allele frequencies is 0.
D) The sum of all allele frequencies is 1.
E) All alleles have the same frequency.

Question 30

In a hypothetical population of sawflies,20 percent of the population is homozygous for allele A and 45 percent is homozygous for allele a.Assuming that A and a are the only alleles at this locus,what percent of the population is heterozygous?

A) 10 percent
B) 20 percent
C) 35 percent
D) 45 percent
E) 65 percent

Question 31

Due to various causes,including DDT poisoning,the population size of whooping cranes was reduced to about two dozen during the 1940s.The population size has since rebounded,and there are now hundreds of whooping cranes.Which would you not expect to see in the current populations of whooping cranes?

A) Very low levels of genetic variation
B) Very few heterozygous individuals
C) Allele frequencies different from those of historical populations
D) Considerable genetic polymorphism
E) Genotypic frequencies different from those of historical populations

Question 32

Which statement about genetic drift as an evolutionary factor is true?

A) It is more significant in a population with small numbers than in a population with large numbers.
B) It is responsible for the selection of mutations.
C) It is connected to the movements of alleles between populations of a single species.
D) Its strength is proportional to the size of a population: the larger the population,the greater the force.
E) It is the primary process that generates adaptations.

Question 33

You discover a population of mustard plants and find it to be at Hardy-Weinberg equilibrium with respect to the R locus.Suppose that there are two alleles at this locus and the frequency of one of those alleles (the r-6 allele)is 0.2.Of the individuals that carry at least one r-6 allele,what fraction are heterozygotes?

A) ¹/₉
B) ¹/₅
C) ¹/₃
D) ⁴/₅
E) ⁸/₉

Question 34

Which statement about the Hardy-Weinberg equilibrium is true?

A) It explains why dominant alleles favored by natural selection do not necessarily replace recessive alleles in a population.
B) It applies only to populations in which there is gene flow.
C) It assumes that populations are small.
D) It assumes that individuals prefer to mate with individuals with certain genotypes.
E) It predicts that the genotypic frequencies of a population will change even in the absence of evolutionary processes.

Question 35

If a population with two alleles is at Hardy-Weinberg equilibrium and the frequency of one allele is 0.7,what is the heterozygote frequency?

A) 0.7
B) 0.42
C) 0.3
D) 0.21
E) 0

Question 36

Assuming that there are only two alleles at a given locus,if the frequency of one allele is 0.6,what is the frequency of the other allele?

A) -0.6
B) 0
C) 0.4
D) 0.6
E) 1

Question 37

Following a flood,migration from neighboring populations alters genotypic frequencies of a population of river-bottom midges.Assuming that the conditions for Hardy-Weinberg subsequently are met,how many generations of random mating are required to restore the genotypic frequencies to Hardy-Weinberg equilibrium?

A) 1
B) 2
C) Between 3 and 10
D) Between 11 and 20
E) More than 20

Question 38

Which statement about sexual selection is true?

A) Traits favored by sexual selection are often costly to males.
B) Sexual selection operates primarily on survival success.
C) Sexual selection is the only form of nonrandom mating.
D) Darwin's contemporaries immediately recognized the importance of his ideas about sexual selection.
E) Sexual selection applies to the ability of individuals of one sex to compete for access to members of the opposite sex,not to matters of sexual attractiveness.

Question 39

Which statement is true?

A) Two different populations can have the same allele frequencies but different genotype frequencies.
B) Populations that are polymorphic have only one allele at a locus.
C) If an allele is fixed in a population,that population is polymorphic.
D) Allelic frequencies are measures of how a population's genetic variation is distributed among its members.
E) A population that is monomorphic has a great deal of genetic variation.

Question 40

If the frequency of an allele is 0.75,how many copies of this allele should be in a population of 300 diploid individuals?

A) 75
B) 150
C) 225
D) 300
E) 450

Question 41

Use the following to answer questions :
Suppose the size of a population of marmots is 300.

-Assuming that the mutation rate for a particular gene is $\mu$ ,the number of new mutations at this locus in this population is _______ × $\mu$ .

A) 100
B) 200
C) 300
D) 500
E) 600

Question 42

The sizes of horns in males of a particular beetle have an interesting distribution: the highest frequencies are around 15 millimeters and 30 millimeters,with few individuals in between.Based on this observation,which evolutionary process is most likely to be operating on these horns?

A) Stabilizing selection
B) Directional selection
C) Genetic drift
D) Disruptive selection
E) Mutation

Question 43

Use the following to answer questions :
Suppose you have a population of flour beetles with 1,000 individuals.Normally the beetles are red;however,this population is polymorphic for a mutant autosomal body color,black,designated by bb.Red is dominant to black,so BB and Bb genotypes are red.Assume the population is at Hardy-Weinberg equilibrium,with equal frequencies of the two alleles.
What would be the allele frequencies if a population bottleneck occurred and only four individuals survived: one female red heterozygote and three black males?

A) 0.125 red;0.875 black
B) 0.875 red;0.125 black
C) 0.25 red;0.75 black
D) 0.75 red;0.25 black
E) 0.5 red;0.5 black

Question 44

In a sequence of DNA taken from various species of snails,researchers have found that the rates of nonsynonymous substitutions and synonymous substitutions are roughly the same.What can we infer from this pattern?

A) This gene has a high mutation rate.
B) This gene has a low mutation rate.
C) Strong stabilizing selection is acting on this gene.
D) Strong positive selection is acting on this gene.
E) Most of the amino-acid substitutions at this gene are neutral.

Question 45

Use the following to answer questions :
Suppose the size of a population of marmots is 300.
According to genetic drift theory,what is the probability that a newly arisen mutation will become fixed in this population?

A) ¹/₁₀₀
B) ¹/₃₀₀
C) ¹/₆₀₀
D) ¹/₁₂₀₀
E) 1

Question 46

Which statement is plausible explanation for the typically slow rates of evolution over the long term?

A) Most populations have little genetic variation.
B) Natural selection is typically a stabilizing phenomenon.
C) Directional selection is commonplace.
D) Genetic drift counters the effects of selection,particularly in large populations.
E) Mutation rates are very high.

Question 47

If the exchange of allele b1 for b2 at the b locus does not affect the fitness of individuals,these alleles can be considered _______ alleles.

A) selected
B) neutral
C) neutered
D) missense
E) deleterious

Question 48

Researchers suspect that the gene FOXP2,which is involved in speech and cognition,has been under positive selection in the human lineage.Which observation would provide the strongest support for such a claim?

A) Genotypes at this locus are at Hardy-Weinberg equilibrium.
B) There is a higher rate of nonsynonymous substitutions than synonymous ones.
C) There is a lower rate of nonsynonymous substitutions than synonymous ones.
D) The gene evolves following the molecular clock.
E) The gene is a pseudogene.

Question 49

Which mode of selection operates when individuals at both extremes of the distribution have the highest fitness?

A) Stabilizing selection
B) Directional selection
C) Positive selection
D) Disruptive selection
E) Purifying selection

Question 50

According to the neutral theory of molecular evolution,

A) most alleles found in natural populations are neutral.
B) nearly all mutations have some effect on the organism.
C) the rate of fixation of neutral mutations is much faster in small populations than it is in large ones.
D) molecular clocks do not work.
E) most mutations must be neutral.

Question 51

According to the neutral theory of molecular evolution,the fastest rate of fixation of neutral mutations by genetic drift should occur in which population?

A) A population of 200 individuals
B) A population of 400 individuals
C) A population of 10,000 individuals
D) The rates of fixation should be roughly the same in the two smaller populations,and will be much slower in the largest population.
E) The rates of fixation should be roughly the same in all three populations.

Question 52

Rank the following processes with respect to their rate of evolution (from fastest to slowest).

A) Synonymous substitutions,nonsynonymous substitutions,pseudogenes
B) Synonymous substitutions,pseudogenes,nonsynonymous substitutions
C) Pseudogenes,synonymous substitutions,nonsynonymous substitutions
D) Pseudogenes,nonsynonymous substitutions,synonymous substitutions
E) Nonsynonymous substitutions,synonymous substitutions,pseudogenes

Question 53

The hypothesis of neutral evolution asserts that

A) the rate of molecular mutation is influenced by natural selection.
B) most variability in the structure of molecules does not affect their functioning.
C) closely related species have more similar molecular structures than do distantly related species.
D) organisms evolved through neutral changes in their molecules.
E) mutations neither add nor subtract amino acids from molecules.

Question 54

Suppose a biologist wanted to determine the mutation rate in a group of organisms by comparing the rates of evolution between closely related species.Which type of gene or part of a gene should the biologist examine?

A) Synonymous substitutions
B) Nonsynonymous substitutions in a slowly evolving gene
C) Nonsynonymous substitutions in a rapidly evolving gene
D) Pseudogenes
E) Missense substitutions

Question 55

Which mode of selection is most likely to lead to an increase in phenotypic variation?

A) Disruptive selection
B) Stabilizing selection
C) Directional selection
D) Purifying selection
E) Concentrated selection

Question 56

Synonymous substitutions are possible because

A) most changes in DNA are either deleterious or selectively neutral.
B) mutation rates are high.
C) mutation rates are low.
D) most amino acids are specified by more than one codon.
E) most codons are specified by more than one amino acid.

Question 57

Genes from many isolates of the influenza virus have been sequenced.In certain regions of the genome,nonsynonymous substitutions have been found to occur much more frequently than synonymous substitutions.From this pattern we can infer that

A) a great deal of genetic drift is taking place.
B) most of the amino acid changes are neutral.
C) strong stabilizing selection is acting on this gene.
D) strong positive selection is acting on this gene.
E) mutations that change the amino acid are disadvantageous.

Question 58

Several populations of copepods are sampled for variation at the G locus.Population A is found to be 30 percent GG,60 percent Gg,and 10 percent gg.Population B is 62 percent GG,36 percent Gg,and 2 percent gg.Population C is 30 percent GG,40 percent Gg,and 30 percent gg.Which population shows a heterozygote deficiency?

A) Only population A
B) Only population B
C) Only population C
D) Populations A and B
E) None of the populations

Question 59

The fossil record shows a strong and persistent trend of decreased size of a mussel.What is the most likely cause of this phenomenon?

A) Genetic drift
B) Mutation
C) Stabilizing selection
D) Disruptive selection
E) Directional selection

Question 60

A nonsynonymous mutation is also called a _______ mutation.

A) silent
B) missense
C) disruptive
D) neutral
E) beneficial

Question 61

In which group would you expect the greatest extent of lateral gene transfer?

A) Bacteria
B) Plants
C) Arthropods
D) Mammals
E) Birds

Question 62

Which statement about genomes is true?

A) The genome sizes of all plants are smaller than those of all animals.
B) Humans have the largest genome size of all animals.
C) Most of the bacterial genome is noncoding.
D) The variation in genome size among animals is greater than the variation in the number of genes.
E) Most of the DNA in humans codes for proteins.

Question 63

In most mammals,the main role of lysozymes is to

A) perform foregut fermentation.
B) carry oxygen in the blood.
C) defend the body from bacteria.
D) assist in thermoregulation.
E) maintain a stable pH.

Question 64

Sickle cell anemia evolved in Africa.Although homozygotes of this allele have the anemia,the sickle cell allele of $\beta$ -globin has reached high frequencies because individuals with one copy of the allele have a resistance to malaria.The maintenance of both the normal and sickle cell alleles is therefore due to

A) the Hardy-Weinberg principle.
B) stabilizing selection.
C) Muller's ratchet.
D) directional selection.
E) heterozygote advantage.

Question 65

Which observation would provide the strongest evidence that most noncoding DNA is slightly deleterious?

A) Species with larger population sizes have more noncoding DNA.
B) Species with smaller population sizes have more noncoding DNA.
C) Species with larger genomes lose DNA more slowly through mutational processes than those with smaller genomes.
D) Species with larger genomes lose DNA more quickly through mutational processes than those with smaller genomes.
E) There is an inverse relationship between the total amount of DNA in the genome and the percentage of the DNA that is noncoding.

Question 66

A biologist is examining species of plants found in Thailand in the hope of finding a naturally occurring treatment for cancer.This scientist is engaged in

A) an application of Muller's ratchet.
B) bioprospecting.
C) bioremediation.
D) bioinfomatics.
E) an application of the principles of convergent evolution.

Question 67

Studies of enzyme genotypes and flight in Colias butterflies showed that

A) males that are heterozygous for the PGI gene have greater mating success than homozygous males because they are able to fly farther in a broad range of temperatures.
B) males that are heterozygous for the PGI gene are always inferior in flight compared to homozygotes.
C) genotypes for the PGI gene do not affect flight ability.
D) flight ability and mating success are not correlated.
E) flight ability can be explained by Muller's ratchet.

Question 68

Which condition would be most conducive to the evolution of sexual reproduction and recombination?

A) Large population size
B) Steady temperatures
C) A very efficient DNA repair system
D) The elimination of pathogens
E) A rapidly changing environment

Question 69

Which event is least likely to occur after a gene duplication event?

A) One gene retains its function,while the other becomes a pseudogene.
B) Both genes retain their function,but they are expressed in different tissues.
C) Both genes retain their function,but they are expressed at different times.
D) Both genes become pseudogenes.
E) One gene retains its function,while the other evolves to have a new function.

Question 70

Use the following to answer questions :
A gene family has been accumulating nucleotide substitutions at a rate of 0.25 substitutions per million years.On average,there have been 80 substitutions between the common ancestor of this gene family and each of the various living forms of this gene.
Based on these figures,this gene family likely originated _______ million years ago.

A) 20
B) 80
C) 160
D) 200
E) 320

Question 71

Use the following to answer questions :
A gene family has been accumulating nucleotide substitutions at a rate of 0.25 substitutions per million years.On average,there have been 80 substitutions between the common ancestor of this gene family and each of the various living forms of this gene.
How many substitutions are likely to have evolved between any pair of living forms of genes from this gene family?

A) 20
B) 40
C) 80
D) 160
E) 320

Question 72

The percentage of the genome that encodes functional genes _______ as genome size increases.

A) steadily increases
B) increases to a point,and then levels off
C) stays more or less the same
D) increases at first,and then declines
E) steadily decreases

Question 73

The tetrodotoxin found in puffer fish is a toxin because it

A) is a mutagen.
B) blocks sodium channels.
C) accelerates destruction by free radicals.
D) stops glucose metabolism.
E) accelerates heart rate.

Question 74

Charles Darwin's early thinking about geology was shaped by the work of _______,who claimed that Earth's features are shaped continuously by slow-acting forces.

Question 75

Sexual reproduction makes natural selection _______ efficient by _______ the _______ of the number of deleterious mutations among individuals.

A) more;increasing;mean
B) more;increasing;variance
C) more;decreasing;mean
D) less;increasing;mean
E) less;increasing;variance

Question 76

A field experiment is conducted to test for a heterozygote advantage in the survival of a mustard plant.When heterozygotes for the A locus are first crossed,the yield is 200 AA,400 Aa,and 200 aa ( i.e. ,a ratio of 1:2:1).In trial 1,35 AA,44 Aa,and 23 aa plants survive.In trial 2,25 AA,68 Aa,and 21 aa plants survive.In trial 3,27 AA,48 Aa,and 23 aa plants.Based on these results,which statement is true?

A) Only trial 1 shows heterozygote advantage.
B) Only trial 2 shows heterozygote advantage.
C) Both trials 1 and 2 show heterozygote advantage.
D) Only trial 3 shows heterozygote advantage.
E) No trial shows heterozygote advantage.

Question 77

The term "_______" refers to the total body of work comprising the understanding and applications of a field of knowledge.

Question 78

A disadvantage of sexual recombination is that it

A) breaks down combinations of beneficial alleles.
B) leads to Muller's ratchet.
C) hampers DNA repair.
D) permits the elimination of deleterious mutations.
E) decreases genetic variation.

Question 79

Charles Darwin and _______ independently articulated the concept of natural selection.

Question 80

Muller's ratchet is the

A) breaking down of adaptive combinations of genes by recombination.
B) elimination of deleterious mutations due to sexual reproduction.
C) accumulation of deleterious mutations in asexual lineages.
D) crossing over and independent assortment of chromosomes during meiosis.
E) maintenance of genetic variation via disruptive selection.