Question 1

Which of the following statements describes an element of the Fisher-Muller hypothesis for adaptive advantage of sexual reproduction?

Accepted Answer

A) Sex builds up linkage disequilibrium. 
B) Sex slows down adaptive evolution by disrupting coadapted gene complexes. 
C) Sex facilitates the combination of favorable mutations that originated in different individuals into advantageous genotypes. 
D) Sex accelerates adaptive evolution. 
E) C and D 
A) Sex builds up linkage disequilibrium. 
B) Sex slows down adaptive evolution by disrupting coadapted gene complexes. 
C) Sex facilitates the combination of favorable mutations that originated in different individuals into advantageous genotypes. 
D) Sex accelerates adaptive evolution. 
E) C and D

Question 2

Which of the following systems lends itself best to the study of the environmental factors that lead to the maintenance of sexual reproduction?

Accepted Answer

A) Cyclical parthenogenetic populations that follow highly predictable seasonal patterns independent of environmental changes 
B) Obligate sexual species taxa, such as most birds 
C) Species that are polymorphic for sexual/asexual reproduction, and show the same proportion of sexual reproduction in all environments 
D) Populations that respond to environmental changes with a change from asexual to sexual reproduction 
A) Cyclical parthenogenetic populations that follow highly predictable seasonal patterns independent of environmental changes 
B) Obligate sexual species taxa, such as most birds 
C) Species that are polymorphic for sexual/asexual reproduction, and show the same proportion of sexual reproduction in all environments 
D) Populations that respond to environmental changes with a change from asexual to sexual reproduction

Question 3

Are there any costs when asexual organisms reproduce automictically as opposed to apomictically?

Accepted Answer

A) Yes, recombination may disrupt coadapted gene complexes. 
B) Yes, recombination is the cause of the twofold cost of sex. 
C) No, both are forms of asexual reproduction. 
D) No, recombination will produce better adapted individuals. 
E) C and D 
A) Yes, recombination may disrupt coadapted gene complexes. 
B) Yes, recombination is the cause of the twofold cost of sex. 
C) No, both are forms of asexual reproduction. 
D) No, recombination will produce better adapted individuals. 
E) C and D

Question 4

Water fleas,Daphnia magna,can switch between asexual and sexual reproduction cycles.Which of the following observations support the hypothesis that sex is favored in unpredictable environments?

Accepted Answer

A) The introduction of predators triggers sexual reproduction. 
B) D. magna reproduces asexually every other generation in a variety of habitats. 
C) D. magna reproduces sexually when its aquatic habitat dries up. 
D) Asexual D. magna strains outcompete introduced competitors. 
E) A and C 
A) The introduction of predators triggers sexual reproduction. 
B) D. magna reproduces asexually every other generation in a variety of habitats. 
C) D. magna reproduces sexually when its aquatic habitat dries up. 
D) Asexual D. magna strains outcompete introduced competitors. 
E) A and C

Question 5

Why is sexual reproduction believed to be the ancestral state in eukaryotes?

Accepted Answer

A) Asexual reproduction is completely absent from basal unicellular eukaryotes. 
B) Under the parsimony principle, the most common form of a trait's state is always the ancestral state. 
C) The "twiggy" distribution of obligate asexual reproduction in phylogenetic trees suggests that asexuality is a derived trait. 
D) Evolutionary models suggest that obligate asexual taxa are more prone to extinction than sexual ones. 
A) Asexual reproduction is completely absent from basal unicellular eukaryotes. 
B) Under the parsimony principle, the most common form of a trait's state is always the ancestral state. 
C) The "twiggy" distribution of obligate asexual reproduction in phylogenetic trees suggests that asexuality is a derived trait. 
D) Evolutionary models suggest that obligate asexual taxa are more prone to extinction than sexual ones.

Question 6

The Amazon molly,Poecillia formosa,is a freshwater fish that is gynogenetic.In order to reproduce,individuals of this all-female species must mate with a male from a closely related species to initiate the development of their offspring.The male's genetic material does not,however,enter the Amazon molly's egg.What costs of sexual reproduction does the Amazon molly potentially experience?

Accepted Answer

A) None. It reproduces asexually. 
B) The costs associated with finding a mate. 
C) The fish may spend energy competing with other females for mates. 
D) It has no means of turning back Muller's ratchet. 
E) B and C 
A) None. It reproduces asexually. 
B) The costs associated with finding a mate. 
C) The fish may spend energy competing with other females for mates. 
D) It has no means of turning back Muller's ratchet. 
E) B and C

Question 7

Why do pathogens tend to evolve faster than their hosts?

Accepted Answer

Pathogens tend to ha

Question 8

Does Muller's ratchet apply to both apomictic and automictic asexual populations?

Accepted Answer

No,Muller's ratchet does not a

Question 9

Under what conditions are asexual and sexual reproduction favored by the three evolutionary models,involving environmental unpredictability,number of niches,and parasite load?
   A)Low environmental unpredictability
B)High environmental unpredictability:
C)Low number of niches
D)High number of niches
E)Low parasite load
F)High parasite load

Accepted Answer

All "Low" conditions

Question 10

The two figures below represent an asexual and a sexual population,respectively.The letters indicate beneficial mutations.The shaded areas represent the frequency of particular combinations of mutations in the population over time.Why does it take longer for the beneficial allele combination of ABC to go to fixation in the asexual population than in the sexual population?

Accepted Answer

A) In the asexual population, new allelic combinations have to arise via de novo mutations. 
B) There is no principal difference between asexual and sexual populations. In the sexual population shown, the favorable mutations just happen to be on different chromosomes. 
C) The effective population size of both populations is the same. 
D) Sexual populations tend to have higher mutation rates. 
A) In the asexual population, new allelic combinations have to arise via de novo mutations. 
B) There is no principal difference between asexual and sexual populations. In the sexual population shown, the favorable mutations just happen to be on different chromosomes. 
C) The effective population size of both populations is the same. 
D) Sexual populations tend to have higher mutation rates.

Question 11

In a population that is polymorphic for sexual/asexual reproduction,a sexually transmitted disease has just eliminated most of the sexually reproducing individuals.When you expose samples of asexuals and sexuals from this population to harsh environmental conditions in the lab,you discover that the sexual individuals are worse at adapting to the new environment than the asexual individuals.(Note that your lab population is free from the sexually transmitted disease.)Which of the following statements is a likely explanation for your results?

Accepted Answer

A) All asexually reproducing strains independently acquired the same beneficial mutation that offset the advantage of the sexuals. 
B) The bottleneck caused by the disease resulted in the fixation of many alleles in the sexually reproducing population. 
C) Asexuals are favored under harsh environmental conditions. 
D) The results support standard evolutionary theory. 
E) B and C 
A) All asexually reproducing strains independently acquired the same beneficial mutation that offset the advantage of the sexuals. 
B) The bottleneck caused by the disease resulted in the fixation of many alleles in the sexually reproducing population. 
C) Asexuals are favored under harsh environmental conditions. 
D) The results support standard evolutionary theory. 
E) B and C

Question 12

In an experiment,Jokela and colleagues reared 14 replicate populations of a snail species that is polymorphic for sexual/asexual reproduction under controlled,identical conditions in the lab.Each population started with 35% asexual and 65% sexual individuals.The figure below shows the percent of asexual individuals after a year-long experimental run.Which of the following statements is a possible explanation for these results?

Accepted Answer

A) Asexual females survived better under the experimental conditions. 
B) Asexual females produced more offspring per individual than sexual females. 
C) Avoiding the cost of males allows faster population growth for the asexual subpopulation. 
D) A novel mutation after the start of the experiment led to the increased survival of the asexual line with the mutations. 
E) A, B, and C 
A) Asexual females survived better under the experimental conditions. 
B) Asexual females produced more offspring per individual than sexual females. 
C) Avoiding the cost of males allows faster population growth for the asexual subpopulation. 
D) A novel mutation after the start of the experiment led to the increased survival of the asexual line with the mutations. 
E) A, B, and C

Which of the following statements describes an element of the Fisher-Muller hypothesis for adaptive advantage of sexual reproduction?

Which of the following systems lends itself best to the study of the environmental factors that lead to the maintenance of sexual reproduction?

Are there any costs when asexual organisms reproduce automictically as opposed to apomictically?

Water fleas,Daphnia magna,can switch between asexual and sexual reproduction cycles.Which of the following observations support the hypothesis that sex is favored in unpredictable environments?

Why is sexual reproduction believed to be the ancestral state in eukaryotes?

Why do pathogens tend to evolve faster than their hosts?

Does Muller's ratchet apply to both apomictic and automictic asexual populations?

An Overview of Evolutionary Biology

Early Evolutionary Ideas and Darwins Insight

Natural Selection

Phylogeny and Evolutionary History

Inferring Phylogeny

Transmission Genetics and the Sources of Genetic Variation

The Genetics of Populations

Evolution in Finite Populations

Evolution at Multiple Loci

Genome Evolution

The Origin and Evolution of Early Life

Major Transitions

Evolution and Development

Species and Speciation

Extinction and Evolutionary Trends

Sexual Selection

The Evolution of Sociality

Coevolution

Evolution and Medicine

Filters

Exam 16: The Evolution of Sex

Which of the following statements describes an element of the Fisher-Muller hypothesis for adaptive advantage of sexual reproduction?

Which of the following systems lends itself best to the study of the environmental factors that lead to the maintenance of sexual reproduction?

Are there any costs when asexual organisms reproduce automictically as opposed to apomictically?

Water fleas,Daphnia magna,can switch between asexual and sexual reproduction cycles.Which of the following observations support the hypothesis that sex is favored in unpredictable environments?

Why is sexual reproduction believed to be the ancestral state in eukaryotes?

Why do pathogens tend to evolve faster than their hosts?

Does Muller's ratchet apply to both apomictic and automictic asexual populations?

An Overview of Evolutionary Biology

Early Evolutionary Ideas and Darwins Insight

Natural Selection

Phylogeny and Evolutionary History

Inferring Phylogeny

Transmission Genetics and the Sources of Genetic Variation

The Genetics of Populations

Evolution in Finite Populations

Evolution at Multiple Loci

Genome Evolution

The Origin and Evolution of Early Life

Major Transitions

Evolution and Development

Species and Speciation

Extinction and Evolutionary Trends

Sexual Selection

The Evolution of Sociality

Coevolution

Evolution and Medicine

Filters