Exam 3: Natural Selection

An evolutionary arms race occurs when natural selection is acting simultaneously on both sides of a host-pathogen interaction. How does an evolutionary arms race constrain evolution?

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Question 1

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Evolutionary arms races prevent organisms from becoming perfectly adapted to their surroundings by continually changing what is "perfect." For example, a host's immune system may evolve to avoid infection by a pathogen, but the pathogen can then evolve a mechanism to escape detection. In this way, so long as the pathogen continues evolving to escape the host's immune response, the host will never be perfectly adapted.

The figure below shows the number of leaves produced by Persicaria maculosa genotypes at differing light intensities. Each shade of gray indicates the norm of reaction for a different genotype. Imagine that natural selection always favors plants with the most leaves. If these plants grow in environments that vary in light intensity, why is it difficult to predict which genotype will be favored by selection?

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Phenotype is determined by the interplay between genotype and environment. In this example different genotypes produce the most leaves depending on the light intensity. Since selection acts on the phenotype, rather than the genotype, we cannot predict which genotype will be favored unless we know the precise light intensity in the environment.

Evolutionary change in one species that affects the selective conditions for a second species is known as which of the following?

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Question 3

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Richard Lenski and his colleagues' long-term evolution experiments in E. coli provide unprecedented insight into natural selection. In the experiment, 12 parallel E. coli lineages were created and maintained, cells from each line were periodically frozen, and the team followed the lineages for more than 60,000 generations. By using multiple independent lineages started from the same colony, these experiments help determine how predictable evolution is. How can you assess predictability from these experiments, and what did they find about predictability in evolution?

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Question 4

The exquisite complexity of traits such as the vertebrate eye seems to pose a problem for evolution by natural selection. How do evolutionary biologists think that complex eyes evolved?

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Question 5

Natural selection acts on _______ differences in a population.

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Question 6

All of the following are types of traits that evolutionary biologists might study in regard to natural selection EXCEPT

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Question 7

In order for traits to evolve by natural selection, individuals must experience differential reproductive success. This means that

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Question 8

Why was it informative for researchers studying evolution of oldfield mouse coat color to find the genes responsible for the light coat color of many beach populations?

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Question 9

Long-term evolution experiments in laboratory populations of E. coli are valuable for all of the following reasons EXCEPT that they allow researchers to

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Question 10

Lens crystallins form the transparent lens of the eye. In guinea pigs, lens crystallins also function as alcohol dehydrogenase. What is this an example of?

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Question 11

In a study of life history evolution in response to predation, guppies that were adapted to high predation sites were transplanted to low predation sites. If the hypothesis is correct that producing larger but fewer offspring is an adaptation to low predation sites, then which of the following would we expect?

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Question 12

In guppy populations that experience low predation by small predators, researchers found that females produced fewer but larger offspring than in populations that experienced high predation by large predators, where females produced many small offspring. Which of the following could explain this observation?

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Question 13

What is meant by the statement "Natural selection lacks foresight"?

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Question 14

A trait that serves one purpose today but evolved under different selective conditions and previously had a different function

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Question 15

To test the hypothesis that natural selection by predators favors a match between coat color in oldfield mice and the color of their environmental background, Hopi Hoekstra and colleagues made silicone models of mice that were colored either light or dark. These model mice were placed in beach environments that had either light or dark backgrounds. If the hypothesis is correct, what do you predict will happen to the different mice in each background?

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Question 16

The figure shows the number of days to first flowering in populations of mustard plants before the 2000-2004 drought (on the left, in pale gray), after the drought (on the far right, in dark gray), and of hybrids between the before-and-after populations. According to this figure, which of the following statements is true?

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Question 17

The figure shows the relationships between oldfield mice populations. Light-colored beach populations are shown with a triangle; dark-colored inland populations are shown with circles. Which of the following statements is consistent with this phylogeny?

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Question 18

Your text describes two possible explanations for how complex traits can evolve. These explanations posit that complex traits are either adaptations or exaptations. Describe one way in which these two explanations for the evolution of complex traits are similar and one way in which they differ.

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Question 19

The figure shows the norm of reaction for the number of leaves (B) and the mean leaf area (C) at different light intensities for 10 different genotypes (each shown in a different color) of Persicaria maculosa (A). According to this figure, which of the following statements is true? A B C

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Question 20

Showing 1 - 20 of 47

An evolutionary arms race occurs when natural selection is acting simultaneously on both sides of a host-pathogen interaction. How does an evolutionary arms race constrain evolution?

Evolutionary change in one species that affects the selective conditions for a second species is known as which of the following?

The exquisite complexity of traits such as the vertebrate eye seems to pose a problem for evolution by natural selection. How do evolutionary biologists think that complex eyes evolved?

Natural selection acts on _______ differences in a population.

All of the following are types of traits that evolutionary biologists might study in regard to natural selection EXCEPT

In order for traits to evolve by natural selection, individuals must experience differential reproductive success. This means that

Why was it informative for researchers studying evolution of oldfield mouse coat color to find the genes responsible for the light coat color of many beach populations?

Long-term evolution experiments in laboratory populations of E. coli are valuable for all of the following reasons EXCEPT that they allow researchers to

Lens crystallins form the transparent lens of the eye. In guinea pigs, lens crystallins also function as alcohol dehydrogenase. What is this an example of?

What is meant by the statement "Natural selection lacks foresight"?

A trait that serves one purpose today but evolved under different selective conditions and previously had a different function

The figure shows the relationships between oldfield mice populations. Light-colored beach populations are shown with a triangle; dark-colored inland populations are shown with circles. Which of the following statements is consistent with this phylogeny?

Your text describes two possible explanations for how complex traits can evolve. These explanations posit that complex traits are either adaptations or exaptations. Describe one way in which these two explanations for the evolution of complex traits are similar and one way in which they differ.

The figure shows the norm of reaction for the number of leaves (B) and the mean leaf area (C) at different light intensities for 10 different genotypes (each shown in a different color) of Persicaria maculosa (A). According to this figure, which of the following statements is true? A B C

An Overview of Evolutionary Biology

Early Evolutionary Ideas and Darwin S Insight

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

The Evolution of Sex

The Evolution of Sociality

Coevolution

Human Evolution

Evolution and Medicine

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