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Chapter 3: Darwinian Natural Selection

Chapter Study Questions

Chapter Study Questions


This activity contains 23 questions.

	Successful artificial selection, such as that practiced by plant and animal breeders to modify their crops and livestock, depends on which of the following?   Breeders must be able to selectively breed the individuals with the most desirable traits. Some individuals must have more desirable traits than others. When individuals with the most desirable traits are bred, their traits must be passed from parents to offspring. All of these are necessary for artificial selection to take place.

	Which is the best definition of Darwinian fitness?   The ability of an individual to survive and reproduce in a certain environment, compared to other individuals. The ability of a population to survive in any environment, compared to other populations. The ability of a species to survive in a certain environment, compared to other species. The ability of a species to survive over time, compared to other species. The ability of an individual to survive and reproduce in any potential environment, compared to other individuals.

	An adaptation is best defined as _______________.   the relative ability of organisms to survive and reproduce any trait that increases fitness the absolute ability of organisms to survive and reproduce any trait that increases longevity

	Name the two scientists who independently discovered the principle of natural selection. Which one is more famous, and why?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Match each characteristic of Jones' and Reithel's snapdragons with its correct counterpart among Darwin's postulates. Using the pull-down menus, match each item in the left column to the corresponding item in the right column. variation is heritable organisms vary reproduction is nonrandom; organisms with favorable traits survive and reproduce better than others some individuals are more successful and surviving and reproducing than others 5.1 3/4 of the snapdragons had almost pure white flowers; 1/4 of the plants had yellow flowers. [hint] A B C D 5.2 Flower color is determined by a gene with two alleles; SS and Ss individuals are white; ss individuals are yellow. [hint] A B C D 5.3 Plants varied in the number of pollinator visits and seeds produced. [hint] A B C D 5.4 White flowers attracted twice as many bee visits as yellow flowers. [hint] A B C D

	Based on their observation of the color preferences of the bumblebees visiting their snapdragons, Jones and Reithel predicted (and found) that the proportion of white-flowered plants _________ from the first to the second generation.   increased stayed the same decreased

	Through their studies of medium ground finches, the Grants were able to demonstrate that, as a result of drought ___________.   evolution occurred natural selection occurred adaptation occurred all of these occurred

	By studying medium ground finch populations over the course of several decades, the Grants and their colleagues have demonstrated that, during drought years, natural selection favors birds with _______ beaks; during wet years, natural selection favors birds with ________ beaks.   shallow/deep shallow/shallow deep/deep deep/shallow

	Successful biology research often depends on choosing a good "model" - a particular species, population, or locality that is particularly amenable to study, and/or is a particularly clear case of the research question. Why were the finches of Daphne Major a good choice for an evolution study?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Which of the following statements is true?   Natural selection usually results in an immediate increase in population variation. Natural selection acts on populations, but its consequences occur in individuals. Natural selection generally leads to perfection of existing traits. Natural selection cannot be progressive because of its random nature. Natural selection acts directly on phenotypes, and only indirectly on genotypes.

	The panda's "thumb" is actually a wrist bone modified by natural selection to perform a new function. This is an example of a(n) _____________.   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Which of the following is a true statement regarding preadaptations?   A trait that evolved accidentally (usually due to genetic drift) and has no function. A trait that is currently evolving for a function that will be needed in the future. A trait that is in the initial stages of evolving for a certain function, but has not yet been perfected. A trait that evolved for one function, but that coincidentally is also suited for a new, different function. A trait that is imperfect due to genetic or developmental constraints.

	Although the scientific community rapidly accepted that all organisms are related by descent, Darwin's mechanism for change over time - natural selection - wasn't fully accepted until nearly 100 years after the publication of "The Origin." Explain why.   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	What is blending inheritance, and why did it pose a problem for Darwin's theory? Why is it not considered a problem today?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	What was the "Modern Synthesis" and why did it lead to widespread acceptance of the theory of evolution by natural selection?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Why did Dawkins refer to evolution as a "blind watchmaker"? What famous objection to evolution was he arguing against? Do you think his analogy is a good one? Another analogy that has been proposed is evolution as a "short-order cook." Which do you think is a better analogy?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	The creationist "argument from design" is based on the idea that complex structures and organisms can't arise by chance. The argument fails because, although _________ is random, ___________ is not; it is directed in the sense of increasing adaptation.   selection/mutation adaptation/mutation mutation/selection evolution/selection

	What is unusual about eel sperm, and why is it relevant for a recent United States district court case?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	A key flaw of "intelligent design theory" is that it fails to recognize the importance of _____________.   preadaptation genetic variation DNA the complexity of the molecular machinery of the cell

	Describe the Second Law of Thermodynamics. Does natural selection violate the Second Law? Does the growth of an oak tree from an acorn, or a human being from a fertilized egg, violate the Second Law? Why or why not?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Ivory poachers (illegal hunters) in Africa kill elephants primarily for the ivory in their tusks, and big tusks are worth more money. Based just on this fact, make a prediction about how hunting pressure could cause (or might have already caused) evolution in elephants. Do you think elephant populations meet Darwin's four criteria for selection to occur? How could you test your ideas?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Most large-scale fishing is done with nets of a certain mesh size, which catch larger fish while allowing small, undesirable fish to pass through. In the seas of southeast Asia, fisherpeople have recently had to switch to smaller and smaller mesh sizes. Why? What is happening to the fish population? Can you think of two possible explanations?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Now consider another ocean example, but with a twist. Lobstermen in Maine measure every lobster they catch. They throw back all the small individuals, to allow young lobsters time to grow. This is a fairly common practice in fisheries. However, they also do two unusual things: they throw back the largest lobsters, keeping only the medium-sized ones; and they also throw back any female who has ever been found to be carrying eggs, even if she is not carrying eggs at the moment. ("Eggers," or egg-carrying females, are permanently marked by cutting a V-shaped notch in their tails.) Why do Maine lobstermen throw large lobsters and notched females back into the sea?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

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