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Ch. 51 Animal Behavior
Campbell - Campbell Biology 12th Edition
Urry12th EditionCampbell BiologyISBN: 9785794169850Not the one you use?Change textbook
Chapter 51, Problem 2

According to Hamilton's rule,
a. Natural selection does not favor altruistic behavior that causes the death of the altruist.
b. Natural selection favors altruistic acts when the resulting benefit to the recipient, corrected for relatedness, exceeds the cost to the altruist.
c. Natural selection is more likely to favor altruistic behavior that benefits an offspring than altruistic behavior that benefits a sibling.
d. The effects of kin selection are larger than the effects of direct natural selection on individuals.

Verified step by step guidance
1
Understand Hamilton's rule, which is a principle in evolutionary biology that explains when altruistic behavior can evolve through natural selection.
Hamilton's rule is expressed mathematically as \( rB > C \), where \( r \) is the genetic relatedness between the altruist and the recipient, \( B \) is the benefit to the recipient, and \( C \) is the cost to the altruist.
Analyze each option in the problem statement to determine which one aligns with Hamilton's rule. Focus on the relationship between the benefit to the recipient, the cost to the altruist, and the genetic relatedness.
Option b states that natural selection favors altruistic acts when the resulting benefit to the recipient, corrected for relatedness, exceeds the cost to the altruist. This directly corresponds to Hamilton's rule \( rB > C \).
Review the other options to ensure they do not align with Hamilton's rule. Option a, c, and d do not accurately reflect the mathematical relationship described by Hamilton's rule.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Hamilton's Rule

Hamilton's Rule is a principle in evolutionary biology that predicts when altruistic behavior will evolve. It states that natural selection favors altruistic acts if the benefit to the recipient, multiplied by the coefficient of relatedness, exceeds the cost to the altruist. This rule is often summarized by the inequality: rB > C, where r is relatedness, B is the benefit to the recipient, and C is the cost to the altruist.
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Altruistic Behavior

Altruistic behavior in biology refers to actions by an individual that benefit another individual at a cost to itself. This behavior is puzzling from an evolutionary perspective because it seems to reduce the altruist's fitness. However, through mechanisms like kin selection, altruism can be advantageous if it increases the survival and reproductive success of related individuals who share genes with the altruist.
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Kin Selection

Kin selection is a form of natural selection that considers the role of relatives in the evolution of social behaviors. It suggests that individuals can increase their genetic success through behaviors that help relatives, even at a personal cost. This concept helps explain altruistic behaviors, as aiding relatives can ensure the propagation of shared genes, thus indirectly benefiting the altruist's genetic lineage.
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Related Practice
Textbook Question

Which of the following is true of innate behaviors?

a. Their expression is only weakly influenced by genes.

b. They occur with or without environmental stimuli.

c. They are expressed in most individuals in a population.

d. They occur in invertebrates and some vertebrates but not mammals.

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Textbook Question

Female spotted sandpipers aggressively court males and, after mating, leave the clutch of young for the male to incubate. This sequence may be repeated several times with different males until no available males remain, forcing the female to incubate her last clutch. Which of the following terms best describes this behavior?

a. Polygyny

b. Polyandry

c. Promiscuity

d. Certainty of paternity

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Textbook Question

A region of the canary forebrain shrinks during the nonbreeding season and enlarges when breeding season begins. This change is probably associated with the annual

a. Addition of new syllables to a canary's song repertoire

b. Crystallization of subsong into adult songs

c. Sensitive period in which canary parents imprint on new offspring

d. Elimination of the memorized template for songs sung the previous year

789
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Textbook Question

Although many chimpanzees live in environments with oil palm nuts, members of only a few populations use stones to crack open the nuts. The likely explanation is that

a. The behavioral difference is caused by genetic differences between populations.

b. Members of different populations have different nutritional requirements.

c. The cultural tradition of using stones to crack nuts has arisen in only some populations.

d. Members of different populations differ in learning ability.

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