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.

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1. Hamilton's rule is a fundamental concept in evolutionary biology that explains the conditions under which altruistic behavior, where an individual helps others at a cost to itself, can evolve. It is mathematically expressed as rb > c, where r represents the genetic relatedness between the altruist and the recipient, b is the benefit to the recipient, and c is the cost to the altruist.
2. Option a states that natural selection does not favor altruistic behavior that causes the death of the altruist. This statement is generally true as the extreme cost of death (c becomes very high) would not typically be outweighed by the benefit multiplied by relatedness (rb), making rb > c unlikely.
3. Option b is a correct interpretation of Hamilton's rule. It states that altruistic acts are favored by natural selection when the benefit to the recipient, adjusted by how closely related the recipient is to the altruist (rb), exceeds the cost to the altruist (c). This aligns with the formula rb > c.
4. Option c suggests that natural selection is more likely to favor altruistic behavior benefiting an offspring over a sibling. This is generally true because the relatedness to offspring (r = 0.5) is usually greater than to siblings (r = 0.5 for full siblings, but the certainty of shared genes is often higher with direct offspring).
5. Option d claims that the effects of kin selection are larger than the effects of direct natural selection on individuals. This statement is too broad and context-dependent, as the impact of kin selection versus direct selection can vary greatly depending on specific ecological and evolutionary scenarios.

Key Concepts

Hamilton's Rule

Hamilton's rule is a principle in evolutionary biology that predicts when natural selection will favor altruistic behavior among related individuals. It states that altruism is favored when the genetic relatedness between the altruist and the recipient, multiplied by the benefit to the recipient, exceeds the cost to the altruist. This can be expressed mathematically as rB > C, where r is the coefficient of relatedness, B is the benefit to the recipient, and C is the cost to the altruist.

Kin Selection

Kin selection is a form of natural selection that favors behaviors which help relatives, thereby increasing the chances of shared genetic material being passed on to future generations. This concept explains why individuals may engage in altruistic acts that benefit their relatives, as these actions can enhance the survival and reproductive success of those who share their genes. Kin selection is a key mechanism through which Hamilton's rule operates.

Altruism in Evolution

Altruism in evolutionary biology refers to behaviors that benefit other individuals at a cost to oneself. While such behaviors seem to contradict the self-interest principle of natural selection, they can be explained through kin selection and Hamilton's rule. Altruistic acts are more likely to evolve when they benefit relatives, as this can lead to an increase in the altruist's inclusive fitness, which encompasses both direct and indirect reproductive success.