Kin Selection

Definition

Kin selection is an evolutionary theory that explains how natural selection can favor behaviors that benefit the survival and reproduction of an individual's genetic relatives, even at a cost to the individual's own survival or reproduction. The key idea is that genes that promote behaviors that benefit kin can be favored by natural selection, as they increase the propagation of those shared genes.

5 Must Know Facts For Your Next Test

1. Kin selection explains how natural selection can favor behaviors that benefit the survival and reproduction of an individual's genetic relatives, even at a cost to the individual's own survival or reproduction.
2. The key mechanism of kin selection is inclusive fitness, which is the sum of an individual's own reproductive success and the reproductive success of their genetic relatives, weighted by the degree of relatedness.
3. Kin selection can explain the evolution of altruistic behaviors towards genetic relatives, as long as the benefit to the recipient multiplied by the coefficient of relatedness exceeds the cost to the altruist (Hamilton's rule).
4. Kin selection is particularly important in social insects like ants and bees, where workers often forgo their own reproduction to help raise the offspring of their queen, who is highly related to them.
5. Kin selection can also help explain cooperative behaviors in other animals, such as alarm calls, food sharing, and cooperative breeding, where individuals help raise the offspring of their relatives.

Review Questions

• Explain how kin selection can lead to the evolution of altruistic behaviors.
  • Kin selection explains how natural selection can favor altruistic behaviors that benefit the survival and reproduction of an individual's genetic relatives, even at a cost to the individual's own survival or reproduction. The key mechanism is inclusive fitness, which is the sum of an individual's own reproductive success and the reproductive success of their genetic relatives, weighted by the degree of relatedness. According to Hamilton's rule, altruism will be favored when the benefit to the recipient, multiplied by the coefficient of relatedness, exceeds the cost to the altruist. This allows altruistic behaviors towards kin to be selected for, as they ultimately increase the propagation of shared genes.
• Describe the role of kin selection in the evolution of social behaviors in insects.
  • Kin selection plays a crucial role in the evolution of social behaviors in insects, such as ants and bees. In these social insects, workers often forgo their own reproduction to help raise the offspring of their queen, who is highly related to them. This behavior increases the propagation of the shared genes between the workers and the queen's offspring, even though the workers do not directly reproduce. Kin selection can therefore explain the evolution of altruistic behaviors and the division of labor within insect colonies, where individuals sacrifice their own reproductive success to enhance the survival and reproduction of their genetic relatives.
• Analyze how kin selection can contribute to the understanding of cooperative behaviors in other animals beyond social insects.
  • Kin selection can also help explain the evolution of cooperative behaviors in other animals, such as alarm calls, food sharing, and cooperative breeding. In these cases, individuals may engage in behaviors that benefit their genetic relatives, even at a cost to their own immediate survival or reproduction. By considering the inclusive fitness benefits of these behaviors, kin selection provides a powerful framework for understanding the evolution of cooperation more broadly. For example, an individual may risk its own safety to give an alarm call that warns its kin of a predator, or share food with closely related offspring, as these actions ultimately increase the propagation of shared genes, even if they come at a personal cost. Analyzing animal behavior through the lens of kin selection can thus offer valuable insights into the evolutionary drivers of cooperation in a wide range of species.

Related terms

Inclusive Fitness: Inclusive fitness is the sum of an individual's own reproductive success and the reproductive success of their genetic relatives, weighted by the degree of relatedness. It is the primary mechanism by which kin selection operates.

Altruism:

Altruism is a behavior that benefits another individual at a cost to the individual performing the behavior. Kin selection can explain the evolution of altruistic behaviors towards genetic relatives.

Hamilton's Rule: Hamilton's rule is a mathematical expression that describes the conditions under which kin selection will favor the evolution of altruistic behaviors. It states that altruism will be favored when the benefit to the recipient, multiplied by the coefficient of relatedness, exceeds the cost to the altruist.