Kin selection

Definition

Kin selection is a type of natural selection that favors the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. This phenomenon helps explain altruistic behaviors observed in nature, where individuals may sacrifice their own fitness for the benefit of their kin, ultimately enhancing the overall genetic success of shared relatives.

5 Must Know Facts For Your Next Test

1. Kin selection explains why certain species exhibit behaviors such as warning calls, which may increase the risk for the caller but protect close relatives.
2. The concept of kin selection is closely tied to inclusive fitness, which measures an organism's success in passing on genes not just through its own offspring but also through aiding relatives.
3. Kin selection can lead to the evolution of social structures, like those seen in bee colonies where worker bees sacrifice their own reproduction to support the queen and her offspring.
4. The degree of relatedness plays a crucial role in kin selection; the closer the genetic relationship, the more likely an organism will engage in altruistic behavior towards its kin.
5. Hamilton's rule, expressed as $$rB > C$$, demonstrates that kin selection can lead to evolutionarily stable strategies that promote altruism based on genetic relationships.

Review Questions

• How does kin selection relate to altruistic behavior among animals and what mechanisms support this relationship?
  • Kin selection relates to altruistic behavior in that it provides a framework for understanding why animals may help relatives at their own expense. Mechanisms supporting this relationship include inclusive fitness, where helping kin enhances shared genetic success, and Hamilton's rule, which quantifies when such altruistic acts are favored by natural selection. For example, an animal might give a warning call about a predator, risking its safety but potentially saving close relatives from danger.
• Discuss how Hamilton's rule can be applied to predict patterns of social behavior in animal populations.
  • Hamilton's rule can be applied to predict social behavior by assessing the balance of costs and benefits associated with altruistic actions towards relatives. According to this rule, behaviors are more likely to evolve if the benefit to the recipient, multiplied by their genetic relatedness to the actor (rB), outweighs the cost to the actor (C). This principle helps explain social structures in species such as bees and ants, where non-reproductive individuals work collectively to support closely related queens and offspring.
• Evaluate the implications of kin selection on understanding human social behaviors and cooperative strategies.
  • The implications of kin selection extend into human social behaviors by providing insight into why individuals often prioritize family relationships and engage in cooperative strategies. Altruism towards family members can be seen as a product of evolutionary pressures that favor traits benefiting genetic relatives. As such, understanding kin selection allows us to analyze human behaviors like caregiving and resource sharing within families, emphasizing how our evolutionary history shapes modern social interactions and cultural norms surrounding family loyalty and cooperation.

Related terms

altruism: Behavior by an individual that increases the fitness of another individual while decreasing its own fitness.

inclusive fitness: The total effect an individual has on propagating its genes by producing offspring and helping relatives raise their offspring.

Hamilton's rule: A principle that states that altruistic behavior can be favored by natural selection when the cost to the altruist is less than the benefit to the recipient multiplied by the degree of relatedness between them.