Group selection

Definition

Group selection is a theory in evolutionary biology that suggests that natural selection operates not just at the level of individuals, but also at the level of groups. This means that traits benefiting the survival and reproduction of a group can be favored even if they are costly to individual members, leading to the idea that cooperative behaviors can evolve if they enhance the overall fitness of the group.

5 Must Know Facts For Your Next Test

1. Group selection theory gained prominence in the 1970s as a way to explain certain social behaviors in animals, particularly those seen in social insects like bees and ants.
2. Critics of group selection argue that many behaviors attributed to it can be explained by individual selection or kin selection, which focus on genetic relatedness.
3. Group selection can lead to the evolution of cooperation among individuals in a group, as long as the benefits to the group outweigh the costs to individuals.
4. The concept challenges traditional views of natural selection that prioritize competition among individuals for resources.
5. Empirical evidence for group selection remains controversial, with many studies indicating that individual and kin selection are more robust explanations for social behaviors.

Review Questions

• How does group selection differ from individual selection and kin selection in explaining social behaviors?
  • Group selection differs from individual selection by suggesting that the success of a trait can depend on its effects at the group level rather than solely on individual reproductive success. While individual selection focuses on traits that benefit the individual directly, kin selection emphasizes the importance of genetic relatedness in promoting altruistic behaviors toward relatives. Group selection accounts for situations where cooperation within a group enhances survival and reproductive success, even if it is costly to individuals.
• Discuss the implications of group selection theory for understanding cooperative behaviors in social animals.
  • The implications of group selection theory suggest that cooperative behaviors can evolve when they provide advantages to the group as a whole. This challenges previous ideas that all behaviors must confer direct benefits to individuals. In social animals, such as bees or ants, group selection may help explain why individuals engage in self-sacrificial behaviors that benefit their colony. Understanding this helps researchers appreciate how cooperation can enhance survival chances for groups facing environmental pressures.
• Evaluate the strengths and weaknesses of group selection compared to alternative theories like kin selection and inclusive fitness.
  • Evaluating group selection reveals both strengths and weaknesses compared to kin selection and inclusive fitness. One strength is its ability to explain certain cooperative behaviors that do not seem advantageous at the individual level. However, its weaknesses lie in the lack of strong empirical support; many scientists argue that most social behaviors can be explained more effectively through kin or individual selection. This debate highlights ongoing discussions about how evolutionary pressures operate across different levels of biological organization.

Related terms

kin selection: A type of natural selection that favors altruistic behaviors towards relatives, which can enhance the survival of shared genes.

inclusive fitness: The total effect an individual has on proliferating its genes by producing its own offspring and helping relatives survive.

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