Frequency-dependent selection

Definition

Frequency-dependent selection is an evolutionary process where the fitness of a phenotype depends on its frequency relative to other phenotypes in a population. This means that the success of a trait can vary depending on how common or rare it is, leading to dynamic changes in population structure and diversity over time. In this context, understanding frequency-dependent selection helps explain the maintenance of genetic variation and the evolution of strategies within populations.

5 Must Know Facts For Your Next Test

1. Frequency-dependent selection can lead to polymorphism within populations, where multiple phenotypes coexist due to varying fitness advantages based on their frequencies.
2. This selection mechanism is often seen in predator-prey dynamics, where prey species may evolve traits that become more advantageous when they are less common.
3. In social species, frequency-dependent selection can influence behaviors such as cooperation and competition, shaping social structures based on trait distribution.
4. It plays a key role in maintaining genetic diversity, as no single phenotype can dominate indefinitely due to its changing fitness relative to others.
5. Frequency-dependent selection can also drive speciation events when differing traits become more favorable based on population densities and interactions.

Review Questions

• How does frequency-dependent selection influence the stability of evolutionary strategies within a population?
  • Frequency-dependent selection affects the stability of evolutionary strategies by creating conditions where the fitness of a particular strategy is influenced by its prevalence. For instance, if a certain trait becomes too common, it may lose its advantage and result in a decline in its frequency. This interplay leads to fluctuations in strategy success and encourages diversity, as individuals with less common traits may gain a competitive edge, thus promoting the coexistence of various strategies.
• Discuss the implications of negative frequency-dependent selection in predator-prey interactions and its impact on population dynamics.
  • Negative frequency-dependent selection plays a critical role in predator-prey interactions by giving advantages to rare prey phenotypes. When predators become accustomed to hunting the most common prey types, rare variations may have better survival rates. This dynamic leads to shifts in population dynamics as prey species evolve traits that enhance their survival against specific predation pressures, ultimately influencing overall ecosystem balance and species interactions.
• Evaluate how frequency-dependent selection can contribute to both genetic diversity and speciation in evolutionary processes.
  • Frequency-dependent selection contributes to genetic diversity by ensuring that no single phenotype becomes overwhelmingly dominant, allowing multiple traits to persist within a population. As environmental conditions change or as individuals interact with one another, varying selective pressures can lead to different phenotypes gaining advantages at different times. This ongoing fluctuation can initiate speciation events when certain traits become favored under specific circumstances, leading populations down distinct evolutionary paths based on frequency-dependent advantages.

Related terms

Evolutionary Stable Strategy (ESS): A strategy that, if adopted by a population, cannot be invaded by any alternative strategy, ensuring stability in the evolutionary process.

Negative Frequency-Dependent Selection: A type of frequency-dependent selection where rare phenotypes have a fitness advantage over common ones, promoting diversity in the population.

Game Theory in Evolution: The application of game theory concepts to evolutionary biology, analyzing how organisms strategize in competitive scenarios based on their interactions.