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 common traits may become less advantageous as they become more prevalent, while rarer traits may gain an advantage, influencing genetic diversity and population dynamics.

5 Must Know Facts For Your Next Test

1. Frequency-dependent selection can create a balancing effect in populations, maintaining multiple phenotypes rather than allowing one to dominate.
2. It is particularly important in predator-prey dynamics, where predators may learn to recognize and target the most common prey types.
3. This selection can lead to cyclical changes in phenotype frequencies over time, as the advantages shift between different traits.
4. In social species, frequency-dependent selection can influence behaviors such as mating strategies and group dynamics.
5. The concept plays a significant role in understanding how genetic variation is preserved in populations facing selective pressures.

Review Questions

• How does frequency-dependent selection contribute to maintaining genetic diversity within a population?
  • Frequency-dependent selection contributes to genetic diversity by creating advantages for rarer phenotypes. When certain traits become common, their fitness may decrease, which allows less common traits to thrive and increase their representation in the population. This cycle helps to ensure that multiple traits are maintained rather than allowing one trait to dominate, fostering overall genetic diversity.
• Discuss the role of negative frequency-dependent selection in predator-prey interactions and its implications for evolutionary strategies.
  • Negative frequency-dependent selection plays a critical role in predator-prey interactions by impacting which prey phenotypes are targeted by predators. As certain prey types become more common, predators tend to learn and adapt their hunting strategies to those types, reducing their survival rates. This dynamic encourages the survival of rarer prey phenotypes, leading to a fluctuating balance in prey populations and influencing evolutionary strategies such as camouflage or mimicry.
• Evaluate how positive frequency-dependent selection might impact the long-term evolutionary trajectory of a population and its genetic structure.
  • Positive frequency-dependent selection can significantly impact the evolutionary trajectory of a population by favoring common traits over rare ones. This can lead to reduced genetic variation as certain phenotypes dominate and others diminish or disappear altogether. Over time, this could result in a loss of adaptability within the population, making it more susceptible to environmental changes or diseases. Consequently, while certain traits may be favored in the short term, the long-term effects could jeopardize the population's resilience and evolutionary potential.

Related terms

Negative Frequency-Dependent Selection: A type of frequency-dependent selection where the fitness of a phenotype decreases as it becomes more common, promoting the maintenance of genetic diversity.

Positive Frequency-Dependent Selection: A type of frequency-dependent selection where the fitness of a phenotype increases as it becomes more common, potentially leading to a reduction in genetic variation.

Genetic Drift: A mechanism of evolution that refers to random changes in allele frequencies within a population, which can affect genetic diversity alongside natural selection.