Frequency-dependent selection
An evolutionary process where the fitness of a trait or genotype varies based on its relative frequency within a population.
Frequency-dependent selection
Frequency-dependent selection is a fundamental evolutionary mechanism where the fitness advantage of a trait depends on how common or rare it is within a population. This dynamic process plays a crucial role in maintaining genetic diversity and driving evolutionary change.
Core Mechanisms
The process operates in two main forms:
Negative Frequency Dependence
- Rare variants have higher fitness
- Creates balancing selection
- Examples include:
- predator-prey relationships
- sexual selection mate choice patterns
- immune system pathogen resistance
Positive Frequency Dependence
- Common variants have higher fitness
- Can lead to fixation of traits
- Often seen in:
- social behavior
- Communication systems
- mimicry patterns
Ecological Examples
Predator-Prey Dynamics
When predators develop search images for common prey types, rare variants often gain a survival advantage. This creates a cyclical relationship where:
- Common morphs face increased predation
- Rare morphs proliferate
- Predators shift focus to newly common morphs
Sexual Selection
In many species, rare mating strategies or ornamental traits can provide advantages through:
- Increased attention from potential mates
- Reduced competition
- Novel phenotype recognition
Applications
The concept of frequency-dependent selection has important applications in:
Conservation Biology
- Understanding population dynamics
- Maintaining biodiversity
- Managing endangered species
Disease Ecology
- Explaining pathogen evolution
- Tracking virulence changes
- Predicting epidemic patterns
Agricultural Systems
- Crop diversity management
- pest resistance development
- Sustainable farming practices
Mathematical Models
The process can be modeled using:
- game theory frameworks
- Population genetics equations
- fitness landscapes representations
Significance
Frequency-dependent selection represents a key mechanism in:
- Maintaining polymorphisms
- Driving speciation
- Shaping ecosystem dynamics
- Influencing behavioral evolution
Understanding this process is crucial for both theoretical evolutionary biology and practical applications in conservation and disease management.