Different types of Natural selection
•Selection can be classified by the
traits that increase fitness
Value of trait
# of
individuals
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Types of Natural Selection: Stabilizing, Directional, Disruptive, & Frequency Dependent, Slides of Biology
An overview of different types of natural selection, including stabilizing selection, directional selection, disruptive selection, and frequency dependent selection. Each type is characterized by the traits that increase fitness and the impact on the population's variation and average value. The document also mentions other mechanisms of evolution, such as sexual selection and random selection in small populations.
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2012/2013
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Different types of Natural selection
- Selection can be classified by the traits that increase fitness
Value of trait
# of individuals
1. Stabilizing selection:
- Individuals with average traits are selected.
2. Directional Selection
- Individuals with higher or lower than average traits are selected
- Decreases variation and changes the average value of a trait.
- Occurs when environment changes.
Polluted area
3. Disruptive selection
- Individuals with higher and lower than average traits are selected.
Bill width
4. Frequency dependent selection
- Individuals with uncommon traits are selected.
Other mechanisms of evolution
- Mechanisms that do not result in adaptation to the environment.
Sexual selection
- Also proposed by Darwin.
- Some individuals have traits which may decrease their ability to survive - but
- increase their access to breeding partners.
Random selection of individuals in
small populations
- Change in the genetic makeup of a population by random events.
- Involves elimination of genetic information from a population.
1. Founder effects
- Only a few individuals in a population colonize a new habitat.
- By chance, these few individuals have different traits compared to the parent population.
2. Bottleneck effects
- All but a few individuals in a population are eliminated.
- Surviving individuals do not contain the same genetic structure as the original population.