Question
Directional selection example
Answers
GPT-4o mini
Directional selection is a type of natural selection that favors individuals at one extreme of a trait's distribution. This leads to a shift in the population's overall traits over time.
### Example of Directional Selection:
**The Peppered Moth:**
One of the most famous examples of directional selection involves the peppered moth (*Biston betularia*) in England.
- **Background:** Before the Industrial Revolution, most peppered moths had light coloration, which helped them blend in with the lichen-covered trees and avoid predation by birds.
- **Environmental Change:** During the Industrial Revolution, soot and pollution from factories darkened the trees and killed the lichen. This environmental change favored darker-colored moths because they were better camouflaged against the polluted environment.
- **Selection Pressure:** As a result, the population of moths shifted towards a higher frequency of the darker coloration. Birds began to prey more heavily on the lighter moths, leading to a significant increase in the survival and reproduction of the darker moths.
- **Outcome:** Over time, the proportion of dark-colored moths increased in the population, demonstrating directional selection as the trait of darker coloration became more common.
This example illustrates how changes in the environment can lead to directional selection, favoring one extreme trait over another and causing shifts in population characteristics over generations.
### Example of Directional Selection:
**The Peppered Moth:**
One of the most famous examples of directional selection involves the peppered moth (*Biston betularia*) in England.
- **Background:** Before the Industrial Revolution, most peppered moths had light coloration, which helped them blend in with the lichen-covered trees and avoid predation by birds.
- **Environmental Change:** During the Industrial Revolution, soot and pollution from factories darkened the trees and killed the lichen. This environmental change favored darker-colored moths because they were better camouflaged against the polluted environment.
- **Selection Pressure:** As a result, the population of moths shifted towards a higher frequency of the darker coloration. Birds began to prey more heavily on the lighter moths, leading to a significant increase in the survival and reproduction of the darker moths.
- **Outcome:** Over time, the proportion of dark-colored moths increased in the population, demonstrating directional selection as the trait of darker coloration became more common.
This example illustrates how changes in the environment can lead to directional selection, favoring one extreme trait over another and causing shifts in population characteristics over generations.