Here's why:
* Stabilizing selection favors the average phenotype in a population. This means individuals with traits closest to the average are most likely to survive and reproduce.
* Well-adapted populations already possess traits that allow them to thrive in their environment.
* Unchanging environment means there's no pressure for individuals to evolve new traits.
Example:
Imagine a bird species perfectly adapted to its environment. Its beak size is ideal for cracking open the seeds it eats. If the environment remains stable, there's no need for the beak to change. Birds with slightly larger or smaller beaks might not be as efficient at feeding and would be at a disadvantage, leading to stabilizing selection.
Key takeaways:
* In an unchanging environment, stabilizing selection maintains the status quo.
* It keeps populations well-adapted to their environment by eliminating extreme phenotypes.
* Well-adapted populations in stable environments tend to show low levels of genetic variation.
