Natural Selection Changes Allele Frequencies in Populations
- Natural selection alters allele frequencies by favoring traits that improve survival and reproduction.
- Over generations, these advantageous alleles become more common in the gene pool.
Allele frequencies are expressed as a decimal or percentage.
Natural Selection Acts on Phenotypes but Changes the Gene Pool
- Natural selection acts on phenotypes, but its effects are seen in the gene pool.
- Traits that improve survival and reproduction become more common, increasing the frequency of their associated alleles.
Peppered Moths: During the Industrial Revolution, dark moths had a survival advantage in polluted areas, leading to an increase in the allele for dark coloration.
Key Mechanisms That Change Allele Frequencies
1. Variation in Traits Fuels Selection
- Variation is essential for natural selection.
- It arises from:
- Mutations: New alleles are introduced.
- Sexual Reproduction: Meiosis and fertilization create unique allele combinations.
In green sea turtles, genetic diversity increases offspring survival in changing environments.
