Variation Is Essential for Natural Selection
Definition
Variation
Variation refers to differences in traits among individuals within a population, encompassing physical characteristics, behaviors, and genetic sequences.
- Darwin's theory of evolution hinges on variation within populations.
- Without variation, there would be no differences for selection to act upon.
- Darwin observed that populations exhibit variation in traits such as height, skin color, and blood group in humans.
- In other species, variation may not be immediately obvious, but careful observation always reveals it.
Mutation Creates New Alleles, Expanding the Gene Pool
- Mutation is the original source of variation.
- How Mutation Works:
- Mutations occur as changes in DNA sequences, creating new alleles.
- These new alleles enlarge the gene pool of a population.
Mutation is the only source of new alleles in populations that do not reproduce sexually.
Meiosis Generates New Combinations of Alleles
- Meiosis increases genetic diversity by shuffling existing alleles.
