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Evolution Is a Change in a Population's Heritable Characteristics, Not a Change in Individuals
Definition
Evolution
Evolution is defined as a change in the heritable characteristics of a population over time.
- Evolution is a change in the heritable characteristics of a population over generations.
- Populations evolve, but individual organisms do not: an individual keeps the alleles it was born with for life.
- What changes over time is the allele frequency within the population.
Hint
- An individual cannot evolve during its lifetime.
- A population can change across generations as allele frequencies shift.
Only Heritable Variation Can Drive Evolution
- Heritable characteristics are encoded in DNA and passed from parent to offspring through gametes.
- Example: darker fur colour in a mouse caused by a genetic mutation.
- Acquired characteristics develop during an organism's lifetime through use, environment, or learning.
- Example: a tennis player builds stronger bones and muscle in their dominant arm.
- Only heritable variation can drive evolution, because only DNA passes to the next generation.
Common Mistake
- Acquired characteristics cannot be passed to offspring.
- A trait built by exercise or environment leaves the gametes unchanged.
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- A4.1.1 Evolution as change in the heritable characteristics of a population
- A4.1.2 Evidence for evolution from base sequences in DNA or RNA and amino acid sequences
- A4.1.3 Evidence for evolution from selective breeding of domesticated animals and crop plants