Week 4 - Mechanisms of Evolution

Continuous Variation

Controlled by multiple genes

Discontinuous Variation

Controlled by 1/few genes

Genetic Drift

Random non directional change in allele frequencies due to chance

Bottleneck Effect

1. Event drastically reduce population size

2. Reduce genetic diversity

3. Allele frequencies not representative of original

Founder Effect

1. Small group migrate to new area

2. Reduce genetic diversity

3. Allele frequencies not representative of original

Natural Selection - Process

1. Variation

2. Overproduction

3. Struggle for existence

4. Survival of fittest

5. Allele frequency increases

Small Populations - Cons

More vulnerable

Alleles lost

Less variation/ability to adapt

Hardy Weinberg Principle

Genotype/allele frequencies remain constant across generations

Hardy Weinberg - 5 Criteria

1. Random mating

2. No natural selection

3. No mutation

4. No migration

5. Large population