Genetic diversity and adaptation

Genetic diversity

Number of different alleles of genes in a population

Natural selection

Process that leads to evolution in populations

Evolution

Change in allele frequency over many generations in a population

3 types of adaptations

• Anatomical

• Physiological

• Behavioural

Describe the process of natural selection (4 steps)

1. New alleles for a gene are caused by random mutations

2. If the new allele increases the chances of the individual to survive in that environment, then they are more likely to survive and reproduce

3. This process passes on the advantageous allele to the next generation

4. As a result, over many generations the new allele increases in frequency in the population

What are the 2 types of selection?

• Directional

• Stabilising

Describe directional selection and when it occurs

1. An extreme trait has a selective advantage

2. The modal (most common) trait changes

• Occurs when there is a change in the environment

Describe stabilising selection and when it occurs

1. Modal trait has selective advantage

2. The modal trait remains the same

3. Standard deviation decreases, as individuals with extreme trait decrease

• Occurs when there is no change in the environment

Give an example of when directional selection may occur

Antibiotic resistance in bacteria

Give an example of when stabilising selection may occur

Human birth weights