| Natural Selection | Process of selecting favourable traits |
| Natural Selection Requirements | - Variation in traits between offspring
- Majority of these traits are heritable (characteristics inherited)
- More offspring produced that can survive → competition for limited resources |
| Viability | Ability to survive and reproduce |
| Fercundity | Reproductive rate of an organism, measured by number of offspring produced |
| Allele Frequency | Selective proportion of a specific allele in a population |
| Phenotypic Selection | Normally distributed. Natural selection influences distribution of phenotypes for polygenic traits. |
| Stabilising Selection | - Narrowing distribution resulting in intermediate phenotypes increasing [more homogenous population]
- Extreme phenotypes are disadvantageous |
| Directional Selection | - When one extreme phenotype is better suited to the environment over other phenotypes, shifting distribution toward a preferred phenotype
- Reduced genetic variance |
| Disruptive Selection | - When both extremes are favoured → bimodal spread
- Increased genetic variance, producing two distinct populations with different phenotypes. |
