| Under what condition does 'natural selection' occur? | Natural selection occurs when the pressures of environmental selection confer a selective advantage on a specific phenotype to enhance its survival (viability) and reproduction (fecundity). |
| What are the three main types of 'phenotypic selection'? | Stabilising, directional and disruptive. |
| Describe what 'stabilising selection' is. | A selective pressure that favors the average or intermediate phenotype within a population, leading to a reduction in phenotypic variation over time. |
| Describe what 'directional selection' is. | A selective pressure that favors individuals with phenotypes at one extreme of the distribution, causing a shift in the average phenotype of a population towards that direction over successive generations. |
| Describe what 'disruptive selection' is. | A selective pressure that favors extreme or divergent phenotypes within a population, leading to an increase in phenotypic variation over time and potentially resulting in the formation of distinct subgroups or ecotypes. |
| Define 'genetic drift'. | The random change in gene frequencies that occurs by chance in a population over time, potentially leading to the loss of certain genetic variations. |
| Define 'gene flow'. | The movement of genes from one population to another through the migration and breeding of individuals, leading to the exchange of genetic traits between populations |
| Provide one example of 'natural selection'. | The adaptation of giraffes' long necks, which evolved through selective pressure for individuals with longer necks to reach higher food sources and gain an advantage. |
| Explain microevolutionary change through the main processes of mutation, gene flow and genetic drift. | Mutation introduces new genetic variation, gene flow facilitates the exchange of genetic material between populations, and genetic drift leads to random fluctuations in allele frequencies within populations, collectively shaping the genetic makeup and characteristics of populations over time. |
