Evolution
Descent with modification
Microevolution
Changes in the allele frequency of a gene pool from one generation to the next
Macroevolution
Descent of different species from a common ancestor over many generations
Population
All organisms of the same species, geographical area and capable of interbreeding
Gene pool
Collection of all the genes and various allelic forms of those genes in a particular population
Variation
Differences in characteristics between individual organisms in the same population
Gene flow
Movement of alleles from one population to another due to migration of individuals
Darwin’s theory of natural selection
- All organisms are related through descent; sharing a common ancestor
- Descendants have accumulated modification or adaptation that fir the into their environment
- These descendants are thus different from their ancestors; descent with modification
Directional selection
Only one extreme of the phenotypic range is preferred
Stabilising selection
The intermediate phenotype is preferred
Disruptive selection
Two extremes of phenotypic range is preferred
Heterozygote protection
- Genetic variation is preserved in recessive alleles
- In heterozygous individuals, dominant and favourable alleles mask recessive alleles, allowing the recessive alleles to be passed down
Anatomical homology
- Includes physical structures such as bones, organs
- More similar structures means more recent common ancestor
Homology
The study of similar characteristics found in different species of organisms, inherited from a common ancestor
Molecular homology
Compares similarities in sequences of homologous genes/proteins to determine evolutionary relationships
