Evolution

Evolution is the changes in organisms over generations as a result of genomic variations.
Inheritance usually involves the passing of genetic material from parents to offspring. This is vertical inheritance.
The passing of genetic material is brought about by sexual or asexual reproduction.
Prokaryotes usually reproduce by binary fission, a form of vertical inheritance.
Prokaryotes and viruses can also exchange genetic material between members of the same generation. This is horizontal inheritance.
Horizontal inheritance frequently involves the exchange of whole or parts of a plasmid.
Plasmid exchange will bring about rapid evolutionary change.
Natural selection is the non-random increase in frequency of DNA sequences that increase survival and the non-random reduction in the frequency of deleterious sequences.
Changes in phenotype frequency can be as a result of stabilising, directional and disruptive selection.
In stabilising selection, an average phenotype is selected for and extremes of the phenotype range are selected against.
In directional selection, one extreme of the phenotype range is selected for.
In disruptive selection, two or more phenotypes are selected for.
A species is a group of organisms capable of interbreeding and producing fertile offspring, and which does not normally breed with other groups.
Speciation is the generation of new biological species by evolution as a result of isolation, mutation and selection.
Allopatric speciation occurs when populations become physically separated. This may be due to geographical barriers such as oceans or mountain ranges.
Sympatric speciation is brought about by behavioural or ecological barriers. The process will usually occur within the same habitat.
After a barrier separates a population, different mutations may arise within each subpopulation; natural selection will act differently on each group depending on the selection pressures present and, eventually, the two subpopulations become separate species.