The rise of evolutionary biology - What is evolution?
Evolution means change
The forms of organisms, at all levels from DNA sequences to macroscopic morphology and social behavior, can be modified from those of their ancestors during evolution.
Not all biological change is evolution
Developmental change within the life of an organism is not evolution in the strict sense, and the technical definition of evolution refers to 'change between generations' in order to exclude developmental change.
A change in the composition of an ecosystem, which is made up of a number of species, would also not normally be counted as evolution.
Most of the processes in EVOLUTION on this CD-ROM concern change between generations within a population of a species, and it is this kind of change we shall call evolution.
The biologist John Maynard Smith gives his own definition of evolution.