What is biodiversity?
It is a measure of the amount of variation of life in an ecosystem, community or other defined area.
There are two main components to biodiversity, species richness and composition.
1. species richness is the number of different species present.
The two communities of fish to the left have different species richness.
The one on the right is more diverse because it contains more unique species.
2. compositionis the relative abundance of each species, also called evenness.
These two fish communities have different compositions (evenness)