- Bio = living
- Diversity = Differences
The term 'biodiversity' refers to two aspects of organisms in a given environment:
1) The number of species, sometimes called 'species richness'
2) The number of organisms within each species
Both of these factors vary greatly, depending on where and when you are looking, therefore biodiversity isn't constant.
Biodiversity can vary spatially
The number of species and the number of organisms depend, in part, on the environent.
- More plants grow at high light intensity than at low light intensity, so a bright environment can support more herbivores and therefore more carnivores than a dull environment would be able to.
- More energy flowing through an ecosystem produces more species and more individuals. This means that equatorial regions have a much higher biodiversity than polar regions do.
The map below shows in red the areas of major biodiversity, these are called biodiversity hotspots. They all cluster around the equator and tropics, where high light intensity all year round ensures there's a high energy input into the existing ecosystems.
Biodiversity can vary over time
Biodiversity can increase or decrease, and this is down to three main reasons
1) Succession - over time a community of organisms may change its habitat, this makes it more suitable for other species. The change in the composition of a community over a period of time is called 'succession'. It therefore increases animal biodiversity but decreases plant biodiversity.
2) Natural selection - this generates and changes biodiversity
3) Human influence - human activity has effected many areas of the…