Biodiversity and endemism

• Biodiversity is a measure of the variety of living organisms and their genetic differences in a particular area
• All the organisms in an ecosystem are interdependent on each other, and they affect the physical conditions around them
• Rich biodiversity allows large-scale organisms to function and self-regulate
• If biodiversity is reduced in one area, the natural balance may be destroyed elsewhere. For example if there are no bacteria species then the air and water won’t be purified anymore
• Biodiversity provides the genetic variation that has allowed us to develop crops, livestock, fisheries and forests. It also enables further improvements by cross-breeding and genetic engineering. This variation can help to cope with problems arising from climate change and disease. Plant diversity can lead to the production of new medicines
• There are two factors which need to be considered when measuring biodiversity at a species level. One is the number of different species in an area - the species richness. The other is the number of different species in an area - the relative species abundance of the different types of organism that make up the species richness
• The wet tropics are generally the areas of highest biodiversity. Tropical regions also have areas of high marine and freshwater species richness
• To highlight species richness, scientists have identified some biodiversity hotspots of unusual biodiversity.
• When a species evolves in geographical isolation (for example on an island) and is found only in one place, it is said to be endemic to that place
• The areas or biodiversity are not always the same as the areas with the greatest number of endemic species. This is why it is so difficult to prioritise sreas for conservation
• The best model of why some areas have very rich biodiversity is:

  • a very stable ecosystem allows many complex relationships to develop between species
  • high levels of productivity (e.g high rates of photosynthesis can support more niches
  • when organisms can grow and reproduce rapidly, more mutations are going to occur, meaning adaptations, which allows organisms to exploit more niches
• Imported animals can cause many problems for species as they affect the ecosystem and can spread diseases
• Species abundance is the measure of the relative numbers of different types of organism.
• We measure species abundance of plants using a quadrat