Concept  of  Biodiversity
Levels  of  Biodiversity
Studying  Biodiversity
Threats  to  Biodiversity
Resources

 

   

Distribution of Biodiversity

  • Is biodiversity evenly distributed throughout the world, and if not, what criteria affect its distribution?

Species diversity is usually greater:

  • atlower latitudes;
  • in structurally more complex ecological systems;
  • in more productive ecological systems;
  • on continents rather than islands.

The global distribution of species is also related to pastgeological events, theevolutionary history of the species andfunctional interactions with other species.

  • How species are distributed globally can influence conservation efforts.
       
 

Marine Realms

Marine productivity is higher in coastal regions than in open oceans.

  • How do coastal areas and open ocean compare in their diversity?
     
 

Temperate vs. Tropical Forest

A tropical rainforest in Indonesia is five times richer in insect species numbers than a deciduous woodland in England [Hammond 1992] .

The deciduous woodland site in England yielded, on average, 83 beetle species per Malaise trap, compared to 412 beetle species per trap in the Sulawesi forest.

  • Why is diversity greater in a tropical rainforest compared to a temperate forest?
     
 

Tropical Forests

Tropical rainforests are structurally complex habitats.

The forest is stratified into layers, resulting in many diverse niches which vary in height, shade and food availability.

The physiognomyof this biome is one reason for its great biodiversity.

     
 

Cape Floral Region

Theflora of the Cape in South Africa shows an extremely high rate of endemism, making this one of the 25 hotspot regions of [Myers et al. 2000] .

The number of endemic species in this region are:

  • 6,000 higher plants;
  • 15 mammals;
  • 43 reptiles;
  • 23 amphibians.
     
 

 

Endemic Species

Oceanic islands often contain species not found elsewhere. These are called endemics.

Lemurs are endemic to Madagascar. (left photo.)

 
     
 

Biodiversity Hotspots

Because biodiversity is not evenly distributed on the Earth, certain areas may have higher levels of biodiversity and so may be more important for conservation efforts.

This map shows the 25 biodiversity hotspot areas (in red) identified by [Myers et al. 2000] . These are areas of high plant species endemism that are threatened by habitat loss, and so are considered as areas of global conservation importance.