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Biodiversity
• What is Biodiversity?
– Short for “biological diversity”
– Includes the diversity of …
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genes
species
populations
living communities
ecosystems
Richness vs.
Diversity
What affects biodiversity?
• Area effects: species-area relationships
• Climate effects: Temperate / tropical
comparison
– Compare Corcovado vs N.A.
Species : area relationships
Effect of habitat area
• larger islands contain more
species than smaller islands
Reptiles & amphibians
Log # of Bat species
Bats
Island size (Log km2)
Effect of habitat isolation
• isolated (distant) islands contain fewer
species than nearby islands
Lesser
Antilles
Communities on Landscapes
Island Biogeography Theory
Area effect - Larger islands support
higher S:
• more habitats
• lower extinction rates
•(bigger population sizes)
Isolation effect - Nearer islands
support higher S:
• Greater immigration / recolonization
Communities on Landscapes
Island Biogeography Theory
S
Lowest
As distance increases,
S decreases;
Mainland
As size increases,
S increases.
S
Highest
Island biogeography and species equilibrium
Species differ in their dispersal capabilities and their susceptibility to extinction.
I curve: species that disperse well arrive soon, poor dispersers show up later.
E curve: more S = more competition (extinction)
Islands aren’t the only isolated habitats
lakes and ponds
mountaintops
Forest patches