EE37 Flashcards
what does SAR stand for?
Species area relationships
olof arrhenius
species area relationship
equilibrium theory of island biogeography?
under this model larger and less isolated islands have more species. Near islands increase immigration and larger islands have greater immigration and less extinction.
looking at size (island biogeography graph), what will it look like?
2 extinction lines and 2 immigration lines
larger islands support larger populations so have lower extinction rates.also larger targets so will have higher immigration rates
looking at distance in island bio geography,what will the graph of 2 islands look like?
the extinction rate will be the same (same size islands) but the immigration rate of the nearer island will be greater. 2 immigration lines 1 extinction line
is the equilibrium theory of island biogeography neutral?
yes. species’ fates are independent of their traits or niches
what 2 things explain species numbers best together?
area and isolation expain species numbers better than either does alone
what is the opposing theory to equilibrium theory of island biogeography?
Niche theory of biodiversity
Niche theory problems?
maybe larger areas have more sorts of habitat/ niche
possibly S=KH and H scales with area
problem:habitat is hard to measure. multiple regression does not work efficiently when explanatory variables are strongly correlated
we cannot easily separate the effects of area and habitat
who first developed the neutral theory of biodiversity?
Stephen hubbell whilst trying to explain diversity in forest plots on Baro Colarado island in Panama
what was the past niche theory of biodiversity?
ecological differences between species enable them to co-exist(ghost of competition past)
-environmental heterogenity/relief/soil type/rainfall etc
neutral theory of biodiversity
random mortality opens a gap for colonisation . biodiversity is thus down to chance
species abundance fluctuates by drift –> dwindling to zero by chance and immigration can bring a new species
SADs
species abundance distributions
like SARs, SADs can arise even with neitral theory of biodiversity
what is one of the most widespread patterns i biodiversity?
SARs
How can SAR be explained?
1) niche based processes
2) neutral processes
it is often not clear whether habitat diversity or area determines species richness.