Flashcards in Ecological Concepts Deck (18)
Who proposed island biogeography and when?
MacArthur and Wilson, 1963
What are the two patterns of island biogeography?
Large islands have more species than small islands
Near islands have more species than far islands
What are the two processes of island biogeography?
The farther the island, the slower the immigration rate
Extinction rate is higher on small islands
What provides the source of immigrants for the islands?
The species look on the mainland
How do you work out the equilibrium number of species on an equilibrium model of fauna?
Draw the immigration of new species curve on one side and the species extinction on the other side
Where the lines cross on the graph is where there is equilibrium
What is countryside biogeography?
Where the edges around the habitat can be occupied by other species, rather than being surrounded by an inhospitable sea
What types of islands are there?
Oceanic islands e.g Seychelles
Land bridge islands e.g Britain
Habitat islands e.g forest patches surrounded by farmland
What is a meta population?
A set of local populations occupying various habitat patches and connected to one-another by the movement of individuals among them
Give an example of a forest generalist that can occupy the forest edge and one that can’t:
Tupaia longpipes are a core forest species- won’t occupy edge
Muntjak deer are generalists and can occupy the whole forest
What is the theory of drivers and passengers and who came up with it?
Removing drivers causes a cascade effect
But loss of passengers leads to little change in the rest of the ecosystem
What is the rivet popping hypothesis and who came up with it?
Species are rivets holding together a complex machine
All species make a contribution to ecosystem functioning
Ehrlich and Ehrlich 1981
What is the insurance hypothesis and who came up with it?
Increasing biodiversity insures ecosystems against declines in their functioning
Yachi and Loreau 1999
What are the three types of positive relationships between species richness and ecosystem functioning?
Redundancy, linear and idiosyncratic
What is the idiosyncratic hypothesis?
The magnitude and direction of changes are unpredictable, as the role of species is complex and varied
The sequence in which species are removed matters
What can ecological resilience be defined as?
The capacity of an ecosystem to absorb disturbance without shifting to an alternative state and losing function and services
What happens if you pass the tipping point of resilience?
It leads to a completely different ecosystem state
What is social ecological resilience?
The whole ecological resilience including humans