Week 2 Part 2 Flashcards
What is the equilibrium theory of island biogeography
If imimigration and extinction rates are plotted the number of species on the island should fall where two curves intersect
What is the equilibrium number represent
The number of species that should theoritcally fit on the island regardless of the turn over (the replacement of one species with another)
What are assumptions of equilibrium theory of island biogeography
Island size mainly controls extinction rate- populations on small islands have higher chances of going extinct due to small population size and increased effects of competition and predation
Distance from the mainland controls immigration rates - distant islands should have lower immigration rates than near islands
What simberloff and wilson example
Manipulated mangrove islands in Florida by spraying with insecticides to remove all insects and spiders the species numbers were similar to numbers found before the experiment; and islands closest to a source of colonizers had the most species
What is the regional species pool
Provides an upper limit on the number and types of species that can be found in a community
What is the dispersal of regional species pool
Starts with dispersal or immigration and then is influenced by abiotic factors so they may not be able to tolerate the abiotic conditions
and then they have to survive species interactions
What is biotic resistance
Occurs when interactions with the native species exclude the invader
What is resource partitoning:
Competing species coexist by using resources in different ways. It reduces competition and increases species richness
What does it mean when the more the resource use overlaps
More competition between species. The less overlap the more specalized species have become and the less strongly they compete
What are process that promote and prevent coexistence
Competion can prevent species coexistence but disturbance stress predation and positive interacations cna mediate resource availability allowing co existence and increasing species diveristy
When can competitive exclusion not occur
When the dominant competitor is unable to reach its own carrying cpacity and coexistence will be maintained
What is intermediate disturbance hypothesis
Species diversity is greatest at intermediate disturbance. At low distrubance competition determine diversity At high disturance many species cannot surrvive
What can increase a communitys species diversity
Positive interacations
What is the lottery model
Species have equivalent interaction strengths emphasis the role of chance in maintaining species diversity .
All species have equal chance of obtaning resources that were made avilable by disturbances and this allows coexistence
Must have similar interaction strengths and growth rates and be able to respond quick to disturbances that free up resources
What is the diversity stability theory
Species richness is positively related to community stability the tendency of a community to remain the same in structure and function
