13 Flashcards
Under the assumptions of IBT, is species composition stable at equilibrium?
No since new species may be immigration and extinction at the same time.
If IBT assumptions are not met, is species composition stable at equilibrium?
It depends since overall species composition generally differs and some species (particularly the ecologically dominant organisms) are expected to be similar across replicate islands)
Why is there predictability if IBT is not met? 5•
•abiotic factors differ
•biotic interactions differ
•Not all organisms are equally likely to colonize
•Evolutionary processes differ
•diversification
Stochasticity is only a factor that?
Decreases species richness
Questions about what determines the number of species on biogeographic, landscape, and community scale? 3•
•Biogeographic scale: Why do the topics have so many more species than the poles
•Landscape (island) scale: Why do large areas have more species than small areas?
•Community scale: What determines the # of species in a community?
What ultimately controls the # of species?
Evolution since it creates genetic and biological diversity, and ecology use evolution for species creation and diversification.
In the geographical level, species diversity is highest in?
Tropics and low diversity in temperate regions and in the poles that are true for vasculature plants, amphibians, mammals, and birds.
Wallace line?
The line that splits two different animal populations in the Indian islands between the two major tectonic plates.
Why do plants occupy larger regions in the global scale?
•Plants have better dispersal abilities
•plant distributions are more responsive to climatic differences.
What causes latitudinal gradients? 3•
•species diversification rate
-Land area
-climatic stability
•diversification time
-cradle
-museum
•productivity
-low extinction rates
-greater species coexistence
-high species richness
Why exactly do species richness is greater in greater land area?
There are more habitat, therefore more niches for organisms, and there are more individuals which means less extinction.
!!!There is lower climatic variation at low latitudes. This results in?
Higher speciation rates due to species forming narrow abiotic tolerances and low extinction rates due to less fluctuations.
tropics have more uninterrupted time for evolution than the temperate. This results in the cradle hypothesis which states?
Species (and higher taxonomic levels) tend to originate in the tropics and disperse to temperate and polar areas. Therefore, tropics have more species.
Museum hypothesis?
Species tend to go extinct in temperate and polar regions because of frequent or extreme changes in climate. Therefore, tropics have more species.
Productivity hypothesis?
Productivity is higher in tropical areas since they have more solar energy for more of the year, and are often wetter. Therefore, more plant biomass can be produced (primary productivity).
