Exam 4

• What is this graph called?

  Theory of Island Biogeography

  
• What is...

  E- Rate of Immigration

  F- Rate of Extinction

  G- Number of Species

  
• What predictions does the Theory of Island Biogeography make?

  Small/distant islands should have fewer species than large/near islands

  Rates of colonization should be higher on near islands

  Extinction rates should be higher on small islands
• What are the central assumptions of the Theory of Island Biogeography make?

  Equilibrium Model: Species richness on an island where immigration = extinction rates

  Habitat suitability: Suitable for mainland species

  Isolation Matters: distance from mainland affects immigration rates

  Island Size Matters: size influences extinction rate
• In the Theory of Island Biogeography what are the relationships between Immigration/Extinction and Species numbers?

  Immigration (negative)

  Extinction (positive)
• In the Theory of Island Biogeography why do close/far and small/large islands have different slopes?

  Greater distance from mainland = lower immigration rate (negative slope)

  Smaller Islands = higher extinction rate (positive slope)
• In the Theory of Island Biogeography what is the importance of the intersection points?

  The point where immigration and extinction curves intersect is equilibrium for that number of species.

  Islands favoring immigration = higher equilibrium species number
• In the Levins Model of Metapopulations why do extinction rates increase linearly with proportion of occupied patches?

  More occupied patches mean that there are more subpopulations at risk of extinction due to random events.
• In the Levins Model of Metapopulations why is the colonization rate parabolic?

  More empty patches available increases colonization eventually less empty patches are available causing colonization to level off then decline.
• In the Levins Model of Metapopulations when does colonization reach its peak?


  Colonization Peaks when empty patches = occupied patches
• In the Levins Model of metapopulations what are the central assumptions?

  Homogeneous Landscape: All habitat patches are identical in quality and resources.

  Random Dispersal: Colonization attempts are random

  Simple Population Dynamics: Local populations are either present or absent within a patch.

  Equilibrium Focuses: Proportion of occupied patches at equilibrium, where colonization and extinction rates balance each other.
• How does Hanski’s Metapopulation Model differ from Levin’s Model?

  Levins assumes all patches are identical, Hanski allows variation in quality. Levin assumes a constant pool of colonists Hanski considers colonization to come from nearby patches.
• What is the Rescue effect? Which model does it belong too?

  Since colonization often comes from nearby patches a subpopulation in a lower quality patch can persist from immigration. This reduces extinction rate.

  Comes from Hanski's model
• What possible outcomes does the Hanski Model predict

  Persistence in suboptimal habitat

  Higher Equilibrium Occupancy

  Metapopulation Dynamics
• What is the potential importance of “propagule rain” for metapopulations?

  Increases colonization (fresh blood and empty patches filled)

  Reduced Extinction Rate (Rescue Effect)

  Increases Metapopulation Persistence and Maintains connectivity.
• What are temperature anomalies?

  Difference between the observed temperature and a baseline temp, typically an average over a specific period.
• How are temperature anomilies calculated?

  Calculate by choosing a baseline temperature, use a 30-year period, calculate a average temp from a month/year of this period, and subtract the average temp of that month/year with the Baseline temp.
• What pattern of global temperature anomalies is observed over the past ~130 years? 

  Overall warming and constantly breaking records.
• How are the patterns of global temperature anomalies different in Arctic, High Latitudes, Mid Latitudes and Equatorial zones?

  Artic: warming faster due to the loss of reflective sea ice

  High latitudes: similar to the Artic

  Mid latitudes: warming at a rate close to average

  Equatorial regions: show the least warming, still seeing a rise in temperature
• Define Metapopulation

  Set of local populations within some larger area, where typically migration from one local population to at least some other patches is possible
• Define Rescue effect

  If more patches are occupied, then more likely that colonists from nearby patches will reduce probability of local extinction.
• Define Propagule rain

  colonization is independent of external sources
• Define source vs sink populations

  High-quality habitat (source) has a surplus individuals which emigrate to the lower-quality habitats (sink)
• Define temperature anomalies

  Difference between the observed temperature and a baseline temp, typically an average over a specific period.