Metapopulation Theory ES 100 10/20/06

Remember from last time: Population ecology Life Tables Cohort-based vs. Static Identifying vulnerable age stages + (in section) Age-specific birth rate Computing fitness, net reproductive rate and generation time Population projections

Today: Metapopulation Theory Immigration and Emigration Source and Sink Populations Maintaining Genetic Diversity Implications for Management

Is the Population Increasing, or Decreasing? Fitness is one indication….. But… Populations vary dramatically over time (boom/bust cycles) Individuals move in (immigration) and out (emigration) of populations Metapopulations (18.5 Bush) Nt+1 = Nt + (B-D) + (I-E)

Populations across the landscape Metapopulation: sum of multiple interacting sub-populations sub-population A sub-population C sub-population B sub-population D

Populations across the landscape Most mating occurs within a sub-population sub-population A sub-population C sub-population B sub-population D

Populations across the landscape Genetic diversity is maintained by exchange of genes between the sub-populations sub-population A sub-population C sub-population B sub-population D

Populations across the landscape Some habitat patches are better than others hot and dry few nesting sites most ideal many predators

Populations across the landscape Sub-populations can be source populations or sink populations sink sink hot and dry source few nesting sites most ideal many predators sink

Populations across the landscape In source population habitats: living conditions are good, so births meet or exceed deaths competition may be great, forcing some members out sink sink hot and dry source few nesting sites most ideal many predators sink

Populations across the landscape If a sub-population goes extinct, it can be revived by recruits from another sub-population…. sinks are important too! sink source locally extinct source of recruits

Controls on immigration Distance to source population Lots of immigration mainland Little immigration Obstacles Mountains Waterways mountains hills

Sample Metapopulation Data Is this population assessment static or cohort based? Which sub-population(s) are sources? Sinks? Can you develop a life table for each sub-population? Can you develop a life table for the total population?

Endangered Species: Mountain Pygmy-possum Burramys parvus

NEXT WEEK: Fun with Mathematical Models