Chapter 36: Population Ecology

Population density

• The # of individuals of a species per unit area or volume

• Dispersion pattern: the way individuals are spaced within an area

• 1. clumped dispersion: grouped in patches

Dispersion patterns

Uniform dispersion: distributed evenlyRandom distribution: spaced unpredictably

Life Tables

• Track survivorship• Survivorship curves:

plot survivorship as a proportion of individuals from an initial population that are alive at each age

• 3 types: I, II, and III

Exponential Growth model

• An idealized picture of unregulated population growth- a J curve

• G=rN– G- growth rate– R-the max capacity of

members of that population to reproduce

– N-population size

Logistic growth model

• Description of idealized population growth that is slowed by limiting factors as population size increases- S shaped curve

Carry capacity

• Maximum population size that an environment can sustain

Density dependent

• Population growth decreases as density increases

• Competition• Availability of space• Predation• Weather• Environmental factors

Boom and Bust

• Boom: rapid exponential growth

• Bust: population falls back to normal levels

Sustainable Resource Management

• Harvest crops without damaging the resource

• Maximum sustained yield: harvesting should be done at a level that produces a consistent yield without forcing a population decline

Demographic Transition

• A shift from 0 population growth where birth and death are = to 0 population growth where there is are low birth and death

• Age structure: # of individuals in different age groups

Ecological footprint

• An estimate of the amount of land required to provide the raw materials an individual or nation consumes