Population Growth Population Density # of organisms per unit area Factors that affect population size: # of births # of deaths # of people immigrating and emigrating

Exponential Growth Individuals in a population reproduce at a constant rate Population gets larger and larger very quickly Occurs under ideal conditions Unlimited space, food, no predators, etc.

Logistic Growth Many real life situations have limitations on growth Eventually the growth of the population will slow down or stop

What limits population growth? (Limiting Factors) Density-Dependent Produces a logistic growth pattern Only become limiting when the population gets large: Competition (for food, water, space, shelter) Predation Parasitism Disease Density-Independent Produces a “Boom and Bust Curve” Limit growth of the population regardless of the size of the population: Weather Natural disasters Seasonal cycles Certain human activities

Boom and Bust Curve: Results from Density-Independent Factors

Application: complete Analyzing Data on p.123 in your text