1. Ch. 20.2 Population Ecologypp.383-387 Growth rate = birth rate – death rate ADD: • Immigration = individuals move into the pop. • Birth rate = SUBTRACT: • Emigration = individuals move out of pop. • Death rate =

2. Ch. 20.2 Population Ecologypp.383-387 Exponential growth = population is growing without limits • Common for bacteria, and in early growth • Sometimes called “doubling” • Cannot continue forever because soon goes to infinity • Resources always become limited

3. Ch. 20.2 Population Ecologypp.383-387 Limiting factor = a resource that runs out and limits growth • Food, habitat,… Logistic growth = when a population grows to a maximum that the environment can support • Often starts exponentially but eventually reaches the limit

4. Ch. 20.2 Population Ecologypp.383-387 Carrying capacity = number of individuals (capacity) that the environment can carry for a long period of time • Abbreviated K • Birth rate = death rate; or balanced How many days are the Paramecia below in exponential growth? The daphnia…?

5. Ch. 20.2 Population Ecologypp.383-387 Density- independent limiting factors = limit growth but NOT related to population density • Weather, fire, pollution… • The limiting factor is independent of the size of the population

6. Ch. 20.2 Population Ecologypp.383-387 density-dependent limiting factor = does depend on the size of the population in the area • Food, nesting sites, finding mates, diseases Inbreeding = loss of genetic diversity because of few individuals • Close relatives mating • Increase in genetic disease

7. Ch. 20.2 Population Ecologypp.383-387 flux = populations fluctuate, or constantly increase or decrease • Common in predator- prey interactions • Lynx and Snowshoe hare