1. Populations

2. Objective
Students will be able to define population and explain important characteristics of a population.

3. What is a population?
Group of individuals of the same species that live in the same area.

4. Important Characteristics of a Population
Geographic Distribution
Density
Growth Rate

5. Geographic Distribution
Range: describes the area inhabited by a population
Can range from a few cubic centimeters to millions of square kilometers
Ex: Rotting Apple vs. Pacific Ocean

6. Population Density Number of individuals per unit area
Can vary depending on the species and its ecosystem
Ex: Saguaro Cactus vs. smaller desert plants

7. Population Growth Rate
A population will increase or decrease in size depending on how many individuals are added to it or removed from it
3 Factors affect population size:
# of births
# of deaths
# of individuals that enter or leave the population

8. Population Growth Rate
Immigration: movement of individuals into an area
Emigration: movement of individuals out of an area
Exponential Growth: individuals in a population reproduce at a constant rate
Logistic Growth: Population’s growth slows or stops following a period of exponential growth.

9. Carrying Capacity
The largest number of individuals of a population that a given environment can support