Measuring Populations

• Growth Rate- the amount by which a population’s size changes over time.– Birth, death, immigration, and emigration

• Immigration- how many individuals move into a population.

• Emigrating- when an individual leaves a population.

• Birth rate - death rate = growth rate

Exponential Growth

Logistic Model

Population Regulation

• There are two limiting factors which control population size – Density dependant factors – ex water, food– Density independent factors – ex weather,

floods, fires

Predator Prey Relationships

Perils of Small Population

• Small populations are vulnerable to extinction.

• With small populations there is often increased likelihood of inbreeding

• Inbreeding causes a decrease in genetic variation an thus the population would be less likely to be able to adapt to the environment.