
Population Density
The number of individuals per unit area.

What are 3 characteristics of a population?
Its geographic distribution, density, and growth rate.

What are 3 factorsthat can affect population size?
The number of births, the number of deaths, and the number of individuals that enter or leave the population.

Immigration
The movement of individuals into an area, which can cause a population to grow.

Emigration
The movement of individuals out of an area, which can cause a population to decrease in size.

Exponential Growth
Occurs when the individualsin a population reproduce at a constant rate. A J shaped curve shows exponential growth over time!!!!!

Exponential Growth
Under ideal conditions with unlimited resources, a population will grow exponentially.

Logistic Growth
Occurs when a population's growth slows or stops following a period of exponential growth.

Logistic Growth
As resources become less available, the growth of a population slows or stops.

Carrying Capacity
The horizontal line through the region of the graph where the growth has leveled off.

Limiting Factor
A factor that causes population growth to decrease.

Densitydependent limiting factor
A limiting factor that depends on population size. Densitydependent factors become limiting only when the population densitythe number of organisms per unit areareaches a certain level.

Predatorprey relationship
Populations in nature are often controlled by predation. The regulation of a population by predation takes place within a predatorprey relationship.

Densityindependent limiting factors
Affect all populations in similar ways, regardless of the population size.

Densityindependent limiting factors
Unusual weather, natural disasters, seasonal cycles, and certain human activities such as damming rivers and clearcutting forests are all examples of densityindependent limiting factors.

