Biology PHall Red - Chapter 05 Population Ecology

Population Density

The number of organisms per unit area; a measure of crowding.

Immigration

This occurs when organisms enter a population from other places.

Emigration

This occurs when organisms leave a population to go to new places.

Dispersion

The way in which members of a population are spread across the landscape.

Exponential Growth

Growth without limits that increases in its rate over time.

Positive Growth

A steady increase over time.

Negative Growth

A steady decrease over time.

Zero Growth

No change in a population over time.

Boom-and-Bust

This occurs when a population grows exponentially, exceeds its carrying capacity, and then comes crashing down.

Logistic Growth

This occurs when a population starts to grow exponentially, but then levels off around the carrying capacity.

Carrying Capacity

The maximum number of organisms of a given species that an area can support indefinitely.

Limiting Factor

Any factor that can control the growth of a population.

Density-Dependent Limiting Factor

A limiting factor that operates strongly on large, dense populations. Predation, disease, competition, parasitism, etc.

Density-Independent Limiting Factor

A limiting factor that affects all populations equally, regardless of their size or density. Natural disasters.

Predators

Animals that capture, kill and consume other organisms for food.

Prey

Organisms that are captured, killed and consumed by predators.

Demography

The scientific study of HUMAN populations.

Demographic Transition

A dramatic change from high birth and death rates to low birth and death rates in HUMAN populations.

Age Structure

The number of males and females of each age in a population.