Biology, Ch 4 Population Ecology, Sec 1 and 2

Carrying Capacity

the maximum number of individuals in a species that an environment can support for the long term

Age Structure

the number of males and females in each of three age groups: pre-reproductive stage (before 20), reproductive stage (20-44), and post-reproductive stage (after age 44)

Population Density

the number of organisms per unit area

Dispersion

the pattern of spacing of a population within an area

Demography

the study of human population size, density, distribution, movement, and birth and death rates

Immigration

the term ecologist use to describe the number of individuals moving into a population

Emigration

the term ecologists use to describe the number of individuals moving away from a population

Zero Population Growth (ZPG)

when births plus immigration equals deaths plus emigration

Summarize the concepts of carrying capacity and limiting factors.

1. Carrying capacity is the maximum number of individuals in a species that an environment can support for the long term. If population exceeds the carrying capacity, deaths outnumber births. 2. Limiting factors are any biotic or abiotic factors that restrict the growth of a population, carrying capacity of the population, and population distribution and keep a population from being able to increase indefinitely. Limiting factors are either density-independent or density-dependent

What do trends in human population growth show?

1. Developed countries tend to have lower birth and death rates or population decline 2. Developing countries tend to have higher birth and death rates or expanding population

What are the population dispersion patterns?

1. Random - organisms are randomly dispersed, just where they land. 2. Uniform - animals are dispersed evenly with aggressive territorialism. 3. Clumped - animals group around food; social animals.

Compare and contrast spatial distribution, population density, and population growth rate

1. Similarities: All populations have the following characteristics - spatial distribution, population density, and population growth rate - are measuring populations. 2. Differences: Spatial distribution is the way organisms are dispersed in their environment and measures the settlement patterns of populations. Population density is the number of organisms per unit area. Population growth rate explains how fast a given population grows or increases.

What is population growth due to?

Technological advances, i.e. agriculture and domestication of animals, medicine, shelter, etc.

When does aero population growth occur?

When the birthrate of a population equals the death rate; means that the population has stopped growing.

Density-dependent Factor

any factor in the environment that depends on the number of members in a population per unit area

Density-independent Factor

any factor in the environment that does not depend on the number of members in a population per unit area

Demographic Transition

change in a population from high birth and death rates to low birth and death rates

Population Growth Rate

explains how fast a given population grows