Organisms VS EnvironmentObjective: Population changes occur which introduce, reduce, influence changes.

Standard #6: EcologyEcology is the study of relationships among living organisms and their interactions with the physical environment. These relationships are in a constant state of flux, and even small changes can cause effects throughout the ecosystem. Students in grades nine through twelve can be taught to think of ecology as changing relationships among the components of an ecosystem. Students also need to recognize that humans are participants in these ecosystem relationships, not just observers. A goal of classroom teaching should be to develop a strong scientific understanding of ecology to establish the basis for making informed and valid decisions.

Biosphere6. Stability in an ecosystem is a balance between competing effects. As a basis for understanding this concept:

Biodiversity refers to the collective variety of living organisms in an ecosystem. This structure is influenced by alterations in habitat, including but not limited to climatic changes, fire, flood, and invasion by organisms from another system.

Biosphere6. Stability in an ecosystem is a balance between competing effects. As a basis for understanding this concept:

Biodiversity refers to the collective variety of living organisms in an ecosystem. This structure is influenced by alterations in habitat, including but not limited to climatic changes, fire, flood, and invasion by organisms from another system.

Death Rate6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

The number of deaths and emigrations over time will decrease a population’s size.

Death Rate6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

The number of deaths and emigrations over time will decrease a population’s size.

Birth Rate6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

The number of births and immigrations over time will increase it.

Birth Rate6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

The number of births and immigrations over time will increase it.

Immigration6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

The number of births and immigrations over time will increase it.

Immigration6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

The number of births and immigrations over time will increase it.

Emigration6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

The number of deaths and emigrations over time will decrease a population’s size.

Emigration6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

The number of deaths and emigrations over time will decrease a population’s size.

Growth Rate6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

Comparing rates for death and emigration with those for birth and immigration will determine whether the population shows a net growth or a decline over time.

Growth Rate

• Stage 1: High birth rates are balanced by high death rates. Common of pre-industrial societies.

• Stage 2: Death rates drop rapidly while birth rates remain high. Common of developing countries. The death rates drop due to advances in sanitation, food supply, which improves health levels and health care, and increases life spans. Because birth rates remain high while death rates decline, a country in this stage experiences a high increase in population growth.

• Stage 3: Birth rates begin to decline due to increasing urbanization, increasing wages, access to contraception, a reduction in child labor, greater equality between men and women including better education for women, and additional social changes. The population begins to head towards equilibrium again in this stage.

• Stage 4: Low birth rates are balanced by low death rates, and the population becomes stable. Characteristic of highly developed countries.

• Stage 5: The traditional model only has four stages, but some social scientists argue that a fifth stage is needed in the model to illustrate what occurs in countries that have deindustrialized and transitioned from a manufacturing and industrial based economy to a post-industrial service oriented economy. Scholars believe that this stage is characterized by populations reproducing below their replacement levels, which means they are not reproducing often enough to replace their parents' generation in a particular country.

6. c. Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

Comparing rates for death and emigration with those for birth and immigration will determine whether the population shows a net growth or a decline over time.

Goal #1Investigate Population Factors• What are the four factors?

Goal #1Investigate Population Factors

Goal #2Interpret, Calculate, Determine Fluctuation Factors from graphsU.S. Population

Goal #2Interpret, Calculate, Determine Fluctuation Factors from graphs

Goal #3Determine the time, doubling of a population

Goal #3Determine the time, doubling of a population

Goal #4Determine, distinguish between open and closed population

Goal #4Determine, distinguish between open and closed population

Factors affecting population size

Factors affecting population size