PD - Population Dynamics Module Overview

Population Dynamics

Image of a crowd of people in MadridOur growing population, as well as our growing consumption, affects the environment and our ability to meet the needs of humanity. However, there are at least two major reasons to be encouraged. First, although the global population is still rising, the rate of growth has decreased nearly everywhere, and some countries are even seeing population declines. Most developed nations have passed through the demographic transition showing that is possible. A second reason to feel encouraged is the progress in expanding rights for women worldwide. Women are receiving a better education, more economic independence, and more ability to control their reproductive decisions. Aside from the clear ethical progress these developments entail, they are helping slow population growth.

Internet Earth imageSeek and Find

Conduct an Internet search. See if you can locate a world population clock.

 

Essential Questions

  • Can there be long-term solutions to environmental problems without a decrease in the human population growth rate?
  • What factors control the rate of human population growth?
  • How many people can the earth sustain?
  • What has been the impact of modern medical practices, improvements in sanitation, control of disease-spreading organisms, and supplies of human necessities, on the birth rates and death rates of human populations?
  • Why have countries with a high standard of living moved more quickly to a lower birth rate than have countries with a low standard of living?

 

Key Terms

  • age structure pyramid - the number and proportion of people at each age in a population.
  • birth rate - the number of births per 1000 people per year; also called natality.
  • carrying capacity: (K) - The maximum number of individuals of a given species that a particular environment can support sustainably (long-term), assuming there are no changes in that environment.
  • death rate: the number of deaths per 1000 people per year; also call mortality.
  • demographic transition: the process whereby a country that is industrializing moves from relatively high birth and death rates to relatively low death rates, followed within a few generations by reduced birth rates.
  • demographics: the application of demographic science that provides information on the populations of various countries or groups of people
  • developing countries: a country that is not highly industrialized and is characterized by high fertility rates, high infant mortality rates, and low per capita incomes. Developing countries fall into two subcategories: moderately developed and less developed.
  • less developed or underdeveloped countries: a developing country with a low level of industrialization, a high fertility rate, a high infant mortality rate, and a low per capita income (relative to highly developed counties).
  • emigration: a type of dispersal in which individuals leave a population and thus decrease its size.
  • density-dependent factors: an environmental factor whose effects on a population change as population density changes; density-dependent factors tend to retard population growth as population density increases and enhance population growth as population density decreases.
  • exponential growth: The accelerating population growth that occurs when optimal conditions allow a constant rate of increase over time. When the increase in population number versus time is plotted on a graph, exponential population growth produces a characteristic J-shaped curve.
  • density-independent factors: an environmental factor that affects the size of a population but is not influenced by changes in population density
  • immigration: movement of a population into an area.
  • highly developed country: an industrialized country that is characterized by a low fertility rate, low infant mortality rate, and high per capita income.
  • IPAT model- summarizes how environmental impact (I) results from interactions among population size (P), affluence (A), and technology (T)
  • life expectancy: the amount of time that the typical person in a population or cohort is expected to live.
  • K-selected species: a reproductive strategy in which a species typically has a large body size, slow development, long life span, and does not devote a large proportion of its metabolic energy to the production of offspring.
  • limiting resources: any environmental resource that, because it is scarce or at unfavorable levels, restricts the ecological niche of an organism.
  • population: a group of organisms of the same species that live in the same geographic area at the same time.
  • population density: the number of individuals of a species per unit of area or volume at a given time.; Population density: number of people ÷ the area they occupy = population density.
  • population growth momentum: the continued growth of a population after fertility rates have declined as a result of a population's young age structure; population growth momentum can be either positive or negative but is usually discussed in a positive context.
  • population ecology: the branch of biology that deals with the numbers of a particular species that are found in an area and how and why those numbers change (or remain fixed) over time.

 

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