APES Withgott & Laposata Chapter 8 Human Population

Population

A group of individuals that belong to the same species and live in the same area

Population Dynamics

A branch of knowledge concerned with the sizes of populations and the factors involved in their maintenance, decline, or expansion

Population Density

Is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans.

Population Dispersion

The process by which groups of living organisms expand the space or range within which they live.

Age Structure

The age structure of a population is the distribution of people among various ages. In graphic form, age structure is portrayed as an age pyramid whose relatively broad base indicates the number of children while the peak reflects the increasing likelihood of death as people age. A population whose age structure has a very broad base and a sharp narrow peak is said to be "young," while a structure whose base is not much wider than the rest of the pyramid is "old."

Survivorship Curve

A survivor ship curve is a graph showing the number or proportion of individuals surviving at each age for a given species or group.

Immigration

A category of population dispersal covering one-way movement into the population area.

Emigration

A category of population dispersal covering one-way movement out of the population area.

Limiting Factor

The variable, or combination of variables, which limits the rate of growth of an organism or a population, or which limits the rate of a physiological process.

Density Dependent Factors

Is one where the effect of the factor on the size of the population depends upon the original density or size of the population

Density Independent Factors

Is one where the effect of the factor on a population does not rely on the total number of individuals in the population.

Biotic Potential

Is the maximum reproductive capacity of a population under optimum environmental conditions.

r-selection

Selection occurring when a population is far below the carrying capacity of an unstable environment: tends to favor individuals that reproduce early, quickly, and in large numbers so as to make use of ephemeral resources and ensure that at least some offspring survive. This selection favors generalist species in successional communities.

K-selection

A form of selection that occurs in an environment at or near carrying capacity, favoring a reproductive strategy in which few offspring are produced. This selection favors specialist species in climax communities.

Demography

The study of statistics such as births, deaths, income, or the incidence of disease, which illustrate the changing structure of human populations.

Zero Population Growth

The maintenance of a population at a constant level by limiting the number of live births to only what is needed to replace the existing population.

Fertility

The birthrate of a population

Total Fertility Rate

The average number of children born to a woman during her childbearing years.

Birth Rate

the ratio of live births in an area to the population of that area

Death Rate

The ratio of deaths per thousand of population per year.

Growth Rate

The rate of increase in size per unit time

Doubling Time

The time it takes for a particular level of population to double in size.

Morbidity

Refers to the state of being diseased or unhealthy within a population.

Mortality

Death rate in a population, such as number of deaths per thousand people per year.

Natality

Birth rate in a population, such as number of births per thousand people per year.

IPAT Model

It describes the multiplicative contribution of population (P), affluence (A) and technology (T) to environmental impact (I). Environmental impact (I) may be expressed in terms of resource depletion or waste accumulation; population (P) refers to the size of the human population; affluence (A) refers to the level of consumption by that population; and technology (T) refers to the processes used to obtain resources and transform them into useful goods and wastes. The formula was originally used to emphasize the contribution of a growing global population on the environment, at a time when world population was roughly half of what it is now. It continues to be used with reference to population policy.

Sex Ratio

The sex ratio is the ratio between the number of males and the number of females.

Infant Mortality Rate

The ratio of the number of deaths in the first year of life to the number of live births occurring in the same population during the same period of time.

Life Expectancy at Birth

The number of years that an individual is expected to live as determined by statistics.

Exponential Growth

Growth whose rate becomes ever more rapid in proportion to the growing total number or size. It forms a J-shaped curve when graphed.

Logistic Growth

Occurs when a population's growth slows or stops following a period of exponential growth due to limited resources. It forms an S-shaped curve when graphed.

Carrying Capacity

The number or quantity of people or things that can be conveyed or held by a vehicle or container.

Demographic Transition

Refers to the transition from high birth and death rates to low birth and death rates as a country develops from a pre-industrial to an industrialized economic system.

Population Age Structure

The distribution of the population by age, used in analysis of demographic trends.

Replacement Level Fertility

the number of children a couple must have to replace themselves (averages 2.1 in more developed nations, 2.7 in less developed nations).

Rate of natural increase

Is the crude birth rate minus the crude death rate of a population.

Demographic Fatigue

Describes the combination of high fertility (birth rates) and declining mortality (death rates) in developing countries

Crude Birth Rate

The ratio of total live births to total population in a specified community or area over a specified period of time. The birthrate is often expressed as the number of live births per 1,000 of the population per year.

Crude Death Rate

The ratio of total deaths to total population in a specified community or area over a specified period of time. The death rate is often expressed as the number of deaths per 1,000 of the population per year.