APES Unit 3 Key Terms

Age structure diagram

A visual representation of the number of individuals within specific age groups for a country, typically expressed for males and females.

Biotic potential

Under ideal conditions with unlimited resources available, every population has a maximum potential for growth.

Carrying capacity

The limit to the number of individuals that can be supported by an existing habitat or ecosystem, denoted as K.

Child mortality

The number of deaths of children under age 5 per 1,000 live births.

Crude birth rate (CBR)

The number of births per 1,000 individuals per year.

Crude death rate (CDR)

The number of deaths per 1,000 individuals per year.

Demographer

A scientist in the field of demography.

Demography

The study of human populations and population trends.

Density-dependent factor

A factor that influences an individual’s probability of survival and reproduction in a manner that depends on the size of the population.

Density-independent factor

A factor that has the same effect on an individual’s probability of survival and the amount of reproduction at any population size.

Developed countries

Countries that have relatively high levels of industrialization and income.

Developing countries

Countries that have relatively low levels of industrialization and income.

Dieback (Die-off)

A rapid decline in a population due to death.

Doubling time

The number of years it takes a population to double.

Emigration

The movement of people out of a country or region.

Environmental justice

The study of the disproportionate exposure to environmental hazards experienced by marginalized groups; both an academic field and a social movement.

Exponential growth model

A growth model that estimates a population’s future size based on biotic potential and the number of reproducing individuals.

Family planning

The regulation of the number or spacing of offspring through the use of birth control.

Fecundity

The ability to produce an abundance of offspring.

Immigration

The movement of people into a country or region from another country.

Infant mortality

The number of deaths of children under 1 year of age per 1,000 live births.

IPAT equation

A conceptual representation of the three major factors influencing environmental impact: Population, Affluence, Technology.

J-shaped curve

The curve of the exponential growth model when graphed.

K-selected species

A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches the carrying capacity.

Life expectancy

The average number of years an infant born in a specific year can be expected to live.

Limiting resource

A resource that a population cannot live without, occurring in quantities lower than needed to increase in size.

Logistic growth model

A growth model describing a population whose growth is initially exponential but slows as it approaches carrying capacity.

Net migration rate

The difference between immigration and emigration in a given year per 1,000 people in a country.

Overshoot

When a population exceeds the environment's carrying capacity.

Population growth models

Mathematical equations used to predict population size at any moment.

Population growth rate (Intrinsic growth rate)

The number of offspring an individual can produce in a time period, minus deaths during the same period.

Population momentum

Continued population growth after measures to reduce growth have been implemented.

Population pyramid

An age structure diagram that is widest at the bottom and smallest at the top, typical of developing countries.

r-selected species

A species that has a high intrinsic growth rate, leading to rapid population increase.

Replacement-level fertility

The total fertility rate required to maintain the current population size.

Rule of 70

A method to determine a population’s doubling time by dividing 70 by the growth rate percentage.

S-shaped curve

The shape of the logistic growth model when graphed.

Survivorship curve

A graph representing distinct patterns of species survival as a function of age.

Theory of demographic transition

A theory stating that a country moves from high to lower birth and death rates as it develops.

Total fertility rate (TFR)

An estimate of the average number of children a woman will bear throughout her childbearing years.

Type I survivorship curve

A pattern of survival with high survival throughout most life stages, then a significant decline towards old age.

Type II survivorship curve

A survival pattern with a relatively constant decline in survivorship throughout the life span.

Type III survivorship curve

A pattern of survivorship with low survival early in life, resulting in few individuals reaching adulthood.