APES Unit 3: Populations

Module 15-18

Population growth rate

The number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period. Also known as intrinsic growth rate.

Exponential growth model

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

Biotic potential

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

K-selected species

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

Carrying capacity

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

r-selected species

A species that has a high intrinsic growth rate, and their population typically increases rapidly

Overshoot

When a population becomes larger than the environment’s carrying capacity

Dieback

A rapid decline in a population due to death. Also known as die-off.

Survivorship curve

A graph that represents the distinct patterns of species survival as a function of age.

Type I survivorship curve

A pattern of survival over time in which there is high survival throughout most of the life span, but then individuals start to die in large numbers as they approach old age.

Type II survivorship curve

A pattern of survival over time in which there is a relatively constant decline in survivorship throughout most of the life span

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 reproduction at any population size.

Population growth models

Mathematical equations that can be used to predict population size at any moment in time.

Fecundity

The ability to produce an abundance of offspring.

Exponential growth model

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

J-shaped curve

The curve of the exponential growth model when graphed.

Logistic growth model

A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment.

S-shaped curve

The shape of the logistic growth model when graphed.

Limiting resource

A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size.

Demography

The study of human populations and population trends.

Demographer

A scientist in the field of demography

Immigration

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

Emigration

The movement of people out of a country or region.

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

Net migration rate

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

Life expectancy

The average number of years that an infant born in a particular year in a particular country can be expected to live, given the current average life span and death rate in that country

Infant mortality

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

Child mortality

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

Environmental justice

The study of the disproportionate exposure to environmental hazards experienced by people of color, recent immigrants and people of lower socio-economic backgrounds; and is both an academic field and a social movement.

Age structure diagram

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

Population pyramid

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

Developing countries

Countries with relatively low levels of industrialization and income.

Developed countries

Countries that have relatively high levels of industrialization and income.

Population momentum

Continued population growth after growth reduction measures have been implemented

Total fertility rate (TFR)

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

Family planning

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

Replacement-level fertility

The total fertility rate required to offset the average number of deaths in a population in order to maintain the current population size.

Doubling time

The number of years it takes a population to double.

Rule of 70

A method which dictates that by dividing the number 70 by the percentage population growth rate we can determine a population’s doubling time.

Theory of demographic transition

A theory that states that a country moves from high to lower birth and death rates as development occurs and that country moves from a preindustrial to an industrialized economic system.

IPAT equation

A conceptual representation of the three major factors that influence environmental Impact: Population of humans, Affluence, Technology.

Affluence

the state of having a great deal of money; wealth.

Gross Domestic Product (GDP)

the total monetary value of all finished goods and services produced in a country within a specific period, typically a quarter or a year