Unit 3 - Populations

Age structure diagram

A visual representation of the number of individuals within specific age groups for a country.

Biotic potential

The maximum rate at which a population could increase under ideal conditions.

Carrying capacity

Largest number of individuals of a population that a environment can support long term.

Competition

A common demand by two or more organisms upon a limited supply of a resource; for example, food, water, light, space, or mates.

Contraceptives

A device or drug serving to prevent pregnancy.

Crude birth rate

The total number of live births in a year for every 1,000 people alive in the society.

Crude death rate

The total number of deaths in a year for every 1,000 people alive in the society.

Declining population

The reduction of a country's population over time that is represented by an age structure diagram that is narrower at the base.

Demographic transition model (DTM)

The process of change in a society's population from a condition of high crude birth and death rates to a condition of low crude birth and death rates and a higher total population.

Demography

Scientific study of human populations.

Density-dependent limiting factors

Any biotic or abiotic factor that restricts the numbers of organisms and is affected by the number of individuals in a given area.

Density-independent limiting factors

Any biotic or abiotic factor that restricts the numbers of organisms and is the same regardless of the number of individuals in a given area.

Depletion

Reduction in the number or quantity of something.

Desalinization

A process of removing salt from ocean water for use by humans.

Developed countries

Countries with relatively high levels of industrialization and income.

Developing countries

Countries with relatively low levels of industrialization and income.

Dieback

A sudden population decline; also called a population crash.

Doubling time

The time required for a population to double in size.

Ecosystem

A system formed by the interaction of a community of organisms with their physical environment; includes biotic and abiotic factors.

Emigration

Movement of individuals out of a population

Epidemic

An outbreak of an infectious disease that is widespread in a certain area.

Exponential growth

Population growth that is unhindered because of the abundance of resources for an ever-increasing population. Exhibits a J-shaped growth curve.

Famine

A severe shortage of food in an entire area.

Fecundity

The potential reproductive capacity of an individual or population.

Fertility

The amount of offspring actually produced by an individual or population.

Finite

Having limits, able to run out.

Gene flow

Movement of alleles into or out of a population due to the migration of individuals to or from the population.

Generalist species

Species with a broad ecological niche. They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions.

Gross domestic product (GDP)

A measurement of the total goods and services produced within a country.

Immigration

Movement of individuals into a population.

Infant mortality rate

The total number of deaths in a year among infants under one year old for every 1,000 live births in a society.

Intrinsic growth rate

Number of births minus number of deaths in a population.

Invasive species

Species that enter new ecosystems and multiply, harming native species and their habitats.

K-selected species

Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age.

Lag time

Period of slow population growth due to a small population size.

Life expectancy

The average number of years an individual can be expected to live given current conditions.

Logistic growth

Growth pattern in which a population's growth is exponential but then slows levels off. Exhibits an S-shaped growth curve.

Malnutrition

Condition of the body not getting the correct amount and variety of nutrients.

Malthusian Theory

The theory that population grows exponentially while food supply grows linearly.

Mortality

Death rate

Municipal

Relating to a city, town, or local government.

Overshoot

The number of individuals in an area exceeds the capacity of the environment leading to a dieback.

Pandemic

A outbreak of an infectious disease that is worldwide.

Per capita

Per person

Population

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

Population density

A measurement of the number of people per given unit of land.

Population growth rate

Change in population size due to births, deaths, and migration of individuals in and out of the population.

Population momentum

Continued population growth that does not slow in response to growth reduction measures due to a large number of individuals of reproductive age.

Replacement fertility

The total fertility rate at which women would have only enough children to replace themselves and their partner.

r-selected species

Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period.

Rule of 70

A method for determining the number of years it will take for some measure to double, given its annual percentage increase. 70 divided by the growth rate equals doubling time in years.

Specialist species

Species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic and other environmental conditions, or use only one type or a few types of food.

Stable population

Population where there is no net population growth, as shown by an age structure diagram that is straight up and down.

Succession

A series of predictable and orderly changes within an ecosystem over time.

Survivorship curve

A graph showing the number of members of a cohort that are still alive at each age.

Total fertility rate (TFR)

The average number of children a woman will have throughout her childbearing years.

Type I Survivorship curve

A survivorship curve in which newborns, juveniles, and young adults all have high survival rates and death rates do not begin to increase greatly until old age.

Type II Survivorship curve

A survivorship curve in which individuals experience a constant chance of surviving from one age to the next throughout their lives.

Type III Survivorship curve

A survivorship curve in which individuals die at very high rates when they are young, but those that reach adulthood survive well later in life.

Undernutrition

The condition in which not enough calories are ingested to maintain health.