AP Environmental Science Unit Three Vocab

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.

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.

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.

Type III survivorship curve

A pattern of survival over time in which there is low survivorship (a high death rate) early in life with few individuals reaching adulthood.

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.

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.

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.

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.

Child Mortality

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

Age Structure Diagram

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

Total fertility rate (TFR)

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

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.

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.