APES midterm

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.

Doubling time

The number of years it takes a population to double.

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.

Developed country

A country with relatively high levels of industrialization and income.

Developing country

A country with relatively low levels of industrialization and income.

Life expectancy

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

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.

Net migration rate

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

Age structure diagram

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

Population pyramid

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

Population momentum

Continued population growth after growth reduction measures have been implemented.

Theory of demographic transition

The theory that as a country moves from a subsistence economy to industrialization, it undergoes a predictable shift in population growth.

Affluence

The state of having plentiful wealth including the possession of money, goods, or property.

Family planning

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

IPAT equation

An equation used to estimate the impact of the human lifestyle on the environment: Impact = population x affluence x technology.

Gross domestic product (GDP)

A measure of the value of all products and services produced in 1 year in one country.

Urban area

An area that contains more than 385 people per square kilometer.

Population

The individuals that belong to the same species and live in a given area at a particular time.

Community

All of the populations of organisms within a given area.

Population ecology

The study of factors that cause populations to increase or decrease.

Population size (N)

The total number of individuals within a defined area at a given time.

Population density

The number of individuals per unit area at a given time.

Population distribution

A description of how individuals are distributed with respect to one another.

Sex ratio

The ratio of males to females in a population.

Age structure

A description of how many individuals fit into particular age categories in a population.

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.

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.

Carrying capacity (K)

The limit of how many individuals in a population the environment can sustain.

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.

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.

Intrinsic growth rate (r)

The maximum potential for growth of a population under ideal conditions with unlimited resources.

Exponential growth model (Nt = N0e^rt)

A growth model that estimates a population's future size based on the intrinsic growth rate 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.

S-shaped curve

The shape of the logistic growth model when graphed.

Overshoot

When a population becomes larger than the environment's carrying capacity.

Die-off

A rapid decline in a population due to death.

K-selected species

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

r-selected species

A species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs.

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.

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 early in life.

Corridor

Strips of natural habitat that connect populations.

Metapopulation

A group of spatially distinct populations that are connected by occasional movements of individuals between them.

Inbreeding depression

When individuals with similar genotypes breed with each other and produce offspring that have an impaired ability to survive.

Community ecology

The study of interactions between species.

Symbiotic relationship

The relationship between two species that live in close association with each other.

Competition

The struggle of individuals to obtain a shared limiting resource.

Competitive exclusion principle

The principle stating that two species competing for the same limiting resource cannot coexist.

Resource partitioning

When two species divide a resource based on differences in their behavior or morphology.

Predation

An interaction in which one animal typically kills and consumes another animal.

Parasitoid

A specialized type of predator that lays eggs inside other organisms.

Parasitism

An interaction in which one organism lives on or in another organism.

Pathogen

A parasite that causes disease in its host.

Herbivory

An interaction in which an animal consumes a producer.

Mutualism

An interaction between two species that increases the chances of survival or reproduction for both species.

Commensalism

A relationship between species in which one species benefits and the other species is neither harmed nor helped.

Keystone species

A species that that is not very abundant but has large effects on an ecological community.

Ecosystem engineer

A keystone species that creates or maintains habitat for other species.

Ecological succession

The predictable replacement of one group of species by another group of species over time.

Primary succession

Ecological succession occurring on surfaces that are initially devoid of soil.

Secondary succession

The succession of plant life that occurs in areas that have been disturbed but have not lost their soil.

Pioneer species

A species that can colonize new areas rapidly and grow well in full sunshine.

Climax community

Historically described as the final stage of succession.

Threatened species (IUCN)

Species that have a high risk of extinction in the future.

Near-threatened species

Species that are very likely to become threatened in the future.

Least-concern species

Species that are widespread and abundant.

Intrinsic value

Value independent of any benefit to humans.

Instrumental value

Worth as an instrument or a tool that can be used to accomplish a goal.

Provision

A good that humans can use directly.

Native species

Species that live in their historical range.

Exotic species

A species living outside its historical range.

Invasive species

A species that spreads rapidly across large areas and causes harm.

Lacey Act

A U.S. act that prohibits interstate shipping of all illegally harvested plants and animals.

Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

A treaty formed to control the international trade of threatened plants and animals.

Red List

A list of worldwide threatened species.

Marine Mammal Protection Act

A U.S. act to protect declining populations of marine mammals.

Endangered species

A species that is in danger of extinction.

Threatened species (U.S.)

Species that have a high risk of extinction in the future according to U.S. legislation.

Convention on Biological Diversity

An international treaty to help protect biodiversity.

Edge habitat

Habitat that occurs where two different communities come together.

Biosphere reserve

Protected area consisting of zones that vary in the amount of permissible human impact.

Species richness

The number of species in a given area.

Species evenness

The relative proportion of individuals within the different species in a given area.

Phylogeny

The branching pattern of evolutionary relationships.

Evolution

A change in the genetic composition of a population over time.

Microevolution

Evolution below the species level.

Macroevolution

Evolution that gives rise to new species, genera, families, classes, or phyla.

Gene

A physical location on the chromosomes within each cell of an organism.

Genotype

The complete set of genes in an individual.

Phenotype

A set of traits expressed by an individual.