ENS Test 2

Population

Organisms of the same species living in one area that commonly breed with each other.

Population Biology

Study of populations and how they change.

Demographics

Statistics that describe a population.

Population Size

Total number of individuals in a population.

Population Density

Number of individuals in a certain area or volume.

Population Distribution

How individuals are spaced within an area.

Clumped Distribution

Individuals live close together, often because of resources or social behavior.

Uniform Distribution

Individuals are evenly spaced, usually because of competition.

Random Distribution

Individuals are scattered without a pattern; rare in nature.

Population Sampling

Estimating population size without counting every individual.

Quadrat Sampling

Counting organisms in a small area to estimate the total population.

Mark-Recapture

Capturing, marking, releasing, and recapturing animals to estimate population size.

Population Growth

Occurs when births exceed deaths.

Exponential Growth Model

Rapid population growth when resources are unlimited.

G = r x N

Per Capita Growth Rate (r)

Population growth rate per individual.

Biotic Potential

Maximum possible population growth under ideal conditions.

Logistic Model

Growth slows as population density increases and resources become limited.

Carrying Capacity (K)

Maximum population an environment can support indefinitely.

G = r(1-N/K) x N

Limiting Factors

Conditions or resources that restrict population growth.

Density-Dependent Factors

Factors that become stronger as populations grow, such as competition and disease.

Density-Independent Factors

Events affecting populations regardless of size, such as hurricanes and floods.

Life History Traits

Characteristics such as reproduction rate, development, and lifespan.

Survivorship

Pattern of survival throughout an organism's life.

Opportunistic Life History (r-selected)

Producing many offspring with little parental investment.

Equilibrial Life History (K-selected)

Producing fewer offspring with greater parental investment.

Exponential Growth Formula

G = r × N

Logistic Growth Formula

G = r × N × (1 − N/K)

N

Population size.

r

Per capita growth rate.

K

Carrying capacity.

Human Population

Total number of people living in an area or worldwide.

Population Explosion

Rapid human population growth caused by declining death rates while birth rates remain high.

Thomas Malthus (1798)

Scientist who argued that human populations grow faster than food supplies.

Innovation

New inventions or methods that can increase resources and potentially change carrying capacity.

Demography

Study of human populations.

Immigration

Moving into a country or area.

Emigration

Moving out of a country or area.

Crude Birth Rate (CBR)

Number of births per 1,000 people per year.

Crude Death Rate (CDR)

Number of deaths per 1,000 people per year.

Doubling Time

Number of years needed for a population to double.

Rule of 70

Formula used to estimate population doubling time.

70/% = __yrs

Population Stabilization

When population size stops increasing significantly.

Total Fertility Rate (TFR)

Average number of children a woman is expected to have.

Replacement-Level Fertility

Fertility rate needed to replace the existing population.

Development Level Fertility

Offset to Total Fertility Rate the average # of deaths in a population

Life Expectancy

Average number of years a newborn is expected to live.

Infant Mortality Rate

Deaths of children under age 1 per 1,000 live births.

Child Mortality Rate

Deaths of children under age 5 per 1,000 live births.

Infectious Disease

Disease caused by microbes that can spread between people.

Wide-Based Population Pyramid

Many young people; suggests rapid future growth.

Even Age Distribution

Similar proportions across age groups; suggests slow or stable growth.

Inverted Population Pyramid

More older people than younger people; suggests population decline.

Preindustrial Stage

High birth and death rates; slow population growth.

Early Industrial Stage

Death rates decline while birth rates remain high; rapid growth.

(China and India)

Mature Industrial Stage

Birth rates decrease and population begins stabilizing.

(U.S., Canada, Australia)

Postindustrial Stage

Low fertility and possible population decline.

(Italy, Germany, Russia)

Affluence

Wealth and access to resources.

IPAT Equation

Estimates human environmental impact using population, affluence, and technology.

I = P x A x T

Population (P)

Number of people consuming resources and producing waste.

Affluence (A)

Level of consumption associated with wealth.

Technology (T)

Tools and processes that can increase or decrease environmental impact.

Destructive Technology

Technology that causes environmental damage or pollution.

Global Population Growth Rate (%)

(CBR − CDR) ÷ 10.

National Population Growth Rate (%)

[(CBR + immigration rate) − (CDR + emigration rate)] ÷ 10.

Doubling Time Formula

70 ÷ annual growth rate (%).

IPAT

Impact = Population × Affluence × Technology.

Community Ecology

Study of interactions between different populations.

Competition

Struggle between organisms for limited resources.

Liebig's Law of the Minimum

The scarcest needed resource limits population growth.

Competitive Exclusion Principle

Two species competing for the same limiting resource cannot coexist indefinitely.

Ecological Niche

A species' way of life and how it uses resources.

Resource Partitioning

Species dividing resources to reduce competition.

Resource Overlap

When species use the same resources.

Temporal Resource Partitioning

Species use resources at different times.

Spatial Resource Partitioning

Species use different physical areas.

Morphological Resource Partitioning

Differences in body shape or size allow species to use different resources.

Niche Specialization

Species becoming adapted to using particular resources.

Predation

One species uses another species as a resource.

True Predator

Organism that kills and consumes most of its prey.

Herbivore

Organism that eats plants.

Behavioral Defense

Avoiding predators through actions such as hiding or reduced movement.

Morphological Defense

Physical protection such as spines or camouflage.

Chemical Defense

Using toxins or unpleasant chemicals to discourage predators.

Camouflage

Blending into surroundings to avoid detection.

Mimicry

Resembling a more dangerous organism for protection.

Symbiosis

Close relationship between two different species.

Parasite

Organism that lives on or inside a host and consumes its resources.

Parasitoid

Organism whose young develop inside a host and eventually kill it.

Mutualism

Relationship in which both species benefit.

Commensalism

Relationship where one species benefits and the other is unaffected.

Keystone Species

Species whose removal has an unusually large effect on the community.

Trophic Cascade

Changes in one part of a food chain affect several other levels.

Predator-Mediated Competition

Predators influence competition among other species.

Ecological Engineer

Species that creates or maintains habitats for other organisms.

Ecological Succession

Gradual replacement of one group of species by another.

Primary Succession

Community development in an area without soil.

Secondary Succession

Community recovery after disturbance when soil remains.

Pioneer Species

Species that quickly colonize new or disturbed environments.

Disturbance

Event such as a fire or hurricane that changes a community.

Core

Earth's innermost layer, mostly iron and nickel.