Ecology, Population Dynamics, and Human Impact: Key Concepts for BIO 105

Biosphere

All ecosystems on Earth; the global sum of all living organisms and environments.

Biotic

Living components of an ecosystem (plants, animals, microbes).

Abiotic

Nonliving components (temperature, water, soil, sunlight).

Ecosystem

A community of organisms interacting with each other and the abiotic environment.

Climate

Long-term patterns of temperature, precipitation, and humidity in an area.

Weather

Short-term conditions of the atmosphere.

Global warming

The increase in Earth's average surface temperature due to rising greenhouse gases.

Climate change

Long-term changes in climate patterns (temperature, precipitation, storms).

Greenhouse gases

Gases that trap heat in the atmosphere (CO₂, methane, nitrous oxide).

Atmospheric carbon dioxide

CO₂ in the air; increased by human activity.

Carbon sink

A reservoir that absorbs more carbon than it releases (forests, oceans).

Carbon source

A process or system that releases more carbon than it absorbs (burning fossil fuels).

Solar radiation

Energy from the sun.

Infrared radiation

Heat energy re-radiated from Earth's surface.

Immigration

Individuals entering a population.

Emigration

Individuals leaving a population.

Population size

Number of individuals in a population.

Population density

Number of individuals per unit area.

Exponential growth

Population grows at a constant rate; produces a J-shaped curve.

Logistic growth

Growth slows as carrying capacity is reached; produces an S-shaped curve.

Carrying capacity (K)

Maximum population size an environment can support long-term.

Cyclical fluctuation

Population naturally rises and falls over time.

Ecological community

All interacting species in a particular area.

Relative species abundance

How common each species is relative to others.

Species richness

Number of different species in a community.

Food chain

A linear sequence of who eats whom.

Food web

Complex network of feeding relationships.

Keystone species

Species with a disproportionately large effect on its community.

Producer

Organisms that make their own food (plants, algae).

Consumer

Organisms that eat others (herbivores, carnivores, omnivores).

Mutualism

Both species benefit (+/+).

Competition

Species compete for resources (-/-).

Commensalism

One benefits, the other unaffected (+/0).

Predation

Predator kills and consumes prey.

Parasite

Lives on/in a host and harms it.

Host

The organism a parasite lives on/in.

Succession

Gradual change in an ecological community over time.

Primary succession

Begins on surfaces with no soil (lava rock, glacier retreat).

Secondary succession

Begins where soil already exists (after fire, farming).

Mimicry

One species evolves to resemble another.

Climax community

Stable, mature community resulting from succession.

Ecological footprint

Amount of land/water required to support an individual's lifestyle; measured in global hectares (gha).