Ecology: Key Concepts, Levels, and Community Interactions

Ecology

The study of the interactions between an organism and its environment (both living and nonliving components)

Biotic factors

The living components of an ecosystem (e.g., animals, plants, bacteria, fungi)

Abiotic factors

The physical and chemical components of an ecosystem (nonliving) (e.g., temperature, humidity, pH, salinity)

Organism

An individual living thing

Population

A group of organisms who are the same species, live in the same area, and regularly reproduce

Community

All the interacting populations in an area

Ecosystem

The interacting biotic and abiotic factors in an area

Interdependence

All organisms rely on/are connected to other organisms and the abiotic factors around them

Biosphere

The layer of the Earth where all living things live

Producers

Organisms that create their own food (and the food for the entire ecosystem) from the sun's energy (e.g., plants, some protists, and some bacteria)

Consumers

Organisms that gain energy from eating other organisms

Herbivore

Consumer that only eats producers

Carnivore

Consumer that only eats other consumers

Omnivore

Consumer that eats both producers and other consumers

Detritivore

Consumer that breaks down dead producers and consumers

Trophic level

An organism's position in a sequence of energy transfers

Food chain

A single pathway/line of feeding relationships

Food web

All of the food chains in an ecosystem

Carrying capacity

The maximum population size that can be sustained by an ecosystem

Keystone species

A species whose impact on an ecosystem is disproportionate to its population size

Predation

An individual of one species eats all or part of an individual of a different species

Competition

Two or more species use the same limited resource

Niche

The way of life of an organism in its environment

Symbiosis

A close, long-term relationship between two species

Parasitism

When one species (parasite) benefits at the expense of another species (host)

Mutualism

Both species benefit from each other

Commensalism

One species benefits while the other species is unaffected