Ecology Key Terms and Concepts

A comprehensive vocabulary review of foundational ecology terms covering trophic levels, species interactions, population dynamics, biogeochemical cycles, and human impacts on biodiversity.

Autotroph

An organism that produces its own organic nutrients from inorganic substances, typically using light or chemical energy (e.g., photosynthetic plants or chemosynthetic bacteria).

Heterotroph

An organism that cannot manufacture its own food and must obtain nutrients and energy by consuming other organisms.

Abiotic

Non-living physical and chemical components of an environment, such as sunlight, temperature, water, and soil minerals.

Biotic

Living or once-living biological components and organisms that interact within an ecosystem.

Higher order Consumer

An organism (such as a tertiary or quaternary consumer/apex predator) positioned near the top of the food chain that preys upon lower-level consumers.

Population

A group of individuals of the same species living and interacting within the same geographic area at the same time.

First Trophic level

The base trophic level in an ecological food chain or web, composed of primary producers (autotrophs) that synthesize biomass from energy sources.

Primary Consumer

An organism, typically an herbivore, that feeds directly on primary producers at the second trophic level.

Secondary Consumer

A carnivore or omnivore that preys upon primary consumers to obtain energy.

Ecosystem

A community of living organisms interacting alongside the non-living (abiotic) components of their environment as a functioning system.

Community

All the populations of different species that inhabit and interact within a shared geographic area.

Scavenger

An animal that consumes dead animal carcasses or decaying plant matter that it did not kill itself.

Decomposer

An organism, such as a fungus or bacterium, that breaks down organic matter externally via chemical decomposition and releases nutrients back into the ecosystem.

Detritivore

An organism (such as an earthworm or millipede) that consumes decomposing particulate organic material (detritus) by ingesting and internally digesting it.

Symbiosis

A close and prolonged biological association between individuals of two different species, categorized as mutualism (both benefit), commensalism (one benefits, one unaffected), or parasitism (one benefits at the expense of the other).

Interspecific Competition

Competition that occurs between individuals of different species competing for the same limited ecological resources.

Intraspecific competition

Competition that occurs among members of the same species competing for limited resources such as mates, territory, or food.

Invasive species

A non-native species introduced to an ecosystem that multiplies rapidly, outcompetes native organisms, and causes environmental or economic disruption.

Mimicry

An evolutionary adaptation where one organism closely resembles another organism or object for survival advantages, such as Batesian mimicry (a harmless species mimicking a dangerous one) or Müllerian mimicry (two harmful species resembling each other).

Density dependent Limiting factor

An environmental condition whose regulatory effect on population size intensifies as population density increases (e.g., disease, competition, predation).

Density Independent Limiting factor

An environmental factor that affects population mortality or size regardless of population density (e.g., weather events, floods, wildfires).

Dispersion pattern

The spatial arrangement of individuals within a population across a geographic area, classically occurring in clumped, uniform, or random distributions.

K strategist

A species characterized by traits adapted to stable environments near carrying capacity ($K$), including slow growth, large body size, few offspring, delayed reproduction, and significant parental investment.

R strategist

A species adapted to maximize growth rate ($r$) in unstable or disturbed environments, characterized by small body size, rapid development, early maturity, large numbers of offspring, and minimal parental care.

Carbon flux

The rate of transfer or exchange of carbon between various global pools or spheres, such as photosynthesis taking up carbon from the atmosphere or cellular respiration releasing it.

Carbon reservoir

A natural pool or storage location that accumulates and holds carbon, such as fossil fuel deposits, the atmosphere, vegetation, deep ocean waters, and carbonate rocks.

Nitrogen flux

The biochemical transformation and movement of nitrogen through different forms and locations in the biosphere via processes like nitrogen fixation, nitrification, and denitrification.

Nitrogen reservoir

A physical compartment where nitrogen is stored, with the atmosphere serving as the largest global reservoir as dinitrogen gas ($N_2$).

Phosphorus flux

The movement and slow geochemical cycling of phosphorus through the lithosphere, hydrosphere, and biosphere, notably lacking a significant gaseous atmospheric phase.

Phosphorus reservoir

A natural storage pool where phosphorus is held for extended periods, predominantly found in sedimentary rock formations, marine sediments, and mineral deposits.

Habitat loss

The reduction, fragmentation, or destruction of natural ecosystems caused by human expansion or development, rendering areas incapable of supporting native species.

Pollution

The introduction of harmful chemical substances, contaminants, or energetic disturbances (e.g., plastics, toxins, light, thermal energy) into natural environments.

Climate change

Long-term shifts and variations in global temperatures and weather patterns, largely driven by anthropogenic greenhouse gas emissions.

Overharvesting

The unsustainable extraction or hunting of renewable biological resources or wild populations at a rate faster than they can naturally reproduce or replenish.