Biological Diversity & Ecosystem Dynamics – Core Vocabulary

Key vocabulary covering evolution evidence, selection pressures, abiotic & biotic factors, ecological relationships, adaptations, and population-sampling techniques from Biology Modules 3 & 4.

Biological Diversity (Biodiversity)

The variety and relative abundance of different species of plants, animals and micro-organisms in an ecosystem.

Ecosystem

A community of interacting organisms (biotic) and their physical (abiotic) environment.

Community

All the populations of different species that live and interact in the same habitat.

Population

A group of individuals of the same species living in a defined geographic area.

Organism

An individual living entity of a particular species.

Biogeography

The study of the geographic distribution of species, used as evidence for evolution.

Selective Breeding (Artificial Selection)

Human-mediated breeding of organisms to enhance desired traits, illustrating evolutionary principles.

Natural Selection

Process where individuals with advantageous traits survive and reproduce more successfully.

Survival of the Fittest

Phrase describing the differential survival and reproduction of organisms best suited to their environment.

Divergent Evolution

Evolution of different traits in closely related species as they adapt to varied environments.

Convergent Evolution

Independent evolution of similar traits in unrelated species occupying similar niches.

Microevolution

Small-scale genetic changes within a population over time.

Adaptation

An inherited characteristic that increases an organism’s chance of survival in a specific environment.

Structural Adaptation

A physical feature of an organism (e.g., thick fur, spines) that aids survival.

Physiological Adaptation

An internal functional process (e.g., CAM photosynthesis, venom production) that improves survival.

Behavioural Adaptation

An action or pattern of activity (e.g., migration, burrowing) that increases survival chances.

Selection Pressure

Any environmental factor that affects an organism’s ability to survive and reproduce.

Abiotic Factor

A non-living environmental component (temperature, salinity, light, pH, etc.).

Biotic Factor

A living component of the environment (predators, competitors, disease organisms, etc.).

Viscosity

Resistance of a fluid to movement; higher in water than air, influencing aquatic locomotion.

Buoyancy

The upward force in water supporting organisms against gravity.

Osmosis

Diffusion of water across a semipermeable membrane from low to high solute concentration.

Allelopathy

Chemical inhibition of one plant by another via released biomolecules.

Symbiosis

Long-term biological interaction between two different species.

Predation

An ecological interaction where one organism (predator) kills and eats another (prey).

Competition

Interaction where two organisms vie for the same limited resource.

Parasitism

Symbiosis in which one species benefits (parasite) and the other is harmed (host).

Mutualism

Symbiosis where both species benefit (e.g., bees and flowering plants).

Commensalism

Symbiosis where one species benefits and the other is unaffected (e.g., remora and shark).

Infectious Disease

Illness caused by a pathogen that can be transmitted between organisms.

Ecological Niche

The role and position a species has in its environment, including resources used and interactions.

Fundamental Niche

The full range of environmental conditions under which a species can survive and reproduce.

Realised Niche

The actual conditions under which a species exists, limited by biotic interactions.

Population Dynamics

Changes over time in population size, density and composition.

Quadrat Sampling

A square or circular frame used to estimate abundance of stationary or slow-moving organisms.

Transect

A line or strip across a habitat along which organisms are recorded to study distribution.

Capture-Mark-Recapture

A method to estimate mobile animal populations by tagging, releasing and recapturing.

Abundance

The number of individuals of a species in a given area.

Distribution

The geographic area or pattern where a species is found.

CAM Photosynthesis

Plant pathway where stomata open at night to reduce water loss; common in succulents.

Countercurrent Heat Exchange

Physiological mechanism conserving heat by transferring it between outgoing and incoming blood vessels.

Spatial Sorting

Evolutionary change where the fastest-dispersing individuals accumulate at an invasion front.

Cane Toad (Rhinella marina)

Invasive amphibian introduced to Australia; now a major biotic selection pressure on native species.

Cactoblastis Moth

Biological control agent whose larvae feed on prickly pear cactus.

Prickly Pear (Opuntia spp.)

Invasive cactus in Australia controlled successfully by the cactoblastis moth.

Milankovitch Cycles

Long-term variations in Earth’s orbit and tilt affecting global climate patterns.

Agricultural Salinity

Soil salt accumulation due to irrigation or land clearing, affecting plant growth.

Trophic Cascade

Ecological phenomenon triggered by addition/removal of a top predator, altering food-web structure.

Endoparasite

Parasite that lives inside the host’s body (e.g., tapeworm).

Ectoparasite

Parasite living on the outside of the host’s body (e.g., tick).

Xerophyte

Plant adapted to arid environments, often with water-saving features.

Sclerophyll

Hard-leaved plant adapted to dry, nutrient-poor soils (e.g., eucalypts).

Succulent

Plant with thick, fleshy tissues for water storage.

Nastic Movement

Non-directional plant movement in response to a stimulus (e.g., Venus flytrap snap).