apes test 2

Ecological tolerance

The range of environmental (abiotic) conditions within which a species can survive, grow, and successfully reproduce.

Abiotic factors

Nonliving environmental conditions (e.g., temperature, pH, salinity, water availability, dissolved oxygen) that affect organisms.

Niche

A species’ role in an ecosystem, including the resources it uses and the environmental conditions it requires.

Limiting factor

An environmental variable that, when too low or too high, restricts the growth, abundance, or distribution of an organism or population.

Shelford’s Law of Tolerance

Principle that a species’ presence, abundance, and success depend on whether environmental conditions remain within its tolerance limits.

Tolerance range

The full span of conditions (for a specific abiotic factor) under which a species can persist by surviving and reproducing.

Tolerance curve

A graph showing species performance across a gradient of an environmental factor (x-axis = condition; y-axis = performance such as growth or reproduction).

Zone of intolerance

Part of a tolerance curve where conditions are too extreme for long-term survival or reproduction.

Zone of physiological stress

Range where a species can survive but with reduced growth and reproduction because energy is diverted to maintenance.

Optimal range (optimum)

The conditions under which a species performs best (highest growth, reproduction, and/or population density).

Generalist species

Species with broad tolerance and flexible resource/habitat use; often better able to persist under environmental change.

Specialist species

Species with narrow tolerance and/or specific habitat/resource requirements; often more vulnerable to disturbance or rapid change.

Dissolved oxygen (DO)

Oxygen gas available in water; a key limiting factor for many aquatic organisms, especially when water warms.

Thermal pollution

Human-caused warming of a water body (e.g., power plant discharge) that can reduce dissolved oxygen and stress aquatic life.

Estuary

Coastal ecosystem where freshwater mixes with seawater; salinity often fluctuates with tides and rainfall.

Osmoregulation

Physiological process of regulating internal water and salt balance; important for organisms living in changing salinity (e.g., estuaries).

Adaptation

An inherited trait that increases an organism’s survival and reproductive success in a particular environment.

Acclimation (acclimatization)

A short-term, non-inherited adjustment by an individual organism in response to environmental change.

Natural selection

Process where heritable traits that improve survival and reproduction become more common in a population over generations.

Structural (morphological) adaptation

A physical body feature that improves survival/reproduction in an environment (e.g., spines, thick fur, blubber).

Physiological adaptation

An internal functional trait that improves survival/reproduction (e.g., concentrated urine, salt regulation, CAM photosynthesis).

Behavioral adaptation

An action pattern that increases survival/reproduction (e.g., nocturnal activity, migration, burrowing).

Trade-off

A cost associated with an adaptation: improving performance in one context can reduce performance in another.

CAM photosynthesis

Plant pathway where stomata open at night to reduce water loss while still allowing carbon uptake; beneficial in hot, dry environments.

Mycorrhizae

Mutualistic association between plant roots and fungi that increases nutrient uptake, especially in nutrient-poor soils.

Natural disruption (natural disturbance)

A naturally occurring event that alters an ecosystem’s structure and function by changing resource availability, physical conditions, or species interactions.

Disturbance regime

The characteristic pattern of disturbance in an ecosystem, described by features like frequency, intensity, duration, and spatial scale.

Frequency (of a disturbance)

How often a disturbance occurs (e.g., seasonal flooding vs. rare major hurricanes).

Intensity (severity)

How strongly a disturbance changes conditions or removes biomass (e.g., low-intensity ground fire vs. high-intensity crown fire).

Duration (of a disturbance)

How long a disturbance lasts (e.g., a short storm vs. a multi-year drought).

Spatial scale

The area over which a disturbance affects an ecosystem (e.g., a small landslide vs. a regional drought).

Resistance (ecosystem response)

How much an ecosystem changes when disturbed; high resistance means relatively little change in structure or function after the event.

Resilience (ecosystem response)

How quickly an ecosystem returns to its previous state (or a stable functioning state) after a disturbance.

Biodiversity

The variety of life in an ecosystem; can increase resilience by providing backup species, genetic diversity, and buffering through complex food webs.

Functional redundancy

When multiple species perform similar ecological roles, so ecosystem processes can continue if one species declines.

Wildfire

A natural (and sometimes human-ignited) disturbance that rapidly oxidizes biomass and releases heat, gases, and ash.

Crown fire

A high-intensity fire that burns through the forest canopy, typically removing more biomass than a low-intensity ground fire.

Nitrogen volatilization

Loss of nitrogen to the atmosphere during intense fires, which can reduce soil nitrogen availability.

Water-repellent (hydrophobic) soil layer

A soil condition that can form after severe fires, reducing infiltration and increasing runoff and erosion.

Storm surge

Coastal flooding pushed inland by severe storms, which can drive saltwater into freshwater wetlands and stress salt-intolerant plants.

Defoliation and treefall

Storm impacts that remove leaves and knock down trees, increasing light on the forest floor and restructuring habitat.

Flooding

A disturbance that redistributes water, sediment, and nutrients, reshaping floodplains and river channels.

Waterlogging (oxygen-poor soils)

Soil conditions caused by flooding where low oxygen stresses plants that need well-aerated roots.

Drought

A prolonged period of below-average precipitation that reduces water availability and can weaken ecosystems.

Heat wave

A period of unusually high temperatures that can intensify drought stress by increasing evaporation and plant transpiration.

Ecological succession

A predictable (but not perfectly linear) process where species composition and community structure change over time after a disturbance as conditions like soil, light, and nutrients shift.

Primary succession

Succession that begins where there is little or no soil (e.g., new volcanic rock or land exposed by retreating glaciers); typically slow because soil must form.

Secondary succession

Succession after a disturbance that leaves soil intact (e.g., fire, hurricane, flood, abandoned farmland); usually faster because seeds, roots, and microbes remain.

Pioneer species

The first organisms to establish in harsh conditions (often lichens and mosses on bare rock) that help start soil formation and community development.

Intermediate disturbance hypothesis

The idea that biodiversity may be highest at intermediate levels of disturbance: too little allows competitive exclusion, too much prevents many species from establishing.

Biodiversity

The variety of life in an area, including variation at multiple biological scales (genetic, species, and ecosystem levels).

Genetic diversity

The variety of genes within a species, including differences among individuals and populations; influences a species’ ability to adapt and persist.

Species diversity

The variety of species in a community, often described using species richness and species evenness.

Species richness

The number of different species present in a community.

Species evenness

How evenly individuals are distributed among the species in a community; low evenness means one/few species dominate.

Keystone species

A species with a disproportionately large effect on ecosystem structure relative to its abundance; removing it can trigger major community changes.

Foundation species

A species that creates or defines a habitat (e.g., kelp in kelp forests, corals in coral reefs); loss can collapse habitat structure.

Ecosystem services

The benefits people obtain from ecosystems; highlights human dependence on ecological processes and functioning ecosystems.

Provisioning services

Ecosystem services that provide physical products, such as food, timber, fresh water, and medicines.

Regulating services

Ecosystem services that regulate ecosystem processes, such as climate regulation (carbon storage), flood control, water purification, and disease regulation.

Cultural services

Nonmaterial ecosystem benefits, such as recreation, tourism, spiritual value, aesthetic value, and education.

Supporting services

Underlying ecological processes that make other services possible, such as nutrient cycling, soil formation, primary production, and habitat provision.

Functional redundancy

When multiple species perform similar ecological roles, so if one declines others can partially compensate, increasing resilience of ecosystem services.

Complementarity

When different species specialize under different conditions (e.g., root depths, flowering times, stress tolerance), stabilizing ecosystem processes across seasons and disturbances.

Island biogeography

A framework predicting species richness on an “island” based on immigration and extinction dynamics, leading to an equilibrium richness.

Habitat island

A patch of suitable habitat surrounded by unsuitable habitat (e.g., a forest fragment in farmland), functionally similar to a true island for many species.

Immigration rate

The rate at which new species colonize an island/fragment; generally decreases as more species are already present.

Extinction rate

The rate at which species already present on an island/fragment disappear; generally increases as more species are present (more competition, smaller populations).

Equilibrium number of species

The balance point in island biogeography where immigration and extinction rates are equal; species composition can still change via turnover.

Species–area relationship (S = cA^z)

A pattern/model showing that larger areas tend to contain more species (S increases with area A), typically not in a linear way due to the exponent z.

Habitat fragmentation

The breaking of a large, continuous habitat into smaller patches, increasing isolation and edges and often raising extinction risk while lowering immigration/gene flow.

Edge effect

Changes in community structure and conditions near habitat boundaries (e.g., more light/wind, altered soil moisture, more invasives/predation), reducing effective interior habitat.

Distance effect

In island biogeography, islands closer to the mainland/source pool have higher immigration rates than far islands due to fewer dispersal barriers.

Size effect

In island biogeography, larger islands tend to have lower extinction rates (larger populations, more habitat types/niches) than small islands.

Wildlife corridor

A connected strip of habitat linking isolated patches, increasing immigration/recolonization and gene flow, though it can also aid spread of disease, invasives, or predators.