APES Unit 2 Review

APES Unit 2 Review

Biodiversity

The variety of life in an area across three levels: genes within species, different species, and different habitats.

Genetic Diversity

Differences in DNA among individuals of the same species.

Species Diversity

The variety of different species in a community, often summarized by richness and evenness.

Habitat Diversity

The range of different habitat types in a region.

Population Bottleneck

A sudden, drastic drop in population size that reduces genetic diversity.

Founder Effect

Reduced genetic variation that occurs when a new population starts from a few individuals.

Species Richness

The number of different species present in a community

Species Evenness

How evenly individuals are distributed among the species present.

Specialists

Species with a narrow niche that require specific resources or conditions.

Generalists

Species with a broad niche that can use many resources and tolerate varied conditions.

Niche

The role and set of resources and environmental conditions a species uses to survive and reproduce.

Habitat Fragmentation

The breaking of a large, continuous habitat into smaller, isolated pieces.

Simpson’s Diversity Index

A metric that combines richness and evenness to quantify biodiversity, ranging from 0 to 1 (higher = more diverse).

Resistance

An ecosystem’s ability to remain largely unchanged during a disturbance.

Resilience

An ecosystem’s ability to recover quickly after a disturbance.

Extinction Risk

The likelihood that a species will disappear permanently.

Ecosystem Services

The benefits people obtain from natural ecosystems, including goods and life-support functions.

Provisioning Services

Material goods we get directly from nature, such as food, freshwater, timber, fiber, medicinal resources, and biofuels.

Regulating Services

Natural processes that control and stabilize environmental conditions, like climate regulation, water purification, pollination, flood and erosion control, and pest control.

Cultural Services

Non-material benefits from nature, including recreation, aesthetics, spiritual value, and education.

Supporting Services

Foundational ecosystem functions that make other services possible, such as photosynthesis, nutrient cycling, soil formation, and primary productivity.

Anthropogenic

Caused by human activities.

Carbon Sequestration

Long-term storage of carbon in plants, soils, or oceans, which reduces carbon dioxide in the atmosphere.

Primary Productivity

The rate at which plants capture solar energy and convert it into biomass.

Nutrient Cycling

The movement and reuse of elements like nitrogen and phosphorus through ecosystems.

Pollination

Transfer of pollen that enables plants to reproduce, often done by insects like bees

Water Purification

Natural filtering by wetlands, soils, and microbes that removes pollutants from water.

Deforestation

Large-scale clearing of forests.

Overfishing

Catching fish faster than populations can reproduce, leading to declines or collapses.

Climate Change

Long-term shifts in climate patterns, largely driven by rising greenhouse gases from human activities.

Island Biogeography

The study of how species arrive on islands, interact there, and how island communities change over time.

Theory of Island Biogeography

MacArthur and Wilson’s model that predicts the number of species on an island based on immigration and extinction rates, influenced by island size and distance from the mainland.

Immigration

The arrival of new species to an island from other places.

Extinction

The loss of a species from an island.

Size of the Island

How large the island is

Distance From Mainland

How far an island is from the source of colonizing species

Invasive Species

Nonnative species that spread rapidly and harm native species or ecosystem function.

Endemic

A species found only in one specific geographic area.

Speciation

The formation of new species over time, often after populations become isolated.

Habitat Islands

Isolated patches of habitat that function like islands within a different surrounding matrix.

Wildlife Corridors

Strips or pathways that connect isolated habitats and allow organisms to move between them.

Ecological Tolerance

The range of environmental conditions under which an organism or species can survive, grow, and reproduce.

Goldilocks Zone

The optimal range of conditions where organisms perform best and reproduction is highest.

Stress Zone

Conditions are survivable but not ideal, so organisms spend more energy on maintenance and less on growth and reproduction.

Intolerance Zone

Conditions are too extreme for survival

Generalist Species

Species that can use many resources and tolerate a wide range of conditions.

Specialist Species

Species with narrow habitat or resource needs that struggle when conditions change.

Thermal Pollution

Human-caused warming of natural waters, often from industrial discharges, which lowers dissolved oxygen and stresses aquatic life.

Acid Rain

Precipitation made acidic by air pollutants that lowers pH in soils and waters and harms organisms.

Food Web

A network of feeding relationships that shows how energy and matter move through an ecosystem.

Glaciation

Long periods when glaciers expand and ice sheets grow, locking up seawater and lowering global sea levels.

Continental Drift

The slow movement of Earth’s tectonic plates over geologic time, rearranging continents and oceans.

Periodic

Describes events that occur at regular, predictable intervals.

Episodic

Describes events that happen occasionally without a fixed schedule.

Random

Describes events whose timing cannot be predicted.

Migration

The movement of organisms from one area to another to find better conditions, resources, or breeding sites.

Sea Levels

The average height of the ocean relative to land, which rises when ice melts and falls when more water is stored as ice.

Estuaries

Coastal zones where freshwater from rivers mixes with ocean saltwater, creating brackish, nutrient‑rich habitats.

Milankovitch Cycles

Long-term changes in Earth’s orbit, tilt, and wobble that alter how sunlight is distributed and drive glacial cycles.

Intermediate Disturbance Hypothesis

The idea that biodiversity peaks when disturbance is neither too rare nor too frequent/intense.

Succession

The natural process of community change after a disturbance, from pioneer species to a more stable, mature community.

Disturbance

A discrete event—like a fire, flood, or storm—that disrupts ecosystem structure and resource availability.

Adaptation

A trait or behavior that increases an organism’s chance of survival and reproduction in a specific environment.

Evolution

Change in the inherited traits of a population over many generations.

Natural Selection

The process where individuals with advantageous traits survive and reproduce more, spreading those traits in the population.

Genetic Variation

Differences in DNA and traits among individuals in a population.

Selective Pressure

An environmental factor that makes some traits more beneficial than others.

Environmental Stress

Challenging conditions that reduce survival or reproduction.

Short-Term Adaptation

Immediate behavioral or physiological adjustments that help individuals cope temporarily

Reproductive Isolation

Barriers that prevent different populations from mating or producing fertile offspring.

Allopatric Speciation

New species form after a physical barrier splits a population, leading to separate evolutionary paths.

Sympatric Speciation

New species arise without a physical barrier, often due to behavioral, ecological, or timing differences.

Ecosystem Resilience

An ecosystem’s ability to resist disturbance or recover after it happens.

Ecosystem Stability

The tendency of an ecosystem to maintain consistent structure and function over time.

Die-Off

A rapid, large drop in a population’s size.

Ecological Succession

The gradual change in species makeup and ecosystem structure over time after a disturbance or initial colonization.

Climax Community

A relatively stable, late-stage community that forms under current climate and conditions after succession.

Primary Succession

Succession that begins on surfaces with no soil or life present, such as fresh lava or exposed rock.

Secondary Succession

Succession that occurs after a disturbance when soil remains, allowing faster recovery.

Pioneer Species

The first organisms to colonize a newly formed or disturbed area, often hardy and fast-growing.

Indicator Species

A species whose presence, absence, or health reveals information about environmental quality or conditions.

Flora

The plant life of a particular region or ecosystem.

Fauna

The animal life of a particular region or ecosystem.

Biomass

The total mass of living organic matter in a given area or ecosystem.

Net Productivity

The rate at which energy is stored as new biomass after subtracting energy used for respiration (often discussed as NPP for producers).

Disturbances

Events that disrupt ecosystems by altering resources or habitat, often setting succession back to earlier stages.

Soil Formation

The gradual creation of soil from rock through weathering and the buildup of organic matter.

Biome

A large regional ecosystem defined by climate, typical vegetation, and associated animal communities.