AP Environmental Science: Biodiversity, Succession, and Population Ecology

Comprehensive vocabulary flashcards reviewing key AP Environmental Science concepts from lecture assessments, covering community succession, island biogeography, tolerance curves, keystone species, and evolutionary dynamics.

Heat-Absorbing Adaptation

A physical or physiological characteristic—such as the dark coloration of a reptile—that enables an organism to absorb thermal energy from its surroundings to maintain internal body temperature.

Climax Community Assessment

The ecological method of tracking community maturity after a major disturbance (such as a volcanic eruption) by recording the specific number and types of producer species present each year until species composition stabilizes.

Theory of Island Biogeography

A model stating that species richness on an island is governed by immigration and extinction rates, which are determined by island area and distance from the mainland; larger islands closer to the mainland (e.g., $50\,km$ away with an area of $1 \times 10^6\,\text{hectares}$) maintain higher species diversity than smaller, more distant islands.

Provisioning Services

Material goods harvested or obtained directly from ecosystems for human use, such as timber, natural gas, and drinking water, which can be disrupted by anthropogenic activities such as air pollution from fossil fuel combustion.

Ecosystem Services

Natural ecological processes that supply benefits to humans and environments, exemplified by bats consuming mosquitoes (pest regulation) and mountain tropical forests controlling downstream flooding.

Secondary Succession

The sequential recolonization and growth of an ecological community in an area where vegetation has been cleared or disturbed but soil remains intact, such as a heavily deforested area of the Amazon or a forest recovering after a wildfire.

Selective Pressure

An external factor—such as the specific types and sizes of seeds or food available on Daphne Island versus Santa Cruz Island in the Galápagos archipelago—that alters the reproductive success of phenotypes, driving natural selection on genetically determined traits like beak size.

Population Bottleneck

A drastic reduction in population size due to environmental events, habitat destruction, or introduced predators (e.g., the Florida panther dropping to $100\text{ to }160$ individuals, or the Chatham Island robin declining to $5$ individuals in 1980), causing an extreme loss of genetic diversity.

Species Richness

The total number of distinct species represented within an ecological community or sample, such as finding $10$ species of benthic invertebrates during pond sampling.

Zone of Optimum

The narrow range along an environmental gradient (such as moderate water temperature) where conditions are ideal and physiological stress is minimal, allowing organisms to maintain health, grow, and successfully reproduce.

Zone of Physiological Stress

The portion of an environmental gradient where abiotic conditions deviate from optimal levels, allowing organisms to survive but causing stress that impairs fitness and limits reproductive capacity.

Zone of Intolerance

The extreme upper and lower boundaries of an environmental gradient where conditions exceed the physiological limits of an organism, resulting in zero individuals surviving.

Canopy Shading

A competitive mechanism in forest succession in which taller, late-successional tree species overtop intermediate species (such as oak trees) and establish a dense overhead canopy, blocking light from the understory.

Primary Succession

Ecological succession that begins on newly exposed or newly formed substrates lacking pre-existing soil, such as cooled volcanic lava or bare rock outcrops, where pioneer species must create soil before subsequent plant communities can establish.

Pioneer Species

The first organisms to colonize a barren or newly cleared habitat, including lichens on bare rock during primary succession or early successional trees like sweetgum under full sunlight following clear-cutting.

Keystone Species

A species that exerts disproportionate control over community structure and biodiversity relative to its abundance, such as sea otters, dung beetles, the grey wolf in Yellowstone, or the ochre starfish (Pisaster) on rocky Oregon shores.

Ecological Resilience

The speed and capacity with which an ecological community recovers and returns to its original equilibrium state following an environmental disturbance, such as northern intertidal communities returning to normal after storm waves.

Trophic Cascade

An ecological phenomenon triggered by top predators—such as the 1995 reintroduction of wolves into Yellowstone National Park, which controlled elk populations and led to reduced browsing and increased growth of riparian and upland aspen trees.

Genetic Variation (in Evolution)

The variety of alleles present in a gene pool that serves as the raw material for natural selection; when depleted by severe bottlenecks, a population lacks the variation necessary for traits to provide reproductive advantages and continue evolving.

Range of Tolerance

The entire span of physical and chemical environmental conditions (e.g., temperature and dissolved oxygen concentrations) in which an organism can stay alive, demonstrated by the Devils Hole pupfish surviving extreme cavern waters in the Mojave Desert.

Directional Selection

A mode of natural selection where environmental changes favor individuals exhibiting one phenotypic extreme over others, such as industrial pollution darkening tree trunks and shifting beetle populations toward darker coloration to avoid predator detection.

Ecosystem Engineer Refugia

Habitats created or modified by an organism that provide critical shelter for other species, such as burrows excavated by African aardvarks that reptiles, birds, and other animals rely on to escape extreme temperatures, reproduce, and avoid predators.