AP Environmental Science - Unit 2: The Living World: Biodiversity

Vocabulary practice flashcards covering AP Environmental Science Unit 2: The Living World: Biodiversity, including evolution, species diversity, ecosystem services, ecological succession, and conservation policy.

Chemical Evolution

The period of roughly 1 billion years of geochemical change that produced organic molecules, biopolymers, and early protocells in the seas prior to the emergence of true living cells.

Biological Evolution

The change in a population's genetic makeup through successive generations over approximately 3.7 billion years, leading to Earth's modern diversity of species.

Natural Selection

The process described by Charles Darwin where individuals with heritable adaptations conferring higher fitness survive and reproduce at higher rates, shifting the population's genetic makeup over generations.

Mutation

A random change in the structure or number of DNA molecules within a cell that can be inherited by offspring, serving as the raw material for genetic variability.

Genetic Diversity

The variety of genetic information and heritable traits present among individuals within a population.

Species Diversity

The variety and relative abundance of different biological species present within a community, habitat, or region.

Habitat Diversity

The variety of distinct terrestrial and aquatic habitats or ecosystems that exist across a given geographic region.

Geographic Isolation

The physical separation of populations into distinct locations, preventing interbreeding and driving divergence of gene pools toward allopatric speciation.

Bottleneck Effect

A sharp reduction in population size resulting from severe environmental stressors or catastrophic events, causing a drastic loss of genetic diversity in surviving generations.

Founder Effect

A type of genetic drift that occurs when a small group of individuals separates from a larger population to establish a new colony with allele frequencies unrepresentative of the original group.

Generalist Species

Species capable of thriving under a broad range of environmental conditions, utilizing varied food resources, and withstanding wide abiotic variations.

Specialist Species

Species adapted to a very narrow range of environmental conditions, specific habitats, or limited food sources, making them uniquely vulnerable to habitat disturbance.

Species Richness

The total count of different biological species present in a specific ecosystem or ecological community.

Species Evenness

The measure of the relative abundance and numerical equality of individuals among each species within a community.

Shannon-Wiener Diversity Index

A quantitative mathematical measure of species diversity represented by $H' = -\sum (p_i) [\ln(p_i)]$, where $s$ is total species richness and $p_i$ is the proportion of total individuals belonging to the $i^{\text{th}}$ species.

Simpson Diversity Index

A quantitative diversity metric represented by $DI = \frac{N(N - 1)}{\sum n(n - 1)}$, where $N$ is the total number of individuals collected and $n$ is the individual count of a given species.

Provisioning Services

Material goods harvested or extracted directly from ecosystems for human consumption and industry, including timber, food crops, fresh water, rubber, and medicinal plants.

Regulating Services

Ecosystem processes that maintain environmental stability, including climate regulation, atmospheric carbon sequestration, water purification, and nutrient cycling.

Supporting Services

Fundamental ecological processes that underpin all other ecosystem services, such as soil formation, primary production, pollination, and natural pest control.

Cultural Services

Non-material benefits that humans derive from natural ecosystems, including recreation, ecotourism, aesthetic inspiration, and spiritual value.

Intrinsic Value

The belief that ecosystems and species have inherent worth independent of their usefulness to human beings.

Instrumental Value

The value attributed to ecosystems and species based on the tangible goods, services, and economic benefits they provide to humans.

Island Biogeography Theory

An ecological model stating that species richness on an island is determined by island size (influencing target area and differential extinction) and distance from the mainland (governing immigration rates).

Ecological Tolerance

The spectrum of abiotic physical conditions—such as temperature, dissolved oxygen, salinity, and pH—that an organism or population can endure before suffering stress or death.

Limiting Factor

A single environmental condition or nutrient in shortest supply that restricts the growth, abundance, or geographic distribution of a population even if all other factors are optimal.

Resistance

The capacity of an ecological system to remain structurally and functionally unchanged when subjected to an external disturbance.

Resilience

The capacity and rate at which an ecosystem recovers and restores its original structure and function after experiencing an ecological disturbance.

Intermediate-Disturbance Hypothesis

The principle proposing that species diversity within an ecosystem reaches its maximum at moderate levels of disturbance frequency and intensity.

Primary Succession

The chronological establishment and development of an ecological community starting on bare rock or lifeless substrate lacking pre-existing soil.

Pioneer Species

Hardy, early-colonizing organisms—such as lichens and mosses—that can establish on barren substrates, breaking down rock and depositing organic matter to initiate soil development.

Secondary Succession

The process of ecological community re-establishment following a disturbance (such as wildfire, clear-cutting, or abandoned agriculture) where the underlying soil remains intact.

Climax Community

A relatively self-perpetuating, mature, and stable ecological community reached through succession that reflects the climate and soil of the region.

Indicator Species

A biological species whose presence, absence, health, or abundance signals distinct environmental conditions or provides early warning of ecological degradation.

Keystone Species

A species whose ecological role exerts critical, disproportionate control over the structural organization and biodiversity of its ecological community relative to its abundance.

Local Extinction

The disappearance of a species from a specific geographic range or habitat it previously inhabited, while populations continue to survive elsewhere on Earth.

Ecological Extinction

A state of population collapse where so few individuals remain that the species can no longer perform its functional ecological role within its community.

Biological Extinction

The absolute, permanent global loss of all individuals of a biological species from the Earth.

Endangered Species

A wild species with such low numbers of surviving individuals that it faces imminent risk of becoming extinct across all or most of its range.

Threatened Species

A wild species that is still abundant in its natural range but displays ongoing population declines that make it likely to become endangered soon.

HIPPO

An acronym identifying the leading anthropocentric drivers of species extinction: Habitat destruction/degradation, Invasive species, Population growth, Pollution, and Overharvesting.

Biomagnification

The progressive increase in concentration of persistent, fat-soluble toxins (such as DDT) within organisms at successively higher trophic levels of a food web.

In Situ Conservation

A wildlife preservation approach focused on protecting threatened species inside their native, wild habitats through legal reserves, law enforcement, and habitat preservation.

Ex Situ Conservation

The preservation of threatened species outside their natural habitats in controlled, captive environments such as zoological parks, aquaria, botanical gardens, and seed banks.

Biodiversity Hotspot

A biogeographic region characterized by exceptional levels of endemic plant and animal species that is experiencing acute, severe habitat destruction.

Reconciliation Ecology

The science and practice of inventing, establishing, and conserving new habitats to foster biodiversity within landscapes and ecosystems heavily dominated by human activities.

Endangered Species Act (ESA) of 1973

A far-reaching United States federal law authorizing the listing and protection of threatened and endangered species, prohibiting commercial exploitation, hunting, taking, or federal habitat disruption.

CITES (Convention on International Trade in Endangered Species)

An international treaty implemented in 1975 that regulates or bans cross-border commercial trade in specimens, parts, and derivatives of endangered and threatened wild fauna and flora.