Unit 2: Living World - Biodiversity

Comprehensive vocabulary flashcards covering levels of biodiversity, ecosystem services, island biogeography theory, ecological tolerance, natural disruptions, evolutionary adaptation, and ecological succession.

Biodiversity

The diversity of life forms within an ecosystem, measured across three fundamental levels: genetic diversity, species diversity, and ecosystem or habitat diversity.

Genetic Diversity

A measure of how different the genomes and individual genes are within a population of a given species, created by random DNA mutations and chromosome crossing over.

Species Diversity

The number of different species present in an ecosystem, combined with the relative abundance or evenness of their population sizes.

Habitat Diversity

The total number and variety of distinct habitats or ecological niches available within a given geographic area.

Species Richness

The total count of different species found within a specified ecological community or ecosystem.

Species Evenness

A measurement of how balanced or equally distributed the individual organisms in an ecosystem are among the various species present.

Generalist Species

Species capable of thriving across a broad range of abiotic and biotic environmental conditions and utilizing a wide variety of resource niches.

Specialist Species

Species adapted to a very narrow range of environmental conditions, strict habitat requirements, or a single specific food source.

Population Bottleneck

A sudden environmental disturbance that drastically reduces population size at random, leaving behind a smaller population with significantly diminished genetic diversity.

Inbreeding Depression

A condition in severely reduced populations where closely related individuals mate, increasing the expression of deleterious recessive alleles, physical deformities, and reduced fertility.

Ecosystem Resilience

The capacity of an ecosystem to recover and return to its original structure, composition, and conditions following a major environmental disturbance.

Ecosystem Resistance

The measure of an ecosystem's ability to remain fundamentally unchanged when confronted with an environmental disturbance.

Ecosystem Services

The quantifiable goods, processes, and life-supporting benefits provided directly or indirectly to human societies by intact natural ecosystems.

Anthropogenic

Originating from, caused by, or resulting from human actions or activities.

Provisioning Services

Tangible products and goods harvested directly from ecosystems for human use or economic trade, including timber, freshwater, medicinal plants, and food.

Regulating Services

Environmental benefits generated by natural ecosystem processes that moderate conditions, including climate moderation through carbon sequestration, water filtration, and flood mitigation.

Supporting Services

Fundamental ecological processes that enable all other ecosystem services to exist, including nutrient cycling, primary production, and insect pollination of crops.

Cultural Services

Non-material benefits provided by ecosystems, including revenue generated from outdoor recreation, ecotourism, aesthetic inspiration, and scientific or educational discoveries.

Theory of Island Biogeography

An ecological model establishing that species richness on an island is governed by the equilibrium between immigration rates and extinction rates, determined primarily by island size and distance from the mainland.

Species-Area Relationship

A mathematical relationship demonstrating that larger geographic areas support higher numbers of species, mathematically modeled on a logarithmic scale as $\log(S) = z\log(A) + \log(c)$.

Adaptive Radiation

The rapid evolutionary divergence of a single ancestral colonizing species into several distinct specialist species adapted to exploit different ecological niches and food resources.

Ecological Range of Tolerance

The spectrum of abiotic conditions (such as temperature, salinity, pH, sunlight, and dissolved oxygen) that an organism or population can endure before suffering impairment or death.

Optimal Range

The specific range within an organism's tolerance curve where physiological conditions allow individuals to thrive, grow, maintain normal activity, and reproduce efficiently.

Zone of Physiological Stress

The environmental range where organisms survive but experience negative sublethal effects, including reduced growth rates, reduced activity, and infertility.

Zone of Intolerance

The extreme conditions beyond an organism's range of tolerance where environmental extremes result directly in thermal shock, suffocation, desiccation, or death.

Limiting Factor

The single abiotic or biotic environmental factor that is in shortest supply, therefore acting as the primary constraint on population growth regardless of other optimal conditions.

Fundamental Niche

The full theoretical range of abiotic environmental conditions under which an organism or species can persist in the absence of biotic competition, predation, and pathogens.

Realized Niche

The actual physical and ecological space an organism occupies within an ecosystem when restricted by interspecific competition, predation, and biotic pressures.

Periodic Disruptions

Naturally occurring ecological disturbances that take place with regular, predictable timing and frequency, such as annual wet and dry seasons.

Episodic Disruptions

Naturally occurring ecological disturbances that happen occasionally and at irregular, non-cyclical intervals, such as hurricanes, severe droughts, and wildfires.

Random Disruptions

Sudden natural catastrophes that occur unpredictably with no cyclical frequency, such as volcanic eruptions, earthquakes, and asteroid impacts.

Natural Selection

The evolutionary mechanism wherein individuals possessing heritable adaptations best suited to their environment survive and produce more viable offspring, shifting population traits over generations.

Selective Pressure

An external environmental agent, stressor, or condition (such as predation, climate shifts, or disease) that removes less-adapted phenotypes from a gene pool.

Allopatric Speciation

The formation of new and distinct species occurring when populations become geographically isolated from one another by physical barriers like rivers, mountains, or tectonic rifting.

Sympatric Speciation

The evolution of reproductive isolation and new species occurring within populations sharing the same continuous geographic territory without geographic separation.

Intermediate Disturbance Hypothesis

The ecological principle postulating that local species diversity is maximized at intermediate levels of disturbance frequency and intensity, preventing dominant competitors from excluding others while avoiding widespread mortality.

Ecological Succession

The predictable, orderly series of progressive changes in species composition and community structure that an ecosystem undergoes over time following a disruption or initial formation.

Primary Succession

Ecological succession initiating on newly exposed, barren geological substrates such as cooled volcanic lava or exposed glacial bedrock completely devoid of pre-existing soil.

Secondary Succession

Ecological succession occurring in an environment where a disturbance has eliminated the vegetative community but left the pre-existing soil layers and seed bank intact.

Pioneer Species

The earliest colonizers in succession, typically characterized by wind-dispersed seeds or spores, rapid life cycles, shade intolerance, and the ability to grow in nutrient-poor or soilless conditions.

Climax Community

The historically defined late, relatively stable terminal stage of ecological succession dominated by large, slow-growing, shade-tolerant canopy trees with complex root structures.

Keystone Species

A species that exercises structural ecological control over community balance and species richness far out of proportion to its relative abundance or biomass.

Indicator Species

An organism whose physical presence, chemical accumulation, abundance, or reproductive failure signals specific underlying ecological conditions, environmental quality, or toxic pollution.

Foundation Species

A species that plays a central structural role in physically creating, modifying, and maintaining physical habitat architecture for other community organisms.

Endemic Species

A species that is geographically restricted to a single defined native habitat, island, or region and found nowhere else on Earth.