UNIT 2 APES

Biodiversity

The variety of life on Earth at all levels—genetic, species, and ecosystem diversity; increases ecosystem stability and resilience.

Genetic Diversity

The variety of genes within a population that allows adaptation to changing environments.

Population Bottleneck

A drastic reduction in population size that reduces genetic diversity and increases extinction risk.

Species Diversity

The number of species and their relative abundance in an ecosystem.

Habitat Diversity

The variety of habitats or ecosystems within a region; more habitats support more species.

Specialists

Species with narrow ecological niches; efficient in stable environments but vulnerable to change.

Generalists

Species with broad niches that can use many resources and tolerate a wide range of conditions; thrive in changing environments.

Ecosystem Diversity

The variety of ecosystems (forests, wetlands, deserts, etc.) within a region.

Species Richness

The total number of different species in an ecosystem.

Species Evenness

How evenly individuals are distributed among species in an ecosystem.

Ecosystem Services

Benefits humans gain from ecosystems—provisioning, regulating, cultural, and supporting.

Provisioning Services

Products obtained from ecosystems such as food, water, timber, and medicine.

Aquaculture

The farming of fish, shellfish, and aquatic plants for food and resources.

Island Biogeography

The study of species distribution on islands balancing immigration and extinction rates based on island size and distance.

Species–Area Curve

A graph showing that larger areas generally support more species due to more niches and resources.

Ecological Tolerance (Fundamental Niche)

The full range of environmental conditions a species can survive and reproduce in without competition.

Realized Niche

The actual conditions a species occupies when competition and biotic factors are present.

Geographic Range

The area where a species is naturally found; limited by climate, habitat, and competition.

Mass Extinction

A global event where many species go extinct in a short time due to rapid environmental change.

Periodic Disruption

Regular, predictable disturbances like seasonal floods or migrations.

Episodic Disruption

Occasional events such as hurricanes or volcanic eruptions that disturb ecosystems.

Random Disruption

Unpredictable events such as wildfires or landslides that suddenly alter ecosystems.

Resistance

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

Resilience

An ecosystem’s ability to recover after a disturbance.

Intermediate Disturbance Hypothesis

Biodiversity is highest at moderate levels of disturbance—not too rare and not too frequent.

Evolution

Change in the genetic makeup of a population over time.

Microevolution

Small-scale genetic changes within a species across generations.

Macroevolution

Large-scale changes that result in new species or groups over long time periods.

Evolution by Artificial Selection

When humans breed organisms for desired traits (e.g., dogs, crops).

Evolution by Natural Selection

Process where individuals with beneficial traits survive and reproduce more, passing on those traits.

Fitness

An organism’s ability to survive and reproduce successfully in its environment.

Adaptation

A heritable trait that improves survival and reproductive success.

Evolution by Random Processes

Genetic change caused by chance events like mutation, drift, or bottlenecks.

Allopatric Speciation

New species form when populations are geographically separated.

Sympatric Speciation

New species form within the same geographic area due to genetic or behavioral isolation.

Genetically Modified Organism (GMO)

An organism whose DNA has been artificially altered to express desired traits.

Ecological Succession

The gradual process of ecosystem change and development over time.

Primary Succession

Succession beginning on bare rock or newly formed land with no soil (e.g., after lava flow).

Pioneer Species

First organisms to colonize bare areas, such as lichens or mosses, that help form soil.

Secondary Succession

Succession in areas where soil remains after disturbance (e.g., after fire or farming).

Climax Community

A stable, mature ecosystem that forms once succession slows and species composition stabilizes.

Keystone Species

A species with a disproportionately large effect on its ecosystem; its removal destabilizes the community.

Indicator Species

Species that signal ecosystem health or pollution due to their sensitivity to environmental changes.

Endemic Species

Species found only in one geographic area; often highly vulnerable to extinction.

Biodiversity Hotspots

Regions with exceptionally high biodiversity and high levels of threat from human activities.

Endangered Species

Species at serious risk of extinction due to habitat loss, small populations, or overexploitation.

Lacey Act

1900 U.S. law prohibiting trade of illegally captured or transported wildlife.

Marine Mammal Protection Act

1972 law protecting marine mammals from hunting, harassment, and capture.

CITES (Convention on International Trade in Endangered Species)

1975 international treaty that regulates trade of endangered species and their parts.

Population Growth Rate

The rate at which a population changes in size over time based on births, deaths, immigration, and emigration.

Biotic Potential

The maximum reproductive capacity of a population under ideal conditions.

K-selected Species

Large-bodied species with few offspring, high parental care, and stable populations near carrying capacity.

Carrying Capacity (K)

The maximum number of individuals an environment can sustainably support.

r-selected Species

Small species with many offspring, little parental care, and rapid growth in unstable environments.

Survivorship Curve

A graph showing the proportion of individuals surviving at each age in a population.

Type I Survivorship Curve

High survival in early and middle life; mortality increases at old age (humans, elephants).

Type II Survivorship Curve

Constant death rate throughout life (birds, rodents).

Type III Survivorship Curve

High mortality early in life with few surviving to adulthood (fish, insects).