Ch 46 Ecosystems, Ch 47 Conservation Biology and Biodiversity

Ecosystem

A community of living organisms and their interactions with their abiotic (nonliving) environment.

Resistance

The ability of an ecosystem to remain at equilibrium in spite of disturbances.

Resilience

The speed at which an ecosystem recovers equilibrium after being disturbed.

Food Chain

A linear sequence of organisms through which nutrients and energy pass.

Trophic Level

The position of a species or group of species in a food chain or a food web.

Primary Producers

Photosynthetic or chemosynthetic organisms at the bottom of the food chain that synthesize their own food.

Primary Consumers

Herbivores that consume the primary producers in an ecosystem.

Secondary Consumers

Carnivores that eat the primary consumers.

Tertiary Consumers

Carnivores that eat other carnivores.

Apex Consumers

Organisms at the top of the food chain that feed on the lower trophic levels.

Food Web

A graphic representation of a holistic, nonlinear web of primary producers, primary consumers, and higher-level consumers.

Grazing Food Web

A type of food web that has plants or other photosynthetic organisms at its base, followed by herbivores and carnivores.

Detrital Food Web

A type of food web consisting of decomposers or detritivores that feed on decaying organic matter.

Ecosystem Dynamics

The study of changes in ecosystem structure caused by environmental disturbances or internal forces.

Mesocosm

A portion of a natural ecosystem partitioned and used for controlled ecological experiments.

Microcosm

A recreation of a natural ecosystem entirely within an indoor or outdoor laboratory environment.

Conceptual Model

An ecosystem model consisting of flow charts showing interactions between living and nonliving components.

Analytical Model

An ecosystem model created using simple mathematical formulas to predict the effects of environmental disturbances.

Simulation Model

An ecosystem model created using complex computer algorithms to holistically predict the effects of environmental disturbances.

Autotrophs

Organisms capable of synthesizing their own food using inorganic carbon.

Photoautotrophs

Autotrophs (like plants and algae) that use sunlight as an energy source.

Chemoautotrophs

Autotrophs (primarily bacteria) that use inorganic molecules as an energy source.

Biomass

The total mass, in a unit area at the time of measurement, of living or previously living organisms within a trophic level.

Gross Primary Productivity

The rate at which photosynthetic primary producers incorporate energy from the sun.

Net Primary Productivity

The energy remaining in primary producers after accounting for cellular respiration and heat loss.

Trophic Level Transfer Efficiency (TLTE)

The measurement of energy transfer efficiency between two successive trophic levels.

Net Production Efficiency (NPE)

A measure of how efficiently organisms of a particular trophic level incorporate received energy into biomass.

Ecological Pyramid

A graphical representation showing the relative amounts of number of organisms, biomass, or energy across trophic levels.

Biomagnification

The increasing concentration of persistent, toxic substances in organisms at each trophic level.

Biogeochemical Cycle

The recycling of inorganic matter between living organisms and their nonliving environment.

Residence Time

A measure of the average time an individual water molecule stays in a particular reservoir.

Eutrophication

A process where nutrient runoff causes excess growth of microorganisms, depleting oxygen and killing fauna.

Dead Zone

An area within a freshwater or marine ecosystem depleted of normal flora and fauna due to oxygen depletion or toxic factors.

Biodiversity

A general term for the number of species present in the biosphere, taking into account both the number of species and their relative abundance to each other.

Adaptive Radiation

A rapid branching through speciation of a phylogenetic clade into many closely related species that "radiate" into different habitats and niches.

Extinction

The complete disappearance of a species from Earth.

Genetic Diversity

The variety of genes or genetic variation within a species or higher taxonomic category, representing the raw material for evolution and adaptation.

Chemical Diversity

The variety of metabolic compounds and proteins produced by different species, which can serve as a valuable source of pharmaceuticals for humans.

Ecosystem Diversity

The number of different ecosystems on the planet or within a given geographic area.

Endemic Species

A species that is native to and found in only one specific geographical location.

Biodiversity Hotspot

A geographical area developed by Norman Myers that contains high numbers of endemic species (at least 1500) and has had at least 70 percent of its area disturbed by human activity.

Mass Extinction

A sudden and dramatic loss of biodiversity in the fossil record where greater than half of all extant species disappear.

Ordovician-Silurian Extinction

The first recorded mass extinction in Earth's history (450-440 mya) that wiped out about 85 percent of marine species, likely caused by glaciation followed by global warming.

End-Permian Extinction

The largest mass extinction in Earth's history (251 mya), losing 96 percent of marine species and 70 percent of terrestrial species, likely due to widespread volcanic activity and runaway global warming.

End-Cretaceous Extinction

The mass extinction (65.5 mya) that eliminated the dinosaurs, caused by a cataclysmic meteorite impact off the coast of the Yucatán Peninsula marked by a worldwide iridium spike.

Pleistocene Extinction

A lesser, recent extinction event (10,000–12,000 years ago) marked by the disappearance of North American and Eurasian megafauna, heavily correlated with the arrival of paleo-humans.

Background Extinction Rate

The natural rate of macroevolutionary species loss, estimated to be about one extinction per million species per year (1 E/MSY).

Species-Area Relationship

The ecological relationship where the number of species present increases incrementally as the geographic size of the surveyed habitat area increases.

Secondary Plant Compounds

Toxins produced as metabolic byproducts by plants to protect themselves from herbivores, many of which work effectively as modern human medications (e.g., aspirin, codeine).

Ecosystem Services

Essential ecological processes resulting from diverse metabolic activities of organisms that provide direct benefits to humans, such as soil conditioning, plant pollination, and natural pest control.

Tragedy of the Commons

An economic principle stating that shared international resources held in common and left unregulated will inevitably be overexploited and depleted.

Bush Meat

A generic term used for wild animals (typically mammals, birds, and reptiles) killed for food, particularly in equatorial Africa, Asia, and the Americas.

Exotic Species

Species that have been intentionally or unintentionally introduced by humans into an ecosystem in which they did not naturally evolve; also called invasive species.

Chytridiomycosis

A devastating fungal disease of amphibians caused by Batrachochytrium dendrobatidis, thought to be a major factor in global amphibian declines.

White-Nose Syndrome

A fungal disease introduced from Europe caused by Geomyces destructans that infects and decimates cave-hibernating bats in eastern North America.

DNA Barcoding

A molecular genetic method that uses rapid sequencing of specific gene portions (like mitochondrial cytochrome c oxidase 1) to identify and catalog eukaryotic species.

Endangered Species Act (ESA)

A 1973 U.S. law requiring the U.S. Fish & Wildlife Service to develop recovery plans to protect and restore listed at-risk species and their critical habitats.

Migratory Bird Treaty Act (MBTA)

An international 1918 agreement between the U.S. and Canada making it illegal to disturb, kill, or distribute parts of listed protected bird species.

Keystone Species

A species that plays an instrumental, disproportionate role in maintaining structure and biodiversity within an ecological community; its removal can cause ecosystem collapse.