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adaptation

any genetically controlled structural, physiological, or behavioral characteristic that helps an organism survive and reproduce under a given set of environmental conditions.

artificial selection

process by which humans select one or more desirable genetic traits in the population of a plant or animal species and then use selective breeding to produce populations containing many individuals with the desired traits.

background extinction rate

normal extinction of various species as a result of changes in environmental conditions.

biodiversity

variety of different species (species diversity), genetic variability among individuals within each species (genetic diversity), variety of ecosystems (ecological diversity), and functions such as energy flow and matter cycling needed for the survival of species and biological communities (functional diversity).

biome

terrestrial regions inhabited by certain types of life, especially vegetation

ecological diversity

the variety of forests, deserts, grasslands, oceans, streams, lakes, and other biological communities interacting with one another and with their nonliving environment.

ecological niche

Total way of life or role of a species in an ecosystem. It includes all physical, chemical, and biological conditions that a species needs to live and reproduce in an ecosystem.

ecotone

transition area between two biomes

edge effect

the changes in population or community structures that occur at the boundary of two habitats.

endemic species

species that is found in only one area. Such species are especially vulnerable to extinction.

evolution

Change in the genetic makeup of a population of a species in successive generations. If continued long enough, it can lead to the formation of a new species. Note that populations, not individuals, evolve.

extinction

complete disappearance of species from the earth. It happens when a species cannot adapt and successfully reproduce under new environmental conditions or when a species evolves into one or more new species.

fossils

Skeletons, bones, shells, body parts, leaves, seeds, or impressions of such items that provide recognizable evidence of organisms that lived long ago.

functional diversity

biological and chemical processes of functions such as energy flow and matter cycling needed for the survival of species and biological communities.

generalist species

species with a broad ecological niche. They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions.

genetic diversity

variability in the genetic makeup among individuals within a single species.

genetic engineering

insertion of an alien gene into an organism to give it a new genetic trait.

genetic variability

diversity in the genetic makeup among individuals within a single species.

geographic isolation

physical separation of populations of the same species into different areas for long periods of time.

habitat

place or type of place where an organism or population of organisms live.

indicator species

species whose decline serves as an early warning that a community or ecosystem is being degraded.

keystone species

species that play important roles in helping to sustain many other species in an ecosystem.

mass extinction

a catastrophic, widespread, often global event in which major groups of species are become extinct over a short time compared with the normal (background) extinction rates.

native species

species that normally live and thrive in a particular ecosystem.

natural selection

Process by which a particular beneficial gene (or set of genes) is reproduced in succeeding generations more than other genes. The result of natural selection is a population that contains a greater proportion of organisms better adapted to certain environmental conditions. See adaptation, biological evolution, differential reproduction, mutation.

nonnative species

species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans.

phylogenetic tree

branching diagram showing the inferred relationships among various biological species based on similarities and differences in their physical or genetic characteristics and arising from a common ancestor.

reproductive isolation

situation where different populations of sexually reproducing species have been geographically isolated for such a long time that their genetic makeup has changed and they can no longer produce live, fertile, offspring.

background extinction rate

normal extinction of various species as a result of changes in local environmental conditions.

bioaccumulation

an increase or build

biomagnification

an increase in the concentration of a chemical in organisms at successively higher trophic levels of a food chain or food web.

biodiversity hotspot

an area especially rich in plant species that are found nowhere else and are in great danger of extinction. Such areas suffer serious ecological disruption, mostly due to rapid human population growth.

biological extinction

Complete disappearance of a species from the earth. It happens when a species cannot adapt and successfully reproduce under new environmental conditions or when a species evolves into one or more new species.

endangered species

wild species with so few individual survivors that the species could soon become extinct in all or most of its natural range.

Endangered Species Act (ESA)

law established in 1973 designed to identify and protect endangered species in the United States and abroad.

habitat fragmentation

breaking up of habitat into smaller pieces, usually as a result of human activities.

HIPPCO

acronym used by conservation biologists for the six most important secondary causes of premature extinction. Habitat destruction, degradation, and fragmentation; Invasive (nonnative) species; Population growth (too many people consuming too many resources); Pollution; Climate change; and Overexploitation.

mass extinction

a catastrophic, widespread, often global event in which major groups of species are wiped out over a short time compared with normal (background) extinctions.

threatened species

wild species that is still abundant in its natural range but is likely to become endangered because of a decline in its numbers.