Evolution
adaptation
Any genetically controlled structural, physiological, or behavioral characteristic that helps an organism survive and reproduce under a given set of environmental conditions. It usually results from a beneficial mutation. See biological evolution, differential reproduction, mutation, natural selection.
adaptive radiation
Process in which numerous new species evolve to fill vacant and new ecological niches in changed environments, usually after a mass extinction. Typically, this takes millions of years.
adaptive trait
See adaptation.
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. Compare genetic engineering, natural selection.
background extinction
Normal extinction of various species as a result of changes in local environmental conditions. Compare mass depletion, mass extinction.
biological 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[[emdash]]not individuals[[emdash]]evolve. See also adaptation, differential reproduction, natural selection, theory of evolution.
chemical evolution
Formation of the earth and its early crust and atmosphere, evolution of the biological molecules necessary for life, and evolution of systems of chemical reactions needed to produce the first living cells. These processes are believed to have occurred about 1 billion years before biological evolution. Compare biological evolution.
coevolution
Evolution in which two or more species interact and exert selective pressures on each other that can lead each species to undergo various adaptations. See evolution, natural selection.
differential reproduction
Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits. See natural selection.
domesticated species
Wild species tamed or genetically altered by crossbreeding for use by humans for food (cattle, sheep, and food crops), pets (dogs and cats), or enjoyment (animals in zoos and plants in gardens). Compare wild species.
ecological niche
Total way of life or role of a species in an ecosystem. It includes all physical, chemical, and biological conditions a species needs to live and reproduce in an ecosystem. See fundamental niche, realized niche.
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[[emdash]]not individuals[[emdash]]evolve. See also adaptation, differential reproduction, natural selection, theory of evolution.
fundamental niche
The full potential range of the physical, chemical, and biological factors a species can use if there is no competition from other species. See ecological niche. Compare realized niche.
gene mutation
see mutation
gene pool
The sum total of all genes found in the individuals of the population of a particular species.
gene splicing
Insertion of an alien gene into an organism to give it a beneficial genetic trait. Compare artificial selection, natural selection.
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. Examples are flies, cockroaches, mice, rats, and human beings. Compare specialist species.
genetic adaptation
Changes in the genetic makeup of organisms of a species that allow the species to reproduce and gain a competitive advantage under changed environmental conditions. See differential reproduction, evolution, mutation, natural selection.
geographical isolation
Separation of populations of a species for long times into different areas.
invertebrates
Animals that have no backbones. Compare vertebrates.
macroevolution
Long-term, large-scale evolutionary changes among groups of species. Compare microevolution.
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. Compare background extinction, mass depletion.
microevolution
The small genetic changes a population undergoes. Compare macroevolution.
mutation
Random change in DNA molecules making up genes that can alter anatomy, physiology, or behavior in offspring. See mutagen.
natural rate of extinction
See background extinction.
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.
niche
See ecological niche.
realized niche
Parts of the fundamental niche of a species that are actually used by that species. See ecological niche, fundamental niche.
reproductive isolation
Long-term geographic separation of members of a particular sexually reproducing species.
specialist species
Species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic and other environmental conditions, or use only one type or a few types of food. Compare generalist species.
speciation
Formation of two species from one species because of divergent natural selection in response to changes in environmental conditions; usually takes thousands of years. Compare extinction.
theory of evolution
Widely accepted scientific idea that all life forms developed from earlier life forms. Although this theory conflicts with the creation stories of many religions, it is the way biologists explain how life has changed over the past 3.6[[endash]]3.8 billion years and why it is so diverse today.
vertebrates
Animals that have backbones. Compare invertebrates.
wild species
Species found in the natural environment. Compare domesticated species.
Leave a Reply
Your email address will not be published.
*
*

BACK TO TOP