Term
|
Definition
| 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. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| Normal extinction of various species as a result of changes in local environmental conditions. Compare mass depletion, mass extinction. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| 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. |
|
|
Term
| differential reproduction |
|
Definition
| Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits. See natural selection. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| Species that is found in only one area. Such species are especially vulnerable to extinction. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| The sum total of all genes found in the individuals of the population of a particular species. |
|
|
Term
|
Definition
| Insertion of an alien gene into an organism to give it a beneficial genetic trait. Compare artificial selection, natural selection. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| Separation of populations of a species for long times into different areas. |
|
|
Term
|
Definition
| Animals that have no backbones. Compare vertebrates. |
|
|
Term
|
Definition
| Long-term, large-scale evolutionary changes among groups of species. Compare microevolution. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| The small genetic changes a population undergoes. Compare macroevolution. |
|
|
Term
|
Definition
| Random change in DNA molecules making up genes that can alter anatomy, physiology, or behavior in offspring. See mutagen. |
|
|
Term
| natural rate of extinction |
|
Definition
| See background extinction. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| Parts of the fundamental niche of a species that are actually used by that species. See ecological niche, fundamental niche. |
|
|
Term
|
Definition
| Long-term geographic separation of members of a particular sexually reproducing species. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
| Animals that have backbones. Compare invertebrates. |
|
|
Term
|
Definition
| Species found in the natural environment. Compare domesticated species. |
|
|
