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macroevolution: A vague term generally used to refer to evolution on a grand scale, or over long periods of time. There is no precise scientific definition for this term, but it is often used to refer to the emergence or modification of taxa at or above the genus level. The origin or adaptive radiation of a higher taxon, such as vertebrates, could be called a macroevolutionary event.
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microevolution: Evolutionary changes on the small scale, such as changes in gene frequencies within a population.
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modern synthesis: The synthesis of the principles of natural selection and Mendelian inheritance into one comprehensive theory of evolution. Also called neo-Darwinism.
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molecular geneticists: Scientists who study genes and characters through work with the molecules that make up and interact with DNA.
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morphology: The study of the form, shape, and structure of organisms.
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mutation: A change in genetic material that results from an error in replication of DNA. Mutations can be beneficial, harmful, or neutral.
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natural selection: The differential survival and reproduction of classes of organisms that differ from one another in one or more usually heritable characteristics. Through this process, the forms of organisms in a population that are best adapted to their local environment increase in frequency relative to less well-adapted forms over a number of generations. This difference in survival and reproduction is not due to chance.
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neo-Darwinism: (1) Darwin's theory of natural selection plus Mendelian inheritance. (2) The larger body of evolutionary thought that was inspired by the unification of natural selection and Mendelism. A synonym of the modern synthesis.
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nucleus: A region of eukaryotic cells, enclosed within a membrane, containing the DNA.
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paleontologist: A scientist who studies fossils to better understand life in prehistoric times.
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paleontology: The scientific study of fossils.
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phenotype: The physical or functional characteristics of an organism, produced by the interaction of genotype and environment during growth and development.
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phylogeny: The study of ancestral relations among species, often illustrated with a "tree of life" branching diagram, which is also known as a phylogenetic tree.
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plate tectonics: The theory that the surface of the earth is made of a number of plates, which have moved throughout geological time resulting in the present-day positions of the continents. Plate tectonics explains the locations of mountain building as well as earthquakes and volcanoes. The rigid plates consist of continental and oceanic crust together with the upper mantle, which "float" on the semi-molten layer of the mantle beneath them, and move relative to each other across the earth. Six major plates (Eurasian, American, African, Pacific, Indian, and Antarctic) are recognized, together with a number of smaller ones. The plate margins coincide with zones of seismic and volcanic activity.
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population: A group of organisms, usually a group of sexual organisms that interbreed and share a gene pool.
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prokaryote: A cell without a distinct nucleus. Bacteria and some other simple organisms are prokaryotic.
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protein: A molecule made up of a sequence of amino acids. Many of the important molecules in a living thing—for example, virtually all enzyme—are proteins. |
