| concerted evolution | The ability of two related genes to evolve together as though constituting a single locus. Synonym: coincidental evolution. (05 Mar 2000) |
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| convergent evolution | The process where two unrelated structures in unrelated organisms evolve to perform similar functions. (The structures are called analogous structures.) For example: the wings of bats, birds, and insects evolved separately from each other but all are used to perform the function of flying. For another example: the complex eyes of vertebrates, cephalopods (squid and octopus), cubozoan jellyfish, and arthropods (insects, spiders, crustaceans) evolved separately, but all perform the function of vision. (09 Oct 1997) |
| cultural evolution | The continuous developmental process of a culture from simple to complex forms and from homogeneous to heterogeneous qualities. (12 Dec 1998) |
| saltatory evolution | The theory that evolution of a new species from an older one may occur as a large jump, such as a major repatterning of chromosomes, rather than by gradual accumulation of small steps or mutations. Compare: emergent evolution. (05 Mar 2000) |
| spontaneous evolution | The unaided delivery of the foetus from a transverse lie. (05 Mar 2000) |
| Darwinian evolution | The proposition that the phylogeny of all species is wholly ascribable to the combined effects of random variation (mutation) in genotypes of the members of a stock as a result of the operation of undirected accidents with consequences to their phenotypes and the operation of preferential (but by no means certain) survival of those resulting phenotypes most suited to survive in the contemporary environment. The proposed system survives largely because of genetic factors that avidly conserve the ontogeny of the stock. (05 Mar 2000) |
| Denman's spontaneous evolution | A mechanism of spontaneous molding of the foetus and impaction of the shoulder with prolapse of the arm noted in some cases of transverse lie; vaginal delivery is achieved with the breech appearing at the vulva immediately after the prolapsed shoulder. (05 Mar 2000) |
| directed molecular evolution | Techniques used to produce molecules exhibiting properties that conform to the demands of the experimenter. (12 Dec 1998) |
| divergent evolution | The process by which a species or gene product gives rise to two or more different products. (05 Mar 2000) |
| Douglas' spontaneous evolution | A mechanism whereby molding of the foetus and impaction of the shoulder and prolapsed arm occurs in transverse lie, allowing vaginal delivery with the lateral aspect of the thorax following the prolapsed shoulder. (05 Mar 2000) |
| quantum evolution | An extremely rapid evolutionarychange in a single genetic lineage, thought to result from a sudden and radical change in the species'environment. (09 Oct 1997) |
| organic evolution | Biologic evolution was contrasted with cultural evolution in 1968 by A.G. Motulsky who pointed out that biologic evolution is mediated by genes, shows a slow rate of change, employs random variation (mutations) and selection as agents of change, new variants are often harmful, these new variants are transmitted from parents to offspring, the mode of transmission is simple, complexity is achieved by the rare formation of new genes by chromosome duplication, biologic evolution occurs with all forms of life, and the biology of humans requires cultural evolution. See Cultural evolution. (12 Dec 1998) |
| emergent evolution | Appearance of a property in a complex system e.g., organism that could have been predicted only with difficulty, or perhaps not at all, from a knowledge and understanding of the individual genotype changes taken separately. (05 Mar 2000) |
| evolution | 1. An unrolling. 2. A process of development in which an organ or organism becomes more and more complex by the differentiation of its parts, a continuous and progressive change according to certain laws and by means of resident forces. Origin: L. Evolutio (18 Nov 1997) |
| evolution, biologic | A.G. Motulsky in 1968 contrasted biologic evolution with cultural evolution, pointing out that biologic evolution is mediated by genes, shows a slow rate of change, employs random variation (mutations) and selection as agents of change, new variants are often harmful, these new variants are transmitted from parents to offspring, the mode of transmission is simple, complexity is achieved by the rare formation of new genes by chromosome duplication, biologic evolution occurs with all forms of life, and the biology of humans requires cultural evolution. See Evolution, cultural. (12 Dec 1998) |