| MPD | main pancreatic duct; maximum permissible dose; mean population doubling; membrane potential differe... |
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| PDL | pancreatic duct ligation; periodontal ligament; poorly differentiated lymphocyte; population doublin... |
| PDT | photodynamic therapy; population doubling time |
| Pop | popliteal; population |
| POPLINE | Population Information Online |
| selection coefficient | The proportion of progeny or potential progeny not surviving to sexual maturity; usually defined artificially by expressing the fitness of a phenotype as a fraction of the mean or optimal fitness to give the relative fitness, and subtracting this fraction from unity. If the mean size of family in the population is 3.2 and that for a particular genotype is 2.4 then the fitness of the phenotype is 2.4/3.2 =0.75 and the selection coefficient =1-0.75 =.25 = 5 (05 Mar 2000) |
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| selection cutting | The periodic removal at short intervals of the oldest and largest trees in the stand, individually or in small groups. (05 Dec 1998) |
| selection (genetics) | Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population. (12 Dec 1998) |
| selection pressure | Impact of effective reproduction due to environmental impact on the phenotype. (05 Mar 2000) |
| sexual selection | A form of natural selection in which, according to Darwin's theory, the male or female is attracted by certain characteristics, form, colour, behaviour, etc., in the opposite sex; thus modifications of a special nature are brought about in the species. (05 Mar 2000) |
| natural selection | The hypothesis that genotype environment interactions occurring at the phenotypic level lead to differential reproductive success of individuals and hence to modification of the gene pool of a population. (18 Nov 1997) |
| suburban population | The inhabitants of peripheral or adjacent areas of a city or town. (12 Dec 1998) |
| synchronous cell population | <cell culture> A culture of cells that all divide in synchrony. Particularly useful for certain studies of the cell cycle, cells can be made synchronous by depriving them of essential molecules, which are then restored. Synchronisation breaks down after a few cycles, however, as individual cells have unique division rates. (19 Jan 1998) |
| q in population genetics | The frequency of the less common of two different alternative (allelic) versions of a gene. (the frequency of the more common allele is p). (12 Dec 1998) |
| insurance selection bias | Adverse of favourable selection bias exhibited by insurers or enrollees resulting in disproportionate enrollment of certain groups of people. (12 Dec 1998) |
| topotypical population | <zoology> Population occurring at the type locality from which the type specimen was taken. (09 Jan 1998) |
| urban population | The inhabitants of a city or town, including metropolitan areas and suburban areas. (12 Dec 1998) |
| k selection | <zoology> In evolution, the selection of traits that aid an organisms competitive capability when the population is at or near its carrying capacity. (21 Mar 1998) |