ABSTRACT
Beau-Geste effect, Beau-Geste hypothesis n. An animal’s ‘pretending’ to be several animals at once, e.g., a male bird’s “fooling” other birds that the density of males in his area is high with his large song repertoire, thus the other birds do not settle in the area (Immelmann and Beer 1989, 283). [named from the novel of the same name in which a unit of the French Foreign Legion used a comparable tactic]
bottleneck effect n. Genetic drift that occurs in a population that has become reduced in size, typically by a natural disaster, and results in a population that is no longer genetically representative of the original population (Lincoln et al. 1985; Campbell 1980, G-3). syn. bottlenecking (Campbell 1996, 422) cf. bottleneck; drift: genetic drift; effect: founder effect Comments: Early Humans might have witnessed the bottleneck effect when calamities decimated tribes (Campbell 1990, 443). Mirounga angustirostris (Northern Elephant Seal) witnessed this effect due to overhunting. This effect caused by the last ice age and overhunting might have caused low genetic variability in Acinonyx jubatus (Cheetahs). [after the metaphor of a population’s genes moving through the narrow neck of a bottle (Campbell 1996, 422, illustration)]
Bruce effect n. In some strains of mice: A recently impregnated female’s failure to implant embryos and rapid return to estrus after she is exposed to a male with an odor sufficiently different from that of her stud (Bruce 1960 in Dewsbury 1978, 185; Whitten and Bronson 1970 and Bronson 1971 in Wilson 1975, 154, 321; Forsyth 1985, 31). cf. infanticide, natural birth control [after Hilde Bruce]
cage effect n. The inadvertent differences in organisms in different cages of an experiment that result from different environments within the cages (or other chambers), although a researcher attempts to maintain the cages under the same conditions. Comments: Rigorous biologists control for cage effects in their experiments. The chambers (cages) include aquaria, terraria, and wire cages. “Plot effects,” which are analogous to cage effects, can occur when a researcher uses areas such as cultivated fields, indoor greenhouse areas, lakes, ponds, streams, watersheds, and woodlots. Regarding a cage effect, consider an experiment that tests the H0 that male longevity = female longevity in adult Mexican Bean
Beetles. A researcher tries to make the environment of each cage identical by putting five 1-day-old beetles of the same sex and a flower pot of five bean seedlings of the same age and variety into each of 20 cages, and using a growth chamber designed to have uniform conditions throughout. However, the cage environments will still vary due to differences among the individual plants, different beetle interactions, slight differences in climate in different parts of the growth chamber, and other possible factors. Further as beetles die, the cages will have different numbers of interacting individuals. In this experiment to control for a cage effect, a researcher uses one mean value of longevity per cage for quantitative analysis. The experiment has 20 longevity means as its data, not 100 individual longevity values which would be a data set with pseudoreplication, q.v. Another way to control for cage effect, is to place only one Beetle in a cage at the onset of an experiment.
