In more realistic conditions, wild Alectinib in vivo birds presented with different artificial prey at varying frequencies in natural surroundings have been shown to attack the more common prey type disproportionately,

with this effect being stronger on more complex backgrounds and at low prey densities (Allen, 1972; Allen, 1976; Cooper, 1984). Similar results have been obtained from experiments with natural prey in semi-natural conditions, using fish (Murdoch, Avery & Smyth, 1975; Maskell et al., 1977; Jormalainen, Merilaita & Tuomi, 1995) and birds (Allen, 1988; Tucker, 1991). It has thus been demonstrated, in laboratory conditions, that vertebrate predators will disproportionally attack prey they encounter more frequently, and that prey switching can happen as a result of the formation of a search image. This, however, does not prove that natural polymorphisms are maintained through apostatic selection. It is necessary to test for the long-term coexistence of prey morphs and dynamics in morph frequencies over time that are consistent with the predicted effects of perceptual switching. Using a ‘virtual ecology’ approach, Bond & Kamil (1998, 2002) not only showed that apostatic selection happens, but also that it can also promote

phenotypic diversity. They created a digital MI-503 chemical structure moth population modelled on the genus Catocala with three discrete morphs in equal numbers and exposed them to predation 上海皓元医药股份有限公司 by blue jays, Cyanocitta cristata. After 50 generations, the frequencies of all three morphs reached an oscillatory equilibrium that was independent of their initial numbers, and was maintained by apostatic

selection alone. To test if apostatic selection could also promote phenotypic diversity, digital moth phenotypes were specified by genomes that were subject to mutation in each generation, starting with a monomorphic population. Experimental lineages were compared with two control lineages: one that was left to evolve by drift alone, and a second one that was under frequency-independent directional selection for crypsis. In both the experimental line and the frequency-independent control, moths developed a higher level of crypsis. However, only in the frequency-dependent line was an increase in phenotypic diversity observed. Although perceptual switching, which is proposed to occur only when prey are cryptic, is the most common mechanism used to explain apostatic selection, there is evidence for apostatic selection from experiments with predators attacking non-cryptic prey (Manly, Miller & Cook, 1972; Harvey, Jordan & Allen, 1974; Cook & Miller, 1977; Willis et al., 1980; Greenwood, Wood & Batchelor, 1981).