Alcock’s definition of adaptation

• Adaptation is a hereditary trait that either (1) spread through the population in the past and has been maintained by natural selection to the present or (2) is currently spreading relative to alternative traits because of natural selection.

"The ground rule -- or perhaps doctrine would be a better term -- is that adaptation is a special and onerous concept that should be used only where it is really necessary . . . A frequent practice is to recognize adaptation in any recognizable benefit arising from the activities of an organism. I believe that this is an insufficient basis for postulating adaptation and that is has led to some serious errors. A benefit can be the result of chance instead of design. The decision as to the purpose of a mechanism must be based on an examination of the machinery and an argument as to the appropriateness of the means to the end. It cannot be based on value judgments of actual or probable consequences." (Williams, 1966)

"The sutures in the skulls of young mammals have been advanced as a beautiful adaptation for aiding parturition, and no doubt they facilitate, or may be indispensable for this act; but as sutures occur in the skulls of young birds and reptiles, which have only to escape from a broken egg, we may infer that this structure has arisen from the laws of growth, and has been taken advantage of in the parturition of the higher animals." (Darwin, 1859, p. 197)

"Following Williams, we may designate as an adaptation any feature that promotes fitness and was built by selection for its current role (criterion of historical genesis). The operation of an adaptation is its function. . . We may also follow Williams in labeling the operation of a useful character not built by selection for its current role as an effect . . . But what is the unselected, but useful character itself to be called? . . . We suggest that such characters, evolved for other usages (or for no function at all), and later "coopted" for their current role, be called exaptations. They are fit for their current role, hence aptus, but they were not designed for it, and are therefore not ad aptus, or pushed toward fitness. They owe their fitness to features present for other reasons, and are therefore fit (aptus) by reason of (ex) their form, or ex aptus. Mammalian sutures are an exaptation for parturition. Adaptations have functions, exaptations have effects. The general, static phenomenon of being fit should be called aptation, not adaptation." (Gould and Vrba, 1982)

Figure 6.8 The logic of the comparative method

Enallagma (Odonata: Coenagrionidae)

Brown, McPeek and May. 2000. Syst. Biol. 49:697-712.

McPeek, Schrot and Brown 1996 Ecology

McPeek, Schrot and Brown 1996 Ecology

McPeek and Brown. 2000.

Ecology 81:904-920.

McPeek and Brown. 2000.

Ecology 81:904-920.

Figure 6.4 Does mobbing protect eggs?

Figure 6.5 Benefit of high nest density for the arctic skua

Figure 6.10 The dilution effect in butterfly groups

Figure 6.11 A recently hatched black-necked stilt

Figure 6.12 The dilution effect in mayflies

Figure 6.22 Personal hygiene by a skipper butterfly larva may be an antipredator adaptation

Figure 6.25 Why behave conspicuously?

Mather and Roitberg

Greene et al.

Figure 6.28 Are pushup displays an honest signal of a lizard’s physiological condition?

Figure 6.30 An optimality model

Figure 6.31 Optimal covey size for northern bobwhite quail

Figure 6.31 Optimal covey size for northern bobwhite quail (Part 3)

Figure 6.32 Selfish herds may evolve in prey species

Figure 6.33 Redshanks form selfish herds

Figure 6.34 A game theoretical model