Reflexive Selection: A Possible Answer to an Old Puzzle

Abstract

With the color vision and learning abilities of birds and teleosts now proved, it appears possible that the hitherto puzzling massive variation in color and pattern of certain species, distributed through at least five phyla, is not the result of the mere free play of mutation but represents a protective variation and is the product of what may be called reflexive selection.

Visual predators select for crypticity and polymorphism in virtual prey

“…It would be surprising, however, if we had obtained discontinuous phenotypic variation in the absence of significant background heterogeneity 35 . Instances of similarly phenotypically diverse, or "massively polymorphic", cryptic species are by no means uncommon in the literature, having been recorded in brittle-stars, 40 bivalves, 4 grasshoppers, 41 fish, 35,38 and noctuid moths. [8][9][10] One feature that these disparate organisms have in common is high levels of local abundance, which ensures that predators will experience short time delays between successive encounters with the species.…”

Population Structure, Frequency-Dependent Selection, and the Maintenance of Sexual Reproduction

“…If we accept that evolutionary divergence is the rule in nature, we may expect even larger values of c. Second, the chance that any individual is detected and successfully attacked by predators or parasites may depend on its phenotypic and genotypic similarity to its neighbors or parents (e.g., Trenbath, 1975;Jaenike, 1978;Glesener, 1979;Rice, unpubl.). For example, actively hunting predators may become expecially proficient at finding and handling common prey items (see Moment, 1962;Clarke, 1962Clarke, , 1969Murdoch, 1969;Murton, 1971;Manly et al, 1972;Lawton et al, 1974;Murdoch and Oaten, 1975;Allen, 1976). Sedentary predators or parasites also may become especially proficient at circumventing common chemical or mechanical defenses of hosts on which they spend large parts of their lives, which can lead to frequency-dependent attack (see Ehrlich and Raven, 1965;Dolinger et al, 1973;Feeny, 1975;Pimentel and Bellotti, 1976;Edmund?…”

Does colour polymorphism enhance survival of prey populations?

“…Several authors have suggested that the coexistence within a population of two or more discrete phenotypic colour variants or morphs may contribute to reduced predation pressure and enhanced survival in polymorphic prey populations (Poulton 1890;Clarke 1962;Moment 1962;Croze 1970;Allen 1988;Knill & Allen 1995;Glanville & Allen 1997). Such a protective function of colour polymorphism, it has been argued, may arise if predators are conservative in their search and choice of prey, display perceptual switching and feed disproportionally for prey similar to well-known items (Allen 1984;Marples et al 1998;Bond & Kamil 1999;Thomas et al 2003), search for one type of prey at a time (Croze 1970;Allen 1988;Bond & Kamil 1998), or if predators that exploit polymorphic populations perceive prey densities as lower than they actually are (Croze 1970).…”