The term “apostatic selection” (Clarke, 1962a) describes the tendency of a
predator to specialize on the most common type of a polymorphic prey,
while overlooking rarer types. Since the selective advantage of a particular
morph is inversely related to its frequency in the population, this is a special case
of frequency-dependent selection (review by Ayala & Campbell, 1974), and the
behaviour of the predator will tend to maintain a balanced polymorphism in the
prey. By concentrating on one or a small number of prey types, predators may
be able to hunt more effectively for cryptic prey. In vertebrates such behaviour
may result from the formation of a search image (Lawrence & Allen, 1983), or
simply through a preference for familiar prey