Apostatic selection

It describes the survival of individual prey animals that are different (through mutation) from their species in a way that makes it more likely for them to be ignored by their predators.

One is the idea of prey switching, which is another term used to look at a different aspect of the same phenomenon, as well as the concept of a search image.

Apostatic selection is important in evolution because it can sustain a stable equilibrium of morph frequencies, and hence maintains large amounts of genetic diversity in natural populations.

[6] It has also been determined that apostatic selection causes stabilization of prey polymorphisms due to the limitations of predators' behaviour.

[7] Since the common prey type is more abundant, they should be able to produce more offspring and grow exponentially, at a faster rate then those with the rare morph since they are in much smaller numbers.

This gives the rare morphs an advantage, as it takes time for the predator to learn a new search image.

[11] Apostatic selection serves as a hypothesis for the persistence of polymorphism in a population because of the variation it maintains in prey.

[12] In order for apostatic selection to occur, and for the rare morph to have an advantage, a variety of criteria need to be met.

[13] Therefore, quickly arising rare morphs are favored by apostatic selection if the predators are not able to change their behavior and search image in a short time frame.

This is based on the assumption that when the predator is learning foraging behaviour, it is going to obtain the common form of prey most frequently.

[3] Foraging behaviour is shaped by the learned preference, thus causing apostatic selection and conferring a fitness benefit on the rare prey morphs.

Though a lot of this work has been experimental and lab controlled, there are some examples of it happening in both wild specimens and in the natural habitat of the species.

[19] In all four of the passerine species that were observed, the more common morph of the artificial prey was consumed more frequently regardless of its color.

[19] This is consistent with the idea that the search image influences apostatic selection: the familiar form that has been encountered more frequently is the preferred prey.

Apostatic selection has also been studied in cichlid fish, which presents a rare polymorphism: the gold ('Midas') colour morph.

Torres-Dowall et al. (2017) discussed how apostatic selection is a plausible mechanism for the maintenance of this Midas morph.