An example of this is how a Blue tit searches for insect prey using a search image, leaving scarcer types of prey untouched. Search image shift require multiple encounters with the new form of prey, and since a rare morph is typically not encountered multiple times, especially in a row, the prey is left undetected. This gives the rare morphs an advantage, as it takes time for the predator to learn a new search image. The rare morph of a species may not fit the search image, and thus not be seen as prey. For the predator to detect something as prey, it must fit their criteria. Search image Blue tit searches for insect prey using a search image, leaving scarcer types of prey untouched.Ī search image is what an individual uses in order to detect their prey. Essentially, unless an environmental change or an evolutionary change in predator or prey occurs, a stable equilibrium is produced. However, due to the fact that the common morph is preyed upon more frequently, it diminishes their expected rate of reproduction, thus maintaining the population in stable amounts of common and rare morphs. 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. It has also been determined that apostatic selection causes stabilization of prey polymorphisms due to the limitations of predators' behaviour. Prey switching is related to prey preference as well as the abundance of the prey. Prey switching, therefore, seems to be a result of apostatic selection. This is related to apostatic selection because when a rare morph is being selected for, it is going to increase in abundance in a specific population until it becomes recognized by a predator. In prey switching, predators switch from primary prey to an alternative food source for various reasons. From a predator's view, being able to select for rare morphs actually increases the predator's own fitness. It is important to note however, that a rare morph being present in a population does not always mean that apostatic selection will occur, as the rare morph could be targeted at a higher rate. 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. Search images are relevant to apostatic selection as it is how a predator is able to detect an organism as a possible prey. 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. There are multiple concepts that are closely linked with apostatic selection. Īpostatic selection can also apply to the predator if the predator has various morphs. ![]() The behavioural basis of apostatic selection was initially neglected, but was eventually established by A.B Bond. The term "apostatic selection" was introduced in 1962 by Bryan Clarke in reference to predation on polymorphic grove snails and since then it has been used as a synonym for negative frequency-dependent selection. ![]() It has also been discussed that apostatic selection acts to stabilize prey polymorphisms. In apostatic selection, the common forms of a species are preyed on more than the rarer forms, giving the rare forms a selective advantage in the population. It operates on polymorphic species, species which have different forms. 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. Apostatic selection is a form of negative frequency-dependent selection.
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