Editing Supernormal stimulus (section)

=== Manipulation by parasites ===
{{main|Behavior-altering parasite}}

In 2001, Holen et al., analyzed the evolutionary stability of hosts manipulation through exaggerated signals. Their model indicated that intensity of parasitic signals must be below a threshold to ensure acceptance from host. This threshold depends directly on the range of parasitism.<ref name="ReferenceA">Òistein HH, Glenn-Peter S, Tore S and Nils C. "Parasites and supernormal manipulation". ''Proc. R. Soc.'' Lond. B 268, 2551–2558</ref>

Supernormal stimuli can be exhibited by [[brood parasite]]s, for example, the parasitic [[cuckoo]] chick and parental care by [[Eurasian reed warbler|reed warblers]].<ref name=":33">{{Cite journal|last1=Grim|first1=T.|last2=Honza|first2=M.|date=2001-02-01|title=Does supernormal stimulus influence parental behaviour of the cuckoo's host?|journal=Behavioral Ecology and Sociobiology|volume=49|issue=4|pages=322–329|doi=10.1007/s002650000295|bibcode=2001BEcoS..49..322G |s2cid=25768229|issn=0340-5443}}</ref> Brood parasites have evolved more dramatic colors, sizes, patterns, and/or shapes that lead to the parasite being interpreted as healthier or more preferable, in contrast to neighboring offspring. Cuckoo chicks are often successful because their begging calls, the supernormal stimulus, are  representative of an entire reed warbler brood.<ref name=":33"/> Due to the host parent's evolutionary instinct, elicited by selective pressures, they will select this exaggerated form of the stimulus. These calls will cause the host parent to primarily invest energy into the parasitic chick and provide it with additional food resources.<ref name=":33"/> Studies show that the supernormal stimuli in cuckoo chicks alter the foraging behavior in parental reed warblers.<ref name=":33"/>

For them, the only evolutionary stable strategy is when the host accepts all signs of the parasite with optimal intensity, which must be below the threshold; if this is not the case, the host can use these signals to identify the parasite.<ref name="ReferenceA"/>

==== Maladaptive behavior ====
Maladaptive behaviors are shown by organisms that display a preference for supernormal stimuli over naturally occurring stimuli. This is often based on instinct to gather as many resources as possible in a resource-sparse environment.<ref name=":1">{{Cite journal|last1=Goodwin|first1=B. C.|last2=Browne|first2=M.|last3=Rockloff|first3=M.|date=2015-10-29|title=Measuring Preference for Supernormal Over Natural Rewards|journal=Evolutionary Psychology|volume=13|issue=4|pages=147470491561391|doi=10.1177/1474704915613914|issn=1474-7049|doi-access=free|pmid=37924197 |pmc=10480800}}</ref> It can also be instinctual for certain species to select the supernormal stimuli that will suggest the best energy investment of the individual, often [[parental investment]].<ref name=":33"/> The selection of the supernormal stimuli must also simultaneously outweigh the cost of the behavior in order for it to evolve. This is shown in the cuckoo chick and the effects on host reed warblers.<ref name=":33"/> These parasitic chicks exhibit irresistible begging calls toward the parental host.<ref name=":33"/> This occurs as a result of selective pressures. The reed warbler increases foraging efforts to feed the parasitic chick and its own offspring.<ref name=":33"/> As a result, this shows a maladaptive behaviour of the host reed warbler as it is investing into a chick that is not biologically related, which does not provide reproductive fitness gain.

==== Biodiversity concerns ====
The significance of supernormal stimuli and brood parasitism or in various other species susceptible to environmental manipulation, is that this can drastically reduce the population numbers of the respective species. Brood parasitism can cause host parents to ignore their own offspring or display a higher parental investment into the parasite.<ref name=":33"/> Animals that are at risk of extinction, extirpation, or vulnerability will be impacted by supernormal stimuli present in brood parasites.