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Evolution and function of polymorphism in warningly coloured prey
Fárová, Monika ; Exnerová, Alice (advisor) ; Šulc, Michal (referee)
Polymorphism can be expected in warningly colored prey if the prey is protected from predation by nothing else but its coloration. On the contrary, in defended prey, polymorphism was only until recently considered a controversial phenomenon due to its longer and costly avoidance learning. Individual moprhs can vary in different components of warning coloration: color, pattern, melanization degree, and internal and external contrast of colour patterns. This makes it difficult for predators to learn and remember warning signals of defended prey and avoid it in the future. Predator selection pressures and mechanisms leading to polymorphism differ between defended and undefended prey. For undefended prey, it is a negative frequency-depended selection that supports rare morphs or the multiple models hypothesis for one mimetic species. For defended prey, the polymorphism can occur temporarily (i. e., be unstable) and it also can be allowed by spatial heterogeneity of morphs or, as for undefended prey, one species can mimic multiple models. Quasi-Batesian mimesis could also contribute to the existence of the polymorphism, due to mechanisms similar to those in unprotected prey. Apart from selection by predators, there are other factors, that contribute to the existence of polymorhism in prey warning...
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Evolution and function of polymorphism in warningly coloured prey
Fárová, Monika ; Exnerová, Alice (advisor) ; Šulc, Michal (referee)
Polymorphism can be expected in warningly colored prey if the prey is protected from predation by nothing else but its coloration. On the contrary, in defended prey, polymorphism was only until recently considered a controversial phenomenon due to its longer and costly avoidance learning. Individual moprhs can vary in different components of warning coloration: color, pattern, melanization degree, and internal and external contrast of colour patterns. This makes it difficult for predators to learn and remember warning signals of defended prey and avoid it in the future. Predator selection pressures and mechanisms leading to polymorphism differ between defended and undefended prey. For undefended prey, it is a negative frequency-depended selection that supports rare morphs or the multiple models hypothesis for one mimetic species. For defended prey, the polymorphism can occur temporarily (i. e., be unstable) and it also can be allowed by spatial heterogeneity of morphs or, as for undefended prey, one species can mimic multiple models. Quasi-Batesian mimesis could also contribute to the existence of the polymorphism, due to mechanisms similar to those in unprotected prey. Apart from selection by predators, there are other factors, that contribute to the existence of polymorhism in prey warning...
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Effect of chromatic component on function of antipredatory warning signals
Truhlářová, Marie ; Exnerová, Alice (advisor) ; Pipek, Pavel (referee)
Warning coloration is used by prey to signal its unprofitability to potential predators. Warning colours may have different effects on various cognitive processes of predators (innate avoidance, avoidance learning, memory and generalization). Typical colours regarded as aposematic are red, orange and yellow. Red colour is considered to be the most effective signal and has a significant effect on avoidance learning, memory and generalization. Orange also represents an effective warning signal, though it has been studied less. Yellow is effective aposematic stimulus but it has frequently been found less effective compared to red and orange. Warning functions of white, blue, violet and ultraviolet colours were studied less frequently and their role in aposematism is not yet clear. Iridescent coloration might also be an effective warning signal affecting avoidance learning, memory and generalization. In this thesis I present a summary of information with regard to different warning colours and their effect on cognitive processes of predators. Key words: aposematism, warning coloration, cognitive processes, red, orange, yellow, iridescence, avoidance learning, innate avoidance, memory, generalization
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