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Evolution and function of hidden anti-predator signals
Ziková, Magdaléna ; Exnerová, Alice (advisor) ; Pipek, Pavel (referee)
Hidden anti-predator signals (HAS) are hidden colour patterns in an otherwise cryptic prey; they are revealed upon encountering a predator. HAS include deimatic signals (DS) and flash signals (FS). DS are used when at risk of predation, typically after being discovered by a predator. Their position in the predation sequence (PS) differs by species. DS are often linked with deimatic behaviour, that boosts their efficiency. The use of DS in later stages of the PS occurs more often in defended prey, which may thus speed up predators' avoidance learning. In undefended prey, DS may trigger startle or fear responses, confusion or sensory overload in the predator, thereby pausing or stopping the attack. FS are exposed during the prey's escape, usually early in the PS before a predator detects the prey. This can cause a predator to form a wrong impression of the prey's appearance, making it harder to find. FS can also attract the predator's attention during pursuit, thus decreasing its chance of noticing an evasive manoeuvre. Dynamic FS, in which different colours alternate during movement, can make it hard to estimate the prey's position. The presence of both types of HAS is often linked with prey body size. The efficiency of FS is affected by the flight initiation distance. The efficiency of DS is related to...
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Factors influencing flight-initiation distance in reptiles and the comparison with endotherm vertebrates
Fictumová, Tereza ; Frýdlová, Petra (advisor) ; Sedláček, Ondřej (referee)
The fleeing behaviour is one of the most common antipredatory strategy. It is intensively studied in many groups of animals. The flight-initiation distance (FID) is used for quantification of fleeing behaviour. The FID represents the distance between a prey and an approaching predator in which the prey starts fleeing. The FID is also used for quantifying of preys fear. The factors influencing FID in reptiles are: temperature, habitat, refuge availability, foraging strategies, predator behaviour etc. I discovered some factors which are different for mammals and birds. The most important difference is the ectothermy in reptiles vs. the endothermy in mammals and birds. Another difference is parental care, alarm calls and grouping. The factors as an influence of predator, refuge availability or type of habitat seems to have very similar or the same impact on FID for both groups.
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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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Investment in reproduction and nest defense in waterfowl
Javůrková, Veronika ; Albrecht, Tomáš (advisor) ; Remeš, Vladimír (referee) ; Weidinger, Karel (referee)
Investment in reproduction is considered to be crucial component of life history traits. Reproductive success is however constrained by generally unpredictable environmental conditions. Based on "bet hedging" theory, individuals are forced to eliminate such unpredictability via the mixed strategy to maximize their long-term fitness. Predation represents underlying factor affecting individual reproductive success, and it undoubtedly lies behind the evolution of alternative reproductive strategies such as extra-pair paternity and conspecific brood parasitism. Behavioral mechanisms related to nest defense are thought to be investment in reproduction in accordance with trade-off between actual and residual reproductive value. Despite the extensive interest in the principles associated with parental investment into the nest defense, studies describing in detail the pattern of particular antipredator strategies are rare. Similarly, mechanisms responsible for maintenance of egg- viability during prolonged egg-laying period in species delayed the onset of incubation are poorly understood. In accordance with mentioned themes, this thesis includes publications aimed at aspects of reproductive biology and antipredator behavior in Mallards (Anas platyrhynchos). Particular publications concretely documented: a)...
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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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Factors influencing flight-initiation distance in reptiles and the comparison with endotherm vertebrates
Fictumová, Tereza ; Frýdlová, Petra (advisor) ; Sedláček, Ondřej (referee)
The fleeing behaviour is one of the most common antipredatory strategy. It is intensively studied in many groups of animals. The flight-initiation distance (FID) is used for quantification of fleeing behaviour. The FID represents the distance between a prey and an approaching predator in which the prey starts fleeing. The FID is also used for quantifying of preys fear. The factors influencing FID in reptiles are: temperature, habitat, refuge availability, foraging strategies, predator behaviour etc. I discovered some factors which are different for mammals and birds. The most important difference is the ectothermy in reptiles vs. the endothermy in mammals and birds. Another difference is parental care, alarm calls and grouping. The factors as an influence of predator, refuge availability or type of habitat seems to have very similar or the same impact on FID for both groups.
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Trade-off in antipredatory strategies of reptiles
Staňková, Jana ; Frynta, Daniel (advisor) ; Kodym, Petr (referee)
Antipredatory strategies determine to some extent a succes of a prey to survive a predator's attack. Many species developed dozens of antipredatory strategies during an evolution. A certain animal must select one of the strategies to use under certain conditions. This selection depends on many factors and also on the prey's willingness to risk in trade-off with the predatory risk. There is a plenty of strategy types and theories that deal with those. These theories also investigate a trade-off concept which the prey must take into account during the attack. Foods abundance, temperature, daytime, prey's age and condition, fitness and many others interfere the decision of which antipredatory strategy is the most convenient at the time. My thesis deals with the use of a trade-off concept in reptilia's antipredatory strategies. Because this order is very varied and many information is available, I focused on the Sauria class.
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Investment in reproduction and nest defense in waterfowl
Javůrková, Veronika ; Albrecht, Tomáš (advisor) ; Remeš, Vladimír (referee) ; Weidinger, Karel (referee)
Investment in reproduction is considered to be crucial component of life history traits. Reproductive success is however constrained by generally unpredictable environmental conditions. Based on "bet hedging" theory, individuals are forced to eliminate such unpredictability via the mixed strategy to maximize their long-term fitness. Predation represents underlying factor affecting individual reproductive success, and it undoubtedly lies behind the evolution of alternative reproductive strategies such as extra-pair paternity and conspecific brood parasitism. Behavioral mechanisms related to nest defense are thought to be investment in reproduction in accordance with trade-off between actual and residual reproductive value. Despite the extensive interest in the principles associated with parental investment into the nest defense, studies describing in detail the pattern of particular antipredator strategies are rare. Similarly, mechanisms responsible for maintenance of egg- viability during prolonged egg-laying period in species delayed the onset of incubation are poorly understood. In accordance with mentioned themes, this thesis includes publications aimed at aspects of reproductive biology and antipredator behavior in Mallards (Anas platyrhynchos). Particular publications concretely documented: a)...
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