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The effect of incubation temperature on cognition and brain cellular composition in geckos Paroedura picta
Polonyiová, Alexandra ; Němec, Pavel (advisor) ; Sedláček, František (referee)
The effect of incubation temperature on different morphological, physiological, cognitive and behavioral characteristics in reptiles is a well-studied topic, although the underlying mechanism leading to the differences between individuals incubated at different temperatures remains largely unknown. In this thesis I studied the effect of incubation temperature on cognitive abilities and the number of neurons and non-neuronal cells in the gecko Paroedura picta incubated at two different temperatures, 24řC and 30řC. The geckos were tested in two cognitive tasks with simulated predatory attack. 14-day-old hatchlings were tested in a Y-maze, while 6-months-old geckos were tested in an arena with shelters of different colors. After testing, the number of neurons and non- neuronal cells in several parts of the brain were estimated using the isotropic fractionator in selected individuals. Although incubation temperature did not affect the success in the cognitive task in hatchlings, it did affect the total time needed to find the shelter. This difference remained significant also in adult geckos. The number of neurons, which was used as a proxy for the information processing capacity of the brain, did not affect success in the cognitive tasks. However, absolute brain size correlated with success in the...
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Phylogeny, diversification dynamics and biogeography of Hemidactylus geckos
Janák, Vojtěch ; Šmíd, Jiří (advisor) ; Kratochvíl, Lukáš (referee)
Hemidactylus is the second-most speciose among all gekkotan genera and also accounts very well for most typical characteristics of the group, such as almost worldwide distribution and significant species diversity. Many new species have been described in recent years, doubling the over all species count. Although the amout of knowledge regarding this genus has grown significantly, there is still some confusion in the matter of clade relationships on high as well as low levels of phylogeny. This thesis aims to summarize current knowledge of phylogeny and biogeography of this genus and its subclades.
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Evaporative water loss in geckos of the genus Paroedura
Myslíková, Tereza ; Starostová, Zuzana (advisor) ; Okrouhlik, Jan (referee)
Keeping a balanced state in terms of liquids in an organism, especially evaporative water loss regulation, is essential for all terrestial animals, including reptiles. Respiratory water loss and cutaneous water loss account for the highest percentage of total water loss. For this reason, the degree of evaporative water loss in reptiles can be primarily influenced by body dimensions, metabolism intensity and morphology of body surface scales. This thesis focuses on water loss through evaporation in Madagascan Paroedura geckos. The Paroedura are suitable for this research because they represent a monophyletic genus with a strongly supported hypothesis about phylogenetic relationships. The thesis adds some facts to this theory. At the same time, individual Paroedura species differ in body dimensions and habitat preference. The aim of the thesis was to find out whether individual representatives of Paroedura differ in TEWL, to specify the characteristics of the ancestral state of TEWL in this genus and to test which morphological and physiological factors influence TEWL. Further aim was to measure cutaneous water loss. Measuring was carried out by flow- through respirometry. The results show that individual representatives of Paroedura differ remarkably in TEWL figures. The reconstruction of the...
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Influence of maternal effect on body size evolution in geckos
Kubát, Jan ; Kratochvíl, Lukáš (advisor) ; Frýdlová, Petra (referee)
In this diploma thesis has been tested potential of maternal influences on body growth at two model groups of geckos with large interspecific body size variability. The effect of egg manipulation to hatchling size was proved to be significant for hatchlings at both model species Paroedura picta and Goniurosaurus lichtenfelderi. However, in adult animals, there were no more significant body size differences caused by egg manipulation. It leads to conclusion that both species of geckos have compensatory growth and its adult size is likely to be primarily genetically determined. Key words: maternal effect, egg manipulation, body growth, allometric engeneering, Paroedura picta, Goniurosaurus lichtenfelderi
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Evolutionary and developmental aspects of dentition of squamate reptiles
Zahradníček, Oldřich ; Horáček, Ivan (advisor) ; Míšek, Ivan (referee) ; Peterková, Renata (referee)
EVOLUTIONARY AND DEVELOPMENTAL ASPECTS OF DENTITION OF SQUAMATE REPTILES Summary of the PhD. thesis Dentition and its evolutionary modifications played important roles during the radiation of reptiles. It is generally accepted that a plesiomorphic state for reptiles is represented by homodont, polyphyodont dentition with conical or cylindroconical teeth. However, in contrast to mammalian dentition which is the object of intensive research, reptilian dentition is studied only rarely. I therefore focused on developmental and evolutionary aspects of squamate dentition and used histological, immunohistochemical and in situ hybridization methods, computerised tomography, rentgenography and scanning electron microskopy. The goals of this work were as following: (a) to choose the model taxa representing squamate lineages relevant from a phylogenetic position as well as possessing dissimilar types of dental adaptations; (b) to evaluate using of these taxa as model species; (c) in these taxa describe basic odontogenic features. As a species with generalized dentition gecko Paroedura picta was chosen, the up coming reptilian model species with features also present in a wide spectrum of other lizards. I focused mainly on the developmental differences between teeth of the null and functional generations, development...
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