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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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Association between melanin ornaments and behavioural traits
Kahounová, Hana ; Frynta, Daniel (advisor) ; Okrouhlik, Jan (referee)
The work summarizes current knowledge about the melanin-based color polymorphism of integument and its relation to other phenotypic traits in vertebrates. The melanin coloration is the most common type of integument pigment coloration. The biochemical pathway for melanin pigment production can be affected by both genes and environment, which results in coloration polymorphism on intraspecific and interspecific level. The melanocortin system is regulated by genes with pleiotropic activity. Through this pleiotropy the melanin coloration is linked with a number of physiological, morphological and behavioral traits. The work describes the mechanisms of color polymorphism development and the adaptive functions of polymorphism (energy homeostasis, thermoregulation, immune response, resistance to stress and parasites, crypsis). It compares the differences between dark- and lightcolored individuals at intraspecific level: variability in phenotype and in behavior (dark color is generally associated with greater aggression, dominance, sexual activity or exploration rate). Many studies suggest the advantageousness of the dark melanin coloration. So the question remains, why the majority of vertebrates is rather lightcolor. Keywords: melanin , pheomelanin, eumelanin, Melanocortin 1 receptor, MC1R , Agouti...
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Final report on the project: Diapause in the spruce bark beetle, Ips typographus, possible way to increase the effectiveness of protective measures
Doležal, Petr ; Davídková, M. ; Okrouhlík, Jan ; Bartošová, E. ; Štefková, Kristýna
The project broadens our knowledge on ecophysiology of the spruce bark beetle, mainly in relation to practical application of the results. As a main practical result of the project, several alterations that improved the effectiveness of currently applied protective measures have been proposed, tested and accepted by the headquarters of the Forests of the Czech Republic, state enterprises.
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Mammalian energetic savings in subterranean environment. The case of African mole-rats.
OKROUHLÍK, Jan
Mole-rats are placental mammals which are perfectly adapted to subterranean life. In this thesis I present novel findings on working metabolism and thermoregulatory physiology of mole-rats. These animals cope with low availability of food and have thus employed multiple strategies how to conserve energy and/or use it more effectively. Among other adaptations this resulted in lower resting body temperature, tolerance to increase in body temperature during exercise or while at rest, surprisingly efficient cooling while digging and precise diurnal and seasonal timing of activity with regards to environmental conditions. My focus in this work is on the digging metabolic rate and thermoregulation of social Fukomys mechowii and solitary Heliophobius argenteocinereus in soft and hard substrate, thermoregulatory abilities of Fukomys darlingi, seasonal changes of activity in free living Heliophobius argenteocinereus measured as daily energy expenditure and, finally, energetic consequences of the daily activity patterns of Fukomys anselli.
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