|
|
Relationship between egg size and incubation time in geckos (Squamata: Gekkota)
Mrskočová, Jana ; Kratochvíl, Lukáš (advisor) ; Frynta, Daniel (referee)
Previous studies of the relationship between egg size and the embryonic development time showed a positive correlation between the two variables at interspecies level, thus offering the idea that the evolution of the latter could be a limiting factor for enlarging the size of eggs during evolution. Some research into interspecies and intraspecific level of reptiles doesn't confirm this correlation. At the same time, the relationship between the development time and egg size is influenced by many factors, such as shifts in ontogenetic stages of the embryo at the time of ablation of eggs, due to temperature and humidity, the presence of embryonic diapause during embryogenesis or synchronization of hatching time, of which the authors of previous studies took no account or filtered out inaccurately. I think that most of these factors can be well controlled in intraspecific studies, but, variation in egg size within species also tends to be small, which prevents a reliable test for correlation. The solution can be to compare closely related species with high variability in the size of the eggs, in our case the geckos of the genus Paroedura and family Eublepharidae. I eliminated temperature effects by comparing the time of incubation in two equal constant temperatures. The results show that, in this...
|
|
|
Evolution of prey-catching behaviour in poikilothermic vertebrates and its relationship with predator's visual perception
Košinárová, Lucie ; Frýdlová, Petra (advisor) ; Robovská, Pavla (referee)
Both the topics of prey-catching mechanism and visual perception are closely connected, affecting each other in many complex situations. The main subjects of this thesis were amphibians and reptiles and the many effects that impact their hunting abilities. We studied their hunting patterns in a few species of frogs and the leopard gecko (Eublepharis macularius) in an arena. We did not find any universal hunting pattern for neither of those groups, moreover even the quantity of individual sequences differed among them. However, hunting in nature is often engaged in habitats that are far from the flat calm arena. Often the animals have to adapt to different conditions, for example an unsteady surface underneath them. In such conditions they need to compensate for the passive movement with their heads and eyes to stabilize the image on their retina. The ability to compensate while hunting in frogs is affecting their behaviour and the success rate of their prey-catching. Another aspect that is influencing frog's hunting efficiency are their protrusible tongues that are commonly divided into three categories: mechanical, inertial and hydrostatic. The last goal of this thesis was looking for the evolution of this trait in frog's phylogenesis and their different effects on hunting movements.
|
|
|
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...
|
|
|
Body surfaces of reptiles as projection screens of evolution
Abramjan, Andran ; Frynta, Daniel (advisor) ; Rehák, Ivan (referee) ; Šulc, Michal (referee)
The PhD thesis deals mainly with the coloration (and also scalation) of selected reptile species and explores evolutionary or ecological contexts indicated by these traits. The main topics can be roughly divided into two groups: 'antipredation signals' and 'effects of parthenogenesis'. The dominant method used in most studies is visual modelling. The work consists of the following case studies. 1) Blue-tongue skinks use their conspicuous blue tongues to threaten potential predators. We found that the tongue has a relatively high UV reflectance, a typical feature of intraspecific communication in lizards. Using visual models, we investigated how the blue tongue is perceived by the conspecifics and predators (birds of prey). In both visual models, the UV-blue tongue appears more conspicuous against the natural background than a pink tongue. In addition, in the conspecifics model, its hue partially overlaps with hues of UV-blue spots, which are sexually selected traits in various species of lizards. Thus, the UV-blue tongue seems to contribute to the effectiveness of the deimatic display and its possible role in intraspecific communication cannot be ruled out either. 2) We detected UV reflectance in non-pigmented areas of the skin in the Leopard gecko (Eublepharis macularius). These form white patches...
|
|
|
Assisted reproductive technology in reptiles
Kánská, Barbora ; Kratochvíl, Lukáš (advisor) ; Frýdlová, Petra (referee)
The thesis deals with assisted reproduction techniques in reptiles. The class of reptiles (Reptilia), as is classically described, is paraphyletic taxa. That is the reason why birds (Aves) are included for completeness of this thesis. For the sake of clarity, the term "reptiles" is used in the thesis within the meaning of traditional reptile orders (squamates, tuataras, chelonians and crocodilians), which together with birds form the monophyletic class Sauropsida. The development of assisted reproduction techniques has been mainly focused on mammals so far. However, given the numbers of endangered species of reptiles and birds, it is clear that more attention should be paid to them, as assisted reproduction techniques can represent one of the ways to prevent their extinction. This thesis deals with those methods. Semen collection and its subsequent storage represent the first step to successful artificial insemination or in vitro fertilization. Cryopreservation and following transplantation of ovarian and testicular tissues (already successful in birds) is a promising method for conservation programs in endangered animal species. Furthermore, captive animal breeding is briefly mentioned, which is not an assisted reproduction technique in the true sense of the word, but offers an example of saving...
|
|
|
Sauroleishmania: development in the vectors and hosts
Tichá, Lucie ; Volf, Petr (advisor) ; Kodym, Petr (referee)
Leishmania of subgenus Sauroleishmania are parasites of reptiles, most often lizards, and are not pathogenic for humans. Therefore, they are neglected group of pathogens and their life cycle is not well-known. They are transmitted probably by ingestion of infected vector which is usually considered as sand flies of genus Sergentomyia (Diptera: Psychodidae). Sauroleishmania are traditionally denominated in Hypopylaria and it is expected that their development is limited to sand fly hindgut. The main aim of this work is to summarize the present knowledge about Sauroleishmania life cycle and to elucidate some aspects of their development in the vector and host. In the first part of thesis we studied development of four Sauroleishmania species in various sand flies of genera Sergentomyia and Phlebotomus. Late-stage infections of Leishmania (S.) adleri and L. (S.) hoogstraali were found in six and two sand fly species, respectively. Hypopylarian infections of Leishmania (S.) adleri were found in Se. schwetzi, P. papatasi and P. sergenti, while in P. argentipes, P. orientalis and P. duboscqi this Sauroleishmania migrated anteriorly in the midgut (peripylarian development). Similar type of development was observed also in P. argentipes and P. orientalis infected by Leishmania (S.) hoogstraali. Both L....
|
|
|
Multi-component signalling in turtles and squamate reptiles
Brejcha, Jindřich ; Kleisner, Karel (advisor) ; Rehák, Ivan (referee) ; Carazo, Pau (referee)
Multicomponent signals are complex stimuli directed to receptors of only single modality. Colourful ornaments of animals are multicomponent signals. In this thesis I present results of studies on the origin of coloration in turtles and squamate reptiles together with notes on relativistic view of the functionality of animal coloration. The results show that turtle coloration, which have been studied only marginally until now, is shaped by sexual selection. It is shown that turtles share mechanisms of coloration by vertical organization of different pigment cell types together with squamate reptiles. Turtles also produce colour by organization of collagen fibres which share trait with birds and mammals. Mechanisms of body coloration differ dramatically between closely related turtle species studied even though the individual constituting components are shared among these species. On the example of polymorphic lizards, it is shown that qualitative categorical difference between groups of individuals of the same population are maintained based on quantitative changes in pigment contents regulated by ancient loci shared by different species. The turtles and reptiles are valuable source of our knowledge on the evolution of multicomponent visual signalling due to their intriguing composition of skin....
|
|
|
Analysis of trends in international trade in reptiles
BOHATÁ, Marie
International reptile trade is regulated by Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Informations about these transactions are entered into the CITES Trade Database. The aim of this thesis was to organize log entries of reptile international trade taken from this database in 1975 2014 time period and their evalution. The focus was directed at the trade volume, whether traded specimen were outsourced from the wild or from captivity, and traded forms of these specimen. For better understanding and orientation in traded volume conversion to whole organism equivalents was used.
|
|
|
Cognitive abilities in reptiles and relevant research methodology
Polonyiová, Alexandra ; Němec, Pavel (advisor) ; Landová, Eva (referee)
Reptiles are a neglected group in the study of cognitive abilities of Amniota. Due to their phylogenetic relationship with birds and mammals, knowledge about reptile brains and cognition is important to understanding their evolution in other amniote groups. In this thesis, I summarized the literature on cognitive abilities in reptiles, which focuses on spatial orientation, such as orientation based on visual cues or compass navigation, associative learning, mainly visual discrimination and operant conditioning, and social learning. It has been shown that some reptilian species are capable of flexible behaviour and, given the right methodology, can successfully solve a number of cognitive tasks. I also briefly treated the size and structure of reptile brains, providing the neural substrate for these abilities. Keywords: reptile, cognitive abilities, brain size, brain structure, spatial orientation, associative learning, social learning
|
|
|
Reptile assemblages along succession gradient in oak forests of Podyji National Park
BALOUN, Jaroslav
This thesis focuses on the effects of succession on forest clearings on reptile assemblages in Podyjí National Park. The topic and results presented here follow up my bachelor thesis evaluating habitat preference of reptiles in Podyjí National Park and their assemblages on experimental clearings in the core zone of NP Podyjí. The reptile monitoring was conducted on the clearings and nearby control habitats using a method of artifical shelters and method of transect walks. Abundance of reptile species on clearings, and effect of gradual succession on the clearings on individual reptile species was studied and evaluated. While the creation of clearings clearly benefited most termophilous reptile species, including e.g. the Green lizard (Lacerta viridis) and the Aesculapian snake (Zamenis longissimus), the effect of succession is more difficult to assess owing to rather high variation among years. Only the L. viridis significantly derceased with the course of succession, while the Slow worm (Anguis fragilis) benefited from it.
|
guest ::
