|
|
Study of the European green lizard, Lacerta viridis, and ecologically interconnected reptile species in the Czech Republic
Chmelař, Jan ; Rehák, Ivan (advisor) ; Vojar, Jiří (referee) ; Moravec, Jiří (referee)
The European green lizard, Lacerta viridis (Laurenti, 1768), is protected in the Czech Republic as critically endangered. Its distribution in the Bohemia region is restricted to small isolated local populations which are located beyond the northern border of continuous range of the species and are closely related to very specific biotopes. We analysed the distribution of the species both on a national and microhabitat scale and created a predictive model of the species distribution. The most relevant factors influencing the species distribution in the Czech Republic were: annual precipitation, terrain slope, average temperature of the warmest quarter and precipitation in the coldest quarter. On the microhabitat level, individuals selected their immediate vicinity with respect to elevated stones/tree stumps, shelter availability and a proximity to shrubs. Places with high percentage of grass and high vegetation were not preferred. Furthermore, we analysed distribution of selected reptile species ecologically interconnected with Lacerta viridis and identified their preferred habitats. We selected the dice snake, Natrix tessellata, the sand lizard, Lacerta agilis and the smooth snake, Coronella austriaca. All created models are compatible with published data and are applicable in both theory and...
|
|
|
Reproductive Strategies of Geckos: The Role of Macroevolutionary Novelties and Phenotypic Plasticity
Kubička, Lukáš ; Kratochvíl, Lukáš (advisor) ; Rehák, Ivan (referee) ; Boukal, David (referee)
Presented Ph.D. thesis contains an introduction and four chapters concerning reproductive strategies in geckos. The chapters include four peer-reviewed papers and a submitted manuscript. All geckos share rather exceptional reproductive trait known as invariant clutch size, which is characterised by low and invariable clutch size. The first chapter demonstrates that invariant clutch size probably evolved in geckos under selection for enlargement of investment per offspring. On the other hand, in anoles (a group not related to geckos possessing the same mode of reproduction) invariant clutch size allowed considerable decrease of female reproductive burden. Moreover, the interspecific allometries of egg mass and clutch mass in anoles and geckos are informative for understanding of reproductive allometries in a broader context of squamate reptiles. The second chapter is focused on a trade-off in energy investment among reproduction, growth and fat storage in a gecko Paroedura picta. Surprisingly, there seems to exist a clear hierarchical rule for allocation among particular life-history traits. Effect of temperature on reproductive rate in the same species of gecko is the subject of the third chapter. Observed thermal dependence is in contrast to the general relationship suggested under the so-called...
|
|
|
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...
|
|
|
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....
|
|
|
Sex ratios in reptiles according to the type of sex determination
Palata, Tomáš ; Kratochvíl, Lukáš (advisor) ; Rehák, Ivan (referee)
There are many factors influencing sex ratios in reptile populations and these factors can differ among sex ratios in different developmental stages. The observed ratio is the result of many complex processes. One of the key factors is the mechanism of sex determination. In reptiles we distinguish two mechanisms of sex determination. The first is genotypic sex determination (GSD), where sex is determined during the fusion of gametes. Species with GSD show just little variation in sex ratios after birth or hatching and during adulthood there is a higher mortality rate of the heterogametic sex. Secondarily, there are reptiles possesing environmental sex determination (ESD). The sex of the developing individual of this species is influenced by incubation temperature during the thermosensitive phase of development. Reptiles with ESD show much greater variability in sex ratios after hatching and this variability may persist to adulthood. This thesis focuses mainly on the differences in sex ratios between GSD and ESD species. One of its interests is also the question of vulnerability of reptiles with ESD in terms of skewed sex ratios during contemporary climate change. Key words: sex ratio, reptiles, sex determination, GSD, ESD, climate change
|
|
|
Ecology of the Dice snake (Natrix tessellata) in the Chrudimka River
Pešanová, Věra ; Rehák, Ivan (advisor) ; Moravec, Jiří (referee)
The dice snake, Natrix tassellata, is legally declared a critically endangered species in the Czech Republic. The history of the herpetologically and conservationally remarkable population on the Chrudimka River is short and fragmented in literary records - first records from the middle reaches of the Chrudimka are from the 1970s and from the lower reaches, they're only from the1990s. Until now, there was no detailed population data, only observations that tended to include mostly single specimens. This thesis therefore focuses on the size, composition and dispersal of the Chrudimka population, on obtaining relevant morphological, ecological, ethological and genetic data, and on identification of important landscape features and threatening factors as a basis for the conservation of the local population. Results from the field data collected in 2019-2021 indicate a viable population with annual reproduction. Based on estimates using a capture-recapture method, the population of the lower reaches of the river in the Pardubice region numbers 220-440 adults. The hibernation site used by the majority of the population is located in the Nemošická stráň PP, with the main hunting grounds located downstream of the weir on the Nemošice river and in the nearby oxbow lake. A smaller part of the population...
|
|
|
Evolutionary dynamics of the genus Hemidactylusekkonidae) in space and time
Janák, Vojtěch ; Šmíd, Jiří (advisor) ; Rehák, Ivan (referee)
Hemidactylus is one of the most succesful groups within the infraorder Gekkota of squamate reptiles. With more than 180 species it represents the second most species-rich gekkotan genus. In last decades it has been the subject of a rather intensive research, which provided great insight into it's phylogeny, inner structure, range, biogeography and taxonomy. The number of described species has more than doubled in the same timespan. Despite this increase of knowledge as well as it's evolutionary success, which make the Hemidactylus genus a good model for study of diversification and evolution, there has been no in depth study conducted regarding these topics. This thesis constitutes an attempt at such a study of the phylogeny and evolution of the genus, it's history, dispersal and diversification dynamics, based on more complete species sampling than has been used in any study so far.
|
|
|
ANALYSIS OF AMPNIBIAN NADITAT PREFERENCES IN THE NORTH - EAST PART OF THE TŘEBÍČ DISTRICT
Jeřábková, Lenka ; Švátora, Miroslav (advisor) ; Rehák, Ivan (referee)
8 ABSTRACT In the north-east part of the Třebíč district 108 water sites were repeatedly monitored to analyze breeding of amphibians where its 11 species were proven by this research. Bombina bombina, Bufo bufo, Bufo viridis, Hyla arborea, Pelobates fuscus were proven in line with previous studies. However, species Triturus cristatus, Triturus vulgaris, Rana temporaria, Rana dalmatina, Rana esculenta synklepton were monitored in the region for the first time ever. Distinctly high values of the species presence were reached by BufBuf (60,2 %), RanEscSyn (78,7 %) and HylArb (48,1 %). In contrast, species TriCri, TriVul, BufVir, RanArv, RanDal were found in the region with low frequency. There were found positive correlations in the proportion of littoral, natant and submerse vegetation and in the transparency of the water column and in contrast negative correlations were found in the extent of urban areas and with the number of amphibians breeding in the water site. The Redundancy analysis (RDA) helped to discover statistically significant influence of the environmental variables (proportion of littoral vegetation, transparency, water site total surface and lastly number of other water sites within the range of 500 metres) on the presence of amphibians on the water sites. Consequently, "ideal breeding sites"...
|
|
|
Ecology,ethology and variability of european green lizard Lacerta viridis in Natural reservation Tiché údolí
Chmelař, Jan ; Rehák, Ivan (advisor) ; Moravec, Jiří (referee)
The european green lizard, Lacerta viridis is a critically endangered reptile species which is in the region of Bohemia present only in relict isolated populations. These populations are closely linked to slopes with a southern exposition in deeply engorged river valleys. These valleys exhibit a unique climatic effect also known as the river phenomenon which allows numerous animal and plant species to survive far beyond their standard northern range. The chosen locality in Tiché údolí is a subject to long-term conservational management and the studied lizard population seems to reflect its effectiveness. This study is aimed to evaluate variability, ecological and ethological characteristics of lizards within the locality and is focused on changes on the population level. Key words: European green lizard, Lacerta viridis, Tiché údolí, river phenomenon, variability, ecology, ethology, population characteristics Abstrakt Ještěrka zelená, Lacerta viridis, je kriticky ohrožený druh plaza, který se na území Čech vyskytuje pouze v reliktních a izolovaných populacích. Ty jsou úzce spjaty se svahy v hluboko zaříznutých říčních údolích. Tato údolí vykazují unikátní klimatický efekt, známý též jako říční fenomén, který umožňuje výskyt četných živočišných i rostlinných druhů i za severní hranicí jejich běžného...
|
|
|
Juvenile coloration of lizards
Bauerová, Anna ; Frynta, Daniel (advisor) ; Rehák, Ivan (referee)
This work summarizes the current knowledge about the coloration of the lizards - the mechanism of colour creation, to color (pigments and structural colors) and hormonal influence on the body colour. It deals with the possible functions of the coloration (antipredator, social, thermoregulation) and its creation. Further it is an overview of the works about juvenile coloration that deal with hypotheses about the function which the juvenile coloration in lizards performs. There are also mechanisms of juvenile coloration and influencing factors mentioned. The thesis includes an experimental part dealing with various coloration characters of juvenile and adult Eublepharidae. We chose several characters: striped tail of the juveniles, striped body of the juveniles, light stripe on the head of the juveniles, striped tail of the adults, striped body of the adults, light stripe on the head of the adults. On several phylogenetic trees we evaluated whether these are the derived characters. After comparing the trees it turned out that in the case of juvenile coloration it is probably an ancestral character. In the case of adult pattern we have not reached a clear conclusion. Key words: juvenile coloration, ontogenetic color change, lizards
|
guest ::
