|
|
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...
|
|
|
Hormonal control of male traits in leopard gecko, Eublepharis macularius
Schořálková, Tereza ; Kratochvíl, Lukáš (advisor) ; Rehák, Ivan (referee)
It is generally believed that the presence of male traits is regulated by androgens. This thesis is designed to reveal the influence of testosterone on male traits in the leopard gecko, Eublepharis macularius. The noninvasive skin application mixture of vegetable oil and testosterone was used to manipulate the hormonal status of females and castrated males. This method has proven to be an effective alternative to the widely used hormonal implants. Manipulation was successfully validated, and there was apparent progressive increase of male sexual behavior in both groups. In females, the onset lasted much longer time, but both groups were able to perform all components of males sexual behaviour. Furthermore, I found that, contrary to widespread view, male sexual behavior persisted several weeks after reduction of testosterone levels in both manipulated groups. These results bring new evidence for temporary organization of male sexual behaviour by testosterone. Powered by TCPDF (www.tcpdf.org)
|
|
|
Territoriality in lizards
Chmelař, Jan ; Rehák, Ivan (advisor) ; Veselý, Milan (referee)
Territoriality in lizads Jan Chmelař Abstract : Territoriality is a widely discussed phenomenon occuring among all groups of vertebrates on intraspecific level. Nevertheless, lizards occupy a prominent position due to a nearly endless variability in forms of territorial behaviour on the levels of higher taxons, species, populations and individuals. Examples could be systems of social dominance hierarchy, female territoriality or interspecific territoriality. Importance of territoriality is obvious as a way of reproduction control and exclusive usage of space and resources and has a positive impact on individuals that are able to defend their territories. On the other hand, there is a higher exposure to predators and a cost in a form of depleted energy. One other thing is that it sometimes complicates efforts of conservational biologists by lowering genetic variability inside populations of endangered species. Key words: territoriality, social dominance, lizards, home range
|
|
|
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
|
|
|
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...
|
|
|
The effects of mating with multiple males on reproductive success of a female: An experimental study in leopard gecko (Eublepharis macularius)
Ševčíková, Pavlína ; Frynta, Daniel (advisor) ; Rehák, Ivan (referee)
The aim of the project was to test female advantages of promiscuous and/or polyandrous mating. Although, previous studies reported improved reproductive success of females copulating with multiple males in many model species, including Eublepharis macularius, this study failed to demonstrate such a benefit of polyandry. Traits reflecting female reproductive success, i.e. the number of produced eggs, egg mass, hatchability, hatchling mass, growth and survival were not influenced by copulation with multiple partners, but some of them were dependent on female condition. Only initial stages of juvenile growth were influenced by female identity and/or investment.
|
|
| |
|
| |
|
| |
|
| |
guest ::
RSS feed.