|
|
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...
|
|
| |
|
|
Mechanisms of asexual reproduction in reptiles
Augstenová, Barbora ; Kratochvíl, Lukáš (advisor) ; Abramjan, Andran (referee)
In the case of reptiles, there has been described an occurrence of an asexual reproduction, especially in the case of a group Squamata; the asexual reproduction of birds (Aves) has been observed, too. Multiple times the asexuality of reptiles has been originated. Occurrences of obligate and facultative asexual species have been described. Most obligate asexual species have theirs origin in one or more hybridization events between closely related species. However, within the family Xantusiidae two exceptions where asexuality apparently originated without hybridization were discovered. Facultative parthenogenesis was originally expected only among reptiles kept in captivity, where the females were separated from males for a long time. However, this assumption was later disproved. The majority of the specimens formed by facultative parthenogenesis has reduced viability, which can be caused by the imperfect mechanism of the formation of parthenogenetic offspring. The terminal fusion is considered to be the probable mechanism of creation of diploid oocytes in the case of facultative parthenogenesis reptiles. The cytological mechanism of the parthenogenetic offspring's genesis was described for the obligate parthenogenetic species just for genus Aspidoscelis. During oogenesis in this case is ploidy...
|
|
|
Self-assessment and mutual-assessment ability in squamate reptiles
Čekal, Jakub ; Frýdlová, Petra (advisor) ; Kubička, Lukáš (referee)
Agonistic interactions throughout the animal kingdom can inflict various costs upon involved animals (decreased fitness, higher risk of predation etc.). To prevent such losses, many species have developed different morphological and behavioural adaptations to display their fighting ability. These adaptations allow animals better assessment of different costs and benefits associated with fighting. Assessment can be divided into two main categories based on the amount of information, that opponents take into account. Self-assessment assumes that rivals consider only their competitive ability and the potential benefits of winning a fight. During mutual-assessment competitors are also capable of considering possible differences in their apabilities and either escalate the fight or back down. My thesis is literary research of this topic in squamate reptiles. The assessment was characterized in several families of Squamata. Additionally, it evaluates the most important traits, that determine a potential winner and introduces different behavioural models of assessment. Used literature suggests that the most reliable predictor of fighting success within these families is the body size, and that mutual-assessment seems to be more prevalent. Keywords: assessment, RHP, aggression, agonistic interactions,...
|
|
|
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.
|
|
|
Mechanisms of asexual reproduction in reptiles
Augstenová, Barbora ; Kratochvíl, Lukáš (advisor) ; Abramjan, Andran (referee)
In the case of reptiles, there has been described an occurrence of an asexual reproduction, especially in the case of a group Squamata; the asexual reproduction of birds (Aves) has been observed, too. Multiple times the asexuality of reptiles has been originated. Occurrences of obligate and facultative asexual species have been described. Most obligate asexual species have theirs origin in one or more hybridization events between closely related species. However, within the family Xantusiidae two exceptions where asexuality apparently originated without hybridization were discovered. Facultative parthenogenesis was originally expected only among reptiles kept in captivity, where the females were separated from males for a long time. However, this assumption was later disproved. The majority of the specimens formed by facultative parthenogenesis has reduced viability, which can be caused by the imperfect mechanism of the formation of parthenogenetic offspring. The terminal fusion is considered to be the probable mechanism of creation of diploid oocytes in the case of facultative parthenogenesis reptiles. The cytological mechanism of the parthenogenetic offspring's genesis was described for the obligate parthenogenetic species just for genus Aspidoscelis. During oogenesis in this case is ploidy...
|
guest ::
