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Factors influencing flight-initiation distance in reptiles and the comparison with endotherm vertebrates
Fictumová, Tereza ; Frýdlová, Petra (advisor) ; Sedláček, Ondřej (referee)
The fleeing behaviour is one of the most common antipredatory strategy. It is intensively studied in many groups of animals. The flight-initiation distance (FID) is used for quantification of fleeing behaviour. The FID represents the distance between a prey and an approaching predator in which the prey starts fleeing. The FID is also used for quantifying of preys fear. The factors influencing FID in reptiles are: temperature, habitat, refuge availability, foraging strategies, predator behaviour etc. I discovered some factors which are different for mammals and birds. The most important difference is the ectothermy in reptiles vs. the endothermy in mammals and birds. Another difference is parental care, alarm calls and grouping. The factors as an influence of predator, refuge availability or type of habitat seems to have very similar or the same impact on FID for both groups.
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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...
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Reproductive biology and sexual dimorphism in the lizard Lepidophyma smithii (Squamata: Xantusiidae)
Kukačková, Dominika ; Kratochvíl, Lukáš (advisor) ; Frynta, Daniel (referee)
The squamata reptiles present a wide array of reproductive strategies. In the genus Lepidophyma from the neotropical family Xantusiidae, there are 19 species, all of them live- bearing and diploid. Obligatory unisexuality is also present in some species. This obligatory unisexuality did not evolve via hybridization, which is unique among vertebrates. The genus thus presents a very interesting, but still poorly little explored group. Only recently our team has discovered a facultative unisexuality in Lepidophyma smithii. The unisexually produced offsprings are not fully homozygous are of both sexes, which is unique for vertebrates as well. The aim of my work is to describe the basic reproductive biology of this species, e.g. the relationship between female size and clutch size and offspring size. Additionally, my work focuses on sexual dimorphism. I tested whether L. smithii is dimorphic in body length and head size. These traits are often sexually dimorphic in squamatesu. Also, I documented the ontogeny of sexual dimorphism and reconstructed growth curves for males and females.
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Metabolic costs of reproduction in vertebrates, particularly in reptiles
Kukačková, Dominika ; Kratochvíl, Lukáš (advisor) ; Hořák, David (referee)
Animal reproduction involves energy expenditures for gamete formation, support of offspring development, and associated behavioural changes. Due to high variability in reproductive traits, reptiles are the ideal study group for this field. Investment in reproductive organs and gametes represent costs of sex products production. The next phase of reproduction is gestation, when females support their developing offspring, which results in additional metabolic costs. Metabolism of pregnant female can be viewed as a sum of resting metabolism, which is the same as in non-pregnant animal, of increased metabolism to support pregnancy, and of embryonic metabolism. Separation of each component is crucial for assessing energy costs of reproduction and for comparison of different reproductive strategies. Certain behavioural changes during reproduction can influence total energy balance as well. These changes include increased locomotion costs or shifts in the thermoregulatory behaviour. Estimation of the real costs of reproduction is a complex matter since a reproduction is a very dynamic process and there are many issues that influence the overall energy consumption of reproducing individuals.
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Evolution of sex chromosomes and karyotypes in the lizard clade Laterata
Buchbauerová, Lucie ; Kratochvíl, Lukáš (advisor) ; Šťáhlavský, František (referee)
The aim of this study was to summarize all what is known about the karyotype and about sex chromosomes in the lizard clade Laterata and to analyze this two gained datasets by means of a phylogeny. Karyotype represents a whole number of chromosomes in a cell and it is an important source of informations on how the genetic information in nucleus is organized and how it works along with the evolution. The Laterata clade consists of four big groups of squamate reptiles: Teiidae, Gymnophthalmidae, Amphisbaenia and Lacertidae. All the groups have a genotypic sex determination system (GSD) and some species within these clades posses sex chromosomes. If they are present, in Teiidae and Gymnophthalmidae it is the XY sex chromosome system which determines the sex of a specimen. On the other hand, in Amphisbaenia and Lacertidae it is the ZW system of sex determination. Sometimes the X1X1X2X2:X1X2Y or Z1Z1Z2Z2:Z1Z2W sex chromosome system occurs in Teiidae / Gymnophthalmidae or in Lacertidae, respectively. The phylogenetical analysis was performed in Mesquite programme and the output from the analysis is a phylogenetical tree with two characters (number of chromosomes and the sex determination system) and the maximum parsimony counted for each of them. Then the interpretation was on the order and it is the main...
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Ecological and phylogenetic effects determining variation of growth patterns in amniotes
Stanková, Veronika ; Frýdlová, Petra (advisor) ; Vohralík, Vladimír (referee)
Growth is a process during which organs or the whole body enlarges. It can be modeled by using growth models and curves. The work is mainly focused on the explanation of two types of growth - the determinate growth, which is finished after the reaching of the sexual maturity, and the indeterminate growth which on the other side continues even after the reproduction or after the reaching of the sexual maturity. In the literature there is generally stated that birds and mammals are characterized by the determinate growth, amphibians and reptiles have the indeterminate growth. The aim of this work was to analyze the current available literature relevant to the growth and to evaluate the above mentioned statements about the growth of the vertebrates. The ecological and the phylogenetic effects influencing the growth, the physiological regulation and the mechanism of the growth are summarized in this work. Powered by TCPDF (www.tcpdf.org)
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Behavioural correlates of lizard colouration
Bauerová, Anna ; Frynta, Daniel (advisor) ; Rehák, Ivan (referee)
The coloration is a significant animal attribute which can be examined from the view of phylogenesis, ontogenesis, ecology or life-history parameters. In this thesis the method of coloration quantification and pattern complexity was developed, with the focus on Leopard gecko (Eublepharidae) family. are one of the most commonly breeded lizards, the great part of their popularity being due to their attractive "leopard" coloration. Yet we only know a little about their "wild" coloration. They have become an important organism for many etological and physiological experiments, the distinct color pattern change during ontogenesis being especially unusual. These aspects make them an ideal subject for coloration change and affecting parameters analysis. The results of this work show clear ekological pattern for coloration. The amount of black color correlates with the humidity and abundance of vegetation in the habitat of the species. The coloration quantification was also verified using spectrophotometry, which confirmed the original assumptions for colors included in the pattern. Given the absence of UV reflectance in the Leopard gecko pattern, we can assume that the UV spectrum pattern is not an essential parameter. Therefore, the photographies can be used for quantification as well. It is apparent...
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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...
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Turtles (Testudines) - their Occurence and Breeding in the Czech Republic
Chotěborová, Tereza ; Andreska, Jan (advisor) ; Hanel, Lubomír (referee)
Bachelor thesis titled "Turtles" (Testudines) - their occurrence and breeding in the Czech Republic was primarily conceived as a research. The objective of this study is to create an information unit about turtles and is divided into several specific areas such as history, origin, anatomy and physiology, occurrence, breeding and diseases. The thesis compares the knowledge of turtles from available resources. KEY WORDS: reptiles, turtle, breeding, red-eared slider (Trachemys scripta elegans)
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Endocrine disruptors in reptiles
Semerád, Jaroslav ; Kratochvíl, Lukáš (advisor) ; Cajthaml, Tomáš (referee)
The ability of environmental contaminants to influence reproduction and development in vertebrates via disruption of the endocrine system is widespread. The mechanisms through which xenobiotics act can be complex and vary greatly among species. Reptiles are particularly good models for studying endocrine affecting compounds due to the fact that different species differ in modes of sex determination (genotypic sex determination or temperature-dependent sex determination) and parity (oviparity or viviparity). The sex of individual is often determined by egg incubation temperature, and exogenous application of steroid hormones and their analogs or steroidogenic enzyme inhibitors can reproduce effects of temperature. The lability of sex determination in some reptile species offers opportunity to use gonadal sex as a marker for effects of endocrine disrupting compounds (EDC), even for the effects of extremely low dosages of EDCs or EDC mixtures. The neonatal offsprings exposed to EDCs during embryogenesis provide yet another way to assess endocrine disruption, i.e., measurement of steroid hormone levels in their blood. In addition, many reptile species are highly aquatic, they use habitats near agricultural areas, where usage of pesticides is the most intense, and they are carnivores or scavengers. Therefore,...
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