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Morphological, behavioural and physiological adaptations of island-dwelling birds
Krpcová, Alena ; Albrecht, Tomáš (advisor) ; Mikula, Ondřej (referee)
Morphological, behavioural and physiological adaptations of island-dwelling birds Alena Krpcová prof. Tomáš Albrecht, Ph.D. Abstract Islands represent a model system of evolutionary biology. They are isolated environments in which specific ecological conditions often operate differently than on the mainland. In this context, island taxa develop unique morphological, physiological and behavioural adaptations, collectively referred to as island syndromes, through convergent evolution. This thesis aims to provide an overview of selected island syndromes that have been detected in a large group of vertebrates typically inhabiting islands, the birds (Aves). Attention is paid to body size, wing length and associated flightlessness, as well as changes in life strategies (life span, offspring care, clutch size and egg size), antipredatory behaviour and island tameness, and finally the relationship between the above-mentioned island syndromes and the extinction of island species caused by humans and the invasive organisms that accompany them. Factors operating in island environments that may influence the evolution of selected island syndromes are discussed, and it is suggested that reduced predation pressure on islands and an energetic trade-offs between investments in survival, defence and reproduction could be...
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Growth and ontogeny of sexual size dimorphism in Cetoniinae (Coleoptera: Scarabaeidae)
Vendl, Tomáš ; Šípek, Petr (advisor) ; Saska, Pavel (referee)
6 Abstract Due to its effect on fitness and many biological processes is body size one of the most important attribute of organisms. Body size is positively correlated with fecundity in insects and other ectotherms. Growth, which determine body size, is therefore crucial feature of animals. Study of growth can elucidate some aspects of body size evolution. Unfortunatelly, many insects life-history studies do not consider its complexity, especially the existence of distinct larval instars. Inaccurate record of growth trajectory may result also in biased differences in growth between sexually dimorphic sexes. Aim of this thesis is to record growth trajectories of two flower beetle species (Coleoptera: Scarabaeidae: Cetoniinae). These growth trajectories enable to define proximate mechanisms of growth with regard to individual instars. Determination of developmental mechanisms of sexual size dimorphism is another goal of this study. The growth is clearly divided in three distinct periods. In each individual period (i.e. instar) is described by asymptotic curve. The instars are not independent on each other - the growth in following instar is influenced by growth in previous. There are no differences in growth characteristics between sexes. Sexual size dimorphism is caused by differences in growth rate between...
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Comparative analysis of sexual and agonistic behaviour in eyelid geckos (Eublepharidae)
Rauner, Petr ; Kratochvíl, Lukáš (advisor) ; Frýdlová, Petra (referee)
Sexual selection is one of main selective pressure affecting body size, and subsequently leads to the evolution of sexual size dimorphism (SSD). The eyelid geckoes, family Eublepharidae, are a monophyletic group with considerable variability in SSD, including both male-larger and female-larger species. In general, it was supposed that eyelid geckos are highly variable in presence of male combats and in complexity of male pre-copulatory behaviour, and that this variability in this conspicuous male behaviour may lead to differences in SSD. The aim of this study was to reveal relationships between the direction of SSD and presence/absence of tail vibration during precopulatory phase and male combat behaviour. Using behavioural testing, it was revealed that male combats are present in all tested species, even in species, where the absence of such behaviour was supposed so far. In several species, the strong effect of seasonality to male aggression was observed, which may play a role in the evolution of SSD. The evolutionary changes in the presence/absence of tail vibration during precopulatory phase were independent on changes in the direction of SSD, the presence of tail vibration seems to be ancestral state for these lizards. During the evolution of this group, the tail vibrations disappeared four...
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Hormonal control of sexual size dimorphism in vertebrates
Tureček, Adam ; Kratochvíl, Lukáš (advisor) ; Frýdlová, Petra (referee)
Males and females of one species share the majority of the genome, often also the joint niche, but their phenotype is usually very different. The biggest difference between the sexes is the achievement of different sizes that can be controlled dimorphic secretion of hormones. Although many researches have been conducted on this topic, we still lack the knowledge that at least in vertebrates exists in this respect a single, common proximate mechanism or whether different types or lines vary considerably in hormonal control of dimorphism in body size. Growth is influenced by a variety of hormones that can interact - for example, growth hormone, somatomedins, thyroid hormones and steroid hormones. However, experimental studies have suggested that influence levels of sex steroid hormones can cause a change in sexual dimorphism in size. My work focuses on summarizing knowledge about hormonal influence dimorphic growth in vertebrates and analyse the methodology used. Powered by TCPDF (www.tcpdf.org)
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Ontogeny and evolution of body size and sexual size dimorphism in reptiles
Frýdlová, Petra
Monitor lizards (Varanidae) are morphologically very uniform in body shape, but much diversified in body size along both phylogenetic and ontogenetic axes. A striking sexual size dimorphism exists in monitor lizards; they are capable of fast growth, metabolism and sexual maturation. I collected the data concerning body size of particular species and verified the validity of Rench's rule, which said that there is bigger difference in body size of a conspecific male and females growing with larger body size of the species. Males are markedly bigger than females. In the next step, I focused on the model species of monitor lizards, Varanus indicus. I monitored its ontogeny very carefully. I found that this monitor lizard has pronounced sexual size dimorphism, but there are only small differences in body shape. It is capable of rapid growth and sexual maturation. The sexual dimorphism in body shape is only poor, but still measurable right in those places where the selection pressures were expected. Blood sampling monitored biochemical and haematological parameters. The concentrations of the biochemical parameters revealed the economy of resources of particular sexes partially, the costs of body growth and reproduction. Although both sexes produce the same amount of biomass (the body growth of males vs....
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The effect of steroid hormones on sexually dimorphic bone growth in geckos
Tureček, Adam ; Kubička, Lukáš (advisor) ; Frýdlová, Petra (referee)
The sexual size dimorphism (SSD) is widespread among animals but proximate mechanisms of its ontogeny are still poorly understood even in important groups of vertebrates such as reptiles. Previous experiments in geckos showed that growth of both sexes slows substantially at their older age. Their SSD develops considerably a long time after sexual maturity, it is associated with earlier growth deceleration in the smaller sex and it is controlled by ovarian rather than testicular steroids. The aim of the thesis was to explore the previous knowledge by studying the ontogenesis of the sexually-dimorphic bone growth of the gecko Paroedura picta, the male- larger species with the most explored proximate mechanisms of SSD among geckos. I was most interested in the ontogeny of the growth plates activity and the epiphyseal ossification of the femur in both sexes and their relationship to age, body length, gonadal activity and levels of sex-specific steroids (estradiol and testosterone). The results show that P. picta has determinate growth and that epiphyseal ossification does not contribute to the SSD. The femoral growth plates close at the same age in both sexes; however, their closure occurs at smaller body length in females than in males. In the context of this and the previous studies, estradiol or other...
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Comparative analysis of sexual and agonistic behaviour in eyelid geckos (Eublepharidae)
Rauner, Petr ; Kratochvíl, Lukáš (advisor) ; Frýdlová, Petra (referee)
Sexual selection is one of main selective pressure affecting body size, and subsequently leads to the evolution of sexual size dimorphism (SSD). The eyelid geckoes, family Eublepharidae, are a monophyletic group with considerable variability in SSD, including both male-larger and female-larger species. In general, it was supposed that eyelid geckos are highly variable in presence of male combats and in complexity of male pre-copulatory behaviour, and that this variability in this conspicuous male behaviour may lead to differences in SSD. The aim of this study was to reveal relationships between the direction of SSD and presence/absence of tail vibration during precopulatory phase and male combat behaviour. Using behavioural testing, it was revealed that male combats are present in all tested species, even in species, where the absence of such behaviour was supposed so far. In several species, the strong effect of seasonality to male aggression was observed, which may play a role in the evolution of SSD. The evolutionary changes in the presence/absence of tail vibration during precopulatory phase were independent on changes in the direction of SSD, the presence of tail vibration seems to be ancestral state for these lizards. During the evolution of this group, the tail vibrations disappeared four...
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Hormonal control of sexual size dimorphism in vertebrates
Tureček, Adam ; Kratochvíl, Lukáš (advisor) ; Frýdlová, Petra (referee)
Males and females of one species share the majority of the genome, often also the joint niche, but their phenotype is usually very different. The biggest difference between the sexes is the achievement of different sizes that can be controlled dimorphic secretion of hormones. Although many researches have been conducted on this topic, we still lack the knowledge that at least in vertebrates exists in this respect a single, common proximate mechanism or whether different types or lines vary considerably in hormonal control of dimorphism in body size. Growth is influenced by a variety of hormones that can interact - for example, growth hormone, somatomedins, thyroid hormones and steroid hormones. However, experimental studies have suggested that influence levels of sex steroid hormones can cause a change in sexual dimorphism in size. My work focuses on summarizing knowledge about hormonal influence dimorphic growth in vertebrates and analyse the methodology used. Powered by TCPDF (www.tcpdf.org)
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Ontogeny and evolution of body size and sexual size dimorphism in reptiles
Frýdlová, Petra ; Frynta, Daniel (advisor) ; Moravec, Jiří (referee) ; Zrzavý, Jan (referee)
Monitor lizards (Varanidae) are morphologically very uniform in body shape, but much diversified in body size along both phylogenetic and ontogenetic axes. A striking sexual size dimorphism exists in monitor lizards; they are capable of fast growth, metabolism and sexual maturation. I collected the data concerning body size of particular species and verified the validity of Rench's rule, which said that there is bigger difference in body size of a conspecific male and females growing with larger body size of the species. Males are markedly bigger than females. In the next step, I focused on the model species of monitor lizards, Varanus indicus. I monitored its ontogeny very carefully. I found that this monitor lizard has pronounced sexual size dimorphism, but there are only small differences in body shape. It is capable of rapid growth and sexual maturation. The sexual dimorphism in body shape is only poor, but still measurable right in those places where the selection pressures were expected. Blood sampling monitored biochemical and haematological parameters. The concentrations of the biochemical parameters revealed the economy of resources of particular sexes partially, the costs of body growth and reproduction. Although both sexes produce the same amount of biomass (the body growth of males vs. the...
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Ontogeny and evolution of body size and sexual size dimorphism in reptiles
Frýdlová, Petra
Monitor lizards (Varanidae) are morphologically very uniform in body shape, but much diversified in body size along both phylogenetic and ontogenetic axes. A striking sexual size dimorphism exists in monitor lizards; they are capable of fast growth, metabolism and sexual maturation. I collected the data concerning body size of particular species and verified the validity of Rench's rule, which said that there is bigger difference in body size of a conspecific male and females growing with larger body size of the species. Males are markedly bigger than females. In the next step, I focused on the model species of monitor lizards, Varanus indicus. I monitored its ontogeny very carefully. I found that this monitor lizard has pronounced sexual size dimorphism, but there are only small differences in body shape. It is capable of rapid growth and sexual maturation. The sexual dimorphism in body shape is only poor, but still measurable right in those places where the selection pressures were expected. Blood sampling monitored biochemical and haematological parameters. The concentrations of the biochemical parameters revealed the economy of resources of particular sexes partially, the costs of body growth and reproduction. Although both sexes produce the same amount of biomass (the body growth of males vs....
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