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Evolution of brain complexity and processing and cognitive capacity in selected vertebrates
Kverková, Kristina ; Němec, Pavel (advisor) ; Stuchlík, Aleš (referee) ; Iwaniuk, Andrew N. (referee)
Brain processing capacity has traditionally been inferred from data on brain size. However, recent studies have shown that similarly sized brains of distantly related species can differ markedly in the number and distribution of neurons, their basic computational units. There- fore, a finer-grained approach is needed to reveal the evolutionary paths to increased cogniti- ve capacity. This quantitative approach to the evolution of brain processing capacity at the cellular level is relatively new, since quick and reliable estimation of the number of neurons in whole brains or large brain regions has only become possible in the past 15 years or so with the introduction of the isotropic fractionator. This method of determining brain cellular com- position is applicable to a wide range of questions. We can assess intraspecific variation, both at the individual and population level, examine the effect of sex and age, and the study se- lection at the intraspecific level. At the other side of the spectrum, we can study large macro- evolutionary trends or try to isolate the effect of specific selective pressures by comparing more closely related and ecologically similar species. In this thesis, I explored variation in brain size and brain cellular composition across vertebrates at both intraspecies and...
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Allometric diversity and plasticity of cellular morphologies of desmids (Desmidiales, Zygnematophyceae)
Mezník, Daniel Heliodor ; Neustupa, Jiří (advisor) ; Kleisner, Karel (referee)
If the proportions of two features of an organism change during its growth, their relationships can be described as allometry. The first partof this thesis quantifies the allometric relationship of semicellular perimeter and area of 11 species of unicellular microalgae from the genus Euastrum. These algae are recognized for their fractalmorphology, which is theorized to be an adaptation for increasing their surface area which is used to absorb nutrients.Thequestion was whether larger individuals within a population have a more complex shape and therefore a longer perimeter. I examined microphotographs of tens of semicells obtained from preserved wild populations. All included species exhibited a marked increase in shape complexity. The same trend could be noticed on and interspecific level. I compared these results to existing studies conducted on the related Micrasterias lineage. The second part of this thesis deals with allometric changes during semicells ontogeny in both Euastrum and Micrasterias. I analyzed growing clonal cultures using geometric morphometry. Specifically, I observed the relative position of 11 structurally homologous landmarks on semicells of different ages. This has been the first experiment of its kind on these model organisms. Idescribed theontogenetic change in landmark...
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Ontogeny of exaggerated structures in dung beetles (Coleoptera: Scarabaeinae)
Žídek, Radim ; Šípek, Petr (advisor) ; Hanus, Robert (referee)
E n g l i s h a b s t r a c t Horns of scarab beetles represent a secondary sexual characters present mostly in males, to whom they serve as weapons in combats over the acces to females. In many species, two discrete male forms occur, "horned" and "hornless", which employ different reproductive strategies. Adult body size and horn morphology are determined by nutritional conditions encountered by larvae during their development. Switching between developmental pathways is accomplished by circulating levels of juvenile hormone (JH) which reflect body size, and genetically determined threshold of sensitivity to it. When body size is larger then threshold, horn growth occur, whereas if it's not, a brief pulse of ecdysone reprogramme the development and hornless adult emerge. Reprogramming the development encompass modifications of the insulin receptor pathway as well as changes in exact domains of genes expression envolved in specifying the proximodistal axis of the developing horn. Development of horns is morphologically reminiscent that of other insect appendages, with which it shares the expression of genes wingless, decapentaplegic, Distal-less, dachshund, homothorax, aristaless and EGFR, parts of gene regulatory network ensuring origin of the outgrowth of the cuticle. Some of them are expressed through...
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Growth and sexual selection in selected representatives of scarabaeoid beetles (Coleoptera: Scarabaeoidea).
Vendl, Tomáš ; Šípek, Petr (advisor) ; Knapp, Michal (referee) ; Skuhrovec, Jiří (referee)
Flower chafers are well-known beetles with apparent sexual dimorphism. Yet, in contrast to other groups of scarab beetles, only little attention has been paid to various aspects of this phenomenon. It concerns also sexual dimorphism in size, which is very common in animals. Although ultimate causes of sexual size dimorphism have been extensively studied, the developmental mechanisms are still only poorly understood. We investigated proximate causes of sexual size dimorphism in several differentially dimorphic flower chafer species. We found that in highly dimorphic species the dimorphism started to develop already in the first instar and tended to accumulate through successive larval development. In contrast, the sexes in species with a relatively low dimorphism diverged in size during only one instar. Moreover, we found variability not only in when the dimorphism arises during development, but also how: sex-related differences in both the instar duration and average growth rate were the proximate causes of sexual size dimorphism. In addition, we showed that the sexes may differ also in growth trajectory - males had relatively longer period of rapid growth than females, even in cases where the absolute development times were similar in both sexes. Further, we focused on systematic survey of sexual...
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Cellular composition of brains for hornbills, woodpeckers and coraciiform birds
Stehlík, Patrik ; Němec, Pavel (advisor) ; Kratochvíl, Lukáš (referee)
Recent comparative studies have shown that bird brains, although small, have a high processing capacity. The brains of parrots and songbirds have higher neuronal densities than brains of mammals; especially large parrots and corvids compete with or even outnumber primates by the number of telencephalic neurons. However, the processing capacity of the avian brain appears to differ significantly between various phylogenetic lineages. Basal groups such as galliform birds have much lower absolute numbers of neurons and lower neuronal densities than songbirds and parrots. In this Master thesis, I used the isotropic fractionator to determine numbers of neurons and non-neural cells in specific brain regions in 19 species of hornbills (Bucerotiformes), woodpeckers (Piciformes) and coraciiform birds (Coraciiformes). The brains of hornbills and woodpeckers (but not coraciiform birds) have numbers of neurons comparable to that of songbirds and parrots and significantly more neurons than equivalently sized brains of pigeons (Columbiformes) and galliform birds (Galliformes). In the crown groups, we can observe similar trends such as a higher degree of encephalization, a proportionally larger telencephalon and increasing percentage of telencephalic neurons. On the contrary, in pigeons and galliform birds, we can...
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Changes of the facial skeleton in Central Europe during the last 1200 years
Bejdová, Šárka
The objective of the Dissertation was to describe, quantify and interpret to which degree the shape and size of the facial skeleton of people living in the territory of today's Czech Republic in the period from the Early Middle Ages to the present day, i.e. in the course of the approx. last 1200 years, have changed. In this time period, morphological differences between populations, changes in the sexual dimorphism, modularity and allometry of the facial skeleton were examined. The evaluation was based on CT-images of skulls from three historical populations, specifically from the Early Middle Ages, High Middle Ages and the early modern period. The current population was represented by CT-images of living people. We studied the facial skeletons of a total of 329 individuals, of which 183 were men and 146 women. The CT- images were used as a base for the creation of virtual 3D surface models. The facial skeleton was divided into three morphological units, which were further examined. These were the skeleton of the upper face, lower jaw and palate. The statistical processing was carried out applying methods of geometric morphometrics allowing the separate studying of the shape and size variability of the examined units. When comparing the size and shape differences between studied populations it is...
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Growth and sexual selection in selected representatives of scarabaeoid beetles (Coleoptera: Scarabaeoidea).
Vendl, Tomáš ; Šípek, Petr (advisor) ; Knapp, Michal (referee) ; Skuhrovec, Jiří (referee)
Flower chafers are well-known beetles with apparent sexual dimorphism. Yet, in contrast to other groups of scarab beetles, only little attention has been paid to various aspects of this phenomenon. It concerns also sexual dimorphism in size, which is very common in animals. Although ultimate causes of sexual size dimorphism have been extensively studied, the developmental mechanisms are still only poorly understood. We investigated proximate causes of sexual size dimorphism in several differentially dimorphic flower chafer species. We found that in highly dimorphic species the dimorphism started to develop already in the first instar and tended to accumulate through successive larval development. In contrast, the sexes in species with a relatively low dimorphism diverged in size during only one instar. Moreover, we found variability not only in when the dimorphism arises during development, but also how: sex-related differences in both the instar duration and average growth rate were the proximate causes of sexual size dimorphism. In addition, we showed that the sexes may differ also in growth trajectory - males had relatively longer period of rapid growth than females, even in cases where the absolute development times were similar in both sexes. Further, we focused on systematic survey of sexual...
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Cellular scaling rules for brains of gallinaceous birds
Zhang, Yicheng ; Němec, Pavel (advisor) ; Kratochvíl, Lukáš (referee)
Galliform birds (Galliformes) make up together with anseriform birds (Anseriformes) the clade Galloanserae, the sister group of Neoaves and the most basal clade of Neognathae. However, to date no quantitative data on cellular composition of their brains have been available. Here, I used the isotropic fractionator to determine numbers of neurons and non-neuronal cells in specific brain regions of 15 species of galliform birds. I find that cellular scaling rules for galliforms differ starkly from those for songbirds and parrots. When compared to these crown avian lineages, galliform birds feature lower degree of encephalization, a proportionally smaller telencephalon, small telencephalic and dominant cerebellar neuronal fractions, generally lower neuronal densities and larger glia/neuron ratios. Consequently, their brains and especially their forebrains harbor much smaller absolute numbers of neurons than those of equivalently sized songbird and parrots, the fact that undoubtedly constrains cognitive abilities of galliforms. However, this not to say that galliform birds are "bird brains" with low numbers of neurons and a limited ability to learn. Because they have high neuronal densities, their relatively small brains contain about equal numbers of neurons as brains of equivalently sized rodents and...
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Hodnocení stability stromu na základě dendrometrických veličin
Maňák, Vladimír
The main concern of this work is to propose analytical relations describing the stabi-lity of trees depending on the dendrometry. Further, the aim is to derive allometric co-efficients of breakage and windthrow failure based on dendrometric quantities and theory of mechanics. Selected individuals of the genus maple, birch, beech, ash, oak and linden are located in urban areas of Prostějov. The allometric relationships are based on the dendrometric measurements of these individuals (a diameter, center of gravity he-ight, crown area etc.) and on mechanics (wood strength; modulus of elasticity of wood, roots and soil; inclination etc). Tree age was calculated from the relationship between the dendrometric variables. The allometric coefficients for tree assessment in the phase of maturity conditioned by tree species and the stability of the tree can not be evaluated only according to the diameter and height of the center of gravity but also according to sail area of the crown. When assesing trees not only the geometry but also material pro-perties should be considered. Of allometric relationships for breakege, windthrow and buckling I find most useful the relationship for the breakage because it uses also the sail area and material properties.
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The shell shape plasticity of Thick Shelled River Mussel (Unio crassus, Unionidae) depending on locality and size variables
Jandáková, Miriam ; Douda, Karel (advisor) ; Petrtýl, Miloslav (referee)
This thesis focuses on shell shape plasticity of Unio crassus at 12 localities. 1129 shape outlines were used for the purposes of this work. The outlines were gained from 260 individuals in the way of analysing the winter growth lines. The Elliptic Fourier Analysis appeared to be reasonable tool for the bivalves' shells shapes assessment. The winter growth lines' consideration showed great potential for morphometric analyses. The results shows that PC1 and PC2 axes (from principal component analysis of shape coeficients) are growth- dependent. The allometry influence was removed by residual values assessment obtained from generalized linear model (GLM). The age, length and width parameters appears to be favourable combination for general allometry influence removal (by using these parameters as describing variables in GLM model). The results point to significant differences among localities in all assessed parameters. Furthermore, the significant difference in growth speed was approved. Speed growth indicator correlates with shape variables. The localities can be divided into two groups with different growth speed each (Bertalanffy growth constant, length in the third year and age relative length). These groups differs in about 10 mm in average lengths. The most similar localities were "Blanice...
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