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Simulation of processes predicted by theory of frozen plasticity
Nekola, Ondřej ; Flegr, Jaroslav (advisor) ; Ponížil, Petr (referee)
The question of the tempo of evolution is amongst the oldest conundrums in evolutionary biology and has not been satisfactorily answered yet. One of the attempts to do so is the frozen plasticity theory, which postulates that a sexually reproducing species is only capable of evolution within short periods of time after its genetic polymorphism decreases e.g. as a consequence of peripatric speciation. In the longer periods of evolutionary stasis, its evolution is limited by frequency- dependent selection and pleiotropy. In this work, I have produced an open source software simulating the respon- ses of populations of sexually reproducing individuals to varying environmental conditions. Using this software, I simulated evolution of populations with different probabilities of arising of alelles affecting more phenotypic traits and frequency- dependent selected alleles that have opposing phenotypic effects when present at the locus in one copy, respectively two copies. I observed trends predicted by the theory of frozen plasticity: slower adap- tation to instant environmental changes, lower achieved fitness and more frequent extinctions of populations with higher portions of investigated types of alleles, but only with low effect sizes and without statistical significance. For future research, it would be desirable...
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Speciation mechanisms and the role of reinforcement in mammals
Horký, Jakub ; Hulva, Pavel (advisor) ; Reifová, Radka (referee)
Speciation, the process of the formation of new species, comprises a diverse range of microevolutionary mechanisms acting in unison, which lead to the gradual formation of reproductive barriers between populations. The study of speciation has significantly progressed since its origins around the midpoint of the nineteenth century, owing to progressively improving analytical methods and the data said methods obtained, allowing us to observe previously invisible patterns and form new hypotheses on their basis. From traditional to modern research, this review's goal is to describe the contemporary understanding of speciation's concepts and mechanisms, focusing on those which are most relevant to mammals. Modern understanding of spatial contexts, prezygotic and postzygotic isolating mechanisms, and character displacement, including a type of reproductive character displacement dubbed reinforcement, are discussed. Significant emphasis is placed on the topics of maladaptive and adaptive hybridization, which, together with reinforcement and development of new genomic methods, has this review identified as the current frontier of speciation research. Keywords: reproductive isolating mechanisms, microevolution, character displacement, hybridization, reinforcement, speciation
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Role of evolutional mechanisms in designing of acoustic signals
Rulfová, Alena ; Policht, Richard (advisor) ; Linhart, Pavel (referee)
Acoustic communication is a wide-spread phenomen in all animal taxones. The theme of evolutional mechanisms and their functioning in acoustic communication has become more and more frequently studied during last years, and geographic variation in acoustic signals has been reported in various taxa such as insect, birds, anurans and mammals. However, some evolutional mechanism still remain poorly understood. The mechanisms comprise mainly stochastics forces such as genetic drift and bottleneck or cultural drift. Genetic drift causes stochastic changes in acoustic signals, whereas bottleneck probably primarily spawns reduction of acoustic variability. Some acoustic parameters are shaped by habitat and others by species' phylogeny. Physical environment and other ecological factors play important role in shaping vocalizations in most species, and thus distantly related populations occupying similar habitats may possess very simmilar vocalization. Because of that, revealing phylogenetic pattern is possible only by careful cladistic analysis of vocal characters in taxa that have simple songs or calls that are not learned, and whose habitat distributions are well understood. By finding the proper acoustic parameters we can also e.g. map connection between acoustic divergence and glaciations, history of colonisation...
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Biosystematic study of the Carlina vulgaris complex in Central Europe based on molecular and morphometric approaches
Mašková, Hana ; Kaplan, Zdeněk (advisor) ; Krak, Karol (referee)
The Carlina vulgaris complex in central Europe includes several lineages defined by their ecology, morphology and distribution. This diploma thesis is focused on relationships between the taxa recognized in the Czech Republic, namely Carlina vulgaris subsp. vulgaris, C. biebersteinii subsp. biebersteinii, C. biebersteinii subsp. brevibracteata and C. biebersteinii subsp. sudetica. Molecular analysis revealed two genetically defined groups. One includes samples from relict populations in western Bohemia and from high mountains classified as C. biebersteinii subsp. biebersteinii and C. biebersteinii subsp. sudetica. The other is represented by plants classified as C. vulgaris and C. biebersteinii subsp. brevibracteata. This genetic differentiation was also confirmed by morphometric analysis. However, relationships within these two groups remain unclear. The Czech populations of Carlina biebersteinii subsp. biebersteinii as well as of C. biebersteinii subsp. sudetica are closely related to the mountain populations in the Alps and Carpathians. Their occurrence in the Czech Republic is relict and they should be in focus of nature conservation. However, the separate taxonomic position of the claimed endemic C. biebersteinii subsp. sudetica is probably unjustified.
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Evolutionary processes responsible for complexity in aquatic vascular plants
Prančl, Jan ; Kaplan, Zdeněk (advisor) ; Oberprieler, Christoph (referee) ; Štech, Milan (referee)
Aquatic plants are a heterogeneous assemblage of species that, although surviving in similar habitats, have evolved from very different genetic and ecological backgrounds. However, many aquatics share a number of anatomical, morphological, metabolic and reproductive adaptations, which have arisen independently in remarkable similarities (through convergence and parallelisms) in many unrelated groups. Despite their evolutionary uniqueness, aquatic plants are markedly underrepresented in contemporary biosystematic studies. Moreover, the taxonomic evaluation of numerous aquatic plant groups is intricate due to the strong morphological reduction and a high degree of phenotypic plasticity. This thesis focuses on two notoriously challenging aquatic plant groups, Callitriche and Ranunculus sect. Batrachium. The combination of several approaches (genome size estimation, chromosome counting, sequencing of nrDNA ITS and plastid trnT-trnL regions, examination of herbarium collections) was applied in order to improve our knowledge on principal evolutionary processes such as hybridization, polyploidization and cryptic variation and demonstrate their role on the shaping of overall aquatic plant diversity. The distribution of particular species in the Czech Republic was mapped for the first time. For both groups,...
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Comparative structural analysis of Borreliella spp. virulent factors focusing on their surface topology conservation
Zdrha, Alois ; Drbal, Karel (advisor) ; Nunvář, Jaroslav (referee)
Gram-negative bacteria of genus Borreliella cause the nowadays spreading illness Lyme borreliosis. However, their classification as gram-negative bacteria is rather mislea- ding because they differ in their complex genome, pathogenic adaptation to their hosts and composition of their outer membrane. One species of borreliella can harbour up to 23 variable plasmids and one conserved chromosome and they still lack many crucial proteins needed for synthesis of key compounds. Hence, they have to obtain these compounds from the host. However, in order for borreliella to utilise the metabolic processes of the host, it has to first survive its immune response. Therefore borreliella contains many virulent factors including highly variable surface lipoproteins. The variability is a major obstacle to overcome when using their surface epitopes for detection and vaccine development because most of the dominant antigenic epitopes of borreliella are usually parts of the most variable regions of the lipoproteins. Nowadays, we can use many different algorithms which determine evolutionary conserved epitopes based on analysis of sequences of given lipoprotein, in order to find suitable targets for antibodies. In general, conserved epitopes are more suitable for vaccines, whereas more variable epitopes are better...
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Tumor in vitro chemosensitivity and resistance assays (CSRA) using flow cytometry
Drozdová, Tereza ; Drbal, Karel (advisor) ; Balounová, Jana (referee)
In vitro chemosensitivity and resistance assay determine the sensitivity of a specific tumor after a specific treatment administration in an experimental setup. A heterogeneous population of cancer cells is exposed to various approved anticancer drugs in short-term ex vivo and their combination thereof. The effect of each drug is then determined based on the viability of specific tumor cells allowing for individual patient treatment using a precise combination of drugs. This approach is an example of the personalized medicine principle, which is focusing on the adjustment of diagnostic procedures and treatment of a specific patient. Therefore, its goal is to avoid treatment failure in patients with poor response to the statistically most effective treatments based on randomized clinical trials. The number of viable cells determined by the flow cytometry provides very accurate statistics for multiparametric analysis. A necessary prerequisite is the presence of dissociated cancer cells in a single cell suspension. This is different from cloning methods, where tumor colonies grow on agar media, or from histocultures, which are specific with its three-dimensional tissue cultivation. We can also sort cells from suspension based on their pre-defined attributes for their subsequent functional testing. The...
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Biosystematic study of the Carlina vulgaris complex in Central Europe based on molecular and morphometric approaches
Mašková, Hana ; Kaplan, Zdeněk (advisor) ; Krak, Karol (referee)
The Carlina vulgaris complex in central Europe includes several lineages defined by their ecology, morphology and distribution. This diploma thesis is focused on relationships between the taxa recognized in the Czech Republic, namely Carlina vulgaris subsp. vulgaris, C. biebersteinii subsp. biebersteinii, C. biebersteinii subsp. brevibracteata and C. biebersteinii subsp. sudetica. Molecular analysis revealed two genetically defined groups. One includes samples from relict populations in western Bohemia and from high mountains classified as C. biebersteinii subsp. biebersteinii and C. biebersteinii subsp. sudetica. The other is represented by plants classified as C. vulgaris and C. biebersteinii subsp. brevibracteata. This genetic differentiation was also confirmed by morphometric analysis. However, relationships within these two groups remain unclear. The Czech populations of Carlina biebersteinii subsp. biebersteinii as well as of C. biebersteinii subsp. sudetica are closely related to the mountain populations in the Alps and Carpathians. Their occurrence in the Czech Republic is relict and they should be in focus of nature conservation. However, the separate taxonomic position of the claimed endemic C. biebersteinii subsp. sudetica is probably unjustified.
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Simulation of processes predicted by theory of frozen plasticity
Nekola, Ondřej ; Flegr, Jaroslav (advisor) ; Ponížil, Petr (referee)
The question of the tempo of evolution is amongst the oldest conundrums in evolutionary biology and has not been satisfactorily answered yet. One of the attempts to do so is the frozen plasticity theory, which postulates that a sexually reproducing species is only capable of evolution within short periods of time after its genetic polymorphism decreases e.g. as a consequence of peripatric speciation. In the longer periods of evolutionary stasis, its evolution is limited by frequency- dependent selection and pleiotropy. In this work, I have produced an open source software simulating the respon- ses of populations of sexually reproducing individuals to varying environmental conditions. Using this software, I simulated evolution of populations with different probabilities of arising of alelles affecting more phenotypic traits and frequency- dependent selected alleles that have opposing phenotypic effects when present at the locus in one copy, respectively two copies. I observed trends predicted by the theory of frozen plasticity: slower adap- tation to instant environmental changes, lower achieved fitness and more frequent extinctions of populations with higher portions of investigated types of alleles, but only with low effect sizes and without statistical significance. For future research, it would be desirable...
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Differentiation within the Carlina vulgaris complex in central Europe
Mašková, Hana ; Kaplan, Zdeněk (advisor) ; Chrtek, Jindřich (referee)
The Carlina vulgaris complex includes in central Europe several forms with specific morphology, ecology and distribution. Their mutual relationships and ancestry are unclear. This fact leads to many different views on their taxonomy. The critically endangered endemic taxon C. biebersteinii subsp. sudetica was described from the Czech Republic. Its differentiation from other central-European populations has not been studied yet. For this reason, my following master thesis will focus on taxonomic re-evaluation of this complex by means of investigation of genetic and morphological variation. Powered by TCPDF (www.tcpdf.org)
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