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Phenotypic plasticity and morphogenesis of desmids (Desmidiales, Zygnematophyceae)
Figallová, Klára ; Neustupa, Jiří (advisor) ; Ráček, Jan (referee)
Desmids are green streptophyte algae classified in the order of Desmidiales. The cells of desmids are notable for the presence of mirror-symmetrical ornamented semicells connected by a plasmatic bridge, the isthmus. This group of organisms is characterised by a rather high ecological specificity, causing them to respond to changes in environmental conditions by modifying their morphological characteristics. The ability of an organism to exhibit several different phenotypes in response to environmental transformations is called phenotypic plasticity. This has often been the subject of morphometric studies, which provide more specific description of the phenotypic changes in desmids. Due to their ability to respond to alterations in external conditions, desmids have shown the potential for practical use as bioindicators.
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Morfologická variabilita a určování terestrických forem středoevropských druhů lakušníků \kur{(Ranunculus} sect. \kur{Batrachium)}
VLČKOVÁ, Linda
Ranunculus sect. Batrachium is a considerably complicated group of aquatic plants. Some of the species can facultatively grow terrestrially on wet sediment surface. Due to their extensive phenotypic plasticity, they form terrestrial modificants in the terrestrial conditions. This theses deals with the Central European species that create the terrestrial modificants, namely Ranunculus aquatilis, R. baudotii, R. peltatus, R. rionii, R. trichophyllus A and R. trichophyllus B (two distinct cytotypes of Ranunculus trichophyllus). The aim of this theses is to establish whether the terrestrial forms of these species differ in their morphology. The species were determined using flow cytometry, and then morphological features were measured. Subsequently, the data were analysed using multivariate statistical methods to assess whether the terrestrial modificants can be determined.
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Plant adaptation to climate change
Koláříková, Veronika ; Münzbergová, Zuzana (advisor) ; Sklenář, Petr (referee)
Climate change represents important selective force for plants. They have to deal with this change otherwise they are facing the risk of extinction. Understanding the mechanism which plants use to avoid the risk is essential for effective conservation of biodiversity. The climate change can exceed the tolerance of plants to abiotic factors. The plants can react to the changes by migration, phenotypic plasticity, evolutionary adaption or by a combination of these strategies. Phenotypic plasticity and evolutionary adaption are manifested by a change of physiology, morphology and/or phenology of plants. This work summarizes the findings of these ecological and evolutionary strategies and also presents methods used for studying species response to climate change. Powered by TCPDF (www.tcpdf.org)
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The effect of urbanization on life-history strategies in birds
Houšková, Karolína ; Sedláček, Ondřej (advisor) ; Poláková, Simona (referee)
Urbanisation process is recently a wide-spread process that causes high-impact environmental transformation. Habitats affected by urbanization tend to change substantially and ongoing changes influence organisms living in this environment. Urban environment modifies many abiotic conditions (e.g. temperature, artificial light and noise) and biotic factors (e.g. food supply, parasite prevalence, predation pressure) in comparison to natural habitats. In this manner, especially urban bird populations have recently gained broad attention by an increasing number of ecologists. Urban avoiders - typically sensitive and specialized bird species often vanish from urbanized landscapes. However, many bird species were able to colonize urban environment and coexist successfully with man. Populations of birds living in such a new type of environment show many characteristics different from populations living in original habitats. The objective of this work is to review current studies about changes of life strategies in urban bird populations such as modifications of acoustic signals, differences in reproductive and food ecology and physiological or behavioural responses.
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Phenotypic plasticity and its role in plant invasions
Hlavička, Matěj ; Herben, Tomáš (advisor) ; Skálová, Hana (referee)
Phenotypic plasticity is the ability of given genotype to produce different phenotypes as a response to environmental cues. Its capability of adaptive response draws an attention of invasion biologists. Although many studies have been performed, the true role of plasticity in an invasion process is still unclear. Comparative experiments suffer from several major constraints - insufficiency in revealing adaptive value of plastic response and uncertain linkage between plasticity and trait value. Further experiments could be focused to reaction norms of fitness instead of trait plasticity. Also, the interspecific interaction of plastic responses is definitely an underestimated mechanism and deserves far more attention than it does today. Possible implications of plant phenotypic plasticity in predicting future invasions require further reaserch.
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Integration of clonal plants in heterogeneous environment
Vinšová, Jana ; Weiser, Martin (advisor) ; Macek, Petr (referee)
Clonal plants may be able to cope with spatial and temporal heterogeneity due to the physiological integration of ramets. To begin with, I discuss basic characteristics of clonal plants and then I provide a review of theoretical and empirical work dealing with the advantages and disadvantages of clonal growth in heterogenous conditions. Three main traits - translocation of resources, division of labour and foraging - are examined in terms of their contribution to the success of clonal plants. Despite a large amount of attention which this topic has received in the past few decades, a number of issues still remain unclear.
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Population differentiation of Ochrophytes
Mensová, Anna ; Jurdíková, Katarína (advisor) ; Kulichová, Jana (referee)
This bachelor thesis deals with a differentiation of populations of Ochrophytes (photosynthetic Stramenopiles). Natural populations can differ in many aspects and their differentiation is observed on several levels. Ecophysiological and morphological differences are very often caused by phenotypic plasticity, which is a flexible answer to changing conditions of habitats. Genetic differentiation could express an adaptation to the local environmental conditions. The adaptation and a long-term isolation of populations are considered to be the leading factors in genetic differentiation. The other factors contributing to genetic differentiation are random evolutionary events such as founder effect or genetic drift. Detailed studies of populations lead to uncover the factors that cause the differentiation of populations as well as they contribute to the understanding of speciation mechanisms. The thesis compiled the information about different types of variability among populations within the classes of Ochrophytes.
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Ability of plants to adapt to changing climate
Brožová, Alžběta ; Münzbergová, Zuzana (advisor) ; Dostál, Petr (referee)
Climate is one of the main selective forces in determining plant distribution and phenotype. Plant populations can cope with climate change through phenotypic plasticity or adaptive evolution or they can track their climatic optimum by migration.These mechanisms are not mutually exclusive and act probably all together. As the rate and intensity of ongoing climate change are very high, rapid adaptation could be of prime importance for many species to survive. There is now ample evidence of distributional and phenological shifts in plant populations, however, less is known about evolution in physiological and morphological traits. This bachelor project is a literature research on plant adaptation to climate change. The first part summarizes mainly theoretical findings, the second part focuses on the methods for testing plant evolution mainly on resurrection approach.
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Developmental plasticity in reptiles
Peš, Tomáš ; Kratochvíl, Lukáš (advisor) ; Frýdlová, Petra (referee)
The environment during incubation can have significant influence upon phenotype of reptile hatchlings. Temperature is one of the main environmental factors affecting developing embryos. The response to variability in the environment can be diverse: short, long-lasting and potentially also sex-specific. A large number of studies focused on this phenomenon but only a small portion of them studied the persistence of the phenotypic effects. I summarized studies on the influence of environmental factors on the phenotype of reptiles in species with both temperature or genotypic sex determination. These studies were evaluated in terms of duration of these effects and if these are sex specific. I also assessed how much they correspond with the predictions of the adaptive model suggested by Charnov & Bull which explains the origin and maintenance of temperature sex determination. Key words: phenotypic plasticity, environment, development, behaviour, morphology, sex determination, phenotype
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Spatial distribution of plant roots in heterogeneous soils
Hrouda, Adam ; Weiser, Martin (advisor) ; Kuťáková, Eliška (referee)
In natural ecosystems, water and mineral nutrients are unevenly distributed in soil. Plants respond to this heterogeneity with active phenotypic plasticity of their root system. This plasticity can be either morphological, physiological or their combination. Both single-plant and competition experiments reveal that species differ in responses to heterogeneous distribution of nutrients. Based on observed differences, several theories emerged that describe the mechanisms of species coexistence in plant communities. Thanks to many experimental studies we currently have a better understanding of plastic root responses to soil heterogeneity, but the role of root plasticity in community establishment and development remains unclear. Precise observation of field soil heterogeneity is needed together with more realistic experiments reflecting the natural environment.
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