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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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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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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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Phenotypic plasticity of Daphnia cucullata in two lowland ponds
Volemanová, Eva ; Petrusek, Adam (advisor) ; Pichlová, Radka (referee)
4 ABSTRACT Characteristic high helmets in Daphnia cucullata, which increase resistance of Daphnia against various invertebrate predators, can be induced by chemical cues released by these invertebrates but also by small-scale turbulence. I evaluated the response of D. cucullata to both factors in several clones originating from two riverine pools differing in their predator regime. In a large pool, the dominant invertebrate predator is the cladoceran Leptodora kindtii, and the Daphnia population there shows a typical cyclomorphosis. In the second (small) pool, Daphnia do not produce helmets, despite the presence of the phantom midge larvae Chaoborus flavicans. I compared phenotypic changes of Daphnia cucullata clones from these pools to Chaoborus kairomones and to a small-scale turbulence in laboratory experiments. Kairomones induced significantly longer helmets in clones from both pools; however, only clones form the large pool reacted also to turbulence. As all daphnids in the experiments responded to chemical cues from Chaoborus, I assume that either the kairomone dose under natural conditions in the small pool is too low to induce helmets or the phenotypic response of the local population is mediated by other factors. On the other hand, the variation of response to small-scale turbulence suggests that...
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Phenotypic plasticity of selected species of aquatic insects
DUDOVÁ, Pavla
Phenotypic plasticity is the ability of the single genotype to pruduce multiple phenotypes in response to evironmental conditions. There are many factors affecting phenotypic plasticity. The aim of this thesis is to summarize the current knowledge of phenotypic plasticity of aquatic insects with emphasis on the role of temperature and food availability. The review is complemented by a laboratory experiments designed to investigate the effect of temperature and food availability on growth and development rate of diving beetle Acilius canaliculatus (Coleoptera: Dytiscidae). The results are discussed in the light of the ecological concepts of temperature-size rule and developmental isomorphy.
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The impact of water dessication on the development of \kur{Rana temporaria} tadpoles.
MODRÁ, Denisa
Common frog (Rana temporaria, Anura: Ranidae) reproduces in various freshwater habitats including shallow ponds with variable water level and hence high risk of mortality due to the water losses. I performed a laboratory experiment with simulated drying and assessed whether continuous water loss supports phenotypic plasticity of common frog. I showed the influence of decreasing water volume on development time, body size and weight of tadpoles.
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Phenotypic plasticity of planktonic rotifers as a response to predator.
VAJDIAKOVÁ, Nikola
The aim of this thesis is to assemble essential information about phenotypic plasticity of zooplankton, especially planktonic rotifers. More specifically, the thesis is focused on predatorinduced morphological changes. I introduced different types of predators and their behavioral, physiological and morphological impacts on zooplankton. Moreover, I examined the effects of inducible morphological defences on the planctic rotifers.
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Phenotypic plasticity of selected species of aquatic insects
DUDOVÁ, Pavla
Phenotypic plasticity is the ability of the single genotype to pruduce multiple phenotypes in response to evironmental conditions. There are many factors affecting phenotypic plasticity. The aim of this thesis is to summarize the current knowledge of phenotypic plasticity of aquatic insects with emphasis on the role of temperature and food availability. The review is complemented by a laboratory experiments designed to investigate the effect of temperature and food availability on growth and development rate of diving beetle Acilius canaliculatus (Coleoptera: Dytiscidae). The results are discussed in the light of the ecological concepts of temperature-size rule and developmental isomorphy.
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Biosystematic studies in the family Cyperaceae
KOŠNAR, Jan
The thesis was focused on the microevolutionary mechanisms that contribute to morphological diversity in selected members of the sedge family (Cyperaceae). Natural hybridization, evidenced from both morphological characters and molecular markers, was revealed to be a potentially important source of diversification in the tropical spikerushes of Eleocharis subgenus Limnochloa. High levels of phenotypic plasticity of clonal growth but rare genetic (ecotypic) differentiation among contrasting morphotypes were found in the polymorphic species Carex nigra, which implied that taxonomic splitting of the species was unreasonable.
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