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Effect of pollination on seedset and yield of buckwheat (\kur{Fagopyrum esculentum}).
NOLČ, Radek
Common buckwheat is a attracting plant for many pollinators, therefore it be helping to restore biodiversity in the landscape. The most important of pollinators of buc kwheat are honeybee and hoverflies. The aim of this thesis was to find out effect of pollination of buckwheat sown with honeybees and the others pollinators on the seed set and yield of archenes in different varieties of buckwheat. A small-plot field experiment was established with three varieties of common buckwheat in the Pilsen Region, in the place of Zábělá. Before flowering began, half of the plots were covered with insect screens. The buckwheat stand was evaluated from the point of: plants height, number of branches, number of flowers and inflorescences on a plant, nectar volume in Thrum flowers, flowering time, number of archenes on a plant, the weight of thousand of archenes and the yield of archenes. Monitoring of pollinators was performed at the time of buckwheat flowering at 9, 10, 11, 12 and 14 hours, during 10 minutes, using photos. Nectar collection took place on five consecu tive days, from 16. 7. until 20. 7., at 9, 10 and 11 hours. Total of 31 insect species were recorded on buckwheat flowers. The most common effective pollinators of buckwheat were honeybees, (39,7 %) and hoverflies (37,5 %). The significant difference in nectar production was found among the tested buckwheat varieties. The yield of achenes on covered plants was 87 % lower than on freely accessible plants.
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Factors affecting behaviour of avian predators to hoverflies (Syrphidae) and their models (Aculeata)
Truhlářová, Marie ; Exnerová, Alice (advisor) ; Sedláček, František (referee)
Batesian mimicry is an antipredator strategy used by harmless species to mimic dangerous models by their appearance. The so-called imperfect mimics are a phenomenon within Batesian mimicry. It would be expected that Batesian mimics are selected to resemble the model as perfectly as possible. However, in some species the resemblance is very poor. The aim of this study was to test reaction of predators towards a textbook example of Batesian mimics with imperfect mimicry, i.e., hoverflies (Syrphidae) and to verify some of the hypotheses describing imperfect mimicry. We conducted two experiments in which the model predators were great tits (Parus major). The topic of the first experiment was the effect of diversity of models on categorization and generalization of hoverflies. Birds were divided into two groups, with the first group receiving high diversity of models (10 species of Hymenoptera) and second group receiving low diversity of models (2 species of Hymenoptera). There were two parts of this experiment. Categorization training when great tits learn to discriminate between two categories of prey, palatable and unpalatable and generalization test, when great tits generalized their experience from categorization training to novel prey. Palatable prey was represented by non-mimetic flies (Diptera),...
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Mimicry in hoverflies
Daňková, Klára ; Hadrava, Jiří (advisor) ; Raška, Jan (referee)
Batesian mimicry, the imitation of harmful species manifested by harmless ones, could bring a lower risk of predation to the mimetic species. Therefore, it occurs in many different taxa. Hoverflies (Diptera: Syrphidae) could stand for one of the most various mimics. This worldwide-distributed family is known for taking shape of many Aculeata species using plenty of different adaptation connected with colouration, morphology and even behaviour. The aim of this work is to review the diversity of mimicry in Syrphidae, highlight the main selection pressures and to put forward a potential field of future research. Hoverflies are being studied for the last two hundred years. However, just several study approaches are dominating the field. In order to open a new chapter of their research, I bring a wider synthesis of knowledge related to the ecological and evolutionary context of this phenomenon.
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Mimicry in hoverflies
Daňková, Klára ; Hadrava, Jiří (advisor) ; Raška, Jan (referee)
Batesian mimicry, the imitation of harmful species manifested by harmless ones, could bring a lower risk of predation to the mimetic species. Therefore, it occurs in many different taxa. Hoverflies (Diptera: Syrphidae) could stand for one of the most various mimics. This worldwide-distributed family is known for taking shape of many Aculeata species using plenty of different adaptation connected with colouration, morphology and even behaviour. The aim of this work is to review the diversity of mimicry in Syrphidae, highlight the main selection pressures and to put forward a potential field of future research. Hoverflies are being studied for the last two hundred years. However, just several study approaches are dominating the field. In order to open a new chapter of their research, I bring a wider synthesis of knowledge related to the ecological and evolutionary context of this phenomenon.
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Reproduction of \kur{Achillea millefolium} agg. and \kur{Achillea ptarmica} in meadows and verges
TOMŠOVÁ, Pavla
Several changes in land use during the last 50 years of 20th century had a significant impact on the composition of traditional meadows. The abundance of many plant species typical for traditionally managed meadows has declined. But some of these species have found a refuge in habitats such as field margins and road verges. The aim of this study was to describe how the reproduction success of two related Achillea species A. millefolium agg. and A. ptarmica depends on (i) the particular habitat in which they grow (meadow/verge); (ii) the abundance of pollinators in the study site; and (iii) timing of flowering within the season. Moreover, the longevity of individual flowers of the two taxa has been studied in order assess the width of the time frame the reproduction takes place in. These objectives were achieved by means of measuring plant total seed production and germination as proxies of reproductive success both in meadow and verge populations at the beginning, peak and end of the flowering season of the two species in 2012. The plants were chosen at plots, where concurrently a pollinator survey has been conducted as the part of the broader project. The durations of the male and female phases of individual flowers have been studied in separate experiments.
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