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Factors affecting pollen transfer effectiveness
Švanda, Petr ; Štenc, Jakub (advisor) ; Straka, Jakub (referee)
Pollen transfer efficiency, i.e., the proportion of pollen that is successfully transferred to a plant of the same species, significantly affects plant reproductive biology and creates a potentially strong selection pressure for the development of specialized strategies to increase pollen transfer efficiency. Precisely because of its importance within pollination biology, the efficiency of pollen transfer was a frequent subject of studies, in which, however, its interpretation differed depending on the method used, making it difficult to compare individual studies. Moreover, the work to date does not offer a satisfactory methodological framework for comparing the effectiveness of pollen transfer across the studied systems. The effectiveness of pollinators is primarily affected by the amount of pollen removed, the amount and quality of pollen deposited and frequency of pollinator visits. These factors are affected by additional influences, for example the behavior of the pollinator, the number of open flowers within the inflorescence or the environment variability. The result of this work is the retrieval of a methodological framework capable of determining and comparing the relevance of pollinators to pollen trasffer across plant species, which will be possible to link with theoretical models...
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The Competition Among Pollinators and the Impact of Managed Bees on Wild Pollinator Populations
Voldřichová, Alžběta ; Straka, Jakub (advisor) ; Štenc, Jakub (referee)
Pollinators play an important role in ecosystems. Their ties to plants are essential for the reproduction of many plant species and thus for the protection of species diversity. Pollinator species therefore need to be protected. But to protect them effectively, it is necessary to understand the relationships between pollinators. However, the interaction between pollinators is a complex topic that needs further research. One of the current threats to pollinator populations is commercial pollinator rearing. Commercially reared species, especially Apis mellifera and Bombus terrestris, have been introduced almost all over the planet due to their positive effects on crop yields and its by-products. Moreover, in their native ranges they are bred in much higher concentrations than would be possible without human intervention. But high concentrations of commercial pollinators do affect populations of wild ones. This thesis describes forms of pollinator competition and addresses the impact of commercially reared pollinators on wild pollinator populations. KEY WORDS: Honeybee - Bumblebee - Hoverfly - Nest usurpation - Pathogen transfer - Species protection - Invasive species
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Influence of plant pollinator spectra generalization on plant reproductive success
Hanusová, Natálie ; Štenc, Jakub (advisor) ; Hadrava, Jiří (referee)
Plants are pollinated by variously wide pollinator spectra. Plants pollinated by a wide spectrum of pollinators are called generalized plants. There are many factors leading to the generalized strategy of plants including their morphology, environment context, local pollinator community, and competition between plants for effective pollinators. However, generalization is connected to potential risk because not all pollinators are equally efficient and effective. The Generalization of plants is a very flexible way how to deal with non-predictable conditions and achieve successful sexual reproduction. Further investigation is needed to understand how the generalization of plant-pollinator spectra shapes plants sexual reproduction. Keywords: pollinator spectra generalization, pollination, plants reproduction, plants reproductive success
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Plant responses to deer browsing and the consequences for further browsing
Dudlová, Tamara ; Lepková, Barbora (advisor) ; Štenc, Jakub (referee)
(English) The bachelor thesis focuses on the interaction of plants and herbivores, specifically deer. The main question is if (and possibly how) the changes induced in the plants by deer browsing affect the probability of re-browsing. I tried to answer the question by reviewing published literature. Plants respond to browsing by tolerance (compensatory growth) or resistance (production of defensive chemical compounds), depending on the plant's life strategy. Tolerance prevails in adult woody plants and grasses; resistance prevails in young woody plants and forbs. In resistant plants, browsing increases the content of phenolic substances and decreases the cellulose content, while tolerant species react in the opposite way. It is the contents of these substances, which are negatively correlated, that are key to food selection by deer. Large species of deer generally prefer plants with more cellulose, which they are able to digest efficiently. Smaller species prefer plants with lower cellulose content and higher concentration of simple sugars. These more nutritious plants are protected from browsing by phenolic substances, which smaller deer species are able to neutralize more effectively. Only a few studies have addressed the issue of re-browsing of the same plants, and their results are ambiguous....
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Changes in pollinator behaviour under different plant spatial aggregation
Štenc, Jakub ; Janovský, Zdeněk (advisor) ; Bartoš, Michael (referee)
Plants often occur aggregated into clusters and this spatial pattern is supposed to affect pollinator behaviour and pollen dispersal. Such pollinator reaction may influence reproductive success of zoogamous plant species both in terms of number of available mates and their genetic diversity (nearby growing plant individuals are also often closely related, especially in clonal plants). In the present thesis, I investigated the influence of plant spatial aggregation on pollinator behaviour and how this translates into pollen transfer. For that purpose, I carried three experiments. In the Experiment 1, I used potted plants placed into arrays and aggregated into four patches in order to track the pollen dispersal by means of a UV-dye pollen analogue. I manipulated distances between plants within clusters (dense × loose) and between clusters (near × far). I conducted this experiment for three plant species differing in their pollinator spectra. In the Experiment 2, I observed pollinator foraging sequences (sequences of visited plant individuals) under the same experimental design as for the first experiment, but I carried out this experiment for five plant species. In addition in one study species, Dianthus carthusianorum, I conducted the Experiment 3 to get better insight into pollination effectiveness...
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Evolutionary significance of visual traits of flowers and their influence on the pollinator constancy
Haveldová, Alice ; Štenc, Jakub (advisor) ; Klečka, Jan (referee)
Flower constancy is a behavior in which the pollinator visits flowers of the same plant species in a sequence more than would correspond to its preference for the given plant. This behavior is advantageous for plants because it can ensure efficient intraspecific pollen transfer which has a positive effect on their biological fitness. More efficient pollen transfer can lead to the selection of (visual and olfactory) flower traits that encourage flower constancy of pollinators. The main visual floral traits that affect constancy include colour, pattern, shape and size. However, these traits are of different importance for pollinators when they are deciding which flower to visit, and therefore their effect on flower constancy varies. The degree of flower constancy also differs between the functional groups of pollinators. Flower constancy is generally low in vertebrates, but insects and especially representatives of the order Hymenoptera are often flower constant.
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The importance of the arrangement of flowers in the inflorescence on the plant reproductive success
Chvojková, Karolína ; Štenc, Jakub (advisor) ; Sklenář, Petr (referee)
Inflorescence and its properties have a fundamental influence on the pollinating behavior of pollinators, which can affect the resulting reproductive success of plants. Clustering of more flowers in the inflorescence is an advantage for plants due to the diversification of pollen sources and greater visual supply, which can attract more pollinators and thus increase the chance of pollen transfer to other individuals and ensure genetic variability of the offspring. The disadvantage of multiple flowers in one inflorescence may be both an increase in energy requirements for the formation and maintenance of multiple flowers and an increased risk of geitonogamy. Plants prevent geitonogamy within the inflorescence by various adaptations. The aim of this work is to evaluate the effect of inflorescence arrangement on successful plant reproduction. When studying the arrangement of flowers in the inflorescence, it is necessary to take into count not only their morphology, i.e. the shape, number, size and arrangement of flowers, but also other functional properties in the form of genitals, sterility and rewards. The resulting effect of flower arrangement on the reproductive success of plants also depends on the vectors that transfer pollen, in this case especially insect pollinators, which are affected by...
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Changes in pollinator behaviour under different plant spatial aggregation
Štenc, Jakub ; Janovský, Zdeněk (advisor) ; Bartoš, Michael (referee)
Plants often occur aggregated into clusters and this spatial pattern is supposed to affect pollinator behaviour and pollen dispersal. Such pollinator reaction may influence reproductive success of zoogamous plant species both in terms of number of available mates and their genetic diversity (nearby growing plant individuals are also often closely related, especially in clonal plants). In the present thesis, I investigated the influence of plant spatial aggregation on pollinator behaviour and how this translates into pollen transfer. For that purpose, I carried three experiments. In the Experiment 1, I used potted plants placed into arrays and aggregated into four patches in order to track the pollen dispersal by means of a UV-dye pollen analogue. I manipulated distances between plants within clusters (dense × loose) and between clusters (near × far). I conducted this experiment for three plant species differing in their pollinator spectra. In the Experiment 2, I observed pollinator foraging sequences (sequences of visited plant individuals) under the same experimental design as for the first experiment, but I carried out this experiment for five plant species. In addition in one study species, Dianthus carthusianorum, I conducted the Experiment 3 to get better insight into pollination effectiveness...
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Pollination efficiency as a function of plant spatial aggregation and pollinator functional traits
Štenc, Jakub ; Janovský, Zdeněk (advisor) ; Tropek, Robert (referee)
Pollen transfer between zoogamous plants is strongly influenced by spatial structure of plant population and functional traits of its vectors - pollinators. Spatial structure of plants can be described by attributes that may affect pollen transfer, such as population size, density, aggregation and composition of surrounding plants. Both the main pollintor groups and individual pollinators differ in pollen transfer distance, pollen carry-over capacity, food specialisation, preferences and sensoric abilities. Due to these differences, they vary in impact on pollen transfer in a different spatial structure of plant population. Understanding the impact of individual attributes of both of these components and their influence on pollination can help us to get a better idea of how sexual reproduction works at the plant population level. Key words pollination, plant-pollinator interactions, spatial structure of population, pollen transfer, pollinators, sexual reproduction of plants
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