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The effect of experience and floral traits on preferences and flower constancy in Eristalis tenax
Haveldová, Alice ; Janovský, Zdeněk (advisor) ; Mikát, Michael (referee)
Intraspecific pollen transfer is crucial for ensuring successful pollination and subsequent reproduction of many plant species. Mechanisms directly influenced by plants, that can increase the proportion of intraspecific pollen through their flower form (individual floral traits) are preferences and constancy of pollinators. The proportion of intraspecific pollen transfer increases with higher preferences or constancy of the pollinator. Pollinator preferences and constancy tend to change over its lifetime based on experience with the flowers they have visited. Very few studies have examined the effect of experience on preferences and especially constancy in relation to multiple floral traits in hoverflies (Syrphidae, Diptera), which are an important pollinator group. In this study, I investigated the degree of preference and constancy of common drone fly Eristalis tenax L (Syrphidae) as a function of two floral traits, colour and size, and as a function of experience. I did so by monitoring visits and flights in arrays of artificial flowers. The hoverflies were of two origins: naïve (reared under laboratory conditions, with no previous experience of visiting flowers) and experienced (captured in the wild with previous experience). Naïve individuals made decisions primarily based on colour, with size...
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Ability to Discriminate Floral Morphotypes by Hoverflies
Matoušková, Eva ; Janovský, Zdeněk (advisor) ; Klečka, Jan (referee)
The attractiveness of flowers to pollinators is mediated by several floral traits. The ability to discriminate the flowers based on these floral traits is crucial for the flower reproduction and pollinator nutrition and reproduction. We tested three floral traits - colour, size and shape - along with their combinations using artificially 3D printed flowers on model organism Eristalis tenax in laboratory conditions. Our findings revealed that the most important floral trait was the colour followed by size. Additionally, the effect of colour was enhanced by size, but only for the preferred colour. This suggests that preferences for specific floral traits can be structured. The effect of symmetry was not significant. Subsequently, we observed non-naïve hoverflies and bumblebees in the field on flower patch consisting of devil's-bit scabious (Succisa pratensis). We were interested in the role of other floral traits when the colour and size were indistinguishable. The most important characteristics were height and effective number of florets in the inflorescence. The hoverflies tend to do longer visits than bumblebees and visited more flowers as well. Conversely, bumblebees did shorter but more efficient visits, likely due to their eusociality. Keywords: Syrphidae, Apidae, Eristalis tenax, Bombus spp.,...
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The efficiency of pollen transfer by selected functional groups of pollinators and the ability of plants to influence it
Freudenfeld, Martin ; Janovský, Zdeněk (advisor) ; Klečka, Jan (referee)
Pollinator functional groups differ in their pollen carryover effectiveness and in the importance for particular species of plants, due to specific functional traits of pollinator functional groups. Plant species differ in their specific functional traits too. I determined pollen loads of pollinators by swabbing their bodies with a jelly to compare pollen carryover effectiveness of pollinator functional groups. This helped me to decide which pollinator functional groups are the most and the least effective in pollen carryover. I considered an influence of the last visited flower to make the comparison of pollen loads more accurate. I also calculated proportions of conspecific and heterospecific pollen grains carried on bodies of pollinators to estimate their carryover effectiveness. Likewise, I compared composition of pollen morphotypes carried on pollinator's bodies to find out differences among pollinator functional groups. My analysis shows that pollen carryover effectiveness of particular pollinator functional groups differ. Apis mellifera and solitary bees have the biggest pollen loads, on the other hand, butterfies and small dipterans have the smallest pollen loads. The last visited flower influences an amount of pollen grains carried on bodies of pollinators. Relative pollen loads of some...
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Microclimatic conditions as determinant of Vaccinium myrtillus pollination
Veljačiková, Hana ; Janovský, Zdeněk (advisor) ; Červenková, Zita (referee)
Climate change affects phenology and distribution of plants and animals and causes a mismatch in plant-pollinator interactions. These changes are clearly manifested in extreme environments such as mountains or the beginning of the growing season. Vaccinium myrtillus is an important temperate and boreal species, inhabiting and often dominating such environments where changes due to global warming are already appearing. Flowers start to appear in April and May at the very beginning of the growing season. Without pollination, flower will almost never form a fruit. When comparing fruit set, it is possible to observe whether the flower has been pollinated and thus the quality of pollination in given conditions. Using experiments on the mountain heath in the Brdy Protected Land Area, I found out how the quality of pollination differs in different microclimatic conditions. I compared fruit set of chosen flowers and seed set in their fruits. Flowers blooming at the end of the flowering season had the greatest success in fruit formation, when I recorded a greater number of pollinators in the experimental environment. V. myrtillus bloomed more intensively at the beginning of the flowering season. Even so, fewer fruits were produced from flowers at that time. Bumblebees abundance was correlated to fruit and...
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Causes of limitation of plant reproduction by pollen and resource availability
Kalousková, Petra ; Janovský, Zdeněk (advisor) ; Sklenář, Petr (referee)
Plant seed production depends on many factors: their life history, the environment they grow in, and other factors such as biotic interactions. However, the immediate cause of the reduction in seed production is the lack of partners or the lack of resources available for seed production. This bachelor thesis aims to summarize and analyze the mechanisms of action and the relative importance of individual causes of limitation of plant seed production. Most plants are pollen limited at least in some seasons or in some localities, in the rest of the situations are plants resource limited. Pollen limitation can be quantitative (low pollen deposition) or qualitative (low quality of pollen). Existing theoretical models of pollen and resource limitation compare use of resources either to attract pollinators (increased flower size, increased number of rewards) and increase the chances of encountering them (change of phenology or prolongation of flowering) or to produce seeds. Plants can sometimes be seemingly pollen limited, with the pollen supplementation increasing seed production at the cost of reducing reproductive effort in the upcoming years. However, the most significant feature of pollination, which is often reflected in the alternation of reduced seed production due to insufficient pollen...
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The influence of intensity of agricultural land use on pollinator diversity and abundance
Tomsová, Lucie ; Janovský, Zdeněk (advisor) ; Černá, Kristýna (referee)
Agricultural intensification is one of the main reasons for the decline of biodiversity and ecosystem services in agricultural landscape. One of the ecosystem services is pollination, which helps to preserve the biodiversity of wild plants in cultural landscape and is also vital for production of food, especially fruits and vegetables. Decreasing management intensity could be one of the potential solutions for maintaining sufficient level of pollination in the agricultural landscape. This can be achieved at least on parts of agricultural land. Also, certain areas of cultivated land can be excluded from production in exchange for subsidies for farmers who agree to implement this method. For this reason, the European Union has introduced organic farming and agri- environmental schemes. The aim of the study was to determine whether currently applied low-intensity management is sufficiently effective to protect wild plants, pollinators and their mutual relations. And if so, whether it is due to the decreased management intensity or due to the floral sources available. Another question dealt with is how the effects of organic farming depend on the landscape structure. Results of various studies dealing with this topic were qualitatively compared. Current studies show that organic farming has positive...
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Succisa pratensis and impacts of herbivores on individual fitness
Janovský, Zdeněk ; Münzbergová, Zuzana (advisor) ; Pergl, Jan (referee)
Zdeněk Janovský Succisa pratensis and impact of herbivores on individual fitness In this master thesis I tried to examine the impact of three herbivore groups on both short- term and long-term fitness of Succisa pratensis individuals. Concretely I studied these three herbivore groups: (i) folivores; (ii) stalk grazers; and (iii) seed predators. The impact of folivores and stalk grazers was studied in a four-year study on repeatedly censused individually marked S. pratensis plants on six sites. The impact of seed predators was studied in a separate experiment. Stalk grazers and seed predators have a direct negative influence on short-term plant fitness. However, the impacts of stalk grazing were offset by affected plants by means of increased long-term flowering probability. On the other hand folivores have a long-term negative effect on plant reproductive effort despite their short-term positive influence on survival and clonal reproduction. Probable explanation of this observed phenomenon could be due to the influence of folivores on reproductive effort of the plants already in the year of their occurrence. The impact of seed predators is very variable, although higher plants suffered from higher proportion of destroyed seeds. A conceptual model of possible impacts of these three herbivore groups on...
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Pollinator movement and orientation at small spatial scales
Matoušková, Eva ; Janovský, Zdeněk (advisor) ; Tropek, Robert (referee)
Pollination is interesting andcomplex interaction between insects and plants which is essential for a wide spectrum of plants and animals. Hoverflies (Diptera: Syrphidae) and bees (Hymenoptera: Anthophila) are one of the most common pollinators in the Central Europe and are mostly involved in pollination of local plants. To maintain pollination, it is necessary the movement of pollinator from one flower of a specific species to another flower of the same species. This movement is affected by a number of factors based on both the environmental and pollinator traits. The aim of this work is to explore the nature of traits affecting pollinator flight between plants on small spatial scales, to classify the knowledge about the influence of pollinator and ambient effects to compare the differences between hoverflies and bees and suggest further possible fields of research. Keywords: pollination, hoverflies, bees, Syrphidae, Anthophila, movement
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The role of biotic interactions in population biology of meadow plants
Janovský, Zdeněk ; Herben, Tomáš (advisor) ; Lepš, Jan (referee) ; Ehrlen, Johan (referee)
In present thesis, I treat the topic of impacts of plant-animal interactions, namely herbivory and pollination, on plant life cycle and lifetime fitness. First, I identify the components of the impact of plant-animal interactions: i) interaction frequency; ii) per-interaction effect; iii) sensitivity of the plant's life cycle to the changes in vital rate impacted by the animals. Furthermore, I also classify other causes changing the outcome of a plant-animal interaction into two categories: i) plant's traits; ii) plant's environment. A review of extant literature on the topic revealed that especially the role of plant's environment in changing the outcome of plant-animal interactions is largely understudied and I attempt to reduce this gap in knowledge in the five detailed studies encompassed in this thesis. The detailed studies focus on a model system of Central European wet grasslands and especially on three species typical to it: Succisa pratensis, Achillea millefolium and A. ptarmica. The first two studies examine the effects of environment on frequency of plant- animal interactions. The next two studies are more integrative, one focusing on the impacts of different herbivore groups on the complete life cycle and the other on interaction of herbivory and pollination on plant lifetime fitness....
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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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