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Influence of landscape fragmentation on characteristics of pollination networks in meadows
Filip, Jan ; Tropek, Robert (advisor) ; Storch, David (referee)
Traditionally managed semi-natural grasslands are unique for their high plant species richness. Pollinators are crucial for maintaining this plant biodiversity. Plant-pollinator interactions of these grasslands are influenced by habitat fragmentation since the 20th century. Main drivers of this landspace disturbance are abandonment and agricultural usage. Network analysis of structural characteristics changes in plant-pollinator interactions can facilitate understanding of habitat fragmentation and its impacts on pollination interactions.
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Impact of fire disturbances on lepidopteran communities
Koďousek, Václav ; Tropek, Robert (advisor) ; Sedláček, Ondřej (referee)
In this work I present the main effects of fire disturbances on lepidopteran communities and changes, that the fire disturbance causes. I primarily deal with characterization of fire disturbance, lepidopteran responses and changes in species composition and diversity, which they create in lepidopteran communities. Both butterflies and moths are in the last decades in decline and on the contrary fire disturbances are getting more frequent. At the same time the understanding of lepidopteran decline grows and management for protection of lepidopterans, where fire plays an important role, is getting more precise. With the use of prescribed burning, we can support the protection of both butterflies and moths and their habitats. The aim of my work was to summarize the knowledge about the effects that fire disturbances can have on Lepidoptera and their communities and also explore its potential use in their protection. Key words: natural disturbance, fire disturbance, lepidopteran communities, prescribed burning, wildfires, pyrophilous species
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Effect of floral rewards on specialization of hoverflies (Diptera, Syrphidae) in meadows of Železné hory
Filip, Jan ; Tropek, Robert (advisor) ; Keil, Petr (referee)
Traditionally managed temperate semi-natural meadows are generally considered as one of the most diverse habitats worldwide. During the past decades, management changes and abandonment of meadows pose serious threats to communities of both flowering plants and pollinators. However, the extent to which are pollinators affected by changes in floral resources still remain unknown. To investigate the effect of floral resources on visitation specialization, species richness and abundance of hoverflies, pollination networks from 13 meadows in the Železné hory PLA were constructed and analysed. Moreover, patterns were recorded on two spatial scales, in transects and in the whole meadows. To specify the specialization of hoverfly pollinators, unvisited plant species and all resources present on a site (transect/meadow), offered by plants as floral abundance and nectar rewards, was added in the networks. Relationships between plant species richness, floral abundance and nectar sugar production were positively correlated with visitation specialization of hoverflies on the meadow scale. Species richness and abundance of hoverflies was affected by floral resources on the transect scale, unlike the specialization of hoverflies. The usage of extended network indices may act as an improvement towards the better...
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Cross-taxon congruence in species diversity in non-forest habitats
Koštíř, Vojtěch ; Sedláček, Ondřej (advisor) ; Tropek, Robert (referee)
Relationships between different groups of organisms are one of the major factors shaping Earth's ecosystems. This thesis analyses correlations in species composition and species richness at different spatial scales. Knowledge of these so-called cross-taxon congruences are crucial for proper nature conservation and management of species-rich localities of non-forest habitats. One of the main aims of the thesis was to find suitable surrogate groups for biodiversity conservation in non-forest habitats. Invertebrates and vascular plants are generally good surrogate groups for biodiversity conservation. For example, ground beetles seem to have good correlations in species richness at large spatial scales. However, their importance deeply declines at small spatial scales. At both scales, the species richness of ants and butterflies positively correlates with general species richness. Vertebrates, on the other hand, appear to be a bad surrogate taxon, except for birds which can be placed into a shopping basket with invertebrates and plants. At small scales, species composition differs with the type of agricultural use at studied localities. Umbrella species can be selected from these specific species communities. Best umbrella species for non-forest habitats are invertebrate herbivores such as butterflies...
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Reproductive strategies of flowering plants in Afromontane grasslands along an elevational gradient on Mount Cameroon
Anýž, Dominik ; Tropek, Robert (advisor) ; Münzbergová, Zuzana (referee)
in English Montane conditions represent a relatively unfavorable climate for most plants and their pollinators. Consequently, zoogamous plant species growing at high elevations are expected to be pollen limited. According to the "reproductive assurance" and "transmission advantage" hypotheses, such pollen-limited plants will adapt more toward self-pollination than plants in communities with more reliable pollination. To test such predictions, I studied reproduction strategies and pollen limitation of ten zoogamous plant species at three elevations (2,800 m a.s.l. 3,500 m a.s.l. and 4,000 m a.s.l.) in montane grasslands on Mount Cameroon, West/Central Africa. I compared seed sets produces by plants with four treatments in our extensive hand-pollination experiments: autogamy, geitonogamy, outcrossing, and natural control. One experimental species was found to be self-incompatible, six species were partially self-compatible, and one was completely self-compatible and predominantly selfing. In five of these plant species, I compared the reproduction strategies and pollen limitation among the elevations. I found that pollen limitation did rise in two species, we expect this to be due to the fact that the species were already pollen limited at 2,800 m a.s.l. Contrary to the two hypotheses, selfing did...
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Causes of bee loss (Anthophila) in the landscape
Bureš, Vít ; Straka, Jakub (advisor) ; Tropek, Robert (referee)
Bees (Anthophila) are one of the most important pollinators in the majority of Earth's biotopes. They interact with almost one-fifth of flowering plants and together with other pollinators they secure one- third of human food sources. Since the end of World war II,along-term decrease in numbers of bees and other insects is observed due to degradation of natural habitats, expansion of agriculture, pesticide usage, parasites, and infections. In North America and Europe, several studies reported a significant loss of bee diversity and abundance. The situation in tropics is unclear and there is not enough evidence if bees are threatened there. Specific changes in relation to the decrease of the bee population are observed in the case of honey bee (Apis mellifera). Due to human beekeeping activities and specific honey bee attributes such as bigger body size or tolerance to lower temperature, honey bees show different trends in their abundance than other bees. This study discusses the causes of these losses and possible future consequences, for example, the collapse of ecosystems as a result of pollination crisis or lack of human food. On the other hand, several phenomena such as extensive agriculture, green cities, or wildfires have a positive impact on bee abundance and diversity. This thesis presents...
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The role of plant functional traits in organising plant-pollinator interactions.
Klomberg, Yannick Geert ; Tropek, Robert (advisor) ; Ollerton, Jeff (referee) ; Lunau, Klaus (referee)
Floral traits have been a key field of research in pollination ecology. The vast extent of traits studied have shown to be of influence in attracting (or deterring) visitors. Because flowers are complex organs with complicated relationships among many traits, studies of trait combinations (so-called pollination syndromes) have often been applied to help understand and predict interactions between flowers and their visitors. However, the role of individual traits should not be overlooked, especially because their roles can differ among pollinator functional groups or vary under particular conditions. In this dissertation I give insights on the plant-pollinator interactions, the role of selected pollination related traits in shaping these interactions, and how such traits influence the mating systems and pollen limitation. We studied these interactions on Mount Cameroon (Cameroon) and in the Iron Mountains (Železné Hory; Czechia) Protected Landscape Area, where we conducted intensive observational studies, exclusion, and hand-pollination experiments. Our results highlighted the importance of individual traits in shaping plant-pollinator interactions and plant mating systems. Nevertheless, the role and predictive ability of floral traits differed spatiotemporally and among pollinator functional...
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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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Influence of anthropogenic pollution by heavy metals on freshwater invertebrates
Varvažovská, Adéla ; Tropek, Robert (advisor) ; Vinkler, Michal (referee)
This bachelor thesis summarizes the effects of heavy metals on freshwater invertebrates in post- industrial areas. There are heavy metals of dual origin in nature, essential and non-essential. Non-essential heavy metals which get to nature by human activities can have a negative impact on lives of organisms in the ecosystem. If the organisms can't cope with and adapt to heavy metals, it can be lethal for them. Some organisms are more tolerant than others and can survive in heavy metal concentrations which would be a big fatal to other organisms. In case of dangerous concentration for more resistant species, the resistant species create special adaptations which help them survive and prosper in the polluted areas. Mechanisms and adaptations that prevent the body from damaging cell structures and organs in the body can be of different nature. Morphological changes consist of changing the color, shape of the body or removing parts where heavy metals accumulate. Physiological mechanisms help to modify the metabolism and mode of accumulation of substances in the body. Many mechanisms, as well as the consequences of heavy metals, can be used to bioindicate polluted waters. Such observation can then be used in other disciplines, for exampl in environmental protection. Study of documents from professional...
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