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Reproductive success in pollinating deceptive orchids
Steffelová, Michaela ; Kindlmann, Pavel (advisor) ; Janeček, Štěpán (referee)
One third of plant species in the Orchidaceae family use a deceptive strategy to fool pollinators. There are many strategies for deceiving orchids, and each has its advantages and disadvantages. Reproductive success is a quantity usually defined as the ratio of the number of fruits to the number of flowers produced by the plant during a given season. It is influenced by many factors. This work is written in the form of a literature review and deals with the factors that influence the reproductive success of deceptive orchids in connection with their pollination. The reproductive success of the orchid depends mainly on the density of the inflorescence, the time of flowering or the place where the plant is located. These factors in turn affect the pollinators, who are largely responsible for the orchid's reproductive success. The specialized strategies of deceptive orchids lead to a decrease in the reproductive success of an individual, but a low population density or lower pollinator attendance at one inflorescence, on the contrary, lead to an increase in the reproductive success of a deceptive orchid individual. Deceptive orchids do not use a strategy that is clearly disadvantageous, so it is unlikely that the orchid will become extinct in the future due to its pollination strategy. Key words:...
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Diversity of floral functional traits and its seasonal changes in alpine environment
Plachtová, Kateřina ; Sklenář, Petr (advisor) ; Janeček, Štěpán (referee)
Floral functional traits characterize flowers and mediate contact between entomogamous flowers and their pollinators. Their form depends on many biotic and abiotic factors. The floral functional traits tend to be similar in high altitudes. However, the overall diversity of the floral functional traits does not vary significantly between altitudes. On the other hand, how temporal diversity of the floral functional traits varies during the flowering season was not studied yet. And this is the focus of this thesis. The aim of this study is to examine the hypothesis, whether the diversity of the floral functional traits changes in plant communities of alpine and montane meadows during the flowering season and also between them. The alpine and montane meadows are located in the area of Luční hora in the Krkonoše National Park. Morphological and spectral characteristics of the flowers were measured on both meadows. Abundance of flowering species and their flowers were measured every three weeks during five periods of the season. Diversity of the floral functional traits was obtained, for both meadows and all the measured periods of season, by weighting the floral functional traits with the species abundances. Using multivariate analysis, differences of temporal and altitudinal diversity were studied....
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Reproductive success in orchid pollination
Steffelová, Michaela ; Kindlmann, Pavel (advisor) ; Janeček, Štěpán (referee)
The family Orchidaceae is very diverse; it is characterized by specialized strategies for attracting pollinators. Orchid species with deceptive flowers are special in that they do not produce nectar. This has advantages and disadvantages. The type of strategy determines the degree of reproductive success of orchids: sometimes positively, sometimes negatively. Although research on orchids has been going on for centuries, these plants are still not sufficiently studied. This bachelor thesis is written in the form of a literature research and examines the mechanisms that influence the reproductive success of orchids in relation to their pollination. The least studied phenomenon in this area is the relationship between floral display and orchid reproductive success. In most of the studies cited here, there is a linear positive relationship, but the results are far from being conclusive. Key words: Orchidaceae, pollination, reproductive success, floral display, rewarding species, deceptive species
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Physiology and functional anatomy of nectarivorous birds
Sejfová, Zuzana ; Janeček, Štěpán (advisor) ; Sam, Kateřina (referee)
Hummingbirds, sunbirds and a large part of honeyeaters belong to the most specialized nectarivores. During the evolution they have developed a number of adaptations in reaction to the specificity of their diet. The amount of studies focused on the adaptations connected with the digestion of nectar is not big, but is still growing. One of the characteristics of these birds is very fast and effective transport of consumed sugars across the intestinal epithelium. Furthermore they are tolerant to a very low nitrogen intake and extremely high daily intake of water. Sunbirds and honeyeaters are able to modulate the rate of water absorption in the intestine, but hummingbirds are not and they absorb almost all the consumed water. During the evolution excessive water intake together with a low concentration of salt presented in the diet led to changes in renal morphology that allows the production of an exceptionally dilute urine. The hovering flight of hummingbirds is well known and very well studied. The unique anatomy of hummingbird's wings allows the power production also during upstroke. Thanks to this hummingbirds are able to hover for a very long time and even in condition that are unsuitable for flight. Also sunbirds and honeyeaters sometimes hover during feeding. Nevertheless the mechanics of their hovering...
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Morphological adaptations for nectarivory in birds
Sailerová, Barbora ; Hořák, David (advisor) ; Janeček, Štěpán (referee)
Scientists have been interested in adaptation of nectar-feeding birds for a long time. I tried to summarize information about these adaptation. About hummingbirds's, sunbird's and honeyeater's bill and tongue, about body size and how flower influences nectar intake. Nectar-feeding birds has extended and curved bill, which is an adaptation to flowers visiting by these birds. The tongue is a tool for nectar intake, its inner structure allows nectar intake. Tongue is tubular and hummingbird's and sunbird's tongue is proximal bifurcate, honeyeater's tongue has brush tip. Nectar-feeding birds are generally of small body size and larger species have to intake more insects because of higher energetic requirements. Some flowers don't allow to perch and nectar-feeding birds have to intake nectar in flight. Therefore especially hummingbirds and some sunbirds evolved a hovering. If its possible, these birds perch when they collect nectar.
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Sunbird foraging behaviour on flowers of Impatiens sakeriana
Sejfová, Zuzana ; Janeček, Štěpán (advisor) ; Fuchs, Roman (referee)
Although the Old World sunbirds are generally considered to be an ecological analogy of the New World hummingbirds, until recently it was believed that in contrast to hummingbirds, sunbirds perch while feeding. This opinion was largely supported by several studies, mostly from South Africa, describing adaptations of plants facilitating this behaviour. However, recent studies have shown that the Old World nectarivores hover while feeding in front of flowers more frequently than previously thought. We focused on a specialised West African pollination system of Impatiens sakeriana and the foraging behaviour of its two major pollinators, the Northern Double-collared Sunbird (Cinnyris reichenowi) and the Cameroon Sunbird (Cyanomitra oritis). Based on continuous monitoring in their natural habitat via camera systems, we evaluated factors influencing bird foraging behaviour on a flower, i.e. bird's decision whether to perch or to hover. Our results indicate that sunbird foraging behaviour choice depends on plant architecture, namely on the length of peduncles and pedicels. Surprisingly, weather affects pollinator's behaviour just slightly. The data also indicate that feeding and moving among flowers require less time if the bird hovers and therefore this behaviour is associated with higher flower...
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Species diversity, distribution and interspecific and intraspecific variation in performance of dry grassland species
Husáková, Iveta ; Münzbergová, Zuzana (advisor) ; Janeček, Štěpán (referee) ; Cousins, Sara (referee)
In fragmented landscapes, survival and dynamics of plant species may be determined not only by local habitat conditions but also by landscape structure and its changes over time as well as by species life-history traits and their local population dynamics. Understanding the factors and processes determining diversity, distribution and variation in performance in species of fragmented habitats is thus very complex. Most previous studies focused only on some particular factors. However, studies that explored the relative importance of all these factors for species diversity and composition are rare, especially in dry grassland communities. Also studies exploring variation in species performance in relation to landscape fragmentation usually deal only with a single species and were often done in different study systems making generalization difficult. The aim of this Ph.D. thesis was to explore factors that are responsible for species diversity, distribution and interspecific and intraspecific variation in performance of dry grassland species occurring in a system of dry grassland-like forest openings in the forested landscape. In Chapter 1 I examined the effect of current and past landscape structure and local habitat conditions on species richness at dry grassland-like forest openings and assessed...
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Sunbird foraging behaviour on flowers of Impatiens sakeriana
Sejfová, Zuzana ; Janeček, Štěpán (advisor) ; Fuchs, Roman (referee)
Although the Old World sunbirds are generally considered to be an ecological analogy of the New World hummingbirds, until recently it was believed that in contrast to hummingbirds, sunbirds perch while feeding. This opinion was largely supported by several studies, mostly from South Africa, describing adaptations of plants facilitating this behaviour. However, recent studies have shown that the Old World nectarivores hover while feeding in front of flowers more frequently than previously thought. We focused on a specialised West African pollination system of Impatiens sakeriana and the foraging behaviour of its two major pollinators, the Northern Double-collared Sunbird (Cinnyris reichenowi) and the Cameroon Sunbird (Cyanomitra oritis). Based on continuous monitoring in their natural habitat via camera systems, we evaluated factors influencing bird foraging behaviour on a flower, i.e. bird's decision whether to perch or to hover. Our results indicate that sunbird foraging behaviour choice depends on plant architecture, namely on the length of peduncles and pedicels. Surprisingly, weather affects pollinator's behaviour just slightly. The data also indicate that feeding and moving among flowers require less time if the bird hovers and therefore this behaviour is associated with higher flower...
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Species diversity, distribution and interspecific and intraspecific variation in performance of dry grassland species
Husáková, Iveta ; Münzbergová, Zuzana (advisor) ; Janeček, Štěpán (referee) ; Cousins, Sara (referee)
In fragmented landscapes, survival and dynamics of plant species may be determined not only by local habitat conditions but also by landscape structure and its changes over time as well as by species life-history traits and their local population dynamics. Understanding the factors and processes determining diversity, distribution and variation in performance in species of fragmented habitats is thus very complex. Most previous studies focused only on some particular factors. However, studies that explored the relative importance of all these factors for species diversity and composition are rare, especially in dry grassland communities. Also studies exploring variation in species performance in relation to landscape fragmentation usually deal only with a single species and were often done in different study systems making generalization difficult. The aim of this Ph.D. thesis was to explore factors that are responsible for species diversity, distribution and interspecific and intraspecific variation in performance of dry grassland species occurring in a system of dry grassland-like forest openings in the forested landscape. In Chapter 1 I examined the effect of current and past landscape structure and local habitat conditions on species richness at dry grassland-like forest openings and assessed...
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Ultraviolet patterns in flowers and their significance as a signal to pollinators
Zitko, Martin ; Pecháček, Pavel (advisor) ; Janeček, Štěpán (referee)
Various animals are sensitive to ultraviolet light and many angiosperms make use of this ability to communicate with their pollinators. Therefore plants often dis- play patterns on their flowers and inflorescences visible only in ultraviolet light. The origin of these patterns is both pigment-based and structural-based, resulting in UV absorbing or UV reflecting flower. The main goal of this thesis is to give a summary of ultraviolet light as well as explore how plants produce ultraviolet pat- terns and present their actual appearance. I also pay attention to the characteristics of pollinators' vision with emphasis on ultraviolet light, and to the biological signifi- cance of ultraviolet flower signals for the pollinators. Gaps in knowledge are implied as well. The result of the thesis shows that ultraviolet light has an unquestionable significance in the relationship of angiosperms and their pollinators. It also shows a coevolution of ultraviolet patterns and pollinators' preferences for them. Keywords: ultraviolet, flower pattern, bull's eye, signalisation, pollinator
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