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Influence of insect herbivory on plant competition
Opltová, Radka ; Kuťáková, Eliška (advisor) ; Florianová, Anna (referee)
Plant communities are influenced by many factors, such as soil properties, humidity, temperature, resource availability or competition and herbivory. This thesis summarizes current knowledge about insect herbivory and its impact on plant competition in the context of plant communities, especially in grasslands. The competition outcome depends on numerous factors, such as the competitiveness of focal as well as neighbouring plants, trade-off between fast growth and production of defensive chemicals, resource availability etc. Insect herbivory can significantly impact plant competition, and the impact depends on herbivore abundance and its specific traits, such as feeding preferences or occupied habitat. Although herbivory often reduces plant biomass, it can stabilize the community structure by suppressing strong competitors and, therefore, keeping higher plant biodiversity. Plant response to herbivory can sometimes develop over a long time, so long-term observations of changes in plant communities are necessary. It is my willingness to continue with research based on this review, within the context of a master thesis. Specifically, I would deal with the impact of belowground herbivory on seminatural mountain grassland in the Krkonoše Mountains. As a model herbivore species I chose the garden chafer...
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Niche width of eukaryotic marine phytoplankton with respect to recent and future climate change.
Junková, Natálie ; Kulichová, Jana (advisor) ; Neustupa, Jiří (referee)
This paper describes the concept of niche breadth of photoautotrophic protists and attempts to introduce us to the basic concepts we may encounter when studying the ecological niche. The review clarifies what a niche is and its components fundamental and realized niche and presents some examples of organisms that are specialists or generalists. It uses diatoms, dinoflagellates and Haptophytes to describe how they can be affected by climate change. Since the number of environmental changes is steadily increasing, it is very difficult to predict the changes in the coexistence of generalists and specialists. The thesis presents some of the main methods used in measuring the width of the ecological niche of protists, which can be MaxEnt, ONE and the most frequently mentioned OMI (outlying mean index) method, which is described in more detail in the thesis. Given the focus of the thesis on photoautotrophic marine plankton, the most frequently mentioned organisms are diatoms, dinoflagellates and Haptophyta. Finally, I summarize the main ocean factors that could be affected by climate change, which are mainly pH, temperature, salinity or the amount of available nutrients (carbon, nitrogen, phosphorus, silicon and iron).
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Phytophagy as an alternative feeding strategy of parasitic Hymenoptera larvae
Böhmová, Julie ; Janšta, Petr (advisor) ; Skuhrovec, Jiří (referee)
Parasitoidism is considered to be the primary larval feeding strategy of parasitic Hymenoptera (Hymenoptera: Apocrita: Parasitoida). However, many species became secondarily phytophagous, in particular some species of Ichneumonoidea, Cynipoidea and Chalcidoidea. The bachelor thesis summarizes the knowledge about phytophagy in these superfamilies and divides them into four categories. The thesis further evaluates morphological and behavioural adaptations related to this way of life as well as other aspects of their coevolution with host plants.
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Parasitoid hymenoptera hosts specialisation and defensive mechanisms of their host species
Bubeníková, Kristýna ; Janšta, Petr (advisor) ; Holý, Kamil (referee)
Parasitoids (Hymonoptera: "Parasitica") are very large group of insects. Their diversity is also enormous in various morphological adaptations and hosts specialisations. The bachelor thesis summarize particular types of host specialisations and compare generalits and specialists from taxonomical, ecological, evolutionary and geographical point of view. The thesis include summary of theories concerning host-defence adaptations against parasitoids (i.e. morphological adaptations, space-time adaptations) as well. Key words: Apocrita, specialist, generalist, defensive mechanism, evolutuion
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