|
|
Factors associated with invasiveness in the genus Impatiens: interaction of species traits, competition and environment
Čuda, Jan ; Pyšek, Petr (advisor) ; Kollmann, Johannes (referee) ; Prach, Karel (referee)
The aim of this thesis was to identify factors that contribute to invasiveness of species in the genus Impatiens. This genus is horticulturally attractive and includes several species that are known to have naturalized outside their native ranges, while others did not escape, in spite of being frequently cultivated. When looking for traits associated with invasiveness, it is useful to focus on congeneric species. Their traits and dispersal modes are less influenced by phylogeny, than when comparing unrelated species or even complete floras. This helps to account for traits that favour invasive species over native ones and thus identify potential invaders more precisely. A superior invader performance is attributed to a competitive advantage over native species that can lead in extreme case to competitive exclusion of the latter. Invasive and native species com- pete only if their niches overlap and the strength of competition depends on niche similarity. Importantly, invasive species are considered to be able to maintain their high competitiveness over a wide range of environmental conditions, while native ones often have narrower environ- mental optima. Lastly, competitive outcome can vary over life stages and depends on the degree of species dominance, which is rarely taken into account. Spread and...
|
|
|
The role of extracellular matrix in mesenchymal stem cell biology
Šimková, Zuzana ; Chudíčková, Milada (advisor) ; Hubálek Kalbáčová, Marie (referee)
The aim of this bachelor thesis is to describe the mutual relations of mesenchymal stem cells and extracellular matrix, their communication and to point out their significance in living body. First part is focused on description of extracellular matrix, its components and characteristics. The interaction between extracellular matrix and surrounding cells is using both receptors and enzymes. Second part addresses the description of mesenchymal stem cells which are crucial producers of extracellular matrix. The matrix is also decisive part of stem cells niche which envelopes them, protects them and decides their future. The last section demonstrates possible utilizations of differentiation potential and paracrine secretion of MSC in therapy and identifies some of the risks bound to it.
|
|
|
Habitat preferences of the members of the family Chydoridae (Crustacea, Cladocera)
Zimová, Tereza ; Sacherová, Veronika (advisor) ; Šorf, Michal (referee)
This thesis is a literature review of ecological niche of some species of Cladoceran family Chydoridae. The aim of this work is to summarize the knowledge about the occurrence of species in various types of environments and what are their preferences or see which factors are limiting for them. This work is focused on the type of habitats in which they are found, the trophic state of water and pH. It also mentions to a lesser extent environmental factors such as concentration of calcium and water depth, which might also influence the niche choice of these species. Species can be divided into opportunists with a wide niche and specialists with a narrow one, yet a large proportion of species have a wide tolerance to most environmental factors. Key words: Chydorids, niche, habitat, macrophytes, open water, pH, trophic state, depth, calcium
|
|
|
Factors associated with invasiveness in the genus Impatiens: interaction of species traits, competition and environment
Čuda, Jan ; Pyšek, Petr (advisor) ; Kollmann, Johannes (referee) ; Prach, Karel (referee)
The aim of this thesis was to identify factors that contribute to invasiveness of species in the genus Impatiens. This genus is horticulturally attractive and includes several species that are known to have naturalized outside their native ranges, while others did not escape, in spite of being frequently cultivated. When looking for traits associated with invasiveness, it is useful to focus on congeneric species. Their traits and dispersal modes are less influenced by phylogeny, than when comparing unrelated species or even complete floras. This helps to account for traits that favour invasive species over native ones and thus identify potential invaders more precisely. A superior invader performance is attributed to a competitive advantage over native species that can lead in extreme case to competitive exclusion of the latter. Invasive and native species com- pete only if their niches overlap and the strength of competition depends on niche similarity. Importantly, invasive species are considered to be able to maintain their high competitiveness over a wide range of environmental conditions, while native ones often have narrower environ- mental optima. Lastly, competitive outcome can vary over life stages and depends on the degree of species dominance, which is rarely taken into account. Spread and...
|
|
|
Influence of competition to structure of protist communities
Škvorová, Marie ; Bestová, Helena (advisor) ; Svoboda, Pavel (referee)
This work deals with competition as well as mechanisms of coexistence of species. The introduction presents comtemporary coexistence theory. There are two types of differences - niche and relative fitness differences. Fitness differences increase inter-species competition. This is a novell result, current theory expected differences decrease competition in any case. This work summarized results of experimental works that have investigated various aspects of co- existence theory, with special focus on protists. Competition was found to be an important mechanism in creating patterns of community assembly, unfortunately drawing common results is complicated. According to competition-relatedness hypotheses, within some competition lines competition decreased with relatedness. This relation however does not hold always. There are two conditions: functional traits must bear a phylogenetic signal and must be evolutionally conserved. Studies on protists imply that higher number of species should be included instead of pairwise combination tests in order to get valid information on relation of species. This could be similar for traits. Plants experiments have shown that competition may be affected by traits only in complex systems with a number of traits included. Such experiment involving protists have...
|
|
| |
guest ::
