National Repository of Grey Literature 72 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Sheep grazing as a controversial tool of nature protection
Daňková, Tereza ; Malíček, Jiří (advisor) ; Sedláček, Ondřej (referee)
Sheep grazing is currently more and more used as a main type of management in protected areas. However, it seems that in many cases this type of management has a negative impact on a habitat or species of interest. This bachelor thesis try to demonstrate how a care about pastures in term of nature conservation should be applied in a selected area. There are examples of endangered species that are directly threatened by an unappropriate sheep grazing. Positive and negative influences of grazing, especially sheep grazing, are summarized.
Behaviour of avian predators to seed bugs (Lygaeoidea): effectiveness of chemical defence
Chalušová, Kateřina ; Exnerová, Alice (advisor) ; Sedláček, Ondřej (referee)
By warning signalling prey advertises its unpalatability to the predators. Typical examples are true bugs (Heteroptera) combining optical and chemical signals. The aim of this study was to find out the effectiveness of chemical defence against wild-caught adults of great tits (Parus major) and blue tits (Cyanistes caeruleus) and towards hand-reared juveniles of great tits. The tested prey were adults and larvae of two invasive species of genus Oxycarenus (Heteroptera: Oxycarenidae) (aposematic O. lavaterae, non-aposematic O. hyalinipennis), adults of Horvathiolus superbus (Heteroptera: Lygaeidae) and crickets (Gryllus assimilis) as a control prey. We were focusing on the influence of seed bugs to the initial reaction, the learning process and to the displays of discomfort behaviour in tits. Reactions affected by the tit species, age and sex were compared in adults. Juveniles were divided into two independent experimental groups, one group was offered adults of genus Oxycarenus, the second was offered sunflower (Helianthus sp.) or Digitalis sp. seed fed adults of H. superbus. The first bug offered did not elicit an initial aversive reaction in tits, but birds reacted aversively to the bugs after having further handling experience. All juveniles, contrary to the adult tits, attacked at least one bug...
Latitudinal trend in feather growth rates and steroid hormone concentrations in avian feathers
Brzobohatá, Tereza ; Albrecht, Tomáš (advisor) ; Sedláček, Ondřej (referee)
Avian life histories range along the axis from slow to fast, with slow life histories being characterized by greater investments in future reproduction, and fast by greater investments in current reproduction. The concept of pace-of-life syndromes refers to the coevolution of life strategies and related physiological, immunological and behavioral traits. Avian species from tropical areas are characterised by slower life histories (longer parental care, later maturation, smaller clutches, reduced metabolic rate) when compared to temperate zone species. Within this latitudinal gradient, investments in the total amount (weight) of body feathers have also been shown to be reduced in tropical birds. It remains unclear, however, whether feather growth itself follows this latitudinal pattern, and is slower in tropical species. Tropical birds have lower basal levels of corticosterone and testosterone, however available studies are based mainly on analyzes of hormone concentrations from plasma. The first aim of this diploma thesis was to evaluate differences between tropical (Cameroon) and temperate zone (the Czech Republic) passerine species in investments in tail feather growth by using methods of comparative ptilochronology. The second aim of the diploma thesis was to analyze concentrations of steroid...
The role of insect herbivory in plant population dynamics - a case study of the Lycaenidae family
Barusová, Anna ; Janovský, Zdeněk (advisor) ; Sedláček, Ondřej (referee)
Herbivory is one of the key interactions of plants, which can result in important consequences for their population dynamics and which can also exert selection pressure on evolution of their traits. This bachelor thesis is concerned with insect herbivore influence on plants at the levels of individuals and population dynamics. It also focuses on interactions of occurrence of herbivory with environmental conditions. This is demonstrated on the family Lycaenidae (Lepidoptera) which is highly specialized in terms of host plants with several cases of coevolution having been described. Some Lycaenid species also evolved associations with ants probably, which help to increase their range of host plants. The relationship of feeding strategies and myrmecophily is illustrated on Czech species of Lycaenidae. The last part focuses on the Great Burnet (Sanguisorba officinalis) and its European-wide declining monophagous herbivore Dusky Large Blue (Phengaris nausithous), their ecology and conservation. Ecology of this study system will be the main topic of the intended master thesis.
Reintroduction of butterflies (Lepidoptera)
Štochlová, Tereza ; Sedláček, Ondřej (advisor) ; Straka, Jakub (referee)
The thesis deals with one of the active means of conservation - reintroduction. By this ap- proach, organisms are released in their historical range from which they have disappeared. Re- introductions typically concern vertebrates, that is, however, why this thesis focuses on a group of invertebrates - butterflies (Rhopalocera). The main aim of this work is to carry out a research of previous experiments, evaluate used methods and discover the best way to proceed with reintroduction of butterflies. This process contains many important steps. Firstly, a suitable species must be chosen, that means one that is declining and has limited dispersal abilities. Secondly, an appropriate habitat for releasing organisms must be found - host plants ought to be sufficiently abundant and the area big enough. If the habitat quality is not satisfactory, it can be achieved through management, most commonly by planting host plants, mowing or grazing. Next step is choosing the right donor population. It should be stable, genetically variable, and genetically and ecologically related to the original extinct population. After transfer and release of sufficient number of organisms, it is crucial to carry out a long-term monitoring of the newly formed population and to modify its management when necessary. All methods...
Are body size and specific species colouration important cues for predator recognition by their potencial prey? Diplomová práce
Antonová, Kateřina ; Fuchs, Roman (advisor) ; Sedláček, Ondřej (referee)
I tested influence of a body size and overal colouration in feeders experiments on recognition of sparrowhawk (Accipiter nisus) by chosen species of passerine. Experiments were conducted in years 2015 ̶ 2018. I used a plush dummies which carried a specific featuress of raptor (hooked beak, claws) and specific features of genus Accipiter (yellow eyes, respectively yellow eyes and overal colouration). As a control, dummy of harmless pigeon was used. Smaller dummies (size of a great tit) were not recognized as a raptor regardless of colouration. Large dummies with colouration of great tit and pigeon were not recognized as a raptor as well. On a contrary, large dummy with colouration of robin was recognized as a raptor, respectively sparrowhawk. Most birds who were flying to the feeders, at first payed attention to global features (size, overal colouration). If these features belong to well-known harmless bird, then local features (particular) which characterize raptor or sparrowhawk had no effect. Birds did not pay attention to them. Therefore it depends on a context, in which potential local key features occure.
Distribution, ecology and conservation of critically endangered Alcon Blue (Phengaris alcon f. alcon) in the Czech Republic
Kupková, Barbora ; Sedláček, Ondřej (advisor) ; Pech, Pavel (referee)
The state of the populations of many insects is critical in the Czech Republic, other species have already extinct. Among the species balancing at the limit of survival is myrmecophilus Alcon Blue (Phengaris alcon), especially its ecological form (P. alcon f. alcon), which is associated with the Marsh Gentian (Gentiana pneumonanthe) during the early larval stages. The general aim of my work was to evaluate the current distribution of the Alcon Blue butterfly (P. alcon f. alcon) in the Czech Republic, to estimate the size of the remaining populations and to propose a practical action plan for conservation of the species in the Czech Republic. The analysis of the databases showed that the species survives theoretically in 11 localities. The field survey in 2016 revealed, however, that at five other sites a species in the recent past was extinct. The remaining 6 localities are concentrated in Southwestern Bohemia on a total area of only 20 hectares. Two population is however close to extinction. The cause of local extinction of Alcon Blues was the extinction of host plants. The main factors influencing the size of butterfly populations in the last localities were the abundace and vitality of host plants (number of fertile shoots, height). Part of my work was an attempt to reintroduce Alcon Blue to a...
New environment grings new interaction:coexistence of closely related birds in urban mosaic
Sedláček, Ondřej ; Fuchs, Roman (advisor) ; Grim, Tomáš (referee) ; Procházka, Petr (referee)
I I New environment brings new interaďions: coexistence of closely related birds in urban mosaic ondřej Sedláček 1. SUMMARYOF THE THESIS The ongoingurbanizationrapidlychangesenvironmentsof mostplantand animal species worldwideand ecologistshave recentlyincreasedtheir attentionto biodiversiýconservationin man-affected|andscapes.HoWeVer,besidesspecia|ised species,whichdisappeardue to dramatichabitatconversion,manyorganismsare ableto changetheirbehaviour,physiologyand life historiesand haveadaptedto humanproximity.Citiesthereforeprovidea,,natura||aboratoý.,whichenablesusto studyecologicaland physiologicaladaptationsof synanthropicorganisms.Urban environmentsare a|soýpica|for theirhabitatheterogeneiý'Thanksto the mosaic natureof diversehabitats,specieswith differenthabitatselectioncometo close contaďin cities.ThisphenomenonWasa re|ative|yneg|eďedresearchareain urban ecology.A good model for this kind of investigationseemsto be a coupleof congenericbirdspecies,whicharerecentlycommonin urbanhabitatsacrossEurope - Black Redstart (Phoenicurusochruros)and Redstaft (P. phoenicurus).The two specieshavesimilarnestingandforagingecologybutoccupydifferenthabitatsunder naturalconditions.The BlackRedstartprimarilybreedsin open,rockyrerrainin mountaineousareas.This relativelyspecia|habitatýpe has spreadacrossEurope with...

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