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The crayfish plague pathogen Aphanomyces astaci in its introduced ranges: vectors, introduction pathways, genetic variation and host-pathogen interactions
Mrugała, Agata ; Petrusek, Adam (advisor) ; Füreder, Leopold (referee) ; Vralstad, Trude (referee)
- ABSTRACT - The crayfish plague pathogen, Aphanomyces astaci, is responsible for substantial declines and local extinctions of native European crayfish populations. As a consequence, the pathogen is now listed among 100 world's worst invasive alien species. The spread of A. astaci is greatly facilitated by its natural hosts, North American crayfish, that thanks to a long co-evolutionary history with the crayfish plague pathogen evolved efficient defence mechanisms. In contrast, European, Australian and Asian crayfish species are highly susceptible to this disease agent. However, progress of A. astaci infection in native European crayfish was observed to differ between distinct pathogen strains, indicating variability in their virulence. Indeed, we demonstrated a relationship between patterns in crayfish immune response and A. astaci virulence in an experimental infection involving the European noble crayfish and three differently virulent crayfish plague strains. The European continent is currently inhabited by at least eight North American crayfish species. The carrier status was confirmed in six of them, including also Orconectes cf. virilis occurring in the Netherlands and the UK. In this country, we detected Aphanomyces astaci presence in some populations of the non-indigenous crayfish species as well...
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Macroecological analysis of economy
Krupička, Jan ; Storch, David (advisor) ; Petrusek, Adam (referee) ; Kratochvíl, Lukáš (referee)
Abstract: Brown et al. (2011) proposed a fundamental similarity between organisms and the economies of nationstates based on the distribution networks necessary for the functioning of the metabolism / economics and limitations arising from them according to the Metabolic theory of ecology. This work is primarily intended to investigate whether these limitations figure even within individual sectors of the economy and their relation to some other macroeconomic and demographic indicators. Key words: ecology, macroecology, metabolic theory of ecology, economy, energy
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Changes in spatial distribution of gelatinous zooplankton: causes and consequences
Krylová, Pavla ; Petrusek, Adam (advisor) ; Rulík, Martin (referee)
During the day, changes in the spatial distributions of organisms in the water column occur repeatedly, especially in diurnal vertical migrations, which affect abiotic and biotic components of ecosystems. The migratory behaviour occurs worldwide in the oceans and in fresh water, in different habitats and under different physical conditions. The main migrants are gelatinous zooplankton, which are a heterogeneous group of invertebrate animals, although phytoplankton, nekton and other representatives of zooplankton also migrate. The main focus of the study of diurnal vertical migrations is proximate and ultimate factors that influence the migration. Furthermore, occurrence and density of organisms are examined. To study vertical migrations of gelatinous zooplankton, it is the easiest to study jellyfish because of their size. The distribution behaviour might also be observed in freshwater zooplankton. Two university studies of diurnal vertical migration of freshwater jellyfish were executed in previous years. This work aims to: summarise the current knowledge about spatial distribution - especially of diurnal vertical migration, describe in detail proximate and ultimate factors and compare them between freshwater jellyfish, gelatinous zooplankton and jellyfish. Key words: gelatinous zooplankton,...
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Microparasites and fecundity of Daphnia at environmental gradients of canyon-shaped reservoirs
Hubová, Jana ; Petrusek, Adam (advisor) ; Macháček, Jiří (referee)
The original aim of my diploma thesis was examination of fixed samples of cladocerans from the Daphnia longispina species complex from reservoirs Vír and Vranov for the presence of 4 groups of microparasites: microsporidia, oomycetes, the protozoan Caullerya mesnili, and the yeast Metschnikowia bicuspidata. The next aim was to determine the effect of parasites on Daphnia fecundity, and determination of their spatial and temporal distribution within reservoirs. From the total number 4452 of examined Daphnia females, however, only 56 individuals were infected. This number was not sufficient for the planned analyses. As I recorded for all examined individuals the clutch size, I thus dealt to a large extent with an alternative issue: the temporal and spatial variation of, and the influence of environmental factors on Daphnia fecundity. Both studied reservoirs are characteristic by canyon-shaped profile that allows formation of environmental gradients on the horizontal as well as vertical axis. The results confirm that reservoir identity, season, and location within the reservoir (or gradient of food supply) have all significant effects on fecundity. During my work I have encountered difficulties associated with determining microparazites from fixed zooplankton samples. The appendix section of my thesis...
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Factors influencing movement and behaviour of animals in riverine environment
Horká, Petra ; Petrusek, Adam (advisor) ; Matěna, Josef (referee) ; Kováč, Vladimír (referee)
Animals living in riverine environments are influenced by various abiotic and biotic factors which shape their behaviour. Among the most distinctive behavioural traits by which animals react and adapt to environmental variability is movement behaviour. In my study I focused on movement and distribution of several species and their response to environmental and anthropogenic factors. The thesis consists of two parts: the first part synthesizes studies on behaviour of European grayling Thymallus thymallus, ide Leuciscus idus and an invasive crustacean Hemimysis anomala; the objectives of individual projects were to determine which environmental factors influence the species' behaviour and how. The first two chapters present extensive radio-telemetry studies which examined diel movements and migration of ide (one year observation in the River Elbe) and European grayling (study conducted in autumn-winter periods of three consecutive years in the River Blanice, focusing on differences between juveniles of wild and hatchery origin). The third study was also conducted in the Elbe and evaluated the diurnal behavioural patterns and spread of the Pontocaspian mysid shrimp Hemimysis anomala. The second part of the thesis consists of two chapters focusing on young-of-the-year (YOY) fish assemblages: the first...
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Genetic diversity of stone crayfish Austropotamobius torrentium in marginal areas of its distribution
Pešek, Pavel ; Petrusek, Adam (advisor) ; Kouba, Antonín (referee)
Central Europe north of the Alps was colonized by one of the Balkan haplotype lineage of stone crayfish Austropotamobius torrentium after the end of the last ice age. Stone crayfish is considered a native species in the basins of the Danube and the Rhine. The origin of populations from the Elbe basin is still debated. Most of recent European studies dealing with the crayfish distribution indicate the stone crayfish in Elbe basin as non-indigenous species. The main aim of my work was to evaluate the question of the origin of stone crayfish in the Elbe catchment by describing the distribution of genetic variability, which has not been yet studied in the Elbe river basin for this species. I have used 617 base pairs long section of mitochondrial gene for small subunit I of cytochrome c oxidase (COI). The variability of this marker is reduced in area on the north of Alps, which agrees with assumption of rapid colonization after the end of last ice age. Observed haplotype diversity is nevertheless sufficient to suggest the most likely scenario. Among 22 populations from Elbe basin, one dominant and three rare haplotypes were found. Individuals from the isolated Luční creek close to the Krkonoše (Giant Mountains) region have a haplotype that has so far been found only in central Slovenia, and this population has...
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Detailed taxonomic and clonal structure of the Daphnia longispina species complex on the longitudinal gradient of the Želivka Reservoir
Stodola, Jakub ; Petrusek, Adam (advisor) ; Vaníčková, Ivana (referee)
Canyon shaped reservoirs are characteristic by specific environmental horizontal gradients, so they enable existence of several species of the Daphnia longispina complex in one water body. Due to preference of distinct environmental conditions Daphnia species occurre in the different localities. The aim of my thesis was to analyze detail taxonomical and clonal structure of Daphnia longispina group by ten microsatellite markers on longitudinal gradient and compare it between two consecutive seasons. Simultaneously I received newly discovered divergent mitochondrial lineage from Želivka reservoir. It was confirmed, that the distribution of species and their hybrids in water reservoir was non-concidental and the taxonomic spatial distribution is in two consecutive seasons relatively constant. On the contrary the spatial and temporal distribution of clones was very heterogeneous. Clonal diversity in the interspecific hybrids was lower than in the coexisting parental species. This finding supports the hypothesis, that there exist reproductive barriers between parental genomes. Most of the clones were substantively variable, but several clones that occurred in both seasons in similar localities were found. It is possible that some clones are able of overwintering in hypolimnion and in the spring...
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Host specificity of pathogens of water fleas of the genus Daphnia
Ružarovská, Jana ; Petrusek, Adam (advisor) ; Vávra, Jiří (referee)
Water fleas of the genus Daphnia are infected by a wide range of parasites with different host range. These parasites are mainly representatives of bacteria, protozoa (group Ichtyosporea), yeasts, microsporidia and oomycetes. Host specificity of these parasites is very different. We can find there those, who infect only one host species, but also those, who infect a lot of host species (also hosts of different subphylums). Antagonistic coevolution is the major driving force for evolution of the parasite-host system. Parasites create on their host negative frequency-dependent selection, that cause a lot of phenomenons such as clonal/isolate specificity of both antagonists, maintenance of genetic polymorphism, decreasing virulence etc. A special group of organisms are epibionts, that live on the surface of their holder. Their specialization manifests as preference of a substrate. This thesis summarizes a current knowledge on the host specificity of chosen parasites of the genus Daphnia and also includes what is known about their life cycles. Key words: Host specificity, specialization, generalist, Daphnia, microsporidia, complex life cycle, epibiont.
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Phylogeography and genetic variation of benthic crustaceans in European inland waters
Pešek, Pavel ; Petrusek, Adam (advisor) ; Sacherová, Veronika (referee)
This thesis summarises published information about geographic distribution of genealogical lineages and genetic variability of benthic crustaceans of European continental waters, and evaluates the historical factors that affected their distribution. it is focused mainly on species for which multiple or in-depth studies have been published. A particular attention is given to crayfish of the genus Austropotamobius. Present distribution of genealogical lineages has been affected by changes in connectedness and availability of aquatic habitats. Species lineages often split in consequence to geological and climatic processes during the Tertiary, as exemplified on species complexes of Austropotamobius crayfish, species lineages of the amphipod Gammarus fossarum species complex, and the isopod Asellus aquaticus. The distribution of intraspecific lineages has been strongly affected by Quaternary cycles of glaciation, which not only destroyed many habitats by moving glaciers but also created new colonisation routes. Such routes were peri-glacial lakes, which had been used by Gammarus lacustris, or retreat of sea level, which enabled white-clawed crayfish to colonise England, and a freshwater crab to colonise Italy. Changes in sea levels are also the likely reasons for colonisation of continental waters by the...
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