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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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Genetic structure of the Daphnia longispina complex in European mountain lakes
Hamrová, Eva ; Petrusek, Adam (advisor) ; Schwenk, Klaus (referee) ; Hobaek, Anders (referee)
I studied the genetic structure of cladocerans from the Daphnia longispina complex in several European mountain ranges. The population genetic structure of the D. longispina complex was studied using mitochondrial (mtDNA; partial sequencing of the 12S rRNA gene) and nuclear markers (nine microsatellite loci). Major part of the work was done in the Tatra Mountains; the genetic structure of populations of the Daphnia longispina complex from two parts of this range (the West and the High Tatras) was compared. The pattern of mtDNA confirmed multiple colonization of lakes from different source populations, detected haplotype diversity was high and haplotype sharing only within the West or the High Tatras was observed. The observed genetic differentiation indicates low level of gene flow and persistent founder effect, consistent with the monopolization hypothesis. The alternation of asexual and sexual reproduction in the life cycle of Daphnia, cyclical parthenogenesis, may affect genetic structure of their populations. This was the topic of a study described in the first chapter. A detailed analysis of population structure of two closely related Daphnia species (D. galeata and D. longispina) living in similar habitats (permanent dimictic mountain lakes) in the Tatra Mountains revealed that populations...
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Factors influencing diurnal activity of crayfish and its seasonality
Plasová, Kateřina ; Petrusek, Adam (advisor) ; Buřič, Miloš (referee)
Crayfish is mainly but not exclusively a nocturnal animal. The crayfish aktivity is taxon specific and can be further affected by various factors. The aim of this thesis is to create an overview of factors affecting the activity and to summarize their impact. Factors can be divided into those influencing daily activity and those influencing seasonal behaviour. This thesis focuses on discussing different reactions to the factors and its intensity by individual species. Insufficient data covering activity during the winter season offers an opportunity for further research. Key words: crayfish; daily activity; abiotic factors; biotic factors; seasonality
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Habitat and pairing preferences among coexisting lineages of the Gammarus fossarum species complex in the Western Carpathians
Bystřický, Pavel Karel ; Petrusek, Adam (advisor) ; Čiampor, Fedor (referee)
In recent years, due to the development of molecular methods, a great level of cryptic diversity across multiple taxa was discovered. One of these groups are freshwater amphipods. Amphipods due to lower dispersal and recolonization abilities present a suitable model system for studying potential ecological interactions among genetically distant lineages during their secondary contact. In this thesis, I studied the cryptic species complex Gammarus fossarum in a contact zone of several genetically divergent lineages known from the previous research in the Vsetin region. I focused on two main questions: Firstly, whether there are preferences among individuals from different lineages for sexual partners from the same lineage rather than from the different one (i.e., I test for the potential existence of prezygotic reproduction barrier between the lineages). I tested this hypothesis by collecting pairs from natural contact zone and also (in a limited extent) by an aquarium experiment. Secondly, I tested whether these lineages differ in mesohabitat (pool versus riffle) distribution in syntopy, which may indicate competition among lineages and potential diversification of their ecological niches. Animals from nine localities (with expected contact of two lineages per locality) were examined. In more than...
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Biogeography, phylogeny, ecology and systematics of epigean freshwater Amphipoda in the Carpathian arc and beyond
Copilas-Ciocianu, Denis ; Petrusek, Adam (advisor) ; Väinölä, Risto (referee) ; Trontejl, Peter (referee)
3 ABSTRACT Freshwateramphipodsarepoordispersersduetothefragmentarynatureoftheir habitat,benthiclife-styleandlackofresistantpropagules.Consequently,mostspeciesare narrowlyendemic,andwidespreadmorphospeciesconsistofnumerousdivergentlineages. Assuch,thesepatternsareconsideredrelict, mainlyreflectinghistoricalratherthan contemporaryfactors.TheCarpathian Mountainsunderwentadramaticgeomorphological evolutionduringthelast20millionyears,risingfromtheParatethysSeathroughaseriesof islandsthateventuallycoalescedintooneofthelongest mountainchainsinEurope. Moreover,these mountainsandsurroundingbasinsareinhabitedbyaubiquitousand diverseamphipodfauna,providinganidealsettingfortestinghistoricalbiogeographical hypotheses.OurresultshaveshownthatinthesouthernhalfoftheCarpathians,montane Gammarus taxadisplayfragmentedandallopatricdistributionpatterns whilelowland speciesbelongingtothegeneraNiphargus andSynurella are mostlysympatricand widespreadoverlargedistances.Subsequent molecularinvestigationsrevealedthatthe patchydistributionofG.fossaruminthewesternandsouthwesternCarpathianshaslikely resultedfromthebreakupofaformerlycontiguouslandmass16 millionyearsago, suggestingthatgeologicalsubsidencecanplayanimportantroleinshapingbiogeographical patterns. Moreover,the WesternCarpathianlineagesineasternCzechiaandSlovakiaare...
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Detection and variation of the crayfish plague pathogen in selected crayfish populations
Mojžišová, Michaela ; Petrusek, Adam (advisor) ; Buřič, Miloš (referee)
Crayfish plague is an emerging disease caused by the oomycete Aphanomyces astaci, a pathogen listed among the 100 World's Worst Invasive Alien Species. It was introduced into Europe in the second half of 19th century from North America and caused collapses of European native crayfish populations. Nowadays, A. astaci is widespread in Europe and has spread also to other parts of the world, threatening all susceptible crayfish of non-North American origin. The aims of this MSc thesis were 1) to provide information about crayfish plague outbreaks from recent years, and by using microsatellite and mtDNA markers reveal A. astaci genotypes involved; 2) to test healthy-looking indigenous crayfish for potential occurrence of chronic infections by A. astaci in Czechia. Six new crayfish plague outbreaks were confirmed from 2016 to 2018, involving at least five distinct pathogen strains. My results provide first evidence of the A. astaci genotype group D causing Astacus astacus and Austropotamobius torrentium mass mortalities in Czechia. MtDNA sequencing revealed two haplotypes of the D haplogroup, indicating two independent sources of infection presumably either from ornamental crayfish or spreading from neighbouring countries. The genotype group A was recorded in two A. astacus mortalities and genotype group...
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Daphnia hybridization in canyon-shaped reservoirs
Ruthová, Štěpánka ; Petrusek, Adam (advisor) ; Wolinska, Justyna (referee)
3 ABSTRACTS Part 1 Canyon-shaped reservoirs, characteristic by elongated morphology and by ecologically diverse conditions along both horizontal and vertical reservoir axes, are good model systems for ecological studies of zooplankton communities. Presence of ecological gradients improves habitat differentiation and may facilitate coexistence of related species. Here we provide detailed study of genetic structure of the Daphnia longispina complex inhabiting three canyon-shaped reservoirs. Using 12 microsatellite loci, we assessed taxonomic and genetic structure of assemblages composed by populations of D. galeata, D. cucullata, D. longispina and their interspecific hybrids. We focused on detailed taxon determination and on patterns of hybridization and introgression. High number of distinct hybrid genotypes in the samples suggested high frequency of hybridization; despite this, later generation hybrids were rare. In one reservoir inhabited by a single species, D. galeata, we also tested if environmental gradients may cause intra-population genetic diversification similar to spatial differentiation in species composition. Subpopulations along horizontal gradient in the reservoir, as well as those in different layers of the stratified water column, were significantly genetically differentiated. We propose...
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Historical changes in species composition and interspecific hybridization of the Daphnia longispina species complex (Crustacea: Cladocera) in Lago Maggiore
Faktorová, Zuzana ; Petrusek, Adam (advisor) ; Wolinska, Justyna (referee)
Hybridizing species of the Daphnia longispina complex are key taxa in plankton communities of many European lakes. In several of these lakes, it has been documented that the taxonomic structure of the complex during the 20th century has substantially changed following human-mediated environmental changes, particularly eutrophication and re-oligotrophication and fish stock changes. We characterize these changes in Lago Maggiore (Italy/Switzerland), a southern pre-alpine lake, which also passed through the human-mediated environmental changes. Lago Maggiore is one of best and longest studied European lakes so a large number of historical Daphnia samples from regular monitoring are available. Because local Daphnia do not form dormant egg banks suitable for genetic analysis (being able to overwinter in the water column), we used a combination of morphology and geometric morphometrics (elliptic Fourier analysis) to evaluate the taxonomic and phenotypic changes in the Daphnia longispina complex in Lago Maggiore since the mid-20th century (1948-2012), and attampted to characterize the impact of environmental changes over the respective period on Daphnia body shape and size. Examination of Daphnia phenotype indicates indeed the prevailing presence of D. longispina (hyalina morph) in the 1940s, dominance of...
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