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Interspecific hybridization in Acrocephalus warblers.
Majerová, Veronika ; Reifová, Radka (advisor) ; Kotlík, Petr (referee)
Acrocephalus warblers have gone through the adaptive radiation during last severalmillion years, which gave rise to thirty one species occupying mainly Eurasia,Africa and Australia. The majority of species are morphologically very similar,however, they differ in ecological requirements, migration strategy, and song.Interspecific hybridization seems to be quite common among Acrocephaluswarblers, not only between sister species, but also between more distantly relatedtaxa. The main goal of this study was to determine whether this hybridization leadsto gene flow between species and which factors affect the rate of interspecific geneflow. For this purpose we conducted population-genetic analysis in three Europeanspecies of the Acrocephalus warblers of the subgenus Notiocichla: reed warbler (A.scirpaceus), marsh warbler (A. palustris), and blyth's reed warbler (A. dumetorum).Our results based on the analysis of sequence data from eight nuclear loci indicate,that gene flow between the studied species occurs, but only in one direction. Thegene flow is higher between genetically more related species than betweenecologically more similar species. We also estimated that the reed warbler and themarsh warbler diverged approximately 1,1 million years ago. The blyth's warblerand ancestor of the reed and marsh warbler...
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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Krahulec, František (referee)
The main drivers of microevolution in the genus Sorbus are interspecific hybridisation and polyploidy. The fate of new hybrid and polyploid taxa is determined by their mode of reproduction. Especially apomixis could be very advantageous for these new taxa. The S. aria agg. (subg. Aria) plays an important role within the genus since its members are involved in all hybridisation events and thereby is responsible for the substantial part of variation of the genus. Flow cytometry, molecular markers and multivariate morphological analyses were employed to evaluate the processes generating the variability in the S. aria group. Three ploidy levels were detected among species from subg. Aria in the Czech Republic. All of them could be found in the South Moravia, whereas only tetraploids occur in the Bohemia region. Moreover, most of the Czech taxa (5 out of 7) grow also only in the South Moravia which is therefore considered as a centre of diversity of the genus Sorbus in the Czech Republic. Flow cytometry seed screen revealed 7 modes of reproduction among the individuals from S. aria agg. A wide range of sexual and apomictic types of reproduction including reduced and unreduced gametes was detected. All of the diploid individuals are completely sexual. Among polyploid taxa, most of the species are...
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Speciation genomics in nightingales
Mořkovský, Libor ; Reifová, Radka (advisor) ; Macholán, Miloš (referee) ; Piálek, Lubomír (referee)
Speciationisusuallyaslowprocessoccurringoverthousandstomillionsofyears.Thismakes speciation research difficult because no direct observation or manipulation is possible. At best, we can gain some insight by inferring the population history and structure in very fine detail by investigating genetic markers in multiple individuals of the nascent species. Today, speciationresearchisinanunprecedentedpositionthankstotheadventofhigh-throughput sequencingmethods,whichmakeiteasier and cheaper than ever before to evaluate multiple markers in many individuals. Speciation is not a straightforward process that happens in the same way every time, but rather a phenomenon occurring when genetic and ecological circumstancesactinginsymphonyultimatelyleadtoreproductiveisolationoftwosubpopula- tions. This is why it is important to study multiple model systems to understand the general principles behind speciation. We worked with two species of nightingales (Luscinia luscinia andL.megarhynchos)thatdivergedapproximately1.8Mya,likelyduetoglacialfluctuations in Europe. Our main goal was to use these new high-throughput sequencing methods to (1) detect interspecific hybrids between the species, (2) estimate levels of interspecific gene flow,(3)findareasofthenightingalegenomethatunderliereproductiveisolationand,finally, (4)...
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Sources of Sorbus aria agg. variation
Bílá, Jana ; Urfus, Tomáš (advisor) ; Chumová, Zuzana (referee)
Genus Sorbus is a very complex group of vascular plants. Various genetic lineages which can be fixed by apomixis are driven by interspecific hybridisation and polyploidy. Species from S. aria agg. have the highest variation probably due to an extra mechanism - introgressive hybridisation. There are several concepts of the aggregate which are usually based on three main species: S. aria, S. umbellatta and S. graeca. Therefore, new microspecies are derived by genome doubling and hybridisation between the main species. Units of the aggregate are assessed differently as the distinction of taxa is very complicated due to the overlap of the morphological variability. The aggregate itself can be sometimes considered as a category for species of uncertain origin or identification. Four species from S. aria agg. occur in the Czech Republic. In addition, the conclusion offers questions that will be addressed in the master's thesis.
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Transformation of trace element speciation in disturbed soil profile
Kochergina, Yulia ; Mihaljevič, Martin (advisor) ; Vaněk, Aleš (referee)
Distributions of toxic trace elements were studied in soils before and after disturbation of their profiles.Two areas with different vegetation cover were selected: beech (Fagus sylvatica) and spruce (Picea abies) forests at the Načetín site in the Ore Mts. In the past, this area belonged to places with extreme levels of acidic atmospheric deposition. The studied areas are not placed too far from each other and have thus approximately the same climatic conditions, geological background and pollution input. On the other hand, physicochemical properties of soils (pH, CEC, BS, Ctot, Stot) and concentrations of major and trace elements are different. At selected sites in spruce and beech stand, two soil probes to a depth of 40-50 cm were dug in 2010 and samples of individual soil horizont were collected for chemical analyses (approximately 0.5 kg). Four samples from L, H, A and B horizons were taken in the spruce forest area and five samples from L, H, A, B and C horizons were taken in the beech forest. In 2011, the sites were re-sampled and samples were taken from horizons that were disturbed in 2010, paralleled by samples of undisturbed soil horizons from the same probe sites. Trace element concentrations were determined by ICP-MS, the speciation of individual elements in the soils was determined by...
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Speciation and isotopic composition of lead in coal samples from selected profile of the Most Basin
Semíková, Hana ; Strnad, Ladislav (advisor) ; Chrastný, Vladislav (referee)
Coal is one of the major energy sources in the world and contains most of the elements from the periodic table. During combustion of coal these elements are released and redistributed. This may lead to environmental problems. Some of these elements are considered to be very dangerous for human and animal health and ecosystems. The knowledge of concentration and speciation of elements in coal is important for the prevention of the adverse environmental phenomena associated with the use of coal. One of the hazardous elements in coal is lead. The purpose of this work is to determine the concentration of lead and its isotopic composition simultaneously with determining the speciation of lead in coal. The ICP-MS method was used to determine the concentration and isotope ratios of lead. A total of 62 samples of subbituminous coal was analyzed. The method of selective extraction analysis BCR was used on 9 samples of subbitumnious coal to identify the speciation of lead in coal. Lead concentrations in coal were measured in the range of 0.25 to 78.84 mg·kg-1 . These concentrations correspond to the average concentrations of lead in most of the coals. Isotope ratio 206 Pb/207 Pb in coal samples ranged from 1.169 to 1.219. Isotopic 208 Pb/206 Pb ratio was measured in the interval 2.047 to 2.093. The isotopic...
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Genomic approach in speciation studies
Habalová, Kateřina ; Hulva, Pavel (advisor) ; Mikulíček, Peter (referee)
Speciation, adaptation and hybridization are three concepts, each one referring to different process but having a common evolutionary context. Maternal line splits into two sister lines or only one line cleaves from maternal one during speciation. However it leads to formation of new species. Adaptation and hybridization can lead to formation of new species as well. New species arise by adapting to new conditions during adaptation. Within hybridization it is a desecendant of two different lines mating amongst themselves. Most of this thesis is being addressed to these issues, the lesser part is addressed to specific examples. The chapter about next-generation sequencing methods is also included, as these methods have been used more frequently recently. Key words: speciation, adaptation, hybridization, genomics, next-generation sequencing
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