National Repository of Grey Literature 23 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Diversity of Epilobium and methods to explore their hybridization
Kuchyňková, Lenka ; Kaplan, Zdeněk (advisor) ; Šemberová, Kristýna (referee)
Willowherbs (Epilobium) belong to the genera whose evolution is significantly affected by interspecific hybridization. Although this process often generates evolutionary novelties and leads to speciation, it can also result in genetic erosion and extinction. This thesis is mainly focused on the Czech Epilobium species that are potentially endangered by interspecific hybridization. The emphasis falls on the group of rare mountain willowherbs including E. nutans, E. alsinifolium and E. anagallidifolium. In addition to frequent interspecific hybridization, the research of this group is also complicated by the subtlety of distinguishing morphological features. The review also summarizes the available methods that can be used to study interspecific hybridization in the follow-up thesis.
Molecular and Genomic Methods for Analyzing Hybridization in Aspergillus and other Fungi
Jirkovský, Pavel ; Sklenář, František (advisor) ; Kolařík, Miroslav (referee)
Interpecies hybridization is being studied since the first half of 20. century, when it was described based on phenotypical traits on plant model. Study of this process was historically centred around botanical studies, while its importance in mycology is just being uncovered in recent years. Introgression is a phenomenon that can occur when hybrid backcrosses with one of the parental species. Based on recent studies it is apparent that hybridization played its role in evolution of MAT locus genes of Neurospora, transfer of adaptive traits with Ophiostoma species (invasive pathogen of elm trees). Within Aspergillus family hybridization was described both on intraspecific and interspecific level. More detailed study of this process and improving of used methods could potentially help in clinical application by uncovering adaptive genes responsible for resistance towards antimycotics, higher virulence and other traits.
Analýza repetic v genomech vybraných druhů modrásků rodů \kur{Polyommatus} a \kur{Lysandra}
HRUBÁ, Monika
This thesis focuses on the analysis of mobile elements in the genera Polyommatus and Lysandra (Lepidoptera) with a potential impact on karyotype fragmentation. The presence of selected mobile elements in genomes of 15 lycaenid species was tested by PCR. Moreover, the same method was used to detect these elements in 13 selected ant species, which may present a source for lateral gene transfer in myrmecophilous blue butterfly species. Selected transposable elements were localized in pachytene nuclei using fluorescence in situ hybridization. The results of this thesis suggest a patchy phylogenetic pattern of studied repeats which can be partly explained by mobile elements spread through interspecific hybridization and horizontal gene transfer among studied Polyommatus and Lysandra species.
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...
Interspecific hybridization in birds: lessons for conservation
Štěpánková, Klára ; Reif, Jiří (advisor) ; Vokurková, Jana (referee)
Interspecific hybridization is quite common in recent years. Favorable factors are rarity of a species, limited time for partner selection, misdirected preference in mating partner selection of females, preference for males with more pronounced sexually selected traits, greater body size and habitat destruction. Factors which lead to the artificially interspecific hybridization due to habitat destruction include deforestation, fragmentation of the territory, urbanization, abandoning agricultural areas, as well as translocation of species into the regions where they did not originally occur. These species can later interbreed with the native species and if the latter are rare and the former aggressive, it can result in increased threat potentially leading to extinction of indigenous populations. Exceptionally, interbreeding can lead to the emergence of a new species; however, this type of origination of a new species is not common in animals. Hybridization is a natural phenomenon important for the evolution. Nevertheless, anthropogenically induced or assisted hybridization represents a serious problem for the species conservation. Finding a solution to overcome the negative impacts of such interspecific hybridization is difficult and there is no exact and universally applied methodology to date. Key...
Assessing the threat of hybridization between Prunus fruticosa and cultivated Prunus species
Musilová, Lenka ; Vít, Petr (advisor) ; Chrtek, Jindřich (referee)
Presented thesis evaluates the risk of ongoing hybridization (antropohybridization) in highly endangered Prunus fruticosa in the Czech Republic and selected adjacent countries. Absolute genome size analysis (estimated by flow cytometry) combined with both numeric and geometric morphometrics were used for evaluation of hybridization. Prunus fruticosa frequently hybridize with naturalized Prunus cerasus (emerging tetraploid hybrid Prunus ×eminens) and native Prunus avium (forming triploid hybrid Prunus ×mohacsyana). Discrimination between P. ×eminens and P. ×mohacsyana is difficult, when using leaf morphology characters only, so the occurrence of triploid hybrids was strongly underestimated in the Czech Republic (only tetraploid hybrids were reported). Both hybrids are surely differentiated using flow cytometry analysis (based on different ploidy level). The majority of analyzed populations is formed by either individuals of pure P. fruticosa or one of the mentioned hybrids. Only four populations were mixed. Continuous variability in absolute genome size was found in two of them, which may indicate hybrid swarm forming (incl. primary hybrids and backcrosses). Our findings can be considered only as indirect evidence for introgression, which needs to be confirmed by molecular markers (for example...
Risk assessment of interspecific hybridization between endemic Campanula bohemica and widespread C. rotundifolia s.l.
Hanušová, Kateřina ; Suda, Jan (advisor) ; Krahulec, František (referee)
The thesis deals with phenotypic, ploidy and genetic variation of two Campanula species occurring in the Krkonoše Mts., namely the endemic C. bohemica and widespread C. rotundifolia subsp. rotundifolia. For comparative purposes subspecies sudetica of the latter species was also included. The main aim was to get insight into population structure and assess the threat of interspecific hybridization to the survival of the endemic bluebell. Flow cytometry, distance-based morphometrics and molecular analysis were used to address these questions. Three distinct groups of fluorescence intensities were revealed by flow cytometry, corresponding to DNA diploids, tetraploids and pentaploids. While diploids morphologically matched the nominate subspecies of C. rotundifolia, tetraploids corresponded either to C. rotundifolia subsp. sudetica or C. bohemica. Most populations from the Krkonoše Mts. were uniform although a sympatric growth of diploids and tetraploids was encountered in 12 populations. Only two pentaploids individuals, most likely of hybrid origin, were found, which indicated that interspecific hybridization is much less common than previously assumed. The two tetraploid taxa were distinguished by molecular markers. A combination of flow cytometry and molecular analyses thus allowed reliable...
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...
Efficient conservation of species endangered by introgressive hybridization with a special respect to genus Pulsatilla
Tröglerová, Aneta ; Urfus, Tomáš (advisor) ; Macková, Lenka (referee)
Interspecific hybridization is a common phenomenon within plants. It is considered a mechanism through which new adaptations and potentially new species arise. Interspecific crossing frequently occurs between closely related taxa. This bachelor thesis summarizes the knowledge of the effects and consequences of hybridization. In particular, negative influences such as demographic and genetic swamping are discussed. These are presented in the context of hybridization of rare species with more common and competitively stronger related taxa. Assessing the degree of interspecific crossing is important to determine an efficient conservation of endangered species. Furthermore, the work deals with selected species of the genus Pulsatilla (Pasque flower), specifically Pulsatilla patens, P. pratensis subsp. bohemica and P. vernalis, which are potentially endangered by hybridization. Populations of Pasque flower have been rapidly decreasing in recent decades not only in the Czech Republic but also throughout Europe. In addition, they are willing to hybridize with each other, which is a problem for their conservatoin. Keywords Interspecific hybridization, demographic swamping, genetic swamping, flow cytometry, Pulsatilla

National Repository of Grey Literature : 23 records found   1 - 10nextend  jump to record:
Interested in being notified about new results for this query?
Subscribe to the RSS feed.