Pavel M. Trávnícek

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BACKGROUND AND AIMS Genome size and chromosome numbers are important cytological characters that significantly influence various organismal traits. However, geographical representation of these data is seriously unbalanced, with tropical and subtropical regions being largely neglected. In the present study, an investigation was made of chromosomal and(More)
DNA ploidy levels were estimated using DAPI-flow cytometry of silica-dried specimens of the European mountain plant Senecio carniolicus (Asteraceae), covering its entire distribution area in the Eastern Alps (77 populations, 380 individuals) and the Carpathians (five populations, 22 individuals). A complex pattern of ploidy level variation (2x, 4x, 5x, 6x,(More)
BACKGROUND AND AIMS Detailed knowledge of variations in ploidy levels and their geographic distributions is one of the key tasks faced in polyploid research in natural systems. Flow cytometry has greatly facilitated the field of cytogeography by allowing characterization of ploidy levels at both the regional and population scale, and at multiple stages of(More)
Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these(More)
BACKGROUND AND AIMS Despite the great importance of autopolyploidy in the evolution of angiosperms, relatively little attention has been devoted to autopolyploids in natural polyploid systems. Several hypotheses have been proposed to explain why autopolyploids are so common and successful, for example increased genetic diversity and heterozygosity and the(More)
BACKGROUND Only fresh plant material is generally used for rapid DNA ploidy estimation by flow cytometry (FCM). This requirement, however, substantially limits convenient FCM application in plant biosystematics, population biology, and ecology. As desiccation is a routine way for sample preservation in field botany, potential utilization of dehydrated(More)
BACKGROUND AND AIMS Hieracium sub-genus Pilosella (hawkweeds) is a taxonomically complicated group of vascular plants, the structure of which is substantially influenced by frequent interspecific hybridization and polyploidization. Two kinds of species, 'basic' and 'intermediate' (i.e. hybridogenous), are usually recognized. In this study, genome size(More)
Polyploidization is one of the leading forces in the evolution of land plants, providing opportunities for instant speciation and rapid gain of evolutionary novelties. Highly selective conditions of serpentine environments act as an important evolutionary trigger that can be involved in various speciation processes. Whereas the significance of both edaphic(More)
Observations by MESSENGER show that Mercury's magnetosphere is immersed in a comet-like cloud of planetary ions. The most abundant, Na+, is broadly distributed but exhibits flux maxima in the magnetosheath, where the local plasma flow speed is high, and near the spacecraft's closest approach, where atmospheric density should peak. The magnetic field showed(More)
Flow cytometric and karyological investigations were performed on the closely related taxaElytrigia repens andE. intermedia (Poaceae: Triticeae) from the Czech Republic. DNA-hexaploids clearly prevailed among 238 examined plants and amounted to 96.2% of all samples. 2C-values ± s.d. for hexaploidElytrigia repens andE. intermedia were estimated at 23.27 ±(More)