|Dorothee Fitze||"Molecular and karyo-taxonomic studies of Hieracium subgen. Pilosella in Upper Lusatia and adjacent areas of Poland and the Czech Republic"|
|Abstract: In the frame of a project on 'Biodiversity, genetic structure and differentiation of Hieracium species' funded by the Deutsche Forschungsgemeinschaft, morphology-based phylogenetic hypotheses of selected subgenus Pilosella species were analysed by molecular methods.|
The PCR-RFLP technique was used for the elucidation of relationships. 16 species of subgen. Pilosella, six Hieracium s.str. and Chionoracium species and two Andryala taxa were included in the investigation.
For the extraction of genomic plant DNA, after comparison to other procedures, a sorbitol extraction method as a fast and cost-efficient alternative to widely used commercial kits (Štorchová et al. 2000) was established.
After successful optimization of PCR conditions, specificly amplified DNA of the chloroplast DNA region between the trnT and trnF gene was obtained and subsequently digested with 15 different restriction enzymes. Five enzymes showed differences between the subgenera Hieracium and Pilosella and were used for further analyses. For all species including Andryala, no polymorphic restriction sites were found, but a number of length variants of the restricted fragments. The following groups showed identical fragments which might be indicative of identical haplotypes: H. cymosum/H. glomeratum; H. aurantiacum/H. lactucella/H. floribundum; H. pilosella/H. piloselliflorum; H. bauhini/H. leptophyton; H. piloselloides subsp. obscurum/H. echioides; H. sabaudum/H. umbellatum as well as three subspecies of H. caespitosum. Tendencies of presumed relationships deducable from these similarities agree with morphological and cytological findings; however, the data set has to be enlarged before further conclusions can be drawn.
Attempts to amplify the nuclear encoded ribosomal internal transcribed spacer (ITS) with universal primers yielded mainly unspecific products. A specific amplificate obviously belonged to a contaminating fungus according to DNA sequencing. Light- and scanning electron microscopic analysis of the respective plant leaves of H. pilosella which looked uninfested macroscopically proved the presence of fungi. Spore morphology and ITS sequence identified it as ascomycete. The competition of the fungal DNA caused a more efficient amplification of its DNA in comparison to the plant DNA. Possible routes for future analyses of the ITS region in Hieracium are discussed.
In order to calibrate the determination of ploidy levels by flow cytometry of the nuclear DNA content, chromosome counts were performed from mitotic metaphases in nine species (H. aurantiacum, H. brachiatum, H. caespitosum ssp. caespitosum, H. floribundum, H. iseranum, H. lactucella, H. pilosella, H. sabaudum, H. umbellatum). Results of both approaches were identical.
|Jiří Kocián||"Microevolution, genetic structure, reproduction, and biogeography of the Hieracium prenanthoides polyploid complex"|
|Abstract: Prenanth hawkweed (Hieracium prenanthoides agg.) is a highly polymorphic polyploid aggregate species. The thesis focuses on reproduction systems of twenty six populations of different ploidy and morphology originating from France, the Czech Republic and Slovakia. Palynological analyses were carried out and the mode of seed development was determined both in natural populations and in seeds originated via experimental hybridization. Two thirds of the populations produced pollen, most of them in big amounts, however, with a mean viability of only 40%. Alexander stain showed false positive results; on the other hand, tetrazolium test showed false negative results; acetocarmine stain was determined as the most reliable pollen viability stain. Pollen of all analysed plants was of heterogenous size. The vast majority of seeds of polyploid plants, both from natural populations and from experimental hybridization, arose via apomixis - the embryos had the same ploidy as the mother plants and the endosperm tissues with double-somatic DNA content. Three rare exceptions were detected in tetraploid populations: 1) a seed with a tetraploid embryo and hexaploid endosperm, 2) a seed with an octoploid embryo, and 3) a seed with a pentaploid embryo. The results are discussed in the species as well as the whole Hieracium genus evolutionary context.|
|Veronika Košťálová||"Studies of selected species in genus Hieracium subgenus Pilosella situated on antropogenic sites in the capital city of Prague area: Variability, distribution and ecological specifications"|
|Abstract: Preferably invasive populations of Hieracium subgenus Pilosella spreading on ruderal localities influenced by humans were investigated in an urban area (Prague City). The number and distribution of these localities, their respective species ratios, ecological and geographic conditions are described. Morphological comparison of the plants, determination of their ploidy level and reproduction experiments were performed in order to assess the species variability. These localities and plant features, considered together, shall lead to a better understanding of the factors influencing the initiation of new hybrid localities and their population parameters.|
In 2003 and 2004, the whole Prague area was systematically screened for invasive species localities. Among the 46 sites, the following species were found: Hieracium pilosella, H. bauhini, H. piloselloides, H. brachiatum (H. pilosella > H. bauhini), H. leptophyton (H. pilosella < H. bauhini), H. anchusoides (H. pilosella - H. zizanum), H. arvicola (H. piloselloides - H. caespitosum), H. fallax (H. echioides - H. cymosum, H. glomeratum (H. caespitosum - H. cymosum), H. rothianum (H. echioides > H. pilosella), H. zizianum (H. piloselloides - H. cymosum). Eight of them are of hybrid origin. Four of these species have been recorded from the explored area for the first time: Hieracium arvicola, H. leptophyton, H. glomeratum and H. piloselloides. The species Hieracium anchusoides was rediscovered after more than 100 years (this species was last found by the Czech botanist Karel Polák in Běchovice by the railway site in 1887). Seven localities with mixed H. pilosella - H. bauhini populations were found. Five localities involved hybrid populations with Hieracium brachiatum and H. leptophyton (and both parental species present). Ten localities of Hieracium anchusoides were discovered.
The following ploidy levels / chromosome numbers and reproduction modes were found for the studied plants: H. pilosella (2n = 36, sexual; 2n = 54, apomictic; 2n = 63), H. bauhini (2n = 45, 54; both apomictic), H. piloselloides (2n = 45; apomictic), H. brachiatum (2n = 36; sterile), H. leptophyton (2n = 45; apomictic), H. anchusoides (2n = 36; apomictic), H. arvicola (2n = 36; apomictic). In the following species only the reproduction mode was studied: H. glomeratum (apomictic), H. fallax (apomictic), H. zizianum (apomictic), H. rothianum (apomictic). The evidence of Hieracium pilosella with heptaploid cytotype was a big surprise, it is the third discovery of this cytotype in Europe. Hexaploid populations are also very rare in Bohemia. The tetraploid cytotype of Hieracium brachiatum and the pentaploid cytotype of H. piloselloides (with apomictic reproduction mode) are the first records in the Czech Republic.
The study of mixed Hieracium pilosella and H. bauhini populations pointed out that hybrid species such as H. brachiatum and H. leptophyton originate de novo at unique localities, because they were never found in absence of their parental species. In contrast, the other hybrid species Hieracium anchusoides forms fixed populations in our study area. This conclusion is supported by similarities in morphological features, ploidy level, apomictic reproduction mode and occurrence in the same kind of habitats (ruderal, synantropic places like ramparts of highways, railway stations etc.). Till now, the only fixed populations of this species have been known from the western Alps and Spain. In Europe, only non-fixed populations have been found so far (Gottschlich, pers. comm.).
Studies of ecological features of all the localities with the investigated species showed a preference of sunny places with rather southern slope-orientation. No northern slope orientation was found. The average slope gradient was not less than 35°.
|Karol Krak||"Trichome types in the tribe Lactuceae"|
|Abstract: The morphological and anatomical diversity of trichomes was investigated in 53 genera of the tribe Lactuceae (Asteraceae) by light and scanning electrone microscopy. The following trichome types were observed: A.) uniseriate glandular trichomes; B.) multi- or biseriate glandular trichomes; C.) multiseriate eglandular trichomes (C1. trichomes with projected apical parts of cells; C2. trichomes with non-projected apical parts of cells; C3. trichomes with branched apical parts); D.) long conical trichomes; E.) short conical trichomes; F.) uniseriate filiform trichomes (F1. uniseriate filiform unbranched trichomes; F2. uniseriate filiform branched trichomes; F3. stellate trichomes; F4. trichomes with elongated apical cells); G.) uniseriate eglandular trichomes with multiseriate basis; H.) uniseriate glandular trichomes with multiseriate basis. Resemblance analysis of these genera based on the distribution of the trichome types among them was performed. The utility of the trichomes as taxonomic markers at the generic level within the tribe Lactuceae is discussed.|
|Jitka Krbcová||"The growth of hawkweeds (Hieracium subgenus Pilosella) in a mountain meadow"|
|Abstract: The previous research surveys demonstrated that members of Hieracium subgen. Pilosella occur only in certain communities. Six taxa of this subgenus (H. pilosella, H. lactucella, H. glomeratum, H. iseranum, H. apatelium, and H. floribundum) have been chosen for my thesis.|
The main question was whether growth of those taxa differed in various communities according to trophic and production gradient and whether it was possible to correlate the differences with the natural occurrence of the taxa in the study area (a grassland in Janovy Boudy, Krkonoše, the Sudeten Mts.). Another question concerned the influence of local differences in biomass upon flowering of selected related taxa. Plants taken from the grassland in Janovy Boudy were after reproduction planted back in grassland, into four communities differing in height of vegetation and amount of nutrients. Parameters characteristic of the above-mentioned plants' growth were measured for three years.
The research data showed that the influence of community upon the growth of the taxa was not significant; the influence of biomass was only significant for H. lactucella, competitively the weakest taxon of the set studied.
|Martina Odvodyová||"Biosystematic study of selected species of the Hieracium nigrescens agg."|
|Abstract: The Hieracium nigrescens group includes taxa of morphologically intermediate position between H. alpinum and H. murorum, which are closer to the former (H. alpinum ł H. murorum). They are distributed in higher mountains of the Central Europe and in the North, from Greenland to the Ural Mts. This research was aimed to propose a new taxonomic treatment of the group in the Western Carpathians (Slovakia, S Poland), and the Sudeten Mts. (N Czech Republic, SW Poland). Based on own observations and studies of previously recognized taxa we prepared a preliminary taxonomic treatment. To test it, we examined morphological variation (total of 23 quantitative characters), the genetic structure of species/populations by use of isozyme markers, chromosome numbers and the mode of reproduction (using castration/isolation experiments). Both multivariate morphometric and isozyme analyses provided support for recognition of 8 taxa, evaluated here at the species level, i.e. H. apiculatum Tausch, H. chrysostyloides (Zahn) Chrtek jun., H. decipiens Tausch, H. nigrescens Tausch (all the Sudeten Mts.), H. mlynicae (Hruby et Zahn) Chrtek jun., H. vapenicanum (Lengyel et Zahn) Chrtek jun. and H. koprovanum (all the Western Carpathians) Isozyme analysis revealed no variation within each species. On the other hand, the recognized species clearly differ from each other in their banding patterns. With respect to the ploidy level (x = 9), tetraploids strongly prevail (2n = 36, H. apiculatum, H. decipiens, H. nigrescens, H. mlynicae), H. vapenicanum is triploid (2n = 27), H. chrysostyloides pentaploid (2n = 45). Agamospermy was confirmed for all species. While all species are genetically formed by one clone each, they differ in morphological variation. The highest phenotypic plasticity was found in H. mlynicae, which also includes genetically the same but morphologially slightly different population from Mt. Babia hora. However, some questions remain still open, such as systematic position of H. vapenicanum (which may be better placed between H. alpinum and H. bifidum).|
|Stanislava Papoušková||"Variability of the reproduction mode in the facultatively apomictic species Hieracium rubrum."|
|Abstract: The versatility of the breeding system in the hybridogenous hexaploid, Hieracium rubrum, was demonstrated in emasculation and crossing experiments. The flow-cytometric ploidy analysis of 1095 seedlings amongst its’ progeny enabled the determination and quantification of the reproductive pathway (apospory, haploid parthenogenesis, cross-fertilization of both reduced and unreduced female gametes) responsible for each progeny class. The progeny profiles were stable between two successive years. The percentage of hybrids arisen from crosses with tetraploid sexual H. pilosella was 7.9%. The rate of trihaploids generated by H. rubrum when crossed to H. pilosella was 3.95%, similar to that of pentaploid (n./n) and octoploid (2n./n) hybrids (3.95% and 3.39%). Unreduced pollen from H. pilosella contributed to hybridization much less frequently (0.56% of all progeny), than unreduced eggs of H. rubrum. The increased frequency of trihaploids formed by crossed compared to emasculated plants suggests an interaction between the presence of pollen and the autonomous development of meiotic embryo sacs. Although the environmental conditions (garden compared to unheated glasshouse) influenced the progeny following the emasculation, no corresponding response to environment was detected amongst the autonomously derived progeny following pollination with H. pilosella. However, there was an influence of pollen parent on progeny which varied under the different environmental treatments. The importance of residual sexuality in reproduction of apomicts is evident. The non-maternal progeny was generated with highly variable frequency especially in the glasshouse, with some capitula reaching up to 50%. Having an autonomous endosperm development, Hieracium subgen. Pilosella is almost unique among other aposporous genera, in which such variable reproduction mode is connected with pseudogamy.|
|Tomáš Peckert||"Hieracium echioides Lumn. and Hieracium rothianum Wallr. in Central Europe"|
|Abstract: Hieracium echioides occurs mainly in steppen regions of Asia and Eastern Europe, westwards the geographic distribution reaches E Germany, Czech Republic and E Austria. Hieracium rothianum mostly occurs in SE and E Europe, westwards the area overlaps that of H. echioides.|
Objectives were as follows: (1) to prepare list of localities of the both species in the Czech Republic and Slovakia, (2) to detect chromosome numbers in selected Central European populations and to assess geographic pattern of particular cytotypes, (3) to examine the mode of reproduction, test pollen viability and correlation between pollen size and ploidy level, and (4) to evaluate patterns of morphological variation of H. echioides in central Europe.
Results of cytological studies of H. echioides (together with previously published data) shed some light into the pattern of karyological differentiation. Co-occurrence of two or three cytotypes (2n = 18, 27, 36) was detected at some localities in SW Moravia, more than one ploidy level was also ascertained at some localities in Central and NW Bohemia. Only diploids were found at localities with a relic character (e.g. ultramafic rocks near the village of Mohelno, SW Moravia). All hitherto examined plants from NE Germany (Kreis Barnim) and adjacent regions in Poland were found to be diploid. Only tetraploids (2n = 36) were recorded in H. rothianum.
Both diploids and tetraploids of H. echioides were proved to be sexual and allogamous, triploids showed very low fertility. All examined plants of H. rothianum were agamospermous. Correlation between pollen size and ploidy level was confirmed. Test of pollen viability (TTC test) did not give interpretable results. Morphologically, population of H. echioides from the Czech Republic and Austria are rather invariable. Distinct type represent populations from NE Germany (Kreis Barnim) with dense long patent hairs in the upper part of stem and on peduncles. In contrast, plants from the Czech Republic, Slovakia, Austria and Hungary have upper part of stem and peduncles with only scattered hairs (or fully without them). H. rothianum is morphologically variable. Most variable characters are presence/absence of glandular hairs in the inflorescence, number and size of heads and number of stem leaves. Introgression from other sympatrically occurring species of subgen. Pilosella is supposed at some localities.
|Michal Severa||"Hieracium villosum Jacq. and related taxa in the Western Carpathians and the Sudeten Mts."|
|Abstract: Hieracium villosum Jacq. belongs, together with its intermediate taxa, to the most interesting groups of mountain hawkweeds in the Western Carpathians (Slovakia, S Poland). We examined pattern of morphological and genetic (using isozyme analysis) variation, chromosome numbers and modes of reproduction of H. villosum (16 populations), H. scorzonerifolium Vill. (H. villosum ł H. bupleuroides, 2 populations), H. dentatum Hoppe (H. villosum ł H. bifidum, 2 populations) and in one still unnamed and taxonomically unclear taxon resembling (but not fully identical with) H. valdepilosum Vill. (H. villosum - H. prenanthoides, 6 populations).|
Based on morphology, chromosome numbers and multilocus isozyme genotypes, 5 types were recognized within H. villosum. Generally, all of them are geographic vicariants, an occurrence of two types was observed at only three localities. The most widespread type, identical with H. villosum subsp. villosum, was proven to be an apomictic triploid (2n=27) with aborted pollen; no genetic variation was discovered. The remaining types are apomictic tetraploids (2n=36) with viable pollen grains, confined to rather small geographic areas. Both intra- and interpopulation genetic variation was detected in two of them, the remainig two are homogeneous in this respect. One of them shares the same multilocus isozyme genotype with H. villosum subsp. villosum; genotypes of two other remarkably differs from H. villosum subsp. villosum by occurrence of unique alleles.
Hieracium dentatum was found to be apomictic tetraploid with surpringly the same genotype as detected in H. villosum subsp. villosum. The same chromosome number and mode of reproduction was found in H. scorzonerifolium; comparison of isozyme genotypes of H. scorzonerifolum and its putative parent species (H. villosum and H. bupleuroides) supports the hypothesis about its hybrid origin. Geographic pattern of both morphological and genetic variation (more or less different races in particular mountain ranges of the Western Carpathians) was detected in the still unnamed taxon from the vicinity of H. valdepilosum; both triploids and tetraploids were found.
In addition, two remarkably distinct isozyme genotype were found in H. bupleuroides. No relationship between genotypes and morphology was observed; on the other hand, geographic areas of particular genotypes are vicariant.
The observed variation pattern of H. villosum resembles generally that of some other "Hauparten" of Hieracium. The core taxon (H. villosum subsp. villosum) is surrounded by tetraploid apomictic (but pollen producing) lineages which have some morphological characters of other Hieracium species (nevertheless, they cannot be treated as "Zwischenarten", because they are very similar to H. villosum subsp. villosum). Their origin is difficult to trace, further detailed studies can perhaps elucidate some particular evolutionary processes.
|Roman Šimek||"Study of the species Hieracium cymosum L. in the Czech and Slovak Republic"|
|Abstract: Hieracium cymosum L. occurs throughout Europe. Its area of distribution reaches from the Massif Central to the Ural Mts., northwards to Scandinavia. Three subspecies are traditionally recognized, i.e., subsp. cymosum, subsp. cymigerum and subsp. sabinum. The main distinguishing characters are the density of glandular and simple eglandular hairs in the inflorescences as well as inflorescence architecture.|
In the course of the diploma studies, chromosome numbers/ploidy levels, mode of reproduction (isolation and emasculation experiments), inter- and intrapopulation genetic variation (DNA fingerprinting, isozyme analysis) and geographic distribution in the Czech Republic and Slovakia were examined.
Two different taxa corresponding to subsp. cymosum and subsp. cymigerum were confirmed from the study area. They differ in ploidy levels, mode of reproduction and levels of intra- and interpopulation genetic variation. While a rather reticulate variation pattern was observed in subsp. cymosum (which probably represents the "core" of the species), subsp. cymigerum comprises many local populations which differ from each other and represent more or less different morphotypes, probably of hybrid origin.
All but four populations of subsp. cymosum were proved to be diploid and sexual (total of 37 populations). Two populations were found to be tetraploid, one consisting of intermingled tetra- and diploids, and one of both diploids and triploids. However, a taxonomic revision of polyploid plants is necessary. DNA fingerprinting and isozyme analysis revealed a high level of intra-population and a low level of inter-population variation which corresponds to the sexual mode of reproduction.
Four populations of subsp. cymigerum from NW Bohemia were studied. Two of them were found to be tetraploid, one pentaploid and one consisting of both tetra- and pentaploid plants. Agamospermy was detected in all plants. Their genetic structure can be attributed to the breeding system - each of the four studied populations has a clonal structure consisting of one prevailing genotype (another genotypes with very low frequency were discovered in two populations). Both tetraploid populations share the same prevailing genotype.
The diploma thesis also includes a comprehensive list and a map of localities of H. cymosum in the Czech Republic and Slovakia.
|Jana Škorničková||"Study of the species Hieracium hoppeanum Schult. s.l. in Central Europe"|
|Abstract: The section Pilosellina Fries forms a relatively clearly defined group within the subgen. Pilosella. Besides the widespread and morphologically extremely variable H. pilosella, three species are recognized in Central Europe, i.e., H. peleterianum Mérat, H. macranthum (Ten.) Ten. (sometimes treated as an intraspecific taxon of H. hoppeanum) and H. hoppeanum Schult. (s.str.). The species markedly differ in their distribution ranges. While H. hoppeanum is mostly confined to the Alps, H. macranthum may be evaluated as an East - submediterranean species, having northernmost localities in the Czech Republic and Slovakia. H. peleterianum has a core of its distribution range in Western Europe and is not a subject of this study.|
Main objectives were as follows: (1) to prepare a comprehensive list of localities of H. macranthum in the Czech Republic, (2) to detect chromosome numbers and mode of reproduction in selected populations of H. macranthum and H. hoppeanum (s.str.), and in mixed populations of H. macranthum and H. pilosella, (3) to determine the genetic structure of selected populations of H. macranthum and H. hoppeanum using RAPD and isozyme markers.
The distribution of H. macranthum in the Czech Republic is restricted to a few localities in Moravia, especially in its southern part (two new localities were discovered during this study). It grows in open grasslands, thermophilous oak forests and occasionally in pine forests.
All studied population of H. macranthum in the Czech Republic, Slovakia and Hungary were proven to be diploid, the same ploidy level was confirmed for H. hoppeanum s. str. from the Alps. Hybrids between H. macranthum and H. pilosella collected in Central Slovakia turned out to be triploid (2n = 27). All cultivated plants of both H. macranthum and H. hoppeanum were found to be sexual and allogamous. Very low intrapopulation genetic variation was found in H. hoppeanum, which can be explained by a capability for clonal growth by above-ground stolons. Genetic variation in H. macranthum is higher, especially at the intrapopulation level. This can be likely due to introgression from sympatrically occurring H. pilosella. Relations between H. hoppeanum and H. macranthum based on data from isozyme and RAPD analysis are discussed.
|Martin Tetera||"RAPD analysis of selected populations of the groups Hieracium alpinum and H. fritzei from the Tatra Mts. (Slovakia)."|
|Abstract: The Hieracium alpinum and H. fritzei (H. alpinum > H. prenanthoides) agg. belong to taxonomically most intricate groups of high mountain hawkweeds in the Tatry Mts. According to recent monographic tretments, 2 species are recognized within the H. alpinum group (H. alpinum and H. halleri) and 4 within the latter one (H. crassipedipilum, H. krivanense, H. pinetophilum and H. slovacum). They have been proved to be agamospermous triploids and tetraploids.|
The diploma thesis was aimed at examination of genetic variation in the recognized species (172 plants from 28 populations) using RAPD analysis. Thirteen primers were tested in the pilot study, 5 of them were chozen for further population screening. 25 polymorphic markers from the total of 35 reproducible were obtained and their combinations revealed 28 distinct repeated RAPD profiles, usually species/population specific. All but four populations (three of H. alpinum, one of H. halleri) were found to be uniform. Between-population variation was detected in H. crassipedipilum and H. pinetophilum. Low genetic variation is in agreement with agamospermous mode of reproduction. Between-population variation in H. crassipedipilum and H. pinetophilum is likely due to repeated polytopic origin of the species (both are suggested to be hybridogeneous).
|Tomáš Urfus||"Sources of variation in Hieracium pilosella"|
|Abstract:DNA ploidy level or chromosome counts were determined for 674 plants of Hieracium pilosella L. (syn. Pilosella officinarum F. W. Schultz et Sch. Bip.; Asteraceae from 184 localities from all over the area of the Czech Republic. Three ploidy levels were recorded within the area: the most widespread cytotype was tetraploid one (2n=36) with 65%, the second most common was pentaploid (2n=45, 18%), and last common was hexaploid level (2n=54, 17%). Detailed distribution maps of the cytotype distribution were carried out. In this way border of cytotypes was accurately defined. Tetraploids clearly prevail in the area of the Czech Massif, pentaploid and hexaploid cytotypes occur mostly in the Western Carpathians (eastern part of Moravia), river canyons of southern Moravia and canyon of the Vltava River in the vicinity of Prague in central Bohemia. Breeding systems were tested in 172 plants. Pentaploid plants were mostly apomictic (73 plants, 90.5%), hexaploids (74 plants) were divided nearly into two halves, which were geographically separated. Sexual hexaploids occur in the area of the Czech Massif in steep canyons of rivers, apomictic hexaploids occur mainly in the Western Carpathians predominantl in lower altitudes. Morphometric analysis was carried out for individual plants of particular cytotypes. Principal Components Analysis, Discriminant Analysis and Nonparametrical Classification Analysis detected, that tetraploid and hexaploid plants are distinctly morphologically separated, while pentaploids share morphological features of both. Nevertheless, pentaploid cytotype keeps special characters that slightly distinguish pentaploid plants from the others. Even the sexual and apomictic hexaploids can be distinguished on the basis of morphological features. Such results indicate that both groups of hexaploids could be unrelated. Sexual hexaploids are considered to be of a relict origin, apomictic hexaploids appear to be connected to possible hexaploid cytotype distribution centre in the Carpathian Mts. as well as majority of pentaploid cytotype. It seems highly probable that besides two distinct recorded groups of hexaploids one more occurs in the area of the Czech Republic. A population of morphologically different plants in the Hrubý Jeseník Mts. was found and acording to habitus is remarkably similar to plants, which were reported from the Oravská Magura Mts. All mountain hexaploid populations together may represent the third distinct group of hexaploids in the area. The study showed that even such common species as Hieracium pilosella has rather complicated pattern on the small area of the Czech Republic. Its explanation is limited by the lack of comparable data from all over the Europe, in spite of the fact that this species belongs to the most studied species of European flora.|
|Jaroslav Zahradníček||"Genome size variation and evolution of Hieracium L"|
|Abstract:In this study, 43 “basic” species (sensu Zahn) of the subgenus Hieracium and three species of the subgenus Chionoracium were studied karyologically and cytometrically. Triploid cytotypes predominate all over Europe. Diploid cytotypes are mainly concentrated in specific areas of presumed glacial refugia in southern Europe. Chromosome counts of plants of subgenus Chionoracium are congruent with all values published so far. The measured monoploid genome size in subgen. Hieracium correlated with the concurrently produced molecular phylogeny (ETS), which also separated two main lineages of species that correspond to their geographic distribution. Both lineages differed significantly in genome size (Cx). On average, members of the “eastern” group had over 1 pg more DNA than members of the “western” group. Some of the “basic” species were marked as hybridogeneous/hybrid between the two lineages by ETS markers. The genome size of these hybridogeneous species was surprisingly higher than the average genome size of both main lineages. Intraspecies variability in genome size was found in seven species. It can be explained by the presence of populations of hybridogeneous origin, multiple polyploidization events. In one species, this turned out to be a methodical artifact. Both subgenera under study markedly differ in genome size (Cx). The mode of reproduction was verified for most species. Polyploid species that reproduce apomictically did not show any sign of residual sexuality. Diploid cytotypes of the subgenus Hieracium, characterized by sexual reproduction, are obligately allogamous. Conversely, members of the subgenus Chionoracium show a high degree of autogamy.|
|Vojtěch Zavadil||"The Hieracium bifidum group in the Czech Republic"|
|Abstract:The diploma thesis deals with the Hieracium bifidum and Hieracium wiesbaurianum groups on the territory of the Czech Republic. Hieracium bifidum is a complex basic (non hybridogeneous) apomictic taxon with the highest morphoplogical diversity occurring in the Alps and the Carpathians. Hieracium wiesbaurianum represents an intermediate apomictic taxon between H. bifidum and H. schmidtii. Besides of detailed revision of herbarium specimens in public collections, 18 populations of H. bifidum, and six populations of H. wiesbaurianum were chosen for (i) detailed morphological and isozyme (5 loci) analysis aimed at intra- and inter-population variation, and (ii) karyological analysis (variation in chromosome numbers). Triploids (2n=3x=27) strongly prevailed among the studied plants; tetraploid plants (2n=4x=36) were detected in the populations of Kozí vrch (most likely bifidum-wiesbaurianum), Ralsko, and Bezděz (a mixed population). Most of the populations were homogeneous with respect to isozyme patterns; several different multilocus phenotypes were detected in populations of H. bifidum from localities in the Moravský kras, Ralsko and Kozí vrch and in H. canofloccosum from the localities Pokratice and Radotín. Unique alleles were detected in populations of H. bifidum from the Krkonoše Mts. and Dívčí kámen. Nine of the populations were identified as H. bifidum subsp. stenolepis, most of them being morphologically uniform (Křivoklát, Kozí vrch, Ralsko, Bezděz, Svatý Jan, Tolštejn, Malé Sedlo). Isozyme analysis confirmed homogeneity at the population level (except of the Bezděz population), and very low diversity at the inter-population level (four populations consisted of the same isozyme phenotype and thus might represent the same apomictic clone). Another two populations, namely Mohelka a Boreč, strongly resembled but were not fully identical with H. bifidum subsp. stenolepis; they bore some marks of hybridization with H. murorum and may be distinguished on a morphological basis. The seven remaining populations of H. bifidum were not assigned to any particular intraspecific taxon and are evaluated as types without a taxonomical rank for the present. They are either ‘pure’ H. bifidum (Moravský kras 1 and Krkonoše) or plants bearing some morphological characters of other species, namely H. murorum (Moravský kras 2, Pálava, Dívčí kámen), H. wiesbaurianum (Kozí vrch, foot), and H. caesium (Hradčany). Plants identified by Zahn as H. bifidum subsp. chartaceum are morphologically most similar to H. wiesbaurianum and it is proposed to transfer this subspecies to the latter species (as H. wiesbaurianum subsp. chartaceum). Hieracium canofloccosum, assigned by Zahn at the subspecies rank to H. wiesbaurianum, is accepted here at the species level (based on a unique combination of morphological characters).|