Prvotní příčinou podivuhodného složení hadcové flóry jsou zvláštní chemické a fyzikální vlastnosti samotného hadce, které se však projevují v různé míře v závislosti na místních klimatických a geomorfologických podmínkách. Extrémní podmínky substrátu a izolovanost hadcových oblastí, které jsou u nás roztroušeny po celé republice, mohly vést až k evoluci hadcových (sub)endemitů. and The primary reason for the special composition of serpentine flora are the special chemical and physical features of the serpentine itself, whose expression differs according to local climatic and geomorphological conditions. The extreme condition of the substrate and the isolation of serpentine areas, dispersed across the whole country in the Czech Republic, can subsequently lead to the evolution of serpentine (sub)endemic species.
Článek je zaměřen na systematiku, evoluci, ekologii a možné příčiny ohrožení čtyř hadcových subendemitů ČR. Zatímco chrastavec rolní hadcový (Knautia arvensis subsp. serpentinicola) a mochna Crantzova hadcová (Potentilla crantzii subsp. serpentini) jsou poměrně dobře definované poddruhy, hvozdík kartouzek hadcový (Dianthus carthusianorum subsp. capillifrons) a trávnička obecná hadcová (Armeria vulgaris subsp. serpentini) jsou možná taxonomicky heterogenní jednotky, které spojuje pouze výskyt na hadcovém substrátu. Přesto však hadcové populace těchto druhů představují významný ekologický a fytogeografický prvek středoevropské flóry. and The article describes the possible reasons why four of the Czech serpentine subendemic species are endangered, as well as their systematics, evolution and ecology. While Knautia arvensis subsp. serpentinicola and Potentilla crantzii subsp. serpentini are relatively well defined subspecies, Dianthus carthusianorum subsp. capillifrons and Armeria vulgaris subsp. serpentini might be heterogeneous units having only the distribution on a serpentine substrate in common. Nevertheless, serpentine populations of these species are an important ecological and phytogeographical phenomenon among Central European flora.
Oba taxony s podobnou evoluční historií jsou dlouhodobě uznávanými endemity českých hadcových substrátů a nejsou doprovázeny dalšími blízkými či velmi podobnými druhy v okolí. Vzhledem k tomu, že oba jsou zařazeny mezi kriticky ohrožené taxony a jsou pod ochranou evropského projektu Natura 2000, zaslouží si naši prvořadou pozornost. and Both taxa (Cerastium alsinifolium and Minuartia Smejkalii) with similar evolutionary history have for years been included among the endemic species of the Czech serpentine substrate, not accompanied by other near or similar species in given localities and their neighbourhood. Both species are critically endangered and protected under the European Natura 2000 project and therefore deserve special attention.
Variation in genome size in a particular taxonomic group can reflect different evolutionary processes including polyploidy, hybridization and natural selection but also neutral evolution. Using flow cytometry, karyology, ITS sequencing and field surveys, the causes of variation in genome size in the ecologically and morphologically diverse high-Andean genus Lasiocephalus (Asteraceae, Senecioneae) were examined. There was a 1.64-fold variation in holoploid genome size (C-values) among 189 samples belonging to 20 taxa. The most distinct was a group of plants with large genomes corresponding to DNA triploids. Disregarding the DNA triploids, the remaining samples exhibited a pronounced (up to 1.32-fold) and rather continuous variation. Plants with the smallest genomes most likely represent intergeneric hybrids with the closely related and sympatric Culcitium nivale, which has a smaller genome than Lasiocephalus. The variation in genome size in samples of diploid Lasiocephalus was strongly correlated with several environmental and life history traits (altitude, habitat and growth form). However, all these factors, as well as genome size itself, were correlated with phylogeny (main split into the so-called ‘forest’ and ‘páramo’ clades), which most probably represents the true cause of the differentiation in intrageneric genome size. In contrast, relationships between genome size and phylogeny were not apparent at lower divergence levels. Instead, here we suggest that ecological conditions have played a role in driving shifts in genome size between closely related species inhabiting different environments. Collectively, this study demonstrates that various evolutionary forces and processes have shaped the variation in genome size and indicates that there is a need for multi-approach analyses when searching for the causes and consequences of changes in genome size.
Zástupci tropického andského rodu Lasiocephalus (hvězdnicovité) tvoří dvě růstové formy – liány osidlující horský les a polokeře osidlující nadlesní biotopy (páramo). Cytometrické a molekulární analýzy naznačují konvergentní vývoj růstových forem během opakované kolonizace párama. and In the tropical Andean genus Lasiocephalus (Asteraceae), two growth forms can be recognized – montane forest climbers and subshrubs of habitats above the timber lime (páramo). Flow cytometry and molecular markers suggest the convergent evolution of these growth forms during the repeated colonization of páramo habitats.
Vyšší rostliny obývající jihoamerická páramos oplývají velkým bohatstvím růstových forem. Polštáře, přisedlé růžice, plazivé keříky, drobnolisté keře i bizarní obří stonkové růžice mohou představovat přizpůsobení na extrémní podmínky páramos (především noční mrazíky a sezónní sucho). Probíhající fylogenetické výzkumy radiujících páramových skupin poukazují na vysokou rychlost jejich evoluce a dokládají opakovaný vznik obdobných růstových forem v rámci téže skupiny. and Vascular plants of Andean páramo are characterized by a striking diversity of growth forms. Cushions, rosettes, prostrate dwarf shrubs, microphyllous shrubs and giant columnar rosettes could be an adaptive response to the extreme páramo environment (night frosts and drought). Recent phylogenetic studies conducted on several groups radiating in páramo documented their rapid diversification and the recurrent origins of similar growth forms within a single group.
Květena páramos Střední a Jižní Ameriky je nejbohatší tropickou alpínskou flórou světa. Výsledky molekulárních fylogenetických studií potvrzují, že se tato květena vytvořila ze dvou hlavních zdrojů: i) (neo)tropických rostlin osídlujících především horský mlžný les, které se postupně adaptovaly na vysokohorské prostředí, a ii) temperátních rostlin, které osídlily rovníkové Andy migrací z vyšších zeměpisných šířek obou polokoulí. Obě skupiny, tj. tropické a temperátní rody se podílely přibližně stejnou měrou na vzniku současné druhové diverzity. Mezi temperátními skupinami však pochází výrazně větší počet páramových druhů z rodů původem ze severní polokoule než z polokoule jižní. and Páramo flora of South and Central America is the richest tropical alpine flora in the world. Molecular phylogenies confirm that it evolved from two major sources: i) (neo)tropical elements of mostly montane forests by gradual adaptation of plants to a high-altitude environment and ii) temperate elements that immigrated to the equatorial Andes from higher latitudes of both hemispheres. Tropical and temperate genera contributed to a similar extent to the modern species richness of the páramo flora. Among the temperate genera, however, the northern hemisphere immigrants gave rise to more páramo species than did genera from the southern hemisphere.
Two new apomictic triploid (2n = 3x = 51) species from the Sorbus latifolia group, S. portae-bohemicae M. Lepší, P. Lepší, P. Vít et K. Boublík and S. albensis M. Lepší, K. Boublík, P. Lepší et P. Vít, putative hybridogenous species originated from a cross between S. danubialis and S. torminalis, are distinguished and described based on a taxonomic and chorological revision of Sorbus bohemica (a hybridogenous triploid species from the same parental combination). A number of contemporary biosystematic techniques, including molecular (nuclear microsatellite markers), karyological (chromosome counts, DAPI flow cytometry) and multivariate and geometric morphometrics were used to assess the variation of the species and justify their independent taxonomic status. All three species occur sympatrically in the České středohoří Mts (NW Bohemia). Sorbus bohemica is recorded from 31 localities, based on a revision of herbarium vouchers and field research. Recent field studies failed to verify five of these localities. Sorbus portae-bohemicae is a stenoendemic in the Porta bohemica gorge (situated ca 7 km WNW of Litoměřice) where it grows in open oak forests (Luzulo-Quercetum and transition vegetation type to Melampyro nemorosi-Carpinetum) on ENE-facing slopes and rocks. The only known population of S. portae-bohemicae consists of 14 adult individuals. Sorbus albensis occurs at 12 localities W to NW of Litoměřice. The total number of individuals is estimated at 600. Most are in acidophilous oak forests (Luzulo-Quercetum and its mesic derivatives), scree forests (Aceri-Carpinetum) or shrubby slopes (Pruno-Ligustretum, Antherico-Coryletum). Populations of the new taxa show little genetic variation and are phenotypically homogenous and well separated from other Bohemian hybridogenous Sorbus species. A distribution map of the three species is provided. Photographs of the type specimens and in situ fructiferous individuals of the new species are presented.
Four European taxa of the Tortula muralis complex (T. lingulata, T. muralis var. aestiva, T. muralis var. muralis, T. obtusifolia) were evaluated using multivariate analysis of morphological characters, a cultivation experiment and cytological screening (flow cytometry, chromosome counts). This study revealed that only T. lingulata is morphologically well defined within the complex and several new sporophytic characters that can be used to distinguish this taxon from the superficially most similar T. obtusifolia. The traditionally recognized taxa T. muralis var. muralis, T. muralis var. aestiva and T. obtusifolia showed continuous variation, with frequent intermediate plants. However, the main character of the gametophyte used for determination (costa excurrency) proved to be stable in cultivation, indicating that this character is under genetic control. Additionally, rather complex and only partly species-specific patterns of ploidy variation were found within the complex. Tortula lingulata and T. obtusifolia appear to be cytologically homogeneous; plants of T. lingulata were found to be diploid, whereas plants tentatively named as T. obtusifolia were haploid. In contrast, both haploid and diploid cytotypes were found in both varieties of T. muralis, with a marked predominance of diploids in var. aestiva and less marked predominance of diploids in var. muralis. Current varietal level of the evaluated infraspecific taxa of T. muralis was thus found to be warranted. It is suggested that plants previously recognized as T. obtusifolia should be treated as a subspecies of T. muralis.