Zdeněk Kaplan

Flora and phytogeography of the Czech Republic.

An overview of the diversity of vascular plants in the Czech Republic is presented. This country is situated at the intersection of several assumed important European migration routes. Consequently, the flora is composed of almost all the floristic elements that occur in Central Europe, of which the Central European geoelement is dominant. The occurrence of various sorts of relicts is discussed in the context of the changes in vegetation caused by Pleistocene climatic fluctuations. An account of Czech endemics includes 82 species and subspecies, which is 2.2% of the total vascular plant diversity in this country. Patterns in the distribution and occurrence of endemics in different habitat types are described. Groups of species with similar ecogeographical features within the Czech Republic are distinguished as regional types of distribution. Phytogeographical division of the country is described and the phytogeographical units distinguished are shown on a map.

Genome Size as a Key to Evolutionary Complex Aquatic Plants: Polyploidy and Hybridization in Callitriche (Plantaginaceae)

Despite their complex evolutionary histories, aquatic plants are highly underrepresented in contemporary biosystematic studies. Of them, the genus Callitriche is particularly interesting because of such evolutionary features as wide variation in chromosome numbers and pollination systems. However, taxonomic difficulties have prevented broader investigation of this genus. In this study we applied flow cytometry to Callitriche for the first time in order to gain an insight into evolutionary processes and genome size differentiation in the genus. Flow cytometry complemented by confirmation of chromosome counts was applied to an extensive dataset of 1077 Callitriche individuals from 495 localities in 11 European countries and the USA. Genome size was determined for 12 taxa. The results suggest that many important processes have interacted in the evolution of the genus, including polyploidization and hybridization. Incongruence between genome size and ploidy level, intraspecific variation in genome size, formation of autotriploid and hybridization between species with different pollination systems were also detected. Hybridization takes place particularly in the diploid – tetraploid complex C. cophocarpa – C. platycarpa, for which the triploid hybrids were frequently recorded in the area of co-occurrence of its parents. A hitherto unknown hybrid (probably C. hamulata × C. cophocarpa) with a unique chromosome number was discovered in the Czech Republic. However, hybridization occurs very rarely among most of the studied species. The main ecological preferences were also compared among the taxa collected. Although Callitriche taxa often grow in mixed populations, the ecological preferences of individual species are distinctly different in some cases. Anyway, flow cytometry is a very efficient method for taxonomic delimitation, determination and investigation of Callitriche species, and is even able to distinguish homoploid taxa and identify introduced species.

Potamogeton schweinfurthii and similar broad-leaved species in Italy

Summary Potamogeton schweinfurthii A. Benn is recorded for the first time from peninsular Italy. This species was recently recorded from Sardinia and other Mediterranean islands, where it was confused with some other similar broad-leaved species of Potamogeton, in particular with P. lucens. The finding of P. schweinfurthii in two Tuscan localities (C Italy) initiated an investigation to verify the presence of further specimens of this plant among the material of similar Potamogeton species (P. lucens, P. alpinus, P. nodosus, P. gramineus) preserved in the main Italian herbaria. The herbarium survey allowed discovery of P. schweinfurthii also in Marche and Apulia regions. The distribution in Italy of four other similar Potamogeton species is specified through the herbarium investigation.

The endangered Florida pondweed (Potamogeton floridanus) is a hybrid: Why we need to understand biodiversity thoroughly

Thorough understanding of biodiversity is a fundamental prerequisite for biological research. A lack of taxonomic knowledge and species misidentifications are particularly critical for conservation. Here we present an example of Potamogeton floridanus, the Florida Pondweed, an endangered taxon endemic to a small area in the Florida panhandle, whose taxonomic status remained controversial for more than a century, and all previous attempts to elucidate its identity have failed. We applied molecular approaches to tackle the origin of the mysterious taxon and supplemented them with morphological and anatomical investigations of both historical herbarium collections and plants recently collected in the type area for a comprehensive taxonomic reassessment. Sequencing of two nuclear ribosomal markers and one chloroplast non-coding spacer resulted in the surprising discovery that P. floridanus is a hybrid of P. pulcher and P. oakesianus, with the former being the maternal parent. The hybrid colony is currently geographically isolated from the distribution range of P. oakesianus. We show that previous molecular analyses have failed to reveal its hybrid identity due to inadequate nuclear DNA sequence editing. This is an example how the uncritical use of automized sequence reads can hamper molecular species identifications and also affect phylogenetic tree construction and interpretation. This unique hybrid taxon, P. ×floridanus, adds another case study to the debate on hybrid protection; consequences for its conservation are discussed.

Reinterpretation of Potamogeton ×nerviger: solving a taxonomic puzzle after two centuries

Hybrids form an important component of Potamogeton diversity but their exact taxonomic identities and distributions are often insufficiently known. Potamogeton nerviger was described from Lithuania in 1827 as a proper species. Based on morphological and anatomical characters, its interpretation has since varied, ranging from synonymization with other species to identification as different hybrids and intraspecific taxa. Currently, it is universally recognized as the hybrid P. alpinus × P. lucens. Using a combined molecular, morphological and anatomical investigation we re-examined the identity of P. ×nerviger, based on both original and recent plant material. We report a successful amplification and sequencing of nuclear ribosomal ITS1 region from a 188year-old type collection. This was shown to be genetically identical to the morphologically matching plants recently collected at the type locality. Comparison with molecular characters of the possible parental species shows that P. ×nerviger is not P. alpinus × P. lucens, as currently believed, but another hybrid, P. nodosus × P. perfoliatus, which is currently called P. ×assidens. This molecular identification is also supported by anatomical evidence. In contrast, the actual existence of the hybrid P. alpinus × P. lucens is doubtful. Consequences for nomenclature and identities of records reported from other sites are discussed.

Flora and vegetation of the Czech Republic

This book provides basic information on the botanical diversity in the Czech Republic and relates the patterns in flora and vegetation to environmental factors, biogeographical history and human impact. Focusing on vascular plants, bryophytes and lichens, it summarizes the data on taxonomic diversity and provides details of relict, endemic, rare, alien and other biogeographically important species. Main vegetation types are characterized in terms of their structure, distribution, ecology and dynamics, emphasizing the long-term vegetation changes since the late Pleistocene, historical impact of humans on vegetation and current changes in vegetation including the impact of alien species. Special attention is paid to the conservation of threatened plant species and their habitats and ecological restoration. An account of the history of botanical research in this country is also provided. The book is illustrated with numerous maps, graphs and photographs of plant species and communities. The book is an essential reference for any biogeographer, botanist and plant ecologist who is working in Central Europe or is searching for both general and more specific information on this part of the world.