Taxonomic principles, reproductive systems, population genetics and relationships within selected groups of genus Taraxacum (Asteraceae)

Abstract

Part I. Preface Chapter 3. Summary - shrnutí consistently, exclusively on the basis of morphological differences. The within-species mi- crosatellite variation corresponded to the mutational clone cluster hypothesis, with a single unclear result. Each microspecies consisted of one, more or less dominant, clone and several minority clones, each usually confined to a single plant. The Taraxacum flora of the West Himalaya represents one of the dandelion diversity hotspots, with at least 17 sections and about 150 known species. A number of names pub- lished from that region were referred to T. sect.Orientalia Handel-Mazzetti in the literature. All these names are revised and newly interpreted, with emphasis on plants erroneously determined as T. stenolepium. An nrDNA ITS sequence analysis including the only sexual member of T. section Squamulosa and the other sexual taxa known in Taraxacum shows a separate position of T. sect. Squamulosa. The new section is compared with sections Primigenia, Coronata and Orientalia. Taraxacum koksaghyz, dandelion from steppes of Kazakhstan, has been known for long time as potential rubber producer, possibly replacing currently the most popular rubber producing tropical tree Hevea brasiliensis. We evaluate its closely related congener, Tarax- acum bicorne. Its taxonomy is...

Chapter 3 Summary - shrnutí English and Czech summaries (abstracts) of the thesis. 3.1 English abstract Genus Taraxacum (Asteraceae), having ∼60 sections and 2,800 species, is known for its complicated evolutionary relationships and taxonomy due to processes like frequent hy- bridization, polyploidization, asexual reproduction, clonality and low structural morpho- logical variability. Various taxonomical concepts and approaches are reviewed, evaluated and discussed from point of view of their ability to deal with such a complicated genera as is Taraxacum. Various processes responsible for the complicated situation within Taraxacum are discussed and reviewed. Section Dioszegia, comprising T. serotinum and its allies, are an exception because only sexuals are reported for all the members of this group. On the basis of the analysis of mi- crosatellite (SSRs) variation, distribution and morphology, we addressed problems related to their mode of reproduction, among-population relationships, taxonomy and within- population variation. As a rule, outcrossing was the dominant mode of reproduction, with one notable exception: T. serotinum subsp. tomentosum (≡ T. pyrrhopappum) was autogamous and not heterozygous. A taxonomic revision of sect. Dioszegia recognizes T. serotinum subsp. serotinum (including an aberrant...