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No description available.

No description available.

Thesis (Doctoral)--Helsingin yliopisto, 2000. / Also available in PDF format. Includes bibliographical references.

Upland plant communities are vulnerable to environmental change, especially if the component species have limited dispersal abilities and consist of fragmented populations. Oceanic-montane liverwort-rich heath is a rare upland vegetation type found in the oceanic areas of the British Isles and Norway. This thesis contributes both fundamental knowledge about the liverworts’ biology and an understanding of how this can be applied in conservation management, taking into account the compositional changes that have already occurred within liverwort heath. These issues were explored by i.) a re-survey of 50- and 20-year old liverwort heath plots, ii.) assessment of the genotypic diversity of one liverwort using microsatellite markers, iii.) ex-situ and in-situ experimental studies on growth and reproduction and, iv.) transplantation of one liverwort to unoccupied sites to assess habitatlimitation and the potential of translocation as a conservation management tool. The re-survey revealed that the liverwort heath has undergone compositional changes. Liverworts and dwarf shrubs decreased while graminoids increased. This was linked to grazing pressure, eutrophication and warmer and drier conditions. High genotypic diversity was demonstrated in a liverwort unknown to reproduce sexually in the British Isles (Anastrophyllum alpinum), suggesting that sexual reproduction must have occurred in the past. The data also indicated clonal growth at the local level, but no dispersal of vegetative fragments between populations. Thus, dispersal limitation is likely to have implications for the species under future environmental change. Ex situ and in situ cultivation of whole liverworts and fragments revealed that most of the species can grow from both fragments and whole shoots. Therefore, in the absence of sexual reproduction, the species can persist locally by growth and vegetative spread. Also, there is potential for ex situ conservation of these species, in situ enhancement of existing populations, and creation of new ones. Translocation of Herbertus hutchinsiae suggested that the species is dispersal limited. Transplants grew at all sites, exhibiting best growth within range. Therefore, translocation is a management option for this species to enhance or increase extant populations, to restore populations that have declined over the last half century and to reach future suitable climate space. These results have large implications for nature conservation management, to safeguard the unique liverwort heath.

Liverworts (Phylum Marchantiophyta) form the earliest diverging lineage of extant land plants and hold a key position in the evolutionary history of land plants. The family Cleveaceae, first defined in 1881 by Leitgeb by its complex thallus anatomy and star-shaped epidermal pores with strongly thickened radial walls, is now included within Marchantiopsida (Complex Thalloid Liverworts). The family is widely distributed in warm temperate to arctic regions throughout the Northern Hemisphere, but very rare in South America and absent from Australia and New Zealand. Since Cleveaceae was described, the number and names of genera and species recognized within the family have changed many times, with three genera currently accepted: Athalamia (12 to 15 species), Sauteria (2 to 5 species) and Peltolepis (1 or 2 species). However, no robust phylogenetic frame work or taxonomic monographs of the family have previously been undertaken and the species diversity within the genera remains uncertain. The study presents the first robust phylogenetic framework for the family, based on three chloroplast genes (psbA, rpoC1 and rps4) and one nuclear ribosomal region (26S) sequenced for 54 ingroup accessions representing a substantial part of the geographic range of the family (except South America) and a large part of its morphological diversity. Samples sequenced include the type species of the three currently accepted genera as well as those of previously synonymised genera; Clevea, Spathysia, Gollaniella and Sauchia. The current circumscription and relationships of the genera were tested using Maximum Parsimony, Bayesian and Likelihood inferences. Cleveaceae was strongly supported as monophyletic with four main lineages resolved within the family, two corresponding to Peltolepis and Sauteria and two composing a polyphyletic Athalamia. The latter is therefore divided into a more narrowly defined Athalamia and a fourth genus, for which Clevea is the earliest published name. Inferred evolutions of twelve morphological characters, that are useful or have been used in classifications of Cleveaceae, were reconstructed using maximum parsimony and maximum likelihood methods. The misleading influence of homoplasy on past morphological classifications and phylogenies is discussed. The study also presents the first worldwide taxonomic revision of Cleveaceae based on around 2300 specimens studied, including all available type specimens. The monographic work is based on morphological and anatomical characters reviewed using dissecting, compound and scanning electron microscopes including both herbarium and fresh material collected on field excursions during the study. Ventral scale morphology, position and aggregation of androecia and shape of receptacle were found to be valuable characters in generic and species delimitation. The traditional definition of genera of Cleveaceae based mainly on two characters (carpocephalum stalk position and anatomy) was rejected. A total of seven species were recognized from 25 formerly described names including one new necessary combination: Clevea hyalina (Sommerf.) Lindb., C. spathysii (Lindenb.) Müll. Frib., C. pusilla (Steph.) Rubasinghe & D.G.Long comb. nov., Athalamia pinguis Falc., Sauteria alpina (Nees) Nees, S. spongiosa (Kashyap) S.Hatt., and Peltolepis quadrata (Saut.) Müll. Frib. Nine excluded and doubtful species are listed along with reasons for their exclusion. Generic and species keys are presented based on vegetative, reproductive and spore morphological characters. For each genus and species, descriptions, illustrations, and distribution maps are given along with ecological, taxonomic and nomenclatural notes.

The Hepaticae of western North America, in contrast to eastern North America and many other parts of the world, are poorly known. This present flora for southwestern British Columbia, Canada, and part of northwestern Washington State, U.S.A., is intended to partially alleviate this problem. The geographical area covered in this study offers great diversity in topography, climate, and vegetation. The region includes the wet Pacific coast of western Vancouver Island, mesic forests and floodplains of low elevations, the dry area around southern Georgia Strait, subalpine forests and meadows of the Coast Range and North Cascade Mountains, alpine soil and rock substrates at highest elevations below summer snowline or glaciers, and dry habitats in the rainshadow northeast of the mountains. The material presented is based on direct study of approximately 4000 personal and 1800 herbarium collections of hepatics. A total of 166 species and two additional varieties, belonging to 64 genera in 37 families, are treated in keys and concise descriptions, accompanied by ecological and phytogeographical information. Additional discussion on taxonomic and systematic difficulties is given where pertinent. Five hepatics new to science were discovered during this study, with Schofieldia monticola Godfr. having been recently described. Hepatics collected which had not been reported previously from continental North America include Eremonotus myriocarpus (Carring.) Lindb. et Pears, in Pears., Jungermannia hattoriana (Amak.) Amak., Marsupella condensata (Ångstr. in Hartm.) Schiffn., and Nardia japonica Steph. Hepatics belonging to, or similar to, Lophozia elongata Steph. and Marsupella adusta (Nees emend. Limpr.) Spruce were collected. Hepatics new to British Columbia include Lophozia ventricosa var. silvicola (Buch) Jones, Riccia frostii Aust., Scapania gymnostomophila Kaal., and S. paludlcola Loeske et K. Müll, in K. Müll. For the first time, fasciculate gemmae were discovered in Ghandonanthus Mitt., and inflated lobules were found in Porella navicularis (Lehm. et Lindenb.) Lindb. Based on specimens exajnined from the study area, Bazzania ambigua (Lindenb.) Trev., Odontoschisma gibbsiae Evans, and Plagiochlla satoi Hatt. were treated as synonyms of other species in this flora. Systematic problems requiring detailed future study were encountered in particular in Bazzania S. Gray and Galypogeia Raddi emend. Nees. Regional distribution-maps depicting all known points of occurrence and general elevation are presented for all hepatics discussed in this flora. Four general categories of distribution were demonstrated by a comparison of the spatial patterns: l) distributions in moist, humid climates influenced to varying degrees by the Pacific Ocean (18% of the total flora), 2) high elevations in the Coast and Cascade Mountains (24%), 3) dry climates in rainshadow areas (16%), and 4) various types of widespread distributions (33%). The remaining 9% of the species are rare or infrequent and cannot be assigned to any particular category. The hepatic taxa were assigned to 14 phytogeographical elements based on total worldwide distributions. Approximately 50% of the hepatics have essentially circumboreal distributions. This figure includes taxa missing from eastern Asia. Ten percent of the hepatics are endemic to western North America. Of the hepatics demonstrating disjunct, or discontinuous distributions, 16% have European affinities, 9% eastern Asian affinities, and 11%, affinities with both regions. Approximately 11% of the hepatics treated in this flora have bipolar disjunctions. In an attempt to reconstruct some events in the development of the modem hepatic flora of southwestern British Columbia, possible Pleistocene refugia and their effect on hepatic populations are discussed. This flora will provide a manual for the Hepaticae and Anthocerotae of southwestern British Columbia, and will serve as a preliminary guide to these plants in the North American Pacific Northwest. / Science, Faculty of / Botany, Department of / Graduate

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Thèse - Université de Paris. / Bibliography: p. [203]-206.

This thesis comprises of two published papers and one accepted manuscript, focused on various aspects of liverwort reproduction. Treated aspects include patterns of asexual reproduction, sex ratio and sex-specic pattern in vegetative growth, and patterns of genetic variation and spatial genetic structure of populations differing in availability of substrate on localities and the population connectivity, and consequently in size, density, and prevailing reproductive mode. These characteristics were studied on representatives of the family Scapaniaceae s.l., belonging to the largest liverwort order Jungermanniales. The results showed that asexual propagules were formed and present in course of the whole growing season and can be considered as a sufficient substitution for sexual reproduction. In contrast with the female-biased sex ratio observed earlier in most dioicous bryophytes, unexpectedly high male-biased sex ratio was observed in the aquatic liverwort, which was speculated to represent a strategy to overcome sperm dilution in aquatic environment. In addition, no size differences between female and male shoots were detected, although the evidence for higher cost of sexual reproduction in females was found. The study of population genetic structure has shown that even small and predominantly asexually reproducing populations are important sources of genetic variation. However, we were able to demonstrate notably low levels of gene flow among populations where habitat fragmentation poses a significant barrier to dispersal of diaspores. The fine scale study of spatial genetic structure revealed a strong aggregation of genotypes, particularly in smaller populations, and at the same time showed that asexual reproduction is an efficient mean of maintaining the populations at not only the short distances, given the spatial extent of clones spanning dozens of meters.