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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

An ecogeographic survey of Trifolium L. in Turkey

Lamont, Emma-Jane January 1998 (has links)
Results are presented of an investigation into the biodiversity of Trifolium L. present in the Republic of Turkey The aim of the project is to provide the information required for planning conservation of 0 Turkish Thfolium germplasm both in situ and ex situ. Diversity contained within the genus is investigated at several levels; species distributions, taxonomic relationships between the species, and for selected taxa diversity between populations is investigated. Interactive, computer based identification aids and a traditional dichotomous key to the relevant species are presented. Distributions of the Trifolium species that occur in Turkey were investigated by compiling a set of georeferenced data from a variety of sources. The data were obtained from herbarium labels, donated by genebanks, collected during fieldwork and taken from the literature. A database formed from the merged data sets was used to create species distribution maps. Ecological information contained in the database is summarised in tabulated form species by species giving altitude ranges, habitat descriptions and soil characteristics of the specimen collection sites. Areas are identified from the distribution maps in which few germplasm samples have been collected, and therefore should be prioritised for future germplasm collecting activities. The priority areas include eastern central Anatolia (Sivas, Yozgat and Kayseri provinces), the province of Istanbul, Turkey-in-Europe (particularly Edirne and Kirklareli) and the regions north and south of Ankara. The species richness coefficient for Trifolium species in Turkey is at a maximum in the provinces of Istanbul, Izmir, Mugla, Usak, Hatay and Gaziantep. Extensive germplasm collections have taken place in all these provinces, except Istanbul. Several of the species recorded as occurring in the province of Istanbul are known in Turkey from a very small number of herbarium specimens that were collected in the nineteenth or early twentieth century. Classification of the provinces of Turkey into six ecogeographical regions on the basis of recorded Trifolium species identifies three well defined groups one occurrjng on the Mediterranean and Aegean coasts, another inland in western Turkey and one in eastern Turkey. Many of the provinces that are not included in any of these well-defined clusters have been under-collected for Trifolium. A morphological data set relating to ninety-seven Trifolium species was collected from herbarium specimens and the literature. Species included in the analysis comprise all those that occur in Turkey, which is at the centre of diversity for the genus. The data set was analysed to study infrageneric relationships of Trifolium taxa, and the results'obtained were compared with previously published taxonomies. Generally, species groupings proposed by previous authors were supported by the phenetic analysis. The differences between the clusters obtained in this study and previous taxonomies occurred within sections Trifolium, Chronosemium Ser. and Lotoidea Crantz. Several changes to the division of section Trifolium into subsections and of section Chronosemium into series are suggested. The analysis also indicates that section Lotoidea should be split into at least two sections. Living specimens of thirteen annual species of Trifolium section Trifolium where characterised morphologically. The specimens were raised in a randomised design and were characterised using quantitative traits. All accessions were of Turkish origin. The data are analysed to investigate variation between the test species using multivariate analysis of variance and cluster analysis. The species groupings obtained are discussed with reference to previous taxonomic treatments. Some of the results obtained from the herbarium-based data set are supported. The suggestions that section Trifolium subsection Lappacea should be divided and that T. sylvaticum should be removed from subsection Stellata are supported. Species of subsections Echinata, Squamosa and Clypeata clustered closely together, which agrees with the suggestions that these subsections should be merged. Several populations were raised of each of five Trifolium section Trifolium species, namely T. purpureum, T. echinatum, T. hirtum, T. angustifolium and T. cherleri. The geographic origin is known for most of these populations, and differences between populations with respect to their origins are discussed. Significant differences occurred between almost all populations raised, suggesting that variation between populations is high for these species. An interactive, computer based key to the ninety-seven species of Trifolium L. occurring in Turkey was created. Traditional dichotomous keys constructed using the same data set are also presented. Data were collected from herbarium specimens, living specimens and literature sources. Herbarium specimens were available for all but five of the species. An average of 135 morphological characters was scored per species, including vegetative, flowering and fruiting characters. The data were coded in DELTA format (which has been endorsed by the International Union of Biological Sciences Commission on Taxonomic Databases). This new interactive key has several advantages over traditional dichotomous keys to Trifolium, including limited usage of technical terms, and use of illustrations. In addition, photographic images of more than 80% of the taxa are contained within the interactive key. Full descriptions of the taxa are also available within the key. The interactive key files are available to download from the Institute of Grassland and Environmental Research web site (HTTP://www.igergru.bbsrc.ac.uk/).

Incompatibility in the genus Campanula (Campanulaceae)

Block, F. May January 1964 (has links)
The numerous methods by which outbreeding is maintained in the plant kingdom suggest that the resultant vigour and stored viability produced by heterozygosit is of great value to the species. There are many methods by which inbreeding is prevented and the consequent heterozygosity is ensured, both in a precise and an imprecise manner. One example is dichogamy, the plant showing either protandry or protogyny. This phenomenon applies to each flower on a plan t and does not prevent self-pollination , for one flower may easily be pollinated by another on the same plant . Outbreeding is also maintained by elaboration of the floral mechanism, thus reducing the chance of self-pollination , e.g. Orohidaoeae and Apooynaoeae. More precise methods of maintaining heterozygosity are by the phenomena of dioecism and incompatibility.

An experimental taxonomic study of Chrysanthemum leucanthemum L

Pearson, P. L. January 1967 (has links)
Within the last few years considerable interest has been generated in the use of cytological characters for assisting in taxonomic treatments of the Composite species Chrysanthemum leucanthemum L. sensu lato. This species is extremely variable and numerous infra-specific taxa have long been recognised. Recent works (see following text) using North American and Continental material have suggested that there might be sufficient grounds for splitting up the species aggregate into specific taxa corresponding to chromosome races.

Studies on formate dehydrogenases on legumes

Peacock, Derek January 1970 (has links)
No description available.

Effects of powdery mildew (Erisyphe cichoracearum D. C. ex Mérat) on the growth and development of groundsel (Senecio vulgaris L.)

Ben-Kalio, Victor Dagogo January 1976 (has links)
No description available.

The phylloplane community of Quercus robur L

Cox, L. A. January 1979 (has links)
No description available.

The experimental taxonomy of Viola lactea SM

Moore, David Moresby January 1957 (has links)
No description available.

Comparative studies on the ecology of "Littorina rudis" (Maton, 1797) (Gastropoda: Prosobranchia)

Faller-Fritsch, Robert John January 1983 (has links)
Littorina rudis (Maton) is the most widely distributed and variable British littorinid. The present study investigates the ecological adaptations which underlie its success in greatly differing habitats. Three contrasting shores, Greenhithe (polluted estuary), Landshipping (unpolluted estuary) and Newhaven (open coast) were studied between October 1972 and July 1975. Reproductive output differed markedly at each site. At Greenhithe large embryos were produced in small numbers, the opposite relationship existing at Newhaven. The Landshipping results, though less pronounced, resembled those from Greenhithe. Reciprocal transplants between Greenhithe and Landshipping provide tentative support for the view that these differences are genetic. There was no evidence that polluted estuarine conditions had ser= ious reproductive or other effects at Greenhithe. Significant embryonic abnormality was recorded, but at ecologically unimportant levels. Collections from additional shores suggested a more general relationship between embryo size and factors associated with shelter. Very high juvenile mortality occurred at each site,, and these reproductive differences are viewed as adaptive responses to prevailing causes of mortality. At Greenhithe and Landshipping these include crushing and desiccation, with possibly some predation by crabs at Landshipping. These factors would'favour larger, stronger hatchlings. At Newhaven, juvenile survival depends upon finding small crevices or empty barnacle shells in which to escape desiccation and wave buffeting. Here, production of numerous small hatchlings appears adaptive. As well as affecting reproductive characteristics, mortality patterns are suggested as a major cause of size structure variations within änd between populations. Individual growth and production rates are high at both estuarine sites, probably resulting from favourable conditions for feeding. Growth and production may be limited in.. exposure by the time available for feeding.

The role of phenolics in disease resistance of the Solanceae

Ward, M. A. January 1980 (has links)
No description available.

Systematic studies in neotropical Myrtaceae with an emphasis on Myrcia s.l. : the evolution and biogeography of a large South American clade

Lucas, E. J. January 2007 (has links)
Low morphological variation at all taxonomic levels give Neotropical Myrtaceae a reputation as a 'difficult' family to identify even to genus, resulting in a lack of taxonomic. data on every front. The subtribal classification ofthe predominantly Neotropical and exclusively fleshyfruited tribe Myrteae (49 genera and c. 2500 species) is unstable, as are generic boundaries within it. Neotropical Myrtaceae are particularly species rich in some of South America's most threatened habitats. The second largest Neotropical genus, Myrcia s.!., comprises >700 taxonomically 'difficult' species with species,diversity reaching its peak in the Brazilian Atlantic rainforest and cerrado, habitats in urgent need of inventories of their plant species before conservation initiatives can be undertaken. Phylogenetic hypotheses are provided for evolutionary relationships within Myrteae and Myrcia s.l. based on nuclear ITS and ETS ribosomal DNA and plastid psbA-trnH and matK DNA sequences, using parsimony and Bayesian inference. Four morphological characters of Myrteae are optimized on the resulting trees and nineteen are used in a cladistic analysis of Myrcia s.l. Myrteae appear monophyletic, comprising seven clades plus two isolated taxa. Of the four previously accepted genera of subtribe Myrciinae sensu DC., two are polyphyletic and all emerge in a single clade treated here as Myrcia s.l. Morphological characters exhibit homoplasy at both ranks, although in combination are useful for clade diagnosis. Biogeographical analysis is inconclusive regarding tribal ancestral areas, but South American colonization before northern radiation via the Andes appears likely. The largest genera, Eugenia and Myrcia s.l., have western and southeastern South American origins, respectively. Nonmetric multidimensional scaling and ordination techniques are employed to divide the distribution of Myrcia s.l. into discrete areas ofendemism and historical biogeographical scenarios are discussed. Finally, modem, natural, subtribal and infrageneric classifications are proposed and concluding inferences are drawn regarding drivers of large genera using Myrtaceae and Myrcia s.l. as case studies.

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