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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.
1

Comparative studies of coenocytic mycelial growth in Pythium

Baxter, C. F. January 1983 (has links)
No description available.
2

Estudos taxonômicos em espécies de Ramalina Ach. (Ascomycota liquenizados, Ramalinaceae)

Gumboski, Emerson Luiz January 2016 (has links)
O gênero Ramalina Ach. possui cerca de 250 espécies aceitas e está distribuído por todo o mundo. Desde a circunscrição inicial do gênero em 1809, aceitava-se que boa parte das espécies possuía distintos graus de plasticidade morfológica e até química, resultando em centenas de nomes na literatura e certa confusão a respeito da sistemática do mesmo. Estudos recentes revelaram uma diversidade oculta para o grupo e que, possivelmente, algumas características estavam sendo negligenciadas. Com o objetivo de contribuir para o entendimento da sistemática de Ramalina, o presente estudo utilizou-se de análises morfológicas, anatômicas, químicas e moleculares. No total foram examinados 2415 espécimes de Ramalina, dos quais 332 representam espécimes tipo. Foram geradas 278 novas sequências relativas a 24 espécies, sendo 195 sequências de ITS, 59 de IGS e 24 de rpb2. O estudo identificou 27 espécies distribuídas por doze estados brasileiros e em diversos ambientes, tais como restingas, mata de araucária, campos de altitude, Cerrado e Caatinga. Duas espécies são novas para a ciência. Ramalina anceps foi cofirmada como espécie distinta de R. usnea. A espécie R. subfraxinea foi excluída da micota brasileira. Foram registradas 33 novas ocorrências em vários Estados brasileiros, o que amplia consideravelmente a distribuição das espécies no país. A importância de ter descrições detalhadas sobre a morfologia e anatomia foi comprovada através dos estudos tendo respaldo das análises moleculares. O presente estudo contribui muito para o conhecimento a cerca dos problemas taxonômicos e sistemáticos das espécies de Ramalina, não apenas em nível nacional, mas mundial. Sobe para 38 o número de espécies de Ramalina conhecidas para o Brasil. A Região Sul teve substancial ganho no conhecimento a respeito das espécies presentes, bem como parte da Região Sudeste e Nordeste. As Regiões Centro-Oeste e Norte ainda carecem de coleções suficientes mesmo em herbários nacionais. Descrições, comentários, ilustrações e chaves de identificação são apresentadas. / Ramalina Ach. has ca. 250 species accepted and is distributed worldwide. Since the initial division of the genus in 1809, it was accepted that many of the species had different degrees of morphological and even chemical plasticity, resulting in hundreds of names in literature and some confusion about the systematic of the group. Recent studies have revealed a hidden diversity to the group and possibly some characteristics were being neglected. In aim to contribute to the understanding of systematic of Ramalina, this study used morphological, anatomical, chemical and molecular analyzes. 2415 specimens of Ramalina were examined, of which 332 represent type specimens. 278 new sequences related to 24 species were generated: 195 sequences of ITS, 59 of IGS and 24 of rpb2. The study identified 27 species distributed on twelve Brazilian states and in different environments, such as coastal vegetation, Araucaria forest, high altitude grasslands, savannah and Caatinga vegetation. Two species are new to science. Ramalina anceps was confirmed as a distinct species of R. usnea. The species R. subfraxinea was excluded from the Brazilian mycota. Thirty three new records were found in some Brazilian states, which considerably expand the distribution of species in the country. The importance of having detailed descriptions of morphology and anatomy has been proven through the studies and supported by the molecular analysis. This study contributes to the knowledge about the taxonomic and systematic problems of the species of Ramalina, not only nationally, but worldwide. The number of Ramalina species known to Brazil increases to 38. The South region had substantial gain to the knowledge about the species present, and part of the Southeast and Northeast regions. The North and Midwest regions still lack of sufficient collections even in national herbaria. Descriptions, comments, illustrations and identification keys are given.
3

Morphological traits in hair lichens affect their water storage

Olsson, Therese January 2014 (has links)
The aim with this study was to develop a method to estimate total area of hair lichens and to compare morphological traits and water storage in them. Hair lichens are an important component of the epiphytic flora in boreal forests. Their growth is primarily regulated by available water, and light when hydrated. Lichens have no active mechanism to regulate their water content and their water holding capacity (WHC, mg H2O/cm2) is thus an important factor for how long they remain wet and metabolically active. In this study, the water uptake and loss in five hair lichens (Alectoria sarmentosa, three Bryoria spp. and Usnea dasypoga) were compared. Their area were estimated by combining photography, scanning and a computer programme that estimates the area of objects. Total area overlap of individual branches was calculated for each species, to estimate total area of the lichen. WHC and specific thallus mass (STM) (mg DM/cm2) of the lichens were calculated. Bryoria spp. had a significantly lower STM compared to U. dasypoga and A. sarmentosa, due to its thinner branches and higher branch density. Bryoria also had a lower WHC compared to A. sarmentosa, promoting a rapid uptake and loss of water. All species had a significant relationship between STM and WHC, above a 1:1 line for all species except U. dasypoga. The lower relationship in U. dasypoga is explained by its less developed branching in combination with its thick branches.
4

Estudos taxonômicos em espécies de Ramalina Ach. (Ascomycota liquenizados, Ramalinaceae)

Gumboski, Emerson Luiz January 2016 (has links)
O gênero Ramalina Ach. possui cerca de 250 espécies aceitas e está distribuído por todo o mundo. Desde a circunscrição inicial do gênero em 1809, aceitava-se que boa parte das espécies possuía distintos graus de plasticidade morfológica e até química, resultando em centenas de nomes na literatura e certa confusão a respeito da sistemática do mesmo. Estudos recentes revelaram uma diversidade oculta para o grupo e que, possivelmente, algumas características estavam sendo negligenciadas. Com o objetivo de contribuir para o entendimento da sistemática de Ramalina, o presente estudo utilizou-se de análises morfológicas, anatômicas, químicas e moleculares. No total foram examinados 2415 espécimes de Ramalina, dos quais 332 representam espécimes tipo. Foram geradas 278 novas sequências relativas a 24 espécies, sendo 195 sequências de ITS, 59 de IGS e 24 de rpb2. O estudo identificou 27 espécies distribuídas por doze estados brasileiros e em diversos ambientes, tais como restingas, mata de araucária, campos de altitude, Cerrado e Caatinga. Duas espécies são novas para a ciência. Ramalina anceps foi cofirmada como espécie distinta de R. usnea. A espécie R. subfraxinea foi excluída da micota brasileira. Foram registradas 33 novas ocorrências em vários Estados brasileiros, o que amplia consideravelmente a distribuição das espécies no país. A importância de ter descrições detalhadas sobre a morfologia e anatomia foi comprovada através dos estudos tendo respaldo das análises moleculares. O presente estudo contribui muito para o conhecimento a cerca dos problemas taxonômicos e sistemáticos das espécies de Ramalina, não apenas em nível nacional, mas mundial. Sobe para 38 o número de espécies de Ramalina conhecidas para o Brasil. A Região Sul teve substancial ganho no conhecimento a respeito das espécies presentes, bem como parte da Região Sudeste e Nordeste. As Regiões Centro-Oeste e Norte ainda carecem de coleções suficientes mesmo em herbários nacionais. Descrições, comentários, ilustrações e chaves de identificação são apresentadas. / Ramalina Ach. has ca. 250 species accepted and is distributed worldwide. Since the initial division of the genus in 1809, it was accepted that many of the species had different degrees of morphological and even chemical plasticity, resulting in hundreds of names in literature and some confusion about the systematic of the group. Recent studies have revealed a hidden diversity to the group and possibly some characteristics were being neglected. In aim to contribute to the understanding of systematic of Ramalina, this study used morphological, anatomical, chemical and molecular analyzes. 2415 specimens of Ramalina were examined, of which 332 represent type specimens. 278 new sequences related to 24 species were generated: 195 sequences of ITS, 59 of IGS and 24 of rpb2. The study identified 27 species distributed on twelve Brazilian states and in different environments, such as coastal vegetation, Araucaria forest, high altitude grasslands, savannah and Caatinga vegetation. Two species are new to science. Ramalina anceps was confirmed as a distinct species of R. usnea. The species R. subfraxinea was excluded from the Brazilian mycota. Thirty three new records were found in some Brazilian states, which considerably expand the distribution of species in the country. The importance of having detailed descriptions of morphology and anatomy has been proven through the studies and supported by the molecular analysis. This study contributes to the knowledge about the taxonomic and systematic problems of the species of Ramalina, not only nationally, but worldwide. The number of Ramalina species known to Brazil increases to 38. The South region had substantial gain to the knowledge about the species present, and part of the Southeast and Northeast regions. The North and Midwest regions still lack of sufficient collections even in national herbaria. Descriptions, comments, illustrations and identification keys are given.
5

Documenting the association between a non-geniculate coralline red alga and its molluscan hos

Rosemary Eager January 2010 (has links)
<p>To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn / 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn / 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association...</p>
6

Documenting the association between a non-geniculate coralline red alga and its molluscan hos

Rosemary Eager January 2010 (has links)
<p>To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn / 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn / 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association...</p>
7

Documenting the association between a non-geniculate coralline red alga and its molluscan host

Eager, Rosemary January 2010 (has links)
Magister Scientiae (Biodiversity and Conservation Biology) / To further investigate the strength of the association and the relative advantages of the association to both organisms, several manipulation experiments were set up. A cage experiment set up in the shallow subtidal zone showed that the coralline survived equally well without the winkle and did therefore not require the winkle or its empty shell for survival. A second controlled laboratory aquarium experiment was designed under both fluorescent (rich in blue light) and incandescent light (rich in red light) to ascertain whether the coralline had a preference for O. sinensis over the similar O. tigrina. This experiment was inconclusive as no recruitment was obtained under either of the light regimes. A third laboratory experiment was designed to determine whether the extra coralline weight had any possible advantage to the winkle, particularly against predation from the rock lobster Jasus lalandii. Results suggested that there were no apparent advantages to the winkle bearing the extra coralline load as adult O. sinensis bearing the coralline alga (3.7 &plusmn; 2.2 winkles 24hr-1) were equally prone to predation than those lacking the coralline (2.3 &plusmn; 1.9 winkles 24hr-1) (p = 0.184). Observations suggested instead that the convoluted nature of the coralline may indeed have promoted predation. We ultimately deduced that the high occurrence of the coralline on the shells of O. sinensis was probably due to the substantial overlap in the niches of the two organisms. This conclusion was supported by the high densities of juvenile O. sinensis combined with the high percent cover abundance of the coralline in intertidal rockpools. Understanding sexual reproduction in coralline algae as well as the life cycle of the winkle, ultimately provided insight into the postulated life cycle of this coralline-winkle association. / South Africa

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