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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

A Taxonomic Study on Fimbristylis Vahl (Cyperaceae) of Taiwan

Lin, Yi-ling 08 September 2008 (has links)
The genus Fimbristylis in Taiwan was taxonomically revised based on morphological, phytogeographical, and ecological evidences. In this study, style and achene morphologies are the most valuable characters for the classification within the genus in Taiwan. The ornamentation of achene surface could be divided into 5 types, which are transversely rugulose, verruculose, smooth, reticulate, reticulate- verruculose. The results showed that these types are taxonomic characters for classification of section, series and species. Twenty-three species, three varieties, and one uncertain species as recognized in conclusion. Fimbristylis microcarya var. tainanensis (Ohwi) H. Y. Liu was elevated to specific status F. tainanemsis Ohwi. F. tomentosa Vahl and F. umbellaris (Lam.) Vahl do not occur in Taiwan in fact, which are previously erroneous identification of F. dichotoma (L.) Vahl and F. littoralis Guad., respectively. Additionally, F. macassarensis Steud. is treated as uncertain species due to insufficiency of evidence.
2

Evaluation of the taxonomic status of Amata wilemani Rothschild, 1911 (Lepidoptera: Erebidae, Arctiinae, Syntomini), a highly variable species, using molecular sequence data

Liu, Yao-Hung 19 July 2011 (has links)
The morphological phenotypic characters involving sexual selection but with highly individual variability are likely to challenge the prezygotic isolating mechanism driven by differentiation of mechanical structures. This kind of characters may also puzzle species identification and taxonomy. Therefore clarifying the correlation between the phenotypic variability and biological/non-biological factors becomes necessary in order to understand the role of this phenomenon under natural selection and sexual selection. The Syntomini represents one of the few lepidopterous groups that exhibit highly individual variability in both wing pattern and reproductive structures. The evolutionary and taxonomic significance of this phenomenon, however, has never been studied using modern methods although it has been documented for long. In order to test several hypotheses relevant to phenotypic variability, the present study focuses the phylogenetic relationship of Amata wilemani Rothschild, 1914, a subalpine moth species with extremely high variability in wing coloration and genitalia. The phylogenetic relationship between the three color morphs of A. wilemani and 38 Syntomini species plus 2 Lithosiinae outgroups was reconstructed using fragments of COI, EF1a and 28S. All color morphs of A. wilemani were recovered to form a monophyletic group under all data partitioning strategies with Amata formosensis (Wileman, 1928) or its closely related species in China as the potential sister group. The result of gene network analysis suggests low divergence between haplotypes of A. wilemani. Because no correlation between color morphs, phenology, geographical distribution, altitudinal gradient, and genitalic morphlogy was detected, it is concluded that A. wilemani should be regarded as a single species with high phenotypic variability, and this may suggest existence of intraspecific competition. The present study also found that Amata karapinensis (Strand, 1915), which was synonymized with A. wilemani by previous authors, should be revived. The incongruence between the phylogenetic relationships based on morphological and molecular characters shows a need of a comprehensive phylogenetic study of this highly diverse group.
3

Intraclonal Morphological Plasticity within the Myzus persicae (Sulzer) Complex Related to Host Plant and Temperature

Marie, Joan 25 August 2004 (has links)
Blackman (1987) used life cycle and morphology to separate Myzus nicotianae Blackman, a tobacco-feeding species of aphid, from Myzus persicae (Sulzer). In the present study, the first objective was to investigate the influence of temperature and host plant on the morphology of M. nicotianae and M. persicae. The second objective was to assess Blackman's 1987 key to Myzus for separating tobacco and non-tobacco originating morphs under different environmental conditions. Four host plants were used: tobacco, turnip, pepper, and okra, and three temperatures, 15°C, 20°C, and 25°C. The intraclonal plasticity of two tobacco collected morphs and one turnip collected morph was investigated in relation to these combinations of host and temperature in a 4 x 3 x 3 factorial experimental design. Fifth generation mature apterous aphids were mounted on slides and 10 different morphological structures utilized in morphometric analysis were measured. Data support a morphologically distinct, host-adapted tobacco race but not a separate tobacco-feeding species of M. persicae. The key developed by Blackman (1987) did not discriminate between the tobacco and non-tobacco originating clones but the canonical variates generated from the analysis successfully separated the tobacco and non-tobacco groups. Other studies have used many different clones to investigate the possible distinctions between M. persicae and M. nicotianae; the objective here was to see how much morphological perturbation may be induced within a clone by rearing at different temperatures and on different host plants. Temperature and host plant had substantial influences on the morphology of these aphids. The physiological interactions of temperature-host plant-aphid morphology are very complex yet controlling only for temperature and host plant was sufficient to group specimens according to these independent variables with remarkable accuracy using the linear discriminant functions generated with these data. Percent of aphids in which rearing temperature was correctly identified using linear discriminant functions generated for temperature classes was 87%, 63%, and 64% for 15°C, 20°C, and 25°C, respectively. Random designations would be 33%. Correct identification of host plant was 65%, 45%, 47%, and 48% successful for tobacco, turnip, pepper, and okra, respectively. Random designations for host plant would be 25%. Canonical variates produced clusters by host, temperature, morph, and combinations of these independent variables with varying degrees of discreteness. CV1 by CV2 for host plants gave a very distinct cluster for tobacco and also separate groupings for aphids reared on turnip and pepper. Aphids from the host plant okra were scattered quite widely across the CV1 by CV2 graph. CV1 by CV2 for temperature conditions showed a tight cluster for aphids from 15°C and still distinct though less closely grouped clusters for both 20°C and 25°C rearing temperatures. CV1 by CV2 for the three morphs gave substantial overlap for the two tobacco originating morphs and a more separate cluster for the morph originally collected from turnip. / Master of Science
4

Nutrient Foraging in Ten Southeast Coastal Plain Plant Species

Einsmann, Juliet Caroline Jr. 09 July 1998 (has links)
Plant root system response to nutrient heterogeneity was tested in ten plant species of varying life form and successional status. All plants tested are native to the South Carolina coastal plain. Morphological responses of the root system (scale, precision and discrimination) and overall plant response (sensitivity) to increasing nutrient heterogeneity were tested. Ten individuals of each species were placed into four treatments which had varying nutrient distribution but the same overall nutrient addition. Plants were harvested when roots reached pot edge. I observed high variation in scale (mass and extent of a root system), precision (the ability to proliferate roots in nutrient patches) and sensitivity (growth benefits gained as nutrient heterogeneity increases; measured as total biomass). No significant discrimination responses were observed, although greatest mean root density occurred at intermediate fertility levels for all species. I tested the hypothesis that scale and precision would be negatively correlated, and I did not observe this relationship in these plant species. However, in herbaceous species scale and precision were positively correlated. Sensitivity was not closely related to precision indicating that proliferating roots in fertile patches does not always yield growth benefits in heterogeneous soils. Further, some sensitive species had very low precision suggesting that other characteristics lead to positive growth response in heterogeneous environments. Plasticity of root uptake rates and demography of roots are proposed as two other mechanisms which may play important roles in plant sensitivity responses. Scale was negatively correlated to sensitivity for herbaceous plants suggesting that plants that monopolize the most soil space are not able to gain benefits from nutrient patches within the soil matrix. There was no trend observed to suggest that plant life form was correlated with precision or sensitivity. However, scale was greater in herbs than in woody plants, possibly because the two life forms develop at different times. / Master of Science
5

Morfologická plasticita chrpy luční \kur{(Centaurea jacea L.).} / Morphologic plasticity of \kur{Centaurea jacea.}

KARÁSEK, Jakub January 2010 (has links)
Morphological plasticity of brown knapweed (Centaurea jacea L.) was examined. South bohemian populations of subsp. jacea were compared to plasticity in larger area. The plasticity of local population overlaps with both subspecies. The correlation between abiotical factors and determination characteristics were found. Molecular survey using ISSR method shows no difference between subspecies. The final resolution of subspecies existence will be questioned in following study.
6

The ecology and morphological variation of Opuntia (Cactaceae) species in the mid-south, United States

Majure, Lucas C 11 August 2007 (has links)
Opuntia species have been poorly studied ecologically and taxonomically in the eastern United States. This study deals with the ecology of Opuntia species in the mid-south United States and covers not only the high degree of morphological variation exhibited by taxa, but also the taxonomy and distributions of the group for Mississippi. The taxa in the mid-south have distinct habitat preferences and can be separated based on habitat characterization. Information from this work provides valuable data useful in predicting possible routes that an invasive species, Cactoblastis cactorum (the cactus moth), might use in its potential westward migration. Phenotypic plasticity exhibited by Opuntia pusilla subjected to experimental conditions exemplifies the care that should be taken when making species delineations. Spine production in certain species is more a function of abiotic environmental pressures than genetic heritage. Two taxa that previously were put into synonymy with other species are recognized from this work.
7

Evoluce a učení virtuálních robotů / Evolution and Learning of Virtual Robots

Krčah, Peter January 2016 (has links)
Title: Evolution and Learning of Virtual Robots Author: RNDr. Peter Krčah Department: Department of Software and Computer Science Education Supervisor: RNDr. František Mráz, CSc. Abstract: Evolutionary robotics uses evolutionary algorithms to automatically design both body and controller of a robot. We describe two contributions to automated design of virtual robotic creatures. First, we introduce a nature-inspired method that allows virtual robots to modify their morphology through lifetime learning. We show that such morphological plasticity makes it possible to evolve robots that can dynamically adjust their morphology to the environment they are placed into. We also show that by reshaping the fitness landscape, learning reduces computation cost required to evolve a robot with a given target fitness even in a single environment. In the second contribution, we show that for certain problems in evolutionary robotics, premature convergence to local optima can be avoided by ignoring the original objective and searching for any novel behaviors instead (a technique known as Novelty Search). Keywords: Evolution of Virtual Creatures, Body-brain Coevolution, Morphological Plasticity, Neural Networks, Learning
8

Aspectos da história de vida de Guadua tagoara (Nees) Kunth (Poaceae:Bambuseae) na Serra dos Órgãos, RJ

Alves, Gilberto Terra Ribeiro 30 May 2007 (has links)
Made available in DSpace on 2016-06-02T19:31:51Z (GMT). No. of bitstreams: 1 3112.pdf: 4538374 bytes, checksum: de855e1830eb260ab2d2aa15c63fa695 (MD5) Previous issue date: 2007-05-30 / Financiadora de Estudos e Projetos / Guadua tagoara (Nees) Kunth is a large sized bamboo native of the Brazilian Atlantic Rain Forest, with a semi-scandent habitat, pachymorphic rhizome and thorns for fixation on trees. Nowadays this bamboo is considered an invasive species in secondary forests, where its populations are supposedly in expansion. The general objective of this study, developed in Parque Nacional da Serra dos Órgãos (PARNASO), RJ, was to investigate the life history of G. tagoara from two perspectives: (a) to know the ecological basis of its supposed invasive potential and (b) to discuss it in the context of theoretical ecology and evolution of mast seeding plants. This dissertation was based primarily on three moments of the G. tagoara life cycle, studied in the scales of clump, genet and ramet. The investigated aspects of its life history were: mast seeding followed by parental death (monocarpy), regeneration from seed, synchrony and reproductive interval, development, morphological plasticity and intra and infra-specific diversity. At least at PARNASO, the life cycle of G. tagoara is strictly monocarpic, its regeneration from seeds occurred mainly in the interior of the senescent clumps. The majority of reproductive events were concentrated in 2004, suggesting a pattern known as flowering distribution for this region. The spatial gregarism of G. tagoara seems to be associated to the intra-clump reproductive synchrony, and the selective advantage of monocarpy seems to be the creation of regeneration sites for the following cohort. The same seems to be valid for other monocarpic species of Guadua with a tendency for gregarism. It was not possible to establish a reproductive interval for G. tagoara, but four possible flowering patterns were proposed for its life history. Although the adult genets have long spacers (necks), the rhizomes in the 2004 and 2006 cohorts did not present this character. Culm ramification occurred before rhizome ramification, and the thorns appeared just in the second year of the young genets. These cohorts (2004 and 2005) differed among them in structural characters, except in the number of living culms per genet, and presented characteristics here considered to be adaptations for the regeneration inside the clumps or other kinds of gaps. The morphological plasticity presented by the different patterns of ramification, by the reiterative growth and by the deviance from obstacles during elongation was observed in the culms of adult genets. The reiterative growth was also seen in the 2004 and 2005 cohorts, as well as articulated culms and the presence of invertebrates in their interior, including the internodes filled with water. Climatic seasonality doesn t restrict the growth of G. tagoara, but it is potentialized in the rainy season. Adult genets of this bamboo seem to grow during the whole year in PARNASO. Morphological plasticity observed in their culms can be considered a foraging behavior searching for light and space in the canopy. G. tagoara also has a large opportunistic growing behavior, expressed in ramets and genets, and can be considered a structural parasite of trees. Morphological elasticity, potential for clonal growth and integration of phalanx and guerilla strategies seem to be key aspects of its life history and its expansion and dominance in secondary forests. The results of this study support the hypothesis that the expansion of G. tagoara in secondary forests is facilitated by activities altering the structure of the forest. I suggest that the selfperpetuating disturbance cycle proposed to explain the formation and expansion of forests dominated by Guadua spp. in the Amazon forest must also act in the G. tagoara dominated forests, but in this latter case the anthropogenic activities seem to be very important for the origin and expansion of dominance. Some possible causes of its intra and infraspecific diversity of G. tagoara were discussed, based on the knowledge acquired about its life history, as well as some possible relations between its life cycle and the forest dynamics. The need and viability of the management of its populations were also discussed. / Guadua tagoara (Nees) Kunth é um bambu de grande porte nativo da Floresta Atlântica, de hábito semi escandente, rizoma paquimórfico e dotado de espinhos para fixação nas árvores. Atualmente este bambu é considerado uma espécie invasiva em áreas de florestas secundárias, onde suas populações supostamente estariam em expansão. O objetivo geral deste estudo, desenvolvido no Parque Nacional da Serra dos Órgãos (PARNASO), RJ, foi investigar a história de vida de Guadua tagoara sob duas perspectivas: (a) conhecer a base ecológica do seu suposto potencial invasiso e (b) discuti-la no contexto teórico da ecologia e evolução das plantas mast seeding. Esta dissertação baseou-se principalmente em três momentos do ciclo vital de G. tagoara, abordados nas escalas de taquaral, geneta e rameta: frutificação maciça seguida de morte parental (monocarpia), regeneração por sementes e desenvolvimento dos genetas adultos. Os aspectos estudados em sua história de vida foram: frutificação maciça, monocarpia, regeneração por sementes, sincronia e intervalo reprodutivos, desenvolvimento, plasticidade morfológica e diversidade intra e infra - específica. Pelo menos no PARNASO, o ciclo de vida de G. tagoara é estritamente monocárpico, e sua regeneração por sementes ocorreu principalmente no interior dos taquarais senescentes. O florescimento foi assincrônico em escala populacional, mas marcadamente sincrônico dentro dos taquarais. O ano de 2004 concentrou a maior parte dos taquarais reprodutivos, sugerindo para esta região um padrão conhecido como distribuição do florescimento. O gregarismo espacial de G. tagoara parece associado à sincronia reprodutiva intra taquaral, e a vantagem seletiva da monocarpia parece ser a criação de sítios de regeneração para a coorte seguinte. O mesmo parece valer para outras espécies monocárpicas de Guadua com tendência ao gregarismo. Não foi possível estabelecer um intervalo reprodutivo para G. tagoara, mas quatro possíveis padrões de florescimento foram propostos para sua história de vida. Embora os genetas adultos possuam espaçadores (pescoços) longos, nas coortes de 2004 e 2005 o rizoma não apresentou esta característica. A ramificação dos colmos ocorreu antes da ramificação do rizoma, e o surgimento dos espinhos ocorreu a partir do segundo ano de vida destes genetas. Estas coortes diferiram entre si em termos estruturais, com exceção do número de colmos vivos por geneta, e apresentaram características interpretadas aqui como adaptações à regeneração no interior dos taquarais ou em outras clareiras. A plasticidade morfológica representada por distintos padrões de ramificação, pelo crescimento reiterativo e pelo desvio de obstáculos durante o elongamento foi observada nos colmos de genetas adultos. O crescimento reiterativo também foi observado nos colmos das coortes de 2004 e 2005, nas quais também foram observados colmos articulados e a presença de raízes nos nós aéreos. Tanto nas coortes jovens quanto nos genetas adultos foram observadas perfurações nos colmos e a presença de invertebrados em seu interior, inclusive nos entrenós preenchidos com água. A sazonalidade climática não restringe o desenvolvimento de G. tagoara, mas o potencializa na época mais chuvosa do ano. Os genetas adultos deste bambu parecem crescer durante todo o ano no PARNASO. A plasticidade morfológica observada nos seus colmos pode ser considerada como um comportamento forrageador por espaço e luz no dossel da floresta. G. tagoara possui grande potencial de crescimento oportunista, o qual pode se expressar nas escalas de rametas e genetas, e pode ser considerado um parasita estrutural de árvores. A plasticidade morfológica, o potencial de crescimento clonal e a integração das estratégias falangeal e guerrilheira parecem ser aspectos-chave da sua história de vida e da sua expansão e dominância em florestas secundárias. Os resultados deste estudo dão suporte à hipótese de que a expansão de G. tagoara em florestas secundárias seja facilitada por atividades antrópicas que alterem a estrutura da floresta. Eu sugiro que o ciclo de distúrbios auto-perpetuante proposto para explicar a formação e expansão das florestas dominadas por Guadua spp. na Amazônia também deve atuar nas florestas dominadas por G. tagoara, mas nesse caso as ações antrópicas parecem ter grande relevância na origem e expansão da dominância. A partir dos conhecimentos obtidos sobre a história de vida de G. tagoara, foram discutidas algumas possíveis causas da sua diversidade intra e infraespecífica, e algumas possíveis relações entre o seu ciclo de vida e a dinâmica florestal. A necessidade e a viabilidade do manejo de suas populações também foram discutidas.
9

Fytoplankton tatranských ples: faktory ovlivňující druhové složení a biomasu / Phytoplankton of the Tatra lakes: factors influencing taxonomic composition and biomass

Červenková, Lenka January 2010 (has links)
The aim of this diploma thesis was to describe species composition and biomass of phytoplankton in the Tatra Mountains lakes (Slovakia, Poland) and environmental factors influencing them. The surface layer of 89 lakes was sampled in September 2004. Flagellates from Chrysophyta, Dinophyta and Cryptophyta most frequently dominated the phytoplankton biomass. Lake in the same valley usually differed in their dominant taxonomic group as a result of different lake morphometry, catchment type and detailed geological structure. Based on the level of phytoplankton biovolume, the majority of lakes were ultraoligotrophic and oligotrophic, however, mesotrophic and even eutrophic conditions were recorded in some forest and meadow lakes. An allometric relationship between phytoplankton biomass and chlorophyll a was revealed. Specific chlorophyll content did not differ among taxonomic groups. Altogether 233 species were determined, the most diverse group were Chlorophyta. Species richness of lake was 3-46 and it was negatively correlated with altitude and positively correlated with lake area. The majority of species were rare both in term of biomass and number of lakes occupied by a particular species. Average local species biomass was positively correlated with regional distribution. The similarity of species...
10

Klonální integrace Agrostis stolonifera v živinově heterogenním prostředí / Clonal integration of Agrostis stolonifera in heterogeneous soil environment

Duchoslavová, Jana January 2014 (has links)
Clonal plants may be able to cope with spatial heterogeneity due to the physiological integration of ramets. Previous studies demonstrated that benefits of clonal integration increase with patch contrast between individual ramets. However, the same magnitude of contrast may be perceived differently in rich and poor environments. According to the theoretical work of Caraco and Kelly (1991), I expected these benefits to be the greatest in overall poor conditions and high between-patch contrast. To test this hypothesis, I conducted experiments with pairs of ramets of a stoloniferous grass, Agrostis stolonifera, grown in variously nutrient rich conditions. The experiment with pairs of ramet of similar developmental age showed only very weak effect of integration on growth of ramets, although integration significantly improved survival of ramets and also affected root-shoot ratio of ramets. Nevertheless, there were considerable benefits of integration in the experiment with developmentally older mother ramets and their daughter ramets. Contrary to the predictions, the benefits of integration were bigger in rich conditions and they decreased with increasing between-patch contrast. In addition, effect of integration on root-shoot ratio of ramets was opposite to the expected specialization for acquisition...

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