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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.
301

Quaternary herpetofaunas of the British Isles : taxonomic descriptions, palaeoenvironmental reconstructions, and biostratigraphic implications

Gleed-Owen, C. P. January 1998 (has links)
This project aims to study fossil amphibian and reptile (herpetofaunal) remains from Quaternary sites in the British Isles. This neglected group of vertebrates hold great potential for Quaternary Science. Collectively, they cover a wide range of ecological tolerances, although individual species often have very specific tolerances. The biology and ecology of individual species are discussed (Chapter 2) to facilitate their use in Quaternary palaeoenvironmental reconstructions, and an account of previous work on fossil herpetofaunas is given (Chapter 3). Very little work on fossil herpetofaunas has been carried out in the British Isles, mainly due to a lack of the required osteological expertise. The preparation and study of a modern osteological collection (Chapter 4), for comparative purposes, has therefore constituted a large and essential part of the project. The resulting manual for the identification of fossil herpetofaunal remains, appropriately illustrated with SEMs and hand-drawn figures, is presented (Chapter 5). The difficulties encountered in identifying some taxa are discussed in detail, and points of caution are stressed where necessary.
302

Taxonomic revision of the Permo-Carboniferous lepospondyl amphibian families Lysorophidae and Molgophidae

Wellstead, Carl F. January 1985 (has links)
The Lysorophia is an order of small, but extremely elongate and tiny-limbed aquatic lepospondyl amphibians existing from the Middle Pennsylvanian through the Lower Permian, primarily in North America. The order comprises one family, Cocytinidae, with three recognized species: Brachydectes newberryi (=Cocytinus gyrinoides), B. elongatus (=Lysorophus tricarinatus, partim) and Pleuroptyx clavatus. Other named species are considered Lysorophia, incertae sedis. Lysorophoids are distinguished by their fenestrated skulls, anteriorly sloping suspensoria, short mandibles (each bearing a lateral mandibular fenestra) and by extensive, well-ossified hyobranchial skeletons. Presacral vertebrae are holospondylous and number between 69 (B. newberryi) and 97 (B. elongatus). Neural arch halves are sutured at their midlines and to their centra. Aspects of lysorophoid anatomy, including the hyobranchial skeleton, suggest that the lysorophoids are neotenic. / While closely similar to one another, lysorophoid species are highly derived relative to other Paleozoic amphibians. They are most closely related to microsaurs, principally through the morphology of the craniovertebral articulation.
303

Chemistry and medical implications of novel amphibian peptides : a thesis submitted for the degree of Doctor of Philosophy / by Paul Andrew Wabnitz.

Wabnitz, Paul Andrew January 1999 (has links)
Copies of author's previously published articles inserted. / Includes bibliographical references. / xv, 210 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A chemical and pharmacological investigation of compounds derived from amphibian skin. Isolates novel amphibian peptides and further investigates the biological activity of some of the peptides discovered. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemistry, 2000
304

Fish and amphibians as test organisms for evaluation of effects caused by chemicals /

Carlsson, Gunnar, January 2007 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 5 uppsatser.
305

Effects of Harvest Gaps and Natural Canopy Gaps on Amphibians within a Northeastern Forest

Strojny, Carol January 2004 (has links) (PDF)
No description available.
306

A influência parasitária de helmintos em aspectos reprodutivos de três espécies de anfíbios da RPPN Foz do Rio Aguapeí, município de Castilho, São Paulo, Brasil. / The parasitic influence of helminths on reproductive aspects of three amphibian species from RPPN Foz do Rio Aguapeí, municipality of Castilho, São Paulo, Brazil.

Forster, Ottilie Carolina 28 August 2017 (has links)
Submitted by Ottilie Carolina Forster (ocforster@gmail.com) on 2017-12-05T21:44:44Z No. of bitstreams: 1 Tese_Ottilie_Versão Final 22 11 2017.pdf: 1968251 bytes, checksum: 8cbd67380fedecc14e72be85ed42be54 (MD5) / Approved for entry into archive by ROSEMEIRE APARECIDA VICENTE null (rose@btu.unesp.br) on 2017-12-07T13:23:00Z (GMT) No. of bitstreams: 1 forster_oc_dr_bot.pdf: 1968251 bytes, checksum: 8cbd67380fedecc14e72be85ed42be54 (MD5) / Made available in DSpace on 2017-12-07T13:23:00Z (GMT). No. of bitstreams: 1 forster_oc_dr_bot.pdf: 1968251 bytes, checksum: 8cbd67380fedecc14e72be85ed42be54 (MD5) Previous issue date: 2017-08-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A referida tese é o resultado de um trabalho que buscou discutir, como tema geral, o impacto que os parasitas podem causar na ecologia de seus hospedeiros. Ela foi divida em dois capítulos: o primeiro capítulo é uma revisão bibliográfica que discute sobre como os parasitas podem influenciar no desempenho reprodutivo de seus hospedeiros; e o segundo capítulo investigou em três espécies de anfíbios anuros (Leptodactylus chaquensis, Leptodactylus podicipinus, e Hypsiboas raniceps), se os indivíduos parasitados por helmintos são acometidos por alterações em aspectos da reprodução. As três espécies de anuros estudadas, não apresentaram evidências que possam ter alguma relação entre a intensidade parasitária de helmintos e caracteres morfológicos associados à reprodução. O que sugere que estas espécies estudadas apresentem respostas imunológicas e/ou adaptações fisiológicas mediante infecção parasitária. / This thesis is the result of a work that sought to discuss, as a general theme, the impact that parasites can have on the ecology of their hosts. It was divided into two chapters: the first chapter is a literature review that discusses how the parasites can influence the reproductive performance of their hosts; and the second chapter investigated in three species of anuran amphibians (Leptodactylus chaquensis, Leptodactylus podicipinus, and Hypsiboas raniceps), if the individuals parasitized by helminths are affected by changes in aspects of reproduction. The three species of anurans studied didn’t present evidence that could have any relation between the parasite intensity of helminths and morphological characters associated to reproduction. This suggests that these species studied present immunological responses and/or physiological adaptations through parasitic infection.
307

Evolution of the caecilian skull

Sherratt, Emma January 2011 (has links)
The results of evolution can be inferred from comparative studies of related organisms. In this doctoral thesis, I use phylogenetic comparative methods along side geometric morphometrics to analyse shape variation in order to infer evolution of the caecilian skull. Caecilians are elongate, limbless amphibians that superficially resemble snakes or earthworms, and use their head as a locomotory organ. I characterise large-scale patterns of cranial morphological diversity and quantify variation across the main family-level clades by describing patterns relating to phylogeny, disparity and ecology. Then I examine the origins and evolution of morphological variation in the skull by describing patterns relating to morphological integration and modularity. This thesis demonstrates a variety of existing statistical techniques that can be used to infer processes from large-scale evolutionary patterns in morphological data using non model organisms. Throughout the thesis, I show that the evolution of the caecilian skull to be multifaceted. On the patterns of diversity, the most striking is a "starburst" arrangement in shape space, which suggests that early in caecilian evolution ancestral lineages traversed greater expanses of the shape space, while subsequent phylogenetic divergence within the main clades entailed less morphological diversification. This may be related to early diversification into different ecological-niches, yet more data are needed to test this. The clades differ considerably in their cranial disparity, but there appears to be no unified pattern across the whole order that indicates disparity is coupled with clade age or speciation events. I show that aquatic species are more diverse than their terrestrial relatives, and that there is convergence of cranial shape among dedicated burrowers with eyes covered by bone. On the patterns of morphological integration and modularity, another remarkable finding is the caecilian cranium is modular with respect to two functional regions, the snout and the back of the cranium. Modularity is important for understanding the evolution of this structure. The main elements of the caecilian anterior skeleton, the cranium, mandible and atlas vertebra, reveal different patterns of morphological integration, suggesting different developmental and evolutionary processes are involved in sorting and maintaining new variation of each structure. Allometry is an important component of integration in each of the structures. Covariation of the cranium-mandible after size correction is significant and follows the same direction of shape change across all levels and as shown for allometry. In contrast, covariation of the cranium-atlas follows different directions at each level. These results suggest the two main joint of the caecilian skull differ substantially in their origin and evolution. I discuss the contribution made in this thesis to caecilian and evolutionary biology and offer an outlook of how theses findings can be used to initiate future studies to better understand of the evolution of the caecilian skull.
308

Populační dynamika obojživelníků a plazů Vlkovské pískovny / Population dynamic of amphibians and reptiles of Vlkovská sandpit

RŮŽIČKA, Jan January 2016 (has links)
The theoretical part contains summary of the literature on the topic of succession, mining, human impacts on biodiversity, land reclamation and ecological requirements of reptiles and amphibians. The practical part contains the observations of these two model groups of animals and subsequent evaluation of their abundance and diversity. During the three years I made total 37 herpetological observation, during which I observed the occurrence of eight species of reptiles and amphibians on five locations. When observing reptiles and amphibians I used non-invasive methods of observation. The found species were Zootoca vivipara (507 individuals), Lacerta agilis (583 individuals), Pelophylax esculentus (976 individuals), Pelophylax ridibundus (710 individuals), Pelophylax lessonae (1,401 individuals), Lissotriton vulgaris (203 individuals), Natrix natrix (32 individuals) and Anguis fragilis (7 individuals). The values in the brackets represent the total number of individuals found during 3 seasons. Generically the richest site was "Jezírka" (8 species), species habitat poorest contrary, "Přesyp" (2 species). In all the years the abundance of two model groups (frogs and lizards) were significantly different (abundance of Pelophylax: Chí Square = 2764; d. f. = 4, p <0.001, Zootoca + Lacerta: Chí Square = 119; d. f. = 4, p <0.001. Pelophylax: Chí Square = 1573; d. f. = 4, p <0.001, Zootoca + Lacerta: Chí Square = 43; d. f. = 4, p <0.001. Pelophylax: Chí Square = 37; d. f. = 4, p <0.001, Zootoca + Lacerta: Chí Square = 741; d. f. = 4; p <0.001). The researchl lasted three vegetation seasons. They had distinctly different climatic conditions. The abundance of reptiles and amphibians in season of 2013 was significantly impacted by the spring floods. Season 2014 any major climatic fluctuations and therefore I considered it as a standard. Season 2015 was greatly influenced by the high summer temperatures and the lack of greater precipitation during the summer months. This fact influenced mainly amphibian populations.
309

Závislost predace a rychlosti metabolismu na teplotě z pohledu kořisti i predátora

MODRÁ, Denisa January 2017 (has links)
Climate changes affect species interactions which can have cascading effect up to the ecosystem level. This work investigates the effects of temperature and predator size on predator prey interactions by measuring the feeding rates of predators and metabolic rates of both predator and prey, using dragonfly larvae Aeshna cyanea and toad tadpoles Bufo bufo as a model system. Possible consequences of the findings for the impacts of climate change and predation on amphibian populations are discussed.
310

Atributos ecológicos de anuros neotropicais: o que podem predizer?

Fontana, Rodrigo Barbosa January 2018 (has links)
O risco de extinção e o declínio populacional de muitas espécies animais na região neotropical estão fortemente relacionados aos processos antrópicos, como a conversão ambiental, mas também aos fatores intrínsecos aos próprios indivíduos, como os atributos. Os anuros correspondem ao grupo vertebrado mais ameaçado atualmente, sofrendo com sérios declínios populacionais. Este trabalho buscou avaliar quais os atributos dos anfíbios neotropicais podem predizer: i) as categorias de ameaça e tendências populacionais destas espécies e ii) a ocorrência de anuros em um ambiente modificado, de matriz agrícola. Para a predição de categorias de ameaça e tendências populacionais utilizamos um banco de dados com atributos de habitat e modos reprodutivos de 3196 espécies de anuros neotropicais. Verificamos que espécies com modos reprodutivos terrestres e desenvolvimento direto tem uma maior tendência a estarem em declínio. Além disso, verificamos que embora os atributos sejam filogeneticamente estruturados, o grau de ameaça parece ser independente de suas histórias evolutivas. Para identificar possíveis relações entre atributos ecológicos e morfológicos de anuros em uma paisagem agrícola no sul do Brasil, registramos a anurofauna com uso de armadilhas de interceptação e queda e procuras ativas em três diferentes distâncias da borda em um ambiente florestal e em uma matriz agrícola. Verificamos que principalmente os atributos ecológicos, como o modo reprodutivo (tanto terrestre como aquático) e o hábito estão relacionados com a ocorrência destas espécies no sistema agrícola, assim como encontramos diferenças entre os atributos morfológicos ao longo do gradiente de distância. Ambos os resultados podem auxiliar na tomada de decisões em planos e projetos de conservação de anuros neotropicais. / The extinction risk and population decline of many animal species in neotropical region are strongly related to anthropic processes, such as environmental conversion, but they are also related to intrinsic factors such as traits. Anurans correspond to the most endangered vertebrate group, suffering serious population declines. This work aimed to evaluate which neotropical anurans traits can predict: i) the categories of threat and population trends of species, and ii) the occurrence of anuran species in modified environments, such as the agricultural matrix. First, we compiled data to 3196 neotropical anuran species. We emphasized the importance of habitat and reproductive modes in threat classifications, as well as verified that species with terrestrial reproductive modes and direct development are more likely to be declining. We also found that although anurans traits being phylogenetically structured, the degree of threat seems to be independent from their evolutionary histories. In addition, to identify possible relation among ecological and morphological anuran traits with agricultural landscape in southern Brazil, we studied the anurofauna using pitfall traps and active searches at three different border distances in a forest environment and in an agricultural matrix. We verified that mostly of the ecological traits, such as the reproductive mode (both terrestrial and aquatic) and the habit, are related to the occurrence of determined species in the agricultural system. And we also found differences among the morphological traits observed through the distance gradient from the border. Therefore, both results present practical importance since it can help herpetologists to making decision about neotropical anurans conservation.

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