Dissertations / Theses on the topic 'Amphibians'
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Rothermel, Betsie. "Movement behavior, migratory success, and demography of juvenile amphibians in a fragmented landscape /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p3099626.
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Patrick, David A. "The Effects of Forest Practices on a Maine Amphibian Community." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/PatrickDA2007.pdf.
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Crockett, Marquette Elaine. "Survey and Comparison of Amphibian Assemblages in Two Physiographic Regions of Northeast Tennessee." [Johnson City, Tenn. : East Tennessee State University], 2001. http://etd-submit.etsu.edu/etd/theses/available/etd-0605101-155522/unrestricted/crockett0611.pdf.
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Regula, Meyer Lisa. "Invasive plants and native amphibians| The implications for amphibian conservation in eastern North America." Thesis, Kent State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3618851.
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Humans introduce non-native plants to new areas at an increasing rate with the increased movement across the globe. These invasive species can become mono-cultures and extremely different from the native floral community. Amphibians, at the same time, are facing global declines with approximately one-third of all amphibians threatened or endangered. Due to the importance of amphibians as prey items for many vertebrates including small birds, mammals, and reptiles, and also predator controls over many invertebrates, including some pest species, the decline of amphibians has large implications for many environments. This study looks at a range of interactions between two invasive plants ( Typha angustifolia and Phragmites australis) and two native anurans (Lithobates clamitans and Lithobates catesbeianus).
As ecosystem engineers, plants form the basis of many communities, and sculpt the physical environment by adding complexity to the earth's surface. They also add chemical constituents either actively or passively too ward off other competitors. This change in the environment on both the chemical and physical level leads to complex possibilities for a changed plant community to impact the rest of the ecosystem, including amphibians. I focus on the physical changes by looking at behavior of amphibians in these invasive plant mono-cultures and non-invaded controls, and their appearance in invaded and non-invaded wetlands, both constructed and naturally occurring. On the chemical side of the matter, I monitor water chemistry measures in natural and constructed wetlands that are either lacking invasive plants or have a substantial presence of these plants, and correlate those measures with tadpole growth and survival.
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Regula, Meyer Lisa K. "INVASIVE PLANTS AND NATIVE AMPHIBIANS: THE IMPLICATIONS FOR AMPHIBIAN CONSERVATION IN EASTERN NORTH AMERICA." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1384952870.
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Schneider, Amy Elizabeth. "Continued study of the use of created ponds for amphibian breeding in fragmented forested areas." [Huntington, WV : Marshall University Libraries], 2008. http://www.marshall.edu/etd/descript.asp?ref=876.
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Regosin, Jonathan V. "Terrestrial habitat use by pool-breeding amphibians in a suburban landscape /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2003.
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Thesis (Ph.D.)--Tufts University, 2003.Adviser: J. Michael Reed. Submitted to the Dept. of Biology. Includes bibliographical references (leaves 124-134). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Penner, Johannes. "Macroecology of West African amphibians." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2014. http://dx.doi.org/10.18452/17035.
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Amphibienpopulationen sind weltweit bedroht. Für fundierte Entscheidungen im Naturschutz ist ein wissenschaftliches Hintergrundwissen notwendig. Eine wichtige Komponente ist die Verbreitung der Arten und die Gründe hierfür. Dies setzt auch Klarheit bezüglich des taxonomischen Status voraus. Vernachlässigte Regionen liegen meist in den Tropen. Um diese Lücke zu füllen, untersucht die vorliegende Arbeit die Makroökologie westafrikanischer Amphibien. Eine neue Art der Familie Phrynobatrachidae wird beschrieben. Anschließend werden die taxonomischen Unterschiede zweier Mitglieder der Familien der Hyperoliidae und der Arthroleptidae untersucht. Dies ebnet den Weg für die Makroökologie. Es wird analysiert, ob Westafrika eine einzigartige biogeographische Region ist. Die Untersuchung zeigen, dass Westafrika in der Tat einzigartig ist. Die Ähnlichkeiten innerhalb der Region sind größer als die innerhalb ähnlicher Habitate aus unterschiedlichen Regionen. Der Cross River ist die wichtigste Barriere. Mehrere geographische Zonierungen innerhalb Westafrikas werden entdeckt. Es wird untersucht, ob der Chytrid Pilz, Batrachochytrium dendrobatidis, (Bd), ein wichtiger Faktor beim Rückgang der Amphibien Populationen, in West Afrika vorkommt. Bisher gibt es keinen positiven Nachweis westlich Nigerias. Dennoch sagen Modelle geeignete Habitate für Bd vorher. Die wahrscheinlichste Erklärung ist, dass die Dahomey Gap als natürliche Barriere die Ausbreitung von Bd verhindert. Als letztes werden die Nischen westafrikanischer Amphibien eruiert. Für die meisten Arten werden Nischenmodelle berechnet. Dies bestätigt bereits bekannte Gebiete hoher Alpha Diversität und zeigt bisher unbekannte Gebiete auf. Des Weiteren werden Erklärungen für unterschiedliche Verbreitungsgebietsgrößen gesucht. Generell wird die Nischenbreite hierfür verantwortlich gemacht. Die vorliegenden Daten lassen allerdings auch den Schluss zu, dass das Ausbreitungsvermögen das beobachtete Muster ebenfalls erklären kann.Amphibian populations are declining globally. For informed conservation decisions a sound scientific background is needed. One major component is species distribution and the underlying causes. This also requires clarity on the taxonomic status. Often neglected regions are located in the tropics. In order to fill this gap, the present thesis examines the macroecology of West African amphibians. A new species of the family Phrynobatrachidae is described. Afterwards, the taxonomic differences between morphologically similar members of the families Hyperoliidae and Arthroleptidae are discussed. Beside other studies, this sets the field for macroecology. It is tested whether West Africa is a unique biogeographic region. The similarity of amphibian assemblages from Sub-Saharan Africa is analysed and it is shown that West Africa contains unique assemblages. Similarities within the region are higher than similarities between habitats across different regions. The main barrier towards Central Africa is the Cross River. Several geographic divisions within West Africa are detected. It is examined whether the chytrid fungus Batrachochytrium dendrobatidis (Bd), one important factor for amphibian population declines in many other regions, occurs in West Africa. So far there is no positive record west of Nigeria. However, models predict that environmental suitability for Bd is high. The most plausible explanation for the absence is that the Dahomey Gap acted as a natural barrier against the spread of the Bd. Finally, the niches of West African amphibians are investigated. For most species environmental niche models are calculated. This confirms previously known areas of high alpha diversity and so far unknown species rich areas are detected. In a further study, explanations for differing range sizes are searched for. Niche breadth is commonly assumed to be the general cause. However, the analysed data also suggests that dispersal ability can also explain the observed pattern.
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Lau, Kwan-wa. "Cloning and characterization of the first amphibian secretins and secretin receptor functional implication of secretin with orexin in amphibians /." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B44143655.
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McMaster, Kellie Anne. "Ecophysiology of Australian cocooning and non-cocooning, burrowing, desert frogs /." Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0138.
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Lau, Kwan-wa, and 劉君華. "Cloning and characterization of the first amphibian secretins and secretin receptor: functional implication ofsecretin with orexin in amphibians." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B44143655.
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Hopkins, Samantha. "Chytridiomycosis in amphibian populations in the Western Cape, South Africa." Thesis, University of the Western Cape, 2002. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_7137_1359702947.
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There have been many cases reported of amphibian populations declining. These are often due to anthropogenic factors such as habitat destruction and pollution. However, some eclines have not had an obvious cause and many of these have been investigated and found to be due to pathogenic disease. Batrachochytrium dendrobatidis is a recently described pathogen of frogs. The population declines that have been associated with chytridiomycosis have occurred in relatively undisturbed areas such as national parks. The declines tend to occur at higher altitudes or in colder climates. This is thought to be because of the frog immune system being slower at lower temperatures. This project gives an overview of chytrid infection in the Western Cape and at a small number of sites in the Northern Cape and Eastern Cape.
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White, Steve. "Population trends, conservation and the trade in amphibians in Asia." Thesis, View the Table of Contents & Abstract, 2005. http://sunzi.lib.hku.hk/hkuto/record/B34737364.
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Ruthsatz, Katharina [Verfasser], and Kathrin H. [Akademischer Betreuer] Dausmann. "Amphibians in a changing world : an ecophysiological perspective on amphibian metamorphosis / Katharina Ruthsatz ; Betreuer: Kathrin H. Dausmann." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1176702076/34.
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Mcmahon, Taegan A. "Understanding Amphibian Decline: the Role of Pesticides and the Pathogenic Chytrid Fungus on Amphibians and Aquatic Communities." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4727.
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Amphibians are the most threatened taxon on the planet. Declines have been associated with over-exploitation, habitat loss, pollution, and pathogenic diseases, but of these factors, pollution and disease have been relatively under-studied. Here, I investigated: 1) the impacts of commonly used pesticides on aquatic communities, 2) the effect of these pesticides on amphibian susceptibility to the pathogenic chytrid fungus, Batrachochytrium dendrobatidis (Bd), and 3) whether there are non-amphibian hosts of Bd and 4) how to best quantify the survival of Bd through ontogeny of the host.
In my first research chapter, I quantified the effects of environmentally relevant concentrations of the mot commonly used synthetic fungicide in the US, chlorothalonil, on 34 species-, 2 community- and 11 ecosystem-level responses in a multitrophic-level system. Chlorothalonil increased mortality of amphibians, gastropods, zooplankton, algae, and a macrophyte (reducing taxonomic richness), reduced decomposition and water clarity, and elevated dissolved oxygen and net primary productivity. These ecosystem effects were indirect but were predictable based on changes in taxonomic richness. A path analysis suggests that chlorothalonil-induced reductions in biodiversity and top-down and bottom-up effects facilitated algal blooms that shifted ecosystem functions.
In my second chapter, I investigated how a wide range of ecologically relevant concentrations of chlorothalonil affected four species of amphibians (Osteopilus septentrionalis, Rana sphenocephala, Hyla squirella and H. cinerea). I also evaluated the effects of chlorothalonil on liver tissue, immune cell density, and the stress hormone, corticosterone. Chlorothalonil killed nearly every amphibian at the expected environmental concentration (EEC) and, at concentrations to which humans are commonly exposed (up to the EEC), it was associated with elevated corticosterone levels and changes in immune cells. Three species (O. septentrionalis, R. sphenocephala, and H. cinerea) showed a non-monotonic dose-response, with low and high concentrations causing significantly greater mortality than intermediate concentrations and controls. Corticosterone exhibited a similar non-monotonic dose response and chlorothalonil concentration was inversely associated with liver tissue and immune cell densities. These studies on chlorothalonil emphasize the need to re-evaluate its safety and to further link anthropogenic-induced changes in biodiversity to altered ecosystem functions.
In my third research chapter, I investigated the effects of chlorothalonil and atrazine, one of the most commonly used herbicides in the US, on amphibian susceptibility to Bd, a leading cause of amphibian extinctions. Relative to controls, atrazine monotonically reduced Bd growth in culture and on tadpoles. In contrast, chlorothalonil non-monotonically reduced Bd growth in culture and on tadpoles, with low and high concentrations causing significantly greater mortality than intermediate concentrations and controls. This study is one of only a handful of studies to document a non-monotonic dose response of an invertebrate (Bd) to a pesticide. Although both pesticides reduced Bd growth on tadpoles and in culture, neither eliminated Bd entirely, and because we know little about the long-term effects of the pesticides on hosts (e.g., immunosuppression), I do not recommend using these chemicals to control Bd.
In my fourth research chapter, I investigated whether there are non-amphibian hosts for Bd. Non-amphibian hosts could explain how Bd is able to persist in the environment after amphibians are extirpated, and the extreme virulence and distribution of Bd. In laboratory and field studies, I found that crayfish, but not mosquitofish, were hosts for Bd. I found that crayfish could be infected with Bd, could maintain that infection long term (at least 3 months) and could transfer that infection to susceptible amphibians. I also revealed that exposure to water that previously held Bd caused significant crayfish mortality and gill recession, suggesting that Bd releases a chemical that can cause host pathology in the absence of infection. Most efforts to conserve and restore amphibian populations challenged by Bd have been unsuccessful, but managing alternative hosts offers a new and potentially more effective approach to managing Bd. Likewise, identifying the specific pathology-inducing chemical released by Bd might facilitate the development of new strategies to reduce the risk posed by this pathogen.
The fifth and sixth research chapters are aimed to improve the quality and efficiency of Bd research. During amphibian development, Bd infections transition from the mouthparts of tadpoles to the skin of post-metamorphic frogs but this transition has never been quantified and thus researchers might be sampling the wrong parts of amphibian bodies to detect Bd. I showed that Bd abundance in O. septentrionalis mouthparts declined from Gosner stages 35-42 and increased on epidermis from Gosner stages 38-46. Assuming our findings are general across species, I recommend sampling mouthparts of amphibians less than Gosner stage 41 and hind limbs of amphibians greater than Gosner stage 41. This should provide researchers with guidance on where to sample to maximize detection of Bd.
I also investigated whether Trypan blue dye could be used to determine the viability of Bd. I showed that the proportion of zoospores stained with Trypan blue dye matched the proportion of known dead zoospores added to cultures. In contrast, all of the zoosporangia stage (including known dead zoosporangia) of Bd stained blue. These results demonstrate that Trypan blue can be used to determine the viability of Bd zoospores but not zoosporangia. I recommend using Trypan blue to report the number of live zoospores to which hosts are exposed and to help determine whether factors have lethal or sublethal effects on Bd.
My work demonstrates that managing exposure to contaminants and biological reservoirs for Bd might provide new hope for imperiled amphibians. Further exploring how pesticides and pathogens are contributing to amphibian declines will allow us to formulate crucial management and conservation plans to begin remediation.
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Ruthsatz, Katharina Verfasser], and Kathrin H. [Akademischer Betreuer] [Dausmann. "Amphibians in a changing world : an ecophysiological perspective on amphibian metamorphosis / Katharina Ruthsatz ; Betreuer: Kathrin H. Dausmann." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://nbn-resolving.de/urn:nbn:de:gbv:18-95339.
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Zainab, Tayyaba. "A study of parapinopsin in amphibians." Thesis, King's College London (University of London), 2014. http://kclpure.kcl.ac.uk/portal/en/theses/a-study-of-parapinopsin-in-amphibians(d10ebd14-a9be-4efc-a8b5-ebca004fb11d).html.
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Parapinopsin (PNP) is a novel pigment protein present in pineal gland of the brain. PNP protein is similar in function to the human visual pigment protein rhodopsin, found in the eye. The aim of project is to sequence and characterize PNP in different frogs species to understand more about PNP as little is known about its structure and function. Tadpole cDNA from different frogs species (X.laevis, Rana temporaria and Rana tigrina) were used during the project. PCR primers were designed against Xenopus tropicalis PNP cDNA the only reported sequence at NCBI. PNP PCR products were cloned into pGEM vectors and sequenced. The cDNA sequencing results of X. laevis showed 100% homology but R. temporaria and R. tigrina showed ~99.9% similarity with X. tropicalis. The 0.1% dissimilarity is due to a point mutation from G to A at the 2nd position in the 156th codon. Genomic DNA sequence study results revealed a heterozygosity in R. temporaria and a point mutation in R. tigrina PNP. This point mutation is very important as it creates a stop codon possibly resulting in protein truncation. These findings were further confirmed by SSP-PCR (sequence specific primers- PCR) results. Western blotting was used to determine more about the size of the protein produced. Two peptides regions were selected at N and C termini. Western Blotting results support the cDNA study results with a 37 kDa protein band of PNP in the X. laevis protein sample only. Bioinformatics softwares were used to study evolutionary genetics and to predict the 2D structural elements and a 3D structural model for PNP from X. laevis. Further studies were conducted on X. laevis melanophores to look for PNP expression. Northern Blotting results indicated the absence of PNP in melanophores. For protein expression studies the entire coding sequence of PNP gene was chemically synthesized and subsequently cloned into the vector pASKGPCR for expression in E. coli. The aim of this study was to overexpress and purify the protein for functional studies as well as structural studies using X-ray crystallography and high field NMR.
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Maddock, S. T. "Systematics and phylogeography of Seychelles amphibians." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1476198/.
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This thesis investigates evolutionary patterns of variation in endemic amphibians from the Seychelles archipelago. Focal groups include the treefrog (Tachycnemis seychellensis), and a radiation of caecilians in three genera (Grandisonia, Hypogeophis and Praslinia), and attempts to place these into a phylogenetic context. The introduction (Chapter 1) discusses the importance of islands in the study of evolution and examines patterns of intraspecific variation that have been reported in other Seychelles organisms. Chapter 2 provides the first intraspecific molecular study of the monotypic Seychelles treefrog Tachycnemis, implementing a species tree approach in order to investigate its relationship with its closest living relatives (Heterixalus) from Madagascar and test whether its ancestor colonised the Seychelles via overseas dispersal. Chapters 3 and 4 explore variation in the six species of Seychelles caecilian, all of which overlap in range on at least one island. To assess within- and among-island intraspecific variation in these subterranean amphibians, Chapter 3 uses genetic data from both mitochondrial and nuclear markers, while Chapter 4 uses morphometric and meristic data. Differing patterns of geographic structure was observed among the caecilian species. The final two data chapters analyse species-level relationships among the Seychelles caecilians. Chapter 5 utilises Next Generation Sequencing to obtain mitogenomic data, and multiple approaches to infer phylogeny, and the effectiveness of alternative methods are evaluated. Chapter 6 attempts to resolve relationships of the island caecilians using 11 nuclear loci and multiple methods of phylogenetic inference. Chapter 7 discusses how the thesis has increased knowledge of the study taxa and of the evolution of amphibians on islands, particularly the Seychelles.
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Pulliam, Robert. "Evolutionary history of amphibians in biodiversity hotspots." Connect to resource, 2006. http://hdl.handle.net/1811/6021.
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Thesis (Honors)--Ohio State University, 2006.Title from first page of PDF file. Document formattted into pages: contains 32 p.; also includes graphics. Includes bibliographical references (p. 17-19). Available online via Ohio State University's Knowledge Bank.
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Fröbisch, Nadia. "Ontogeny and phylogeny of small dissorophoid amphibians." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22015.
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This study considers the ontogeny and phylogeny of branchiosaurids and amphibamids, small dissorophoid amphibians from the Upper Carboniferous and Lower Permian. Both clades play a central role in the discussion of the controversial relationships and origins of the three modern amphibian groups from among possible Paleozoic antecedents. An extraordinary fossil record comprising hundreds of specimens and many ontogenetic stages distinguishes branchiosaurids. This allowed for a detailed study of the ossification sequence of the limb skeleton in the branchiosaurid Apateon, which revealed that branchiosaurids share the unique preaxial dominance in limb development with modern salamanders. A detailed revision of the literature on ossification patterns in the limbs of extant and fossil tetrapods formed the basis for this investigation by showing that ossification sequence in the limbs of tetrapods indeed traces general patterns of early skeletogenesis. Furthermore, the excellent preservation of ontogenetic stages in branchiosaurids facilitated the identification of two distinct life history pathways in branchiosaurids, neoteny and metamorphosis. The vast majority of branchiosaurid taxa is neotenic, but members of the species Apateon gracilis were recognized that clearly metamorphosed into terrestrial adults. Events associated with metamorphosis took place in a very short period of time, which represents the first evidence of a condensed metamorphosis outside the modern amphibian groups. Contrary to branchiosaurids, amphibamids represent terrestrial animals with well-ossified limbs and braincase elements. A new genus and species of amphibamid from the Fort Sill fissure fills is described. An updated phylogenetic analysis of amphibamids including all known amphibamid taxa reveals two distinct clades within Amphibamidae, one comprising more plesiomorphic taxa and a second clade with derived members of the clade. Finally, a comprehensive analysis of dissorophoid relationshCette étude envisage l'ontogénie et la phylogénie des branchiosaurides et amphibamides, des petits amphibiens dissorophoïdes du Carbonifère supérieur et du Permien inférieur. Les deux clades jouent un rôle central dans le débat qui considère les liens et les origines des trois groups d'amphibien modern parmi les possibles antécédents du Paléozoïque. Les branchiosaurides possèdent un record exceptionnel de fossiles comportant des centaines de spécimens et plusieurs étapes ontogéniques. Ceci a permis une étude détaillée à propos de la séquence d'ossification des membres du branchiosauride, Apateon. Ce dernier montre que les branchiosaurides partagent avec les salamandres modernes la caractéristique unique d'une dominance préaxiale dans le développement des membres. Une révision détaillée de la littérature concernant les différentes formes d'ossification des membres chez les tétrapodes, modernes et fossilisés, forme la base pour cette investigation. Ceci est réalisé en montrant que la séquence d'ossification parmi les tétrapodes marque le patron général de la squelettogenèse dans les premières étapes du développement. En outre, la préservation spectaculaire des étapes ontogénétiques parmi les branchiosaurides simplifie l'identification de deux cycles biologique, la néoténie et la métamorphose. La plupart des branchiosaurides sont néoténique, pourtant quelques membres de l'espèce, Apateon gracilis, ont été reconnus comme étant complètement métarmorphosés en adultes terrestres. Cette métamorphose a eu lieu durant une courte période de temps, et elle représente la première évidence d'une métamorphose condensée, hors des groups d'amphibien modern. Contrairement aux branchiosaurides, les amphibamides comportent des tétrapodes terrestres qui possèdent une bonne ossification des membres et de la boîte crânienne. Un nouveau genre et nouvelle espèce d'un amphibamide de la fissure de Fort Sill sont ici dé
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Wood, Laura R. "Diversity and distribution of amphibians in Luxembourg." Thesis, University of Kent, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.544084.
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Rollins, Hilary Byrne. "Ecological Effects of Climate Change on Amphibians." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1559915081386624.
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Bielby, Jon. "Extinction risk and population declines in amphibians." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/4278.
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This thesis is about understanding the processes that explain the patterns of extinction risk and declines that we see in amphibians, how we can use that understanding to set conservation priorities, and how we can convert those priorities into practical, hands-on research and management. In particular, I focus on the threat posed by the emerging infectious disease, chytridiomycosis, which is caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Amphibians display a non-random pattern of extinction risk, both taxonomically and geographically. In chapter two I investigate the mechanism behind the observed taxonomic selectivity and find that it is due to species biology rather than heterogeneity in either threat intensity or conservation knowledge. In chapter three I determine which biological and environmental traits are important in rendering a species susceptible to declines, focussing on susceptibility to Bd. I found that restricted range, high elevation species with an aquatic life-stage are more likely to have suffered a decline. Using these traits, I predict species and locations that may be susceptible in the future, and which should therefore be a high priority for amphibian research and conservation.
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Carey, Marc Brandon. "Brainstem auditory evoked potentials in anuran amphibians." PDXScholar, 1992. https://pdxscholar.library.pdx.edu/open_access_etds/4267.
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In this study, I looked at the effects of sound level, temperature and dehydration/hypernatremia on the brainstem auditory evoked potential (BAEP) of four species of anuran amphibians (Rana pipiens, Rana catesbeiana, Bufo americanus and Bufo terrestris). The BAEP was used because it allowed me to monitor both the peripheral and central aspects of auditory nervous function simultaneously and over a long period of time.
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Enright, Lisa. "Effects of selection logging on amphibian diversity and abundance in shade-tolerant hardwood forests of Algonquin Provincial Park, Ontario." Connect to this title online, 1998. http://www.nlc-bnc.ca/obj/s4/f2/dsk2/ftp03/MQ35886.pdf.
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Gahl, Megan K. "Spatial and Temporal Patterns of Amphibian Disease in Acadia National Park Wetlands." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/GahlMK2007.pdf.
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Gross, Lee M. "Long-term assessment of predatory fish removal on a pond-breeding amphibian community in central Illinois /." View online, 2009. http://repository.eiu.edu/theses/docs/32211131565136.pdf.
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Orton, Frances. "Investigation into the effects of pesticides on amphibians." Thesis, Brunel University, 2008. http://bura.brunel.ac.uk/handle/2438/2456.
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Amphibian population decline is a recognised phenomenon spanning at least the last 40 years, and it is likely that a number of factors have contributed, including environmental contamination. Amphibians are vulnerable to agrochemical uptake as they must breed in water, and often spend the aquatic phase of their lifecycle in agricultural water bodies, which may contain a complex mixture of biologically active chemicals. Endocrine disrupting compounds may cause reproductive effects in humans and wildlife, although the link between pesticides and endocrine disruption is largely unknown. Therefore, in this study, the role of pesticides in endocrine disruption, in relation to amphibian metamorphosis and reproductive development, was investigated. To achieve this objective, population data were used to select suitable field sites, water from which was tested for endocrine activity using the yeast estrogen/androgen screen, hepatocyte culture (estrogenic response), and a transgenic Xenopus test (thyroid disruption). Toad (Bufo bufo) specimens from a subsample of these sites were used to compare morphology, thyroidal, and gonadal development of caged and wild-caught tadpoles/metamorphs, to their laboratory-raised counterparts. In addition, environmentally relevant pesticides were tested for endocrine effects in vitro, and a short-term in vivo exposure was used to assess the predictive ability of the in vitro screens in Xenopus. Mortality of Bufo bufo was high in both laboratory-reared and caged individuals, which hindered the interpretation of results due to low n values. However, laboratory-reared individuals from different sites had distinct morphology and gonadal differentiation, possibly suggesting maternal transfer, a latent effect of the pond environment, and/or genetic effects. In addition, caged and wild-caught individuals were smaller, metamorphosed later, and had retarded gonadal differentiation or increased incidence of intersex, compared to their laboratory-reared counterparts. Extracts of water samples from these sites were predominantly anti-estrogenic, and/or anti-androgenic in yeast based assays, and this was also the effect observed in response to environmentally relevant pesticides tested in the same assays. Pesticides also affected ovarian steroidogenesis in vitro, and pentachlorophenol had a reprotoxic effect on adult female Xenopus laevis. Data reported in this study suggest there may be endocrine disrupting effects in native amphibians in the agricultural landscape, although further investigation is needed to confirm these findings.
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Wombwell, Emma Louise. "Emerging infectious disease and the trade in amphibians." Thesis, University of Kent, 2014. https://kar.kent.ac.uk/48014/.
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Amphibians are the most threatened class of vertebrate, and rates of species decline and extinction far exceed those seen historically. Habitat loss, climate change, over-exploitation and emerging infectious disease have all been identified as threatening processes. The trade in amphibians has been implicated in over-exploitation through the harvesting of wild animals, and as an important pathway for the global spread of the fungal pathogen, Batrachochytrium dendrobatidis (Bd). However, there are no analyses of how Bd may spread through the trade chain. This thesis addresses this issue by (1) determining the prevalence of Bd at different stages of the trade chain; (2) examining knowledge, husbandry protocols and biosecurity among retailers and (3) assessing the risk of Bd dissemination into the wild in the UK. Approximately 20,000 amphibians from at least 11 countries enter the UK annually via Heathrow Animal Reception Centre. Overall Bd prevalence was 3.6%, but was confined to six of the 43 genera encountered, and only detected in shipments from the USA and Tanzania. Amphibians were sold by 30% of the estimated 3500 livestock retailers in the UK, but made a low contribution to overall income. Disease awareness and knowledge in retailers was found to be lacking, although husbandry standards were deemed to be appropriate. Mortality appeared to be influenced by restocking methods and number of species held, but mass die-offs as a result of disease were generally uncommon. Screening of over 2000 amphibians from 148 retailers for Bd revealed a prevalence of 5.8%, but the geographic distribution of infection in the UK was patchy, and was more prominent in aquatic species. A risk assessment conducted according to the framework set out by the World Organisation of Animal Health, identified regions and sections of the trade that pose the greatest threats in terms of introducing Bd, and assessed various mitigation measures. The consequences of novel strains of Bd and a second, recently discovered Batrachochytrium species were found to pose a risk to both native UK and captive amphibians. As trade bans are unlikely to be feasible or effective, alternative measures to mitigate the impact of disease are evaluated.
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Michaels, Christopher. "Evidence based ex situ husbandry for captive amphibians." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/evidence-based-ex-situ-husbandry-for-captive-amphibians(54a41c4e-a6cb-471c-8c16-ef012f61cd35).html.
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Amphibians are declining worldwide in response to pressures that are too numerous, difficult and rapid to ameliorate in the wild before some taxa become extinct. Ex situ conservation, whereby animals are maintained in captivity until threats in the wild have been resolved, is the only means of saving up to five hundred amphibian species. Amongst political, financial and practical hurdles, the most fundamental problem for these programmes is lack of knowledge about how to maintain species successfully in captivity. Captive populations have failed to survive or reproduce and, furthermore, captive husbandry may produce animals unsuitable for reintroduction through intra or inter-generational changes. These problems entirely undermine initiatives and if ex situ programs are to succeed, evidence based captive husbandry is needed to support captive breeding programs. In this thesis, I quantify our ignorance of amphibian requirements in captivity. Furthermore, I present investigations into fundamental areas ofamphibian husbandry, about which we currently know very little. I investigate the relationship between amphibians and Ultraviolet B (UVB) radiation and examine the relationship between UVB provision and calcium provision and evaluate routes of dietary calcium supplementation. I also present data on the effects of enrichment and rearing environment on the growth, fitness, behaviour and dermal bacterial communities of captive amphibians. These results, from a range of areas of amphibian husbandry, together demonstrate the power of the captive environment to influence the phenotype and therefore the fitness of amphibians, even within single generations. Additionally, I provide some of the first data addressing key areas of amphibian husbandry that until now have been led mostly or entirely by anecdote and hearsay.
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Ward, Rocky. "Multivariate Analyses of Amphibian and Reptilian Distribution in Texas." Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc331167/.
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Presence-absence data for amphibians, chelonians, saurians, ophidians, and the terrestrial and aquatic ecological guilds of reptilians were analyzed using multivariate analyses. Geographically consistant distributional patterns were found for all faunal groupings. The correspondence between analyses of the different taxa and guilds was not perfect, but similarities were found. All analyses agreed on the presence of a distinctive region in east Texas. Most analyses also agreed on the presence of distinctive regions in south Texas, the Trans-Pecos, the Edwards Plateau, and north-west Texas. There is strong correspondence between interpretations of the analyses based on the amphibian, saurian, ophidian, and terrestrial reptilian distributions, and the biotic provinces produced by earlier, subjective analyses. The Edwards Plateau and a region on the western periphery of east Texas were found to be transitional between other, more faunally distinctive areas for most fauna! groups. Detailed examination of these regions suggested they are best described as clinal in nature. The environmental variables which were most effective in explaining patterns in the distribution of the various taxa and guilds were related to precipitation. However, variations in temperature and physiography were also important predictors of distribution for several of the groups. The distributions of soil and vegetation associations were also found to be related to amphibian and reptilian distribution.
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James, Stacy M. "Amphibian metamorphosis and juvenile terrestrial performance following chronic cadmium exposure in the aquatic environment." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4140-D1763/.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 24, 2006) Vita. Includes bibliographical references.
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Cowman, Deborah Fay. "Pesticides and amphibian declines in the Sierra Nevada Mountains, California." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4770.
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Pacific chorus frog (Pseudacris regilla) hatchlings were translocated and placed in cages in sites (~2,200 m elevation) located in Lassen, Yosemite, and Sequoia National Parks. DDE was found in 97% of Yosemite National Park samples, 84% in Sequoia National Park samples, and 15% of Lassen Volcanic National Park samples in 2001 and 2002. Total endosulfans were detected in 3% of Sequoia samples, 9% of Lassen samples and 24% of Yosemite samples. Both pesticides were detected in tadpoles and metamorphs raised at the three parks regardless of origin. Because the tadpoles were translocated post hatching, this finding indicates that the pesticides, particularly DDE, were accumulated at the site, instead of through deposition in the egg mass. Liver cells from 108 newly metamorphosed frogs were examined with flow cytometry (FCM) techniques for evaluation of chromosome breakage as measured by the half-peak coefficient of variation (HPCV) of the G1 peak. Regardless of origin, experimental groups raised at Lassen, the reference site, had significantly less chromosomal breakage (p=0.04) than metamorphs raised at the other two parks. This is the first documented evidence of DNA damage in juvenile frogs in the Sierra Nevada Mountains. Cholinesterase (ChE) was measured in tadpoles collected at 28 days and in juvenile frogs collected upon metamorphosis. In 2001, ChE activity was significantly higher in animals raised at Lassen (reference site), than at the other two parks, indicating less exposure to cholinesterase-inhibiting pesticides. This trend was not observed in 2002, although Sequoia ChE values were consistently lower than the other two parks. Temperatures were significantly different among the three parks for both years (p<0.0001) and lower temperatures may correlate with lower ChE levels. Survivorship to metamorphosis, days to metamorphosis, snout-vent lengths (SVL), and malformations were evaluated. Animals raised in Sequoia had shorter SVLs, took longer to metamorphose, and had lower survivorship to metamorphosis than in the other two parks (p<0.0001). Effects noted in P. regilla may be magnified in long lived ranid species. These findings may be important in evaluating the overall impact of aerially transported pesticides on declining frog populations in the Sierra Nevada Mountains.
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Badawy, Gamal Metwally. "Development of the gastro-intestinal regulation in the axolotl (Ambystoma mexicanum)." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273975.
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Dinehart, Simon K. "The effects of Disturbance on Aquatic Breeding Amphibians within the Cuyahoga Valley National Park." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1133815626.
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Northrop, Robert John. "Development and assessment of a wildlife habitat relationship model for terrestrial vertebrates in the state of Maryland." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 152 p, 2009. http://proquest.umi.com/pqdweb?did=1885544331&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Tufts, Bruce Laurie. "Ion exchange mechanisms for the control of volume and pH in fish and amphibian erythrocytes." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/29443.
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The characteristics of the ion exchange mechanisms which regulate volume and pH in fish and amphibian erythrocytes were investigated and compared. Experiments were carried out under steady state conditions and also following adrenergic stimulation both in vivo and in vitro.
Under steady state conditions, a decrease in extracellular pH caused an increase in the volume of rainbow trout erythrocytes, and a decrease in the intracellular pH. These pH-induced volume changes were mainly associated with movements of chloride across the chloride/bicarbonate exchange pathway. The sodium/proton exchange mechanism is quiescent at all pH's studied under steady state conditions.
Beta adrenergic stimulation of rainbow trout erythrocytes promoted cell swelling and proton extrusion from the erythrocytes. Amiloride inhibited both the volume and pH changes associated with adrenergic stimulation indicating that this response is associated with an increase in the activity of the sodium/proton exchange mechanism on the erythrocyte membrane. The adrenergic swelling and pH responses are enhanced by a decrease in extracellular pH. An increase in bicarbonate concentration reduces the adrenergic pH response, but it is still significant even at 10 mM bicarbonate. DIDS markedly enhanced the beta adrenergic effect on the erythrocyte pH, but abolished the increase in erythrocyte volume. The adrenergic response was independent of temperature between 10 and 18°C. These results support a loosely coupled sodium/proton and chloride/bicarbonate exchange model for the adrenergic response in rainbow trout erythrocytes.
The increases in erythrocyte pH and volume following adrenergic stimulation are associated with increases in the haemoglobin:oxygen affinity. The oxygen carrying capacity of the blood is, therefore, increased following adrenergic stimulation in rainbow trout. Carbon dioxide excretion, however, was not significantly affected by adrenergic stimulation. The functional significance of the adrenergic response of fish erythrocytes may be to offset the effects of the Root shift on the oxygen carrying capacity of the blood during acute changes in extracellular pH.
In contrast to fish erythrocytes, the sodium/proton exchange mechanism in amphibian erythrocytes is active under steady state conditions. In the presence of bicarbonate movements, this exchange significantly affects the erythrocyte volume, but not the erythrocyte pH. Similar to fish erythrocytes, protons are passively distributed in amphibian erythrocytes under steady state conditions and in Donnan equilibrium with chloride ions. The erythrocyte volume also increases with decreases in extracellular pH as in fish erythrocytes, due to changes in the chloride distribution across the erythrocyte membrane.
Adrenergic stimulation does not affect the volume or pH of amphibian erythrocytes either in vivo or in vitro. These animals, therefore, do not appear to regulate erythrocyte pH adrenergically. Amphibians are able to efficiently utilize oxygen stores via both central and peripheral shunting. In addition, the blood of these animals does not have a Root shift. Adrenergic regulation of erythrocyte pH in order to enhance oxygen transport during fluctuations in ambient and internal gas tensions, therefore, is probably less important than it would be in fish.Science, Faculty of
Zoology, Department of
Graduate
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Faruk, Aisyah. "The impact of oil palm conversion on tropical amphibians." Thesis, Queen Mary, University of London, 2013. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8458.
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Agriculturally-altered habitats, especially oil palm plantations, are rapidly dominating the Southeast Asian landscape. Although recent studies have shown reduced species diversity associated with this commodity, data on amphibian diversity are rare. The following thesis explores the impact of oil palm plantations on amphibians in Peninsular Malaysia based on (1) amphibian biodiversity, (2) quality and use of breeding sites, (3) habitat use and (4) parasitism. Contrary to expectation, not all metrics of biodiversity differed between oil palm plantations and secondary forest sites. Amphibian community composition, however, differed greatly between the two habitat types, with oil palm communities being dominated by species known to prosper in disturbed habitats, indicating that the community is currently of limited conservation value. Within plantations, temporary pools were found to serve as important breeding habitats for amphibians so a focused study on the characteristics of these pools was carried out. Although we found differences between pools, the proportion of occupied pools did not differ significantly between plantation and forest sites. I did observe evidence of breeding site preferences of least concern, plantation amphibians, along with habitat partitioning between species, a similar pattern also seen in forest communities. I compared parasite burdens between habitats by screening for the fungus Batrachochytridium dendrobatidis (Bd) and for nematode parasite load. Bd was not detected in any of my samples and there was no difference in nematode loads between habitat types. However, patterns of nematode prevalence was affected by host type, while nematode intensity was dependent on an interaction between host and body size. The final chapter indicates that in terms of parasite, the host environment is the most important. Additionally, differences in host-parasite patterns between habitats indicate a possible underlying problem that rapid biodiversity censuses would be unable to detect.
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McConville, J. R. "Brain Mechanisms Associated with Motivation in Amphibians and Fish." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501325.
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Marques, Sérgio Miguel Reis Luís. "Gene expression in understanding mechanisms of toxicity in amphibians." Doctoral thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/8257.
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Doutoramento em BiologiaDe uma forma geral os anfíbios são conhecidos como organismos que apresentam uma grande sensibilidade a vários tipos de contaminantes. Contudo existem casos, como o de Pelophylax perezi (rã-verde), em que estes organismos habitam áreas extremamente contaminadas. Este facto verifica-se na mina de urânio desactivada, da Cunha Baixa (Viseu, centro de Portugal), em que uma população destas rãs habita na lagoa de efluente ácido mineiro (M). Estudos ecotoxicológicos anteriores com estes organismos revelaram apenas efeitos de toxicidade ténues levantando algumas questões. Com o objectivo de elucidar quais os mecanismos que permitem a P. perezi permanecer neste local, sem sofrer aparentemente efeitos perniciosos, encetamos este trabalho. Numa primeira abordagem, avaliámos o sistema de defesa antioxidante de rãs adultas, bem como o conteúdo em metais de alguns órgãos. Desta forma verificámos alterações enzimáticas, principalmente no pulmão e acumulação de metais nos vários órgãos. Posteriormente foi realizado um estudo de expressão genética diferencial, também em organismos adultos e desta feita foram sugeridos alguns mecanismos de protecção basal que estarão por detrás da capacidade de suportar este ambiente extremamente contaminado. Numa etapa seguinte abordámos os efeitos em fases larvares, fazendo inicialmente uma exposição in situ, a vários efluentes, caracteristicamente diferentes, do complexo mineiro. Avaliámos o crescimento, a acumulação de metais e a actividade de alguns biomarcadores de stress oxidativo. Como resultado pudemos constatar que nas fases larvares para além de alguma mortalidade existe acumulação de metais bem como algumas alterações a nível de biomarcadores de stress oxidativo. Numa última abordagem realizamos uma exposição crónica dos girinos a efluente da mina com diversos níveis de pH para distinguir os efeitos da toxicidade do pH, dos efeitos da toxicidade pelo conteúdo de metais. Para tal avaliámos novamente biomarcadores de stress oxidativo, crescimento, acumulação de metais e efectuamos ainda um estudo de expressão genética diferencial. Esta última aproximação permitiu verificar que a toxicidade do efluente resulta primariamente do pH ácido, assumindo a contaminação por metais um papel secundário. Contudo o crescimento dos girinos de P. perezi apresenta-se estimulado por pHs mais baixos. São apontados ainda alguns mecanismos, em girinos, para lidar com o stress causado pela contaminação por metais.De uma forma geral pôde-se constatar que quer anfíbios adultos quer girinos expostos ao efluente apresentam valores altos de metais acumulados. Os biomarcadores de stress oxidativo na sua maioria não apresentaram respostas coerentes mediante as várias exposições. Este trabalho apresentase como um contributo importante para a ecotoxicologia de anfíbios, aumentando os níveis actuais de conhecimento sobre o efeito de contaminação proveniente de efluentes mineiros, sugerindo ainda mecanismos de resistência quer em larvas, quer para adultos.
Amphibians are generally known as organisms that present a great sensitivity to several kinds of contaminants. However, there are some cases as the one of Pelophylax perezi (green frog), where these organisms inhabit extremely contaminated areas. This fact has been recorded, in the deactivated uranium mine of Cunha Baixa (Viseu, Centre of Portugal) where a frogs’ population inhabits the acid mine effluent (M). Previous ecotoxicological studies carried out with these organisms have revealed only mild toxic effects. This has raised some questions on these organisms ability to endure extreme conditions, gaining certainly some advantage in these places in terms of refuge. Aiming to uncover the mechanisms that allow the presence of P. perezi in this area without apparent deleterious effects, this work was carried out. A first approach was to assess the antioxidant defence system in frogs as well as metal content in various organs. Thus enzymatic changes, mainly in lung, and metal accumulation were reported. Afterwards a differential gene expression study was also performed in adult organisms and basal protection mechanisms were suggested as supporting the ability of enduring extremely contaminated environment. These mechanisms encompass the possible increase of the albumin and fibrinogen antioxidants. In the next stage effects on larvae were addressed with an in situ exposure to several mine complex effluents with different characteristics. Growth, metal accumulation and oxidative stress biomarkers were assessed. As a result we can point that in the larval stages, beyond mortality, metal accumulation exists, as well as some oxidative stress enzyme responses. In a final approach, to distinguish metal toxicity effects from pH toxicity effects, tadpoles were exposed chronically to the mine effluent at various pH values. With this purpose, oxidative stress biomarkers, growth, metal accumulation and differential gene expression were performed. This approach allowed verifying that the effluent toxicity results primarily from acidic pH, with metal contamination assuming a secondary role. However P. perezi tadpoles’ growth seems to be stimulated by lower pH values. Some mechanisms in tadpoles are pointed as a way to cope with metal contamination stress. These mechanisms include an increase in osmotic regulation and energy acquisition investment. Overall, it could be noted that both adult amphibians and tadpoles exposed to the effluent have higher metal accumulation. Also the majority of the oxidative stress biomarkers did not present consistent responses throughout the various exposure conditions. This work presents as a new contribution for amphibian ecotoxicology, increasing current knowledge on mine effluent contamination effects and suggesting resistance mechanisms both in larvae and adults.
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Marques, Mariana Pimentel. "Geographical distribution of the amphibians and reptiles of Angola." Master's thesis, Universidade de Évora, 2015. http://hdl.handle.net/10174/13275.
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Angola is among the largest countries in Africa and due to its great geographical and climatic variety, presents a great diversity of biomes and habitats. However, is one of few biodiverse countries in Africa that remains highly incomplete in knowledge of vertebrate diversity. Data regarding the occurrence and geographical distribution of amphibians and reptiles in Angola are currently scattered across museum specimens housed in Natural History institutions and in a diversity of books and papers published since the second half of the nineteenth century, and there is no available distribution database or atlas. Considering the threats faced by amphibians and reptiles worldwide and consequently the need for an update overview of their diversity and distribution in Angola, we compiled a database with the available published bibliographical data on amphibian and reptile occurrences in Angola, updated the taxonomy and nomenclature for every citation and mapped the species occurrences in the country; Distribuição Geográfica dos Anfíbios e Répteis em Angola
RESUMO:
Angola está entre os maiores países de África e, devido à sua ampla variedade geográfica e climática, apresenta uma grande diversidade de biomas e habitats. É considerado um dos países mais ricos em biodiversidade, contudo o seu conhecimento encontra-se extremamente incompleto. Os dados relativos à distribuição de espécies de anfíbios e répteis em Angola encontram-se dispersos por todo o Mundo, em instituições como Museus de História Natural, bem como em livros e artigos publicados desde a segunda metade do século XIX, não se encontrando esta informação atualmente disponível em qualquer base de dados ou atlas. Considerando as ameaças globais enfrentadas por este grupo animal e a consequente necessidade de atualização do seu conhecimento para Angola, procedemos à compilação de uma base de dados atualizada sobre as suas ocorrências, atualizando o status taxonómico e nomenclatural para cada espécie e consequente criação de mapas de distribuição.
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Kluthe, Gregory Joseph. "Relative Heart Ventricle Mass and Cardiac Performance in Amphibians." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/920.
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This study used an in situ heart preparation to analyze the power and work of spontaneously beating hearts of four anurans (R. marina, L. catesbeianus, X. laevis, P. edulis) and three urodeles (N. maculosus, A. tigrinum, A. tridactylum) in order to elucidate the meaning of relative ventricle mass (RVM) in terms of specific cardiac performance variables. This study also tests two hypotheses: 1) the ventricles of terrestrial species (R. marina, P. edulis, A. tigrinum) of amphibians are capable of greater maximum power outputs (Pmax) compared to aquatic species (X. laevis, A. tridactylum, N. maculosus, L. catesbeianus) and, 2) the ventricles of Anuran species (R. marina, P. edulis, L. catesbeianus, X. laevis) are capable of greater maximum power output compared to aquatic species (A. tigrinum, A. tridactylum, N. maculosus). The data supported both hypotheses. RVM was significantly correlated with Pmax, stroke volume, cardiac output, afterload at Pmax, and preload at Pmax. Preload at Pmax and afterload at Pmax also correlated very closely with each other, suggesting that an increase blood volume and/or increased modulation of sympathetic tone may influence interspecific variation RVM and may have played a role in supporting higher rates of metabolism, as well as dealing with hypovolemic stresses of life on land.
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Vasconcelos, Daniel. "Amphibian and Vegetation Dynamics in a Restored Wetland in Maine." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/VasconcelosD2003.pdf.
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Callison, Catherine Mary. "Factors Influencing Oviposition Among Pond-Breeding Amphibians: Exotic Vegetation, Oviposition Braces, and Cover." PDXScholar, 2001. https://pdxscholar.library.pdx.edu/open_access_etds/4333.
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I examined oviposition in four pond-breeding amphibians (northwestern salamander [Ambystoma gracile], long-toed salamander [Ambystoma macrodactylum], Pacific treefrog [Hyla regilla], northern red-legged frog [Rana aurora aurora]), at Burlington Bottoms, a lowland riverine site in northwestern Oregon, to determine whether differential use of native versus exotic plant substrates occurs. I found differential use in all four species, but use was inconsistent with the hypothesis that selection for native plants (or selection against exotic plants) was occurring. If selection was occurring, the pattern implied that reed canarygrass (Phalaris arundinacea), a widespread exotic in this lowland system, was sometimes favored. However, inconsistent use of reed canarygrass led me to examine the alternative that substrate strength (measured as density, diameter, and mass), rather than plant status, might be the basis of selection. Species used for oviposition differed in strength, but eggs were not consistently laid on braces based on my strength measures. Failure to find support for this hypothesis led to examination of a third hypothesis for two species (red-legged frog and northwestern salamander), that cover characteristics of the oviposition brace or nearby vegetation might influence egg mass location. Analysis of structural complexity of species used as a brace (as percent cover within 15 em of the egg mass) did reveal a pattern consistent with complexity, but that was species-specific. Red-legged frogs selected braces with significantly more nearspace cover; northwestern salamanders selected braces with sparser cover. Comparison of marginal shrub and tree cover to the number of red-legged frog egg masses revealed that ponds with < 50% shrub/tree cover had few (< 5) masses. Ponds with ≥ 50% shrub/tree cover had many (≥ 10) masses. More complex vegetation may provide greater protection for egg masses or ovipositing red-legged frogs but further investigation is clearly warranted. Elucidating northwestern salamander cover requirements will require examining more occupied ponds. In particular, more refined examination, using experimental manipulation, is needed to verify the cover relationships revealed in this study. Meanwhile, managers should treat cover as important in red-legged frog oviposition life history, paying special attention to minimizing loss of marginal shrub and tree cover.
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Cunningham, Jesse. "Pond-Breeding Amphibian Species Distributions in a Beaver-Modified Landscape, Acadia National Park, Mount Desert Island, Maine." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/CunninghamJ2003.pdf.
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Blomquist, Sean Michael. "Relative Fitness and Behavioral Compensation of Amphibians in a Managed Forest." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/BlomquistSM2008.pdf.
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Favero, Eduardo Rondelli. "Caracterização citogenetica de especies e populações de Pseudopaludicola (Leiuperidae, Anura)." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317990.
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Orientadores: Shirlei Maria Recco-Pimentel, Ana Cristina Prado Veiga-MenoncelloDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: O gênero Pseudopaludicola, pertencente à família Leiuperidae, compreende atualmente 12 espécies de rãs de pequeno tamanho, distribuídas pela América do Sul, sendo a ocorrência de oito delas foi relatada para o Brasil. Devido à grande semelhança morfológica entre espécies, algumas ocorrendo em simpatria, confusões taxonômicas são freqüentes. Alguns estudos morfológicos acerca deste gênero foram realizados, mas as relações de parentesco inter- e intragenéricas de Pseudopaludicola permanecem pouco esclarecidas. As poucas informações citogenéticas para o gênero Pseudopaludicola restringiam-se apenas à determinação do número de cromossomos e análise do cariótipo por métodos de coloração convencional. Para Pseudopaludicola falcipes, em especial, foi descrita uma variação intra-específica do número de cromossomos, de 2n=16 à 2n=20. O presente estudo visa contribuir com dados citogenéticos para a caracterização de espécies de Pseudopaludicola e para o entendimento dos processos envolvidos na evolução cariotípica do gênero. Foram analisados os cariótipos de exemplares de Pseudopaludicola falcipes, P. ameghini (sensu Cope, 1887) e P. mystacalis de suas respectivas localidades-tipo (região de Porto Alegre, RS e Chapada dos Guimarães, MT), de P. mystacalis e de P. ternetzi, de Uberlândia (MG), de Pseudopaludicola aff. falcipes I, II, III e IV, da região noroeste do estado de São Paulo (municípios de Santa Fé do Sul, Vitória Brasil, Palestina e Icém), de Pseudopaludicola aff. mystacalis I, II, III e IV, dos municípios de Icém (SP), Barreirinhas (MA) e Urbano Santos (MA) e Pseudopaludicola sp. 1, 2 e 3, sendo as duas primeiras provenientes de Poconé (MT) e a terceira de Santa Terezinha (MT). As metáfases foram obtidas de suspensões de células de epitélio intestinal e testículo, e coradas com Giemsa ou submetidas às técnicas impregnação por prata (Ag-NOR) para detecção de NOR e de bandamento C, para a localização de heterocromatina. Os dados obtidos revelaram uma variação interespecífica quanto ao número de cromossomos. Dentre os espécimes provenientes de Poconé, MT, havia dois cariótipos distintos, com 2n=22 e com 2n=16 cromossomos (Pseudopaludicola sp. 1 e 2) e os de Icém, SP, com indivíduos 2n=20 e 2n=16 cromossomos (Pseudopaludicola aff. mystacalis, respectivamente I e II). Pseudopaludicola falcipes e Pseudopaludicola sp.1, de Poconé, apresentaram 2n=22 e a NOR localizada na região pericentromérica do braço longo do par 8. Estas espécies diferiram, na morfologia da NOR, sendo heteromórfica em P. falcipes e homomórfica em Pseudopaludicola sp. 1, e na localização de algumas bandas heterocromáticas. Pseudopaludicola ameghini (sensu Cope, 1887), P. ternetzi e Pseudopaludicola aff. mystacalis I de Icém apresentaram 2n=20 cromossomos e a NOR localizada na região telomérica do braço longo do par 9. O cariótipo de P. ternetzi diferiu do de P. ameghini tanto pela classificação morfológica distinta do par 7 quanto pelo padrão de distribuição de heterocromatina. Pseudopaludicola mystacalis, bem como todos os espécimes de Pseudopaludicola aff. falcipes I, II, III e IV, Pseudopaludicola aff. mystacalis II, III e IV e Pseudopaludicola sp. 2 e 3 apresentaram 2n=16 cromossomos metacêntricos e submetacêntricos, com a NOR localizada na região pericentromérica do braço curto do par 4. Vários espécimes apresentaram um heteromorfismo de tamanho em relação aos homólogos do par 4 (morfo 4 e morfo 4'), alterando a classificação desse cromossomo para metacêntrico em algumas populações. Em P. mystacalis, P. aff. falcipes I, II, III e IV, P. aff. mystacalis II, III e IV e Pseudopaludicola sp 2 e 3 foram detectados blocos de heterocromatina fortemente marcados nas regiões pericentroméricas no braço curto do par 1 e longo do par 2. Os resultados obtidos mostram que P. ameghini (sensu Cope, 1887) com 2n=20 e P. mystacalis com 2n=16, são unidades taxonômicas distintas e que os espécimes tidos como Pseudopaludicola aff. falcipes) e como Pseudopaludicola sp. mostraram-se citogeneticamente relacionados à P. mystacalis e não à P. falcipes que possui 2n=22 cromossomos. Desta forma, os nossos dados sugerem a retirada de P. ameghini da sinonímia de P. mystacalis e reforçam a necessidade de uma revisão taxonômica no gênero.
Abstract: The genus Pseudopaludicola (family Leiuperidae) comprises 12 species of small sized frogs, which are widely distributed in South America. In Brazil, eight species are described within this genus, and several of them are sympatric. The relevant morphological similarities among the Pseudopaludicola species have contributed to the still poor understanding of many aspects of their taxonomy, including inter- and intrageneric relationships. Cytogenetic data on Pseudopaludicola have been restricted to karyotype analyses using conventional Giemsa staining. Variation in intraspecific chromosomal number was described in P. falcipes, ranging from 2n=16 to 2n=20. In the present work, Brazilian Pseudopaludicola species were submitted to cytogenetic analysis aiming at their further characterization and attempting to better understanding the karyotypical evolution of this genus. The analyzed species were Pseudopaludicola falcipes (Porto Alegre, RS), P. ameghini (sensu Cope, 1887) and P. mystacalis (Chapada dos Guimarães, MT), P. mystacalis and P. ternetzi (Uberlândia, MG), P. aff. falcipes I, II, III and IV (respectively from Santa Fé do Sul, Vitória Brasil, Palestina and Icém, SP), P. aff. mystacalis I, II, III and IV (Icém, SP, Barreirinhas, MA, and Urbano Santos, MA), and Pseudopaludicola sp. 1 and sp. 2 (Poconé, MT) and sp. 3 (Santa Terezinha, MT). Metaphases were obtained from suspensions of intestinal epithelium and testicular cells, and stained with Giemsa or submitted to silver staining technique in order to detect the nucleolus organizing regions (Ag-NOR), and C-banding, for heterochromatin localization. The results revealed interspecific chromosomal number variation. In the Pseudopaludicola sp. 1 and 2 specimens (Poconé MT), two distinct karyotypes were identified, respectively with 2n=22 and 2n=16 chromosomes. Within the Pseudopaludicola aff. mystacalis from Icém, SP, the analyzed specimens had 2n=20 and 2n=16 chromosomes, being nominated I and II, respectively. These data clearly indicated two criptic species of Pseudopaludicola within each of those two localities. The P. falcipes and Pseudopaludicola sp.1 (Poconé, MT) had 2n=22 and the NOR was located at the pericentromeric region in the long arm of the pair 8. The species differed in the NOR morphology, which was heteromorphic in P. falcipes and homomorphic in Pseudopaludicola sp.1, as well as in the localization of some C-bands. Pseudopaludicola ameghini (sensu Cope, 1887), P. ternetzi and Pseudopaludicola aff. mystacalis I (Icém, SP) had 2n=20 chromosomes and the NOR was located on the telomeric region in the long arm of the pair 9. The karyotypes of P. ternetzi and P. ameghini differed in the pair 7 morphology and in the heterochromatin distribution pattern. All analyzed specimens of P. mystacalis, P. aff. falcipes I, II, III and IV, P. aff. mystacalis II, III and IV, and Pseudopaludicola sp. 2 and 3, showed 2n=16 chromosomes, which were all metacentric and submetacentric, with the NOR located in the pericentromeric region of the short arm of the pair 4. In several of those specimens, the size heteromorphism of the pair 4 altered, from submetacentric to metacentric, the classification of one of the homologous of that pair. Strong pericentromeric C-bands were detected on the short arm of the pair 1 and on the long arm of the pair 2 in P. mystacalis, P. aff. falcipes I, II, III and IV, P. aff. mystacalis II, III and IV, and Pseudopaludicola sp. 2 and 3. As based on the cytogenetic data, P. ameghini (sensu Cope, 1887), with 2n = 20, and P. mystacalis, with 2n = 16, are distinct taxonomic units, and the specimens formerly identified as P. aff. falcipes and as Pseudopaludicola sp. were indeed cytogenetically closely related to P. mystacalis and not to P. falcipes, which has 2n = 22 chromosomes. Hence, our data suggest that P. ameghini is not a P. mystacalis synonymy and emphasize the importance of a taxonomic review of the genus Pseudopaludicola.
Mestrado
Biologia Celular
Mestre em Biologia Celular e Estrutural
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Mazerolle, Marc J. "Amphibians in fragmented peat bogs, abundance, activity, movements and size." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ49408.pdf.
Full text
49
Griffis-Kyle, Kerry L. "The effects of mineral nitrogen on embryonic and larval amphibians." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.
Full text
50
Pahkala, Maarit. "Evolutionary ecology of ultraviolet-B radiation stress tolerance in amphibians." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-5081-4/.
Full text