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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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Harrison, J. D. "Aspects of the ecology of amphibian larvae". Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356737.
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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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Greenberg, Daniel. "Population dynamics of a declining amphibian". Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121577.
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With concern rising over the global decline of amphibian populations, identifying the onset of declines and the factors driving them is paramount. Amphibian populations are naturally characterized by large fluctuations in abundance, which makes separating natural fluctuations from true declines very difficult. By improving our understanding of the natural dynamics of amphibian populations, we can separate normal fluctuations from altered dynamics associated with decline. I apply this principle to an endangered population of Fowler's toads (Anaxyrus [=Bufo] fowleri) in Long Point, Ontario which appears to have gradually declined in abundance. With over two decades of mark-recapture data, I investigate what factors, intrinsic and extrinsic, drive growth in this population. Over this same period, there have been considerable changes to the toads' habitat, as an invasive strain of the common reed, Phragmites australis, has overtaken the wetlands used by toads for breeding. I show that the expansion of this reed has altered the dynamics of the toad population, causing progressive decline due to breeding habitat loss. Prior to 2002, the population of toads was driven by density-dependent growth and overwinter mortality. After 2002, at which point the reeds had eliminated most of the open water habitat, the population of toads responded only to extrinsic factors, particularly the water level of Lake Erie. I then ask whether the expansion of invasive Phragmites has changed not just the quantity of larval habitat, but also its quality, through the release of secondary compounds. I hypothesize that Fowler's toad larvae, as obligate gill breathers, will experience reduced survival, growth, and development in the presence of gill damaging secondary compounds from the invasive Phragmites and native Typha. In contrast, the sympatric Northern leopard frog (Lithobates [=Rana] pipiens) should exhibit similar performance as tadpoles in the presence of secondary compounds, as a facultative gill breather. Contrary to my expectations, I found that Fowler's toad tadpoles had a similar performance across treatments, despite the presence of secondary compounds. Furthermore, the native plant, Typha, but not the invasive Phragmites, appeared to impede growth in Leopard frog tadpoles. Based on these results, I conclude that the expansion of invasive Phragmites has the potential to impact species through changes to available habitat, but not by reducing larval habitat quality. By incorporating population dynamics into the study of amphibian declines we can improve our ability to infer causal links between population declines and the mechanisms that drive them.Alors que le déclin de la population amphibienne mondiale est de plus en plus préoccupant, il est primordial d'identifier les facteurs qui en sont la cause. Puisqu'une certaine fluctuation de population est normale, il est difficile de déterminer si une variation donnée est naturelle ou symptomatique d'un déclin réel. Une meilleure compréhension des fluctuations de la population amphibienne pourrait servir à distinguer entre les facteurs naturels de variation et une altération de dynamique associée à un déclin. Voilà l'idée directrice de cette étude d'une espèce à risque, le crapaud de Fowler (Anaxyrus [=Bufo] fowleri) de Long Point en Ontario, dont la population semble diminuer graduellement. À partir de l'information recueillie sur deux décennies de marquage-recapture, j'ai examiné les facteurs, internes et externes, de variation de leur population. Au cours de la période, leur habitat de reproduction a été considérablement détérioré par la présence d'une espèce envahissante de roseau commun, le Phragmites australis. J'explore le lien entre cette altération de dynamique et le déclin progressif des crapauds de Fowler. Avant 2002, leur population était régulée par des facteurs internes comme la croissance en fonction de la densité et la mortalité hivernale. Depuis, les roseaux communs ont éliminé la plupart de l'habitat en eau libre des crapauds de Fowler, dont la population ne répond plus qu'à des facteurs externes d'influence, en particulier le niveau de l'eau du lac Érié. Ensuite, je cherche à voir si la présence de l'espèce envahissante a influencé, non seulement la quantité d'habitat de reproduction du crapaud de Fowler, mais aussi la qualité de ce qui reste, par la production de composés secondaires. L'hypothèse explorée est que les composés secondaires nuisibles aux branchies, produits autant par l'espèce envahissante Phragmites que par l'espèce native Typha, réduisent les chances de survie, la croissance et le développement des crapauds de Fowler, qui respirent nécessairement par leurs branchies. En toute logique, l'espèce sympatrique grenouille léopard du Nord (Lithobates [=Rana] pipiens), qui respire par ses branchies de façon facultative, devrait être affectée de façon similaire. Cependant, ce n'est pas le cas ; j'ai remarqué que les têtards de crapauds de Fowler n'étaient pas affectés par la présence de composés secondaires. De plus, c'est l'espèce native Typha qui semblait nuire à la croissance des crapauds de Fowler, plutôt que l'espèce envahissante Phragmites. J'en conclus que l'expansion de cette dernière peut influencer plusieurs espèces par une réduction de l'habitat disponible, mais pas par la détérioration de la qualité de son habitat larvaire. En étudiant le déclin amphibien à partir de la dynamique de population, nous pouvons améliorer notre capacité à établir des liens entre le déclin de populations d'espèces et les mécanismes qui y contribuent.
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Prairie, Marie-Pier. "Landscape ecology of an amphibian community in southern Quebec, Canada". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66684.
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This thesis investigated the factors governing pond-breeding amphibian life stage occurrences at multiple sites within a 467-hectare forest at Mont-Saint-Grégoire, Québec, during 2006 and 2007. Several environmental, landscape characteristics and predator occurrences were tested using different statistical analyses to predict occurrence of these life stages. Life stages responded to different conditions and were not predicted by the same factors. Recruitment can be successful only if conditions are suitable for all life stages. Recruitment was poorly predicted by the detection of breeding adults, while it was better predicted by that of eggs and tadpoles. Different species also responded differently to environmental and biotic conditions, and what was required by amphibia as a taxon was not accurate for predicting population dynamics of individual species. We attempted to study dispersal patterns of three species, but the breeding season of 2007 was brief due to exceptional weather conditions and, thus, no pattern could be detected. These findings illustrate the complexity of pond-breeding amphibian population dynamics and the need for further long-term, multivariate and multi-species studies.Ce mémoire de maîtrise porte sur les facteurs potentiels pouvant influencer l'occurrence des stades de développement chez les amphibiens se reproduisant dans des étangs dans plusieurs sites situés dans une forêt de 467 hectares à Mont-Saint-Grégoire, Québec, en 2006 et 2007. Plusieurs variables environnementales et liées au paysage ainsi que l'occurrence d'espèces de prédateurs ont fait l'objet d'analyses statistiques visant à vérifier leur capacité à prédire l'occurrence des stades. Ceux-ci ont été influencés différemment par les conditions environnementales et leur occurrence n'a pas pu être prédite par les mêmes facteurs. Le recrutement de nouveaux individus est possible seulement si les conditions sont favorables pour tous les stades. La détection d'adultes reproducteurs n'est pas un moyen adéquat pour prédire le recrutement. En effet, la présence d'œufs ou de têtards permet de prédire davantage la présence de recrutement. Les différentes espèces ne sont pas influencées de la même façon par les facteurs et ce que les amphibiens requièrent en général n'est pas représentatif des besoins de chaque espèce. De plus, nous avons tenté de comprendre, sans succès, la dispersion de trois espèces, car la reproduction fut très brève en 2007 en raison des conditions météorologiques. Ces résultats laissent entrevoir la complexité de la dynamique des populations chez les amphibiens se reproduisant dans des étangs et la nécessité de réaliser des études multifactorielles à long terme sur plusieurs espèces.
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Middleton, Jessica. "Population ecology of a declining amphibian in relation to density". Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114513.
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In species with complex life cycles such as amphibians, population regulation can occur in one or multiple stages. Density effects in the larval, aquatic stage of the amphibian life cycle have been widely documented, leading many researchers to assume that this is the stage in which amphibian populations are regulated. However, recent evidence suggests that factors affecting survival and reproduction in the terrestrial stage may play a greater role in the growth and decline of amphibian populations than previously thought. I review the evidence for density-dependent population regulation in the terrestrial stage of amphibians and argue that variation in body size may be an important mechanism linking population density to changes in population growth rate (CHAPTER ONE). I used data from a 23-year population survey at Long Point, Ontario and conducted summer growth-rate surveys to examine the body size-abundance relationship in Fowler's Toad (Anaxyrus fowleri). Over the past 10 years of the population survey at Long Point, we observed a significant increase in body size (R² = 0.874, p = <0.001) that was coincident with a previously detected negative trend in abundance. The age structure of this population is highly unstable, but overall the average age is getting older (R² = 0.325, p= < 0.01) (CHAPTER TWO). Somatic growth rates in Fowler's toad toadlets are also highly variable and are significantly inversely correlated with the density of adults (R² = 0.98, p = 0.010) (CHAPTER THREE). The single most important factor influencing average body size on a long time-scale is abundance (R² = 0.713, p = <0.001) (CHAPTER FOUR). Therefore, body size variation in these toads is likely related to density-dependent resource availability for growth in the terrestrial stage.Pour des espèces ayant des cycles de vie complexes tels les amphibiens, la régulation de leur population peut se produire dans un ou plusieurs stades. Les effets de la densité au stage larvaire aquatique du cycle de vie de l'amphibien ont été largement documentés amenant plusieurs chercheurs à assumer que c'est à ce stage que la régulation de leur population se produit. Toutefois, des preuves récentes suggèrent que des facteurs affectant la survie et la reproduction au stage terrestre peuvent jouer un plus grand rôle dans la croissance et le déclin de la population des amphibiens contrairement à ce que l'on pensait auparavant. Je fais la revue de la preuve de la régulation de la population qui dépend de la densité au stage terrestre des amphibiens et j'argumente que la variation de la masse corporelle pourrait être un mécanisme important reliant la densité de la population aux changements du taux de croissance de la population (CHAPITRE UN). J'ai utilisé les données d'un relevé de la population sur une période de 23 ans à Long Point, Ontario et mené des relevés du taux de croissance durant l'été afin d'examiner la relation entre la dimension et la masse corporelle du crapaud de Fowler (Anaxyrus fowleri). Durant les 10 dernières années du relevé de la population à Long Point, nous avons remarqué une augmentation significative de la masse corporelle (R² = 0.874, p = <0.001) qui coïncidait avec une tendance négative de leur abondance détectée précédemment. La structure de l'âge de cette population est très instable, mais dans l'ensemble la moyenne d'âge est plus vieille (R² = 0.325, p= < 0.01) (CHAPITRE DEUX). Les taux de croissance somatiques des petits du crapaud de Fowler sont hautement variables et inversement corrélatifs à la densité des adultes (R² = 0.98, p = 0.010) (CHAPITRE TROIS). Le seul facteur d'importance qui influence la dimension corporelle moyenne sur une longue période c'est l'abondance (R² = 0.713, p = <0.001) (CHAPITRE QUATRE). Ainsi, la variation de la dimension corporelle de ces crapauds est vraisemblablement reliée à la croissance somatique laquelle dépend de la densité au stage terrestre.
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Gallipeau, Sherrie. "Altered Reproductive Function and Amphibian Declines". Thesis, University of California, Berkeley, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3640434.
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Agrochemical exposure is one of the factors that contributes to worldwide amphibian declines. Most studies that examine agrochemicals and amphibian declines focus on toxicity. However, declines are more likely caused by the sub-lethal effects of agrochemical exposure. Past emphases on the lethal effects of agrochemical exposure have overshadowed the contribution of decreased recruitment in amphibian declines. Additionally, studies that examine agrochemicals and reproductive function tend to focus on the effects of single chemical exposures instead of the effects of ecologically relevant mixtures. To address these issues, this dissertation examined the effects of ecologically relevant agrochemical exposures on the stress response and the reproductive endocrinology, morphology, and behaviors of male amphibians in the laboratory and the wild.
Chapter 1 provides a general review of the factors implicated in amphibian declines and provides an overview of the previous research conducted on the effects of agrochemical exposure on recruitment.
Chapter 2 is a field study that examined whether agricultural run-off alters the stress response and reproductive function of male bullfrogs ( Lithobates catesbeianus). Bullfrogs were collected upstream and downstream of agricultural activity across three California river systems (Salinas, Sacramento and San Joaquin). Size, primary and secondary sex traits, sperm count, and corticosterone and testosterone levels were examined. Overall, bullfrogs living downstream of agricultural activity (i.e. exposure to agricultural run-off) were small and had elevated testosterone and corticosterone levels. In addition, downstream males from the Salinas and San Joaquin Rivers were also small in size and had elevated testosterone levels. However, only downstream males of the San Joaquin River had elevated corticosterone and exaggerated secondary sex traits. Together, these data suggest that living downstream of agriculture can alter size, hormone levels, and the expression of sexually dimorphic sex traits. Such changes to the reproductive endocrinology and morphology of male amphibians can be detrimental to the reproductive health and long-term reproductive success of amphibian populations.
In Chapter 3, I examined corticosterone, testosterone, and the reproductive clasping behaviors of adult male African clawed frogs (Xenopus laevis) exposed to field collected and simulated agricultural run-off. This experiment implemented a novel eco-relevant experimental design to mimic real-life agrochemical exposures. Male frogs were exposed to field water collected downstream (agricultural run-off) and upstream (negative control) of agricultural activity along the Salinas River, CA. In addition, a pesticide mixture containing the top agrochemicals used in the Monterey County was included to simulate agricultural run-off. Mating behavior was suppressed in males exposed to simulated agricultural run-off but enhanced in males exposed to field collected agricultural run-off. In addition, testosterone levels of clasping males were elevated in comparison to controls. Males immersed in simulated agricultural run-off had significantly lower testosterone levels than control males in 2010. These data suggest that agrochemical exposure (both field collected and simulated) can alter reproductive hormones and clasping behaviors. Altered sex hormones and behaviors in male amphibians may play a role in amphibian declines.
Lastly, this dissertation is summarized in Chapter 4. The applicability of this dissertation as a model for amphibian declines and other reproductive related human health concerns are also introduced.
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Gibson, Jennifer C. W. "The effects of methylmercury ingestion on amphibian tadpoles". Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27137.
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Methylmercury (MeHg) is a toxic heavy metal and a health threat to wildlife and humans, however nothing is known about its effects on amphibians. MeHg is produced from inorganic Hg in the aquatic environment, and bioaccumulates in the food chain. This exposes tadpoles to elevated levels of MeHg in their diet, and may pose a risk to development. Tadpoles of the North American species Bufo americanus and Rana pipiens as well as the African frog model species Xenopus tropicalis were subchronically exposed to dietary McHg ranging in concentration from 1ng/g to 1000 ng/g to determine LC50s and species sensitivity differences. A developmental differences study was also performed with B. americanus. The 33-day LC50 estimates indicate that Gosner stage 25 tadpoles of both B. americanus and R. pipiens were the most sensitive, and they exhibited a similar sensitivity to McHg toxicity. The X. tropicales LC50 estimate is significantly higher (p=0.05) than those calculated for B. americanus and R. pipiens Gosner stage 25, and the developmentally advanced B. americanus Gosner stage 27-30 LC50 estimate is also significantly higher (p=0.05) than the B. americanus Gosner stage 25 LC50. (Abstract shortened by UMI.)
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Talley, Brooke Lee. "Host-Pathogen Ecology: Effects of Species Ecology and Environmental Factors on the Intensity and Distribution of Disease Among Illinois Amphibians". OpenSIUC, 2014. https://opensiuc.lib.siu.edu/dissertations/855.
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The worldwide decline of amphibians is due to several interacting factors that vary in their involvement and severity according to species, geography, environment, and individual response (Wake and Vredenburg 2008; Gahl et al. 2011). One of those threats has caused population declines globally (Stuart et al. 2004), Batrachochytrium dendrobatidis (Bd), which is the fungal pathogen that causes chytridiomycosis in amphibians (Berger et al. 1998; Longcore et al. 1999). Bd's effects are not completely known since some areas of the world have been studied (e.g., Panama, Lips et al. 2006; United States Sierra Nevada, Briggs et al. 2010; Australia, Phillott et al. 2013) while other areas have received little or no attention, often because these systems appear stable or because the effect of threats are not known. In the Midwestern United States, widespread anuran population declines occurred historically and are in some cases ongoing (e.g., Vogt 1981, Oldfield and Moriarty 1995, Brodman and Kilmurry 1998, Casper 1998, Hay 1998, Moriarty 1998, Mossman et al. 1998, Varhegyi et al. 1998, Steiner and Lehtinen 2008, Zippel and Tabaka 2008). Large-scale habitat alterations, chemical contaminations, and other threats have likely caused some Midwestern U.S. amphibian declines (Lannoo, 1998), but the role of Bd in historic and current population declines has been limited to small population surveys or incidental discovery of Bd (e.g., Pessier et al. 1999; Beasley et al. 2005; Steiner and Lehtinen 2008). I investigated the current and historic Bd infection levels among amphibians in Illinois and identified species risk factors associated with likelihood of chytridiomycosis-related death. My research questions focused on which biotic and abiotic factors explained Bd prevalence and intensities among current populations, which species risk factors would make them more likely to suffer severe Bd infection, and what the historic Bd status was in Illinois. Working with Illinois amphibians presented the opportunity to answer these research questions because Bd was already known to occur in Illinois (Pessier et al. 1999), there were a variety of anecdotal examples of historic population declines in Illinois (Beasley et al. 2005; Lannoo 1998), and extensive museum holdings were available to document the spatial and temporal pattern of Bd among Illinois populations. In the chytridiomycosis-amphibian disease system, mortality is driven by intensity of infection. Intensity is affected by many factors, including environmental temperatures, amphibian community composition, and fungal traits. However, the relative importance of biotic and abiotic factors on Bd prevalence and intensity in multispecies, natural communities is unknown for any wild populations. In 2008-2009, I conducted one of the first large-scale strategic surveys of both current and historic presence of Bd. I sampled 4,691 Illinois amphibians from current and historic populations to provide a framework of historic Bd infection and current status, and used those results to identify at-risk populations based on natural history and species risk factors. I tested 2,804 amphibians from 12 species for Bd, and determined that Bd was present in all sites, wetlands, and in all species in both years. Statewide prevalence was relatively high (2008 &mu = 34%; 2009 &mu = 55%), as was average individual infection intensity (2008 &mu = 1,773 Zswab; 2009 &mu = 2,159 Zswab). Wetland water temperature best explained Bd prevalence, but several biological factors explained intensity. Higher Bd intensities were correlated with species richness and indicated an amplification effect (Ostfeld and Keesing 2012). Hylid treefrogs may be amplifying species because they had the highest infection intensities and their presence was correlated with increased infection in other taxa. Bd can cause declines and extinctions in amphibian populations (Stuart et al. 2004), but other threats may also be involved (Collins and Storfer 2003). In Illinois, amphibian populations may be threatened by a variety of assaults including disease, habitat loss, chemical contaminants, and invasive species (Lannoo 1998). Management for biodiversity typically focuses on identifying and mitigating threats and prioritizing species susceptibility by identifying risk factors. I proposed to study whether species risk factors for Bd also signal general susceptibility to other threats (e.g., Lips et al. 2003; Bielby et al. 2008; Cooper et al. 2008) in Illinois amphibians. I identified nine potential risk factors for each of 21 Illinois species form the literature, and compared association of those traits with disease intensity. I used Bd intensity data from 1,445 Bd-positive amphibians collected 2008-2010. As in Chapter 2, I found that both biological and environmental factors explained disease intensity at the species levels: air temperature during the breeding season was the best predictor of infection intensity with three species biological traits also contributing (i.e., longevity, clutch size, and aquatic index). Conservation status did not explain Bd intensities, likely because conservation status is based upon rarity, population trends, and presence of threats, but which does not always include Bd susceptibility. Since most of the study species were common prior to my disease survey with relatively stable populations with no prior Bd threat, the conservation statuses used in this analysis did not predict Bd risk. Now that I have shown Bd to be widespread and at high intensities in the state, a reassessment of data included in the species status would be timely and might be warranted. I found that Bd was geographically and taxonomically widespread in Illinois, which suggested an established infection status, perhaps longer than the first report from the 1990s (Pessier et al. 1999). Also, this suggests that population declines from chytridiomycosis might have occurred historically. I used museum holdings to determine spatial and temporal distributions of Bd in Illinois amphibians. I tested 1,008 museum specimens from the vertebrate collections at Southern Illinois University, Illinois Natural History Survey, and the University of Illinois Museum of Natural History to determine the oldest date of anuran Bd infection in Illinois. I detected 110 Bd positive specimens (10.7%, CI: 9.0-12.8%) in four species collected during the 1890s-1980s. The earliest Bd record was from a Lithobates sphenocephalus collected in southern Illinois in 1900. I determined that Illinois amphibians have been living endemically with Bd for at least 113 years, extending the date of the oldest U.S. record of Bd infection by 61 years. The long-term presence of Bd, coupled with multiple anecdotal reports of population declines, suggest that Bd may have been involved in historic population declines in Illinois amphibians. I found widespread taxonomic and geographic distribution of Bd among current and historic populations of Illinois amphibians. I found a surprisingly long history of Bd in Illinois that transforms the way we consider impacts on historic species and potential co-evolution of disease in Midwestern U.S. amphibians. My finding is as old as the oldest records from Brazil, Africa, and Asia (Weldon et al. 2004; Goka et al. 2009; Schloegel et al. 2010, 2012), suggesting a more ancient history of Bd and amphibians.
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Radik, Gabrielle A. "Assessing Risks of Amphibian Declines using Multiple Stressors". Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1244474946.
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LaCivita, Lisa Frances. "Amphibian Monitoring for Ecosystem Services, Citizen Engagement and Public Policy". Thesis, George Mason University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13421066.
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This dissertation has both science and policy components. The research examines the presence or absence of two amphibian species in one Virginia County. Two amphibian species Pseudacris crucifer (Spring Peeper) and Hyla versicolor (Gray Tree Frog) are proposed to serve as a biotic indicator, or proxy, for water quality/watershed condition and ecosystem services. My dissertation hypothesized that amphibian presence of the target species would correlate with watershed integrity values, which was verified by statistical analysis. Greater amounts of amphibian presence correlated with higher watershed integrity scores. Detailed studies of amphibian occurrence, with continued monitoring, can document trends and behaviors of the target species. Facing concern for thresholds and factors that allow or limit amphibian presence, amphibian monitoring contributes to our understanding of anthropogenic impacts on biotic communities.
Both of the targeted amphibian species were distributed county-wide; occurrences were recorded in each of the major sub-watersheds. Areas surrounding the monitored road segments were calculated (using GIS technology) for the amount of areas assigned to one of four watershed integrity values. Amphibian occurrences correlated with watershed integrity scores using Spearman Rank Correlation.
What it means to possess watershed integrity sufficient to host amphibian populations brings science into the realm of public policy. Values, economics, demographics, education, politics and culture come into play. Watershed integrity, water quality and ecosystem condition, function and services directly impact human health and wellbeing, and can have profound influences on economic and cultural circumstances.
County-wide amphibian monitoring can establish an important baseline for ecological conditions, with the potential for citizen engagement. It is one more portal through which citizens may connect with the natural world. Connections to nature, along with environmental literacy and forward-looking public policies will be required to protect the ecosystem services upon which our communities depend. Monitoring for two or three amphibian species from public roads can become a citizen science effort that raises awareness of water resource issues. Aware and engaged citizens are needed to inspire governments and elected representatives to plan for 21st century conditions and sustainability. If engaging citizens, of all ages, in the workings of their own watershed will deepen their understanding of this vital, complex and dynamic system, then we may realize higher levels of water stewardship and sustainability.
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Linhoff, Luke Jack. "Linking Husbandry and Behavior to Enhance Amphibian Reintroduction Success". FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3688.
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Wildlife in captivity has a long history of benefiting global conservation goals. Captive animals can raise awareness and appreciation for the conservation of endangered species. Additionally, captive animals can be used as source populations to reintroduce animals back to the wild or to supplement existing wild populations. The rapid increase in amphibian species threatened with imminent extinction has necessitated the creation of dozens of captive-breeding programs. The focus of this dissertation has integrated topics across the spectrum of animals in captivity and the wild, and the results provide useful recommendations for conservation action. First, I describe how market pressures over a 28-year period are causing meteoric increases in the prices of amphibians sold in the pet trade, indicating a high risk of overexploitation. Pet amphibians may facilitate greater understanding and appreciation of amphibians, but the pet trade must be sustainable. Improving amphibian husbandry will increase the number of captive-bred animals available in the pet trade, and it will allow greater production of threatened species for reintroductions. Secondly, by performing a systematic review of husbandry for 289 amphibian species native to the US, I identified a critical lack in taxon-specific husbandry and developed husbandry research prioritizations. Next, I used a combination of laboratory and field studies to examine domestication processes in amphibians by comparing defensive behaviors in two species of captive-bred and wild poison frog. Captive-bred amphibians had significantly reduced defensive behaviors compared to wild conspecifics, likely resulting from habitation processes related to their husbandry. Finally, I performed three reintroductions of the critically endangered Wyoming Toad (Anaxyrus baxteri) in Wyoming, US. I demonstrated how providing a transitionary period, called a soft-release, to captive-bred toads moving to a novel, wild environment can improve reintroduction success. My work illustrates how improving our understanding of the nexus between captivity and the wild can improve conservation action for endangered species.
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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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Dehling, Jonas Maximilian [Verfasser]. "Taxonomy, systematics, and ecology of selected amphibian taxa from Rwanda / Jonas Maximilian Dehling". Koblenz : Universitätsbibliothek Koblenz, 2014. http://d-nb.info/1054354693/34.
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Menezes, Barata Izabela. "Frogs in plants : ecology and conservation of a bromeliad-dwelling amphibian from Brazil". Thesis, University of Kent, 2018. https://kar.kent.ac.uk/70123/.
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This thesis investigates the population ecology and population dynamics of a species of bromeligenous frog, Crossodactylodes itambe, endemic to a highland area in the Atlantic Rainforest of Brazil, within the Espinhaço Mountain Range. Bromeligenous frogs spend their entire life cycle inside bromeliads and dispersal of individuals is still unknown. There are 99 species of bromeligenous frogs, all restricted to the Neotropics, and most species are threatened. Crossodactylodes is comprised of five small-sized bromeligenous frogs and there is little information on their ecology and natural history of the whole genus. Crossodactylodes itambe occurs at the Itambé summit, above 1700 m in elevation, with an estimated area of occurrence of < 0.5 km2. Individuals are known to occupy a single species of bromeliad, which is also endemic to just two localities, including the Itambé summit. Species abundance was influenced by specific features of habitat structure, such as size of plant and presence of water, which were considered more important than local climate. Number of adults in a single plant was usually limited to one individual and the structure of the bromeliad was considered extremely important for species persistence. Distribution of plants at the Espinhaço Range was influenced by topography and specific climatic conditions, such as temperature seasonality and annual precipitation. Given the strong dependence of the frogs on the plant, using bromeliads as a surrogate for modelling frog distribution can be extended to many bromeligenous species that lack distributional data. Despite extensive survey effort, Crossodactylodes itambe cannot be found anywhere else within the southern limits of the Espinhaço Range, and the species is indeed naturally rare. Detecting declines in amphibian populations is challenging and surveys should be species-specific and designed to meet specific monitoring goals. A sampling design was suggested for Crossodactylodes itambe, which can detect large to moderate population changes with 80% statistical power. The first analysis of population trends for a bromeligenous frog was provided. Although population changes were detected at all elevational ranges covering the current species distribution, a decline was only significant at lower elevations, where bromeliads are smaller and occur at lower density. While colonization of bromeliads by frogs was driven by habitat characteristics, local extinction was explained by seasonal variation in local weather conditions. Colonization rates were negatively affected by a stochastic fire event, which decreased dramatically in burnt plants. This thesis provides valuable information on the drivers of distribution and abundance of this threatened frog species. The same methodological approaches could be broadly applied to many Data Deficient bromeligenous frogs, for which little information is available. This research also demonstrates how the frog-bromeliad system can be a useful small-scale model for investigating key demographic parameters, such as extinction and colonization, which might be unfeasible on a larger scale or in patchy habitats. Considering the population dynamics of this bromeligenous frog, in the short-term, habitat conservation should be a priority action when compared to climate change mitigation.
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Corey, Sarah J. "Understanding Amphibian Vulnerability to Extinction: A Phylogenetic and Spatial Approach". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244036842.
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Dietrich, Andrew Evans. "Stream-Associated Amphibian Habitat Assessment in the Portland-Vancouver Metropolitan Region". PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/604.
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This study assessed the influence of landscape development on stream-associated amphibians in forested riparian areas within the Portland-Vancouver metropolitan region. Human alteration of landscapes may dramatically affect the ecology of neighboring aquatic systems. It was hypothesized that lotic amphibians would be negatively associated with greater amounts of landscape development and positively associated with forested area within the surrounding watershed. Thirty-seven 1st-3rd order streams were sampled between June 21st and September 21st in 2011. Streams potentially providing adequate habitat for stream-obligate amphibians were randomly selected. Amphibians were surveyed along 30-meter stream transects using an active-cover search (ACS). Environmental variables associated with development in surrounding landscapes were measured in situ. GIS delineation was conducted to define landscape-scale variables at stratified distances from riparian networks up-stream of each site via the utilization of the 2006 NLCD dataset and a finer-scale, regional dataset compiled by the Institute for Natural Resources (INR). Amphibians were detected at seventeen of the thirty-seven sampled streams. The most commonly detected species were Dicamptadon tenebrosus, Plethadon vehiculum and Plethadon dunni. Streams where amphibians were observed had lower average water temperature and conductivity, coarser stream substrate and were located on public property more often than streams where no amphibians were detected. Landscape variables were most significant to amphibians within 100 and 200 meters of the upstream stream network. Occupancy of a site by facultative species was best explained by the proportion of mixed forest in the surrounding watershed (R2=0.343, p<0.001). Occupancy of a stream by obligate species was best predicted by measurements of water quality and in-stream cover (Water Temperature: R2=0.275, p<0.001; Water Conductivity: R2=0.248, p<0.001; Cover: R2=0.323, p<0.001). Occupancy of stream refugia by all observed amphibians was positively influenced by higher percentages of forest cover and lower percentages of urban development and herbaceous vegetation in the surrounding watershed. Results of this study indicate that urban refugia must contain adequate riparian forest area, coarse stream substrate and clean, cool water to sustain stream-amphibian communities. Protection of remnant forested headwater stream networks is essential to the conservation of lotic amphibians in this urbanized region.
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Lucas, Amy P. "Amphibian Habitat Usage of Two Restored Bogs in Shady Valley, Johnson County, Tennessee". Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etd/1785.
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Adjacent terrestrial habitat surrounding wetlands are critical for the survival and success of many species that use them. The primary purpose of this study was to determine amphibian movement from adjacent habitats into Orchard Bog, a restored bog located in Shady Valley, Johnson County, Tennessee. In addition, a secondary bog, Quarry Bog, was also studied determining baseline presence/absence data
A total of 16 species from six families were observed throughout the study sites. Seven species of anurans, Bufonidae, Hylidae, and Ranidae and nine species of caudates in the families Plethodontidae, Ambystomatidae and Salamandridae were identified. Fourteen of the 16 species were found within Orchard Bog.
Data collected can be used to help determine more beneficial land acquisitions and management strategies. Survey methods included pitfall traps, funnel traps, coverboard arrays, and opportunistic surveys.
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Bishop, David Christopher. "Ecology and distribution of the Florida bog frog and flatwoods salamander on Eglin Air Force Base". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28103.
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I studied the ecology and distribution of the Florida bog frog (Rana okaloosae) and flatwoods salamander (Ambystoma cingulatum) on Eglin Air Force Base in northwest Florida. I report data on the breeding ecology, population dynamics, home ranges, microhabitat, and distribution of the endemic bog frog and make comparisons to its closest relative, the bronze frog (Rana clamitans clamitans). Bog and bronze frogs occur in the same habitats and are suspected to hybridize.
I investigated the potential for auditory and visual mate recognition errors between R. okaloosae and R. clamitans. I also described the vocal repertoire of the bog frog and observed the response of resident males to the playback of unfamiliar conspecific and heterospecific (R. clamitans) calls. The advertisement calls of bog frogs vary among individuals, and individual voice recognition is possible.
I exposed tadpoles of bog frogs, bronze frogs, and leopard frogs (R. sphenocephala) to chemical cues from 2 predators, the banded water snake (Colubridae: Nerodia fasciata) and the red fin pickerel (Esocidae: Esox americanus) to evaluate whether swimming behavior or habitat selection differed among tadpole species. The time spent swimming differed among tadpole species and predator treatments, differences which potentially could affect growth rates, survivorship rates, and distribution patterns.
Lastly, I discuss the relationship between fire and the federallyâ threatened flatwoods salamander (Ambystoma cingulatum). I compared 13 breeding wetlands with different fire histories in addition to burned and unburned halves of a partiallyâ burned wetland. In general, areas that burned more recently had more open canopies, higher dissolved oxygen concentrations, higher water temperatures, more understory vegetation, and were shallower than unburned areas. Rangewide surveys indicate that prescribed fires typically are applied in winter and early spring in areas inhabited by flatwoods salamanders. Based on what is known about the natural history of the species, the historical burning regime of the longleaf ecosystem, and the effects of fires on ephemeral wetlands, I suggest that land mangers diversify their fireâ management strategy to increase the likelihood of burning the breeding wetlands of flatwoods salamanders.Ph. D.
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Baker, Gillian Clare. "The enigmatic protist - the taxonomic affinities of Prototheca richardsi and its role in amphibian ecology". Thesis, University of Sussex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263149.
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Kilburn, Vanessa. "Persistence and prevalence of the enzootic chytrid fungus, «Batrachochytrium dendrobatidis», in relation to amphibian population decline in Panama". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32555.
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The pathogenic chytrid fungus, Batrachochytrium dendrobatidis, causes population decline and extinction of numerous species of tropical, principally montane, amphibians. Is B. dendrobatidis an enzootic pathogen emerging as a disease, or rather a novel invasive pathogen infecting naïve amphibians? Are only high-elevation amphibians susceptible to the pathogen? If the chytrid is enzootic, then it may be in the environment before or after epidemic decline and may infect both montane and lowland amphibians as well as other organisms. To determine distribution of the pathogen and corresponding anuran abundance, I established eight research sites of varying elevations and stages of epidemic infection from west to east, ranging from 45 m to 1215 m elevation throughout Panama west of the Canal. Differential infection susceptibility among anurans was addressed in relation to three ecological factors: anuran body size, season and habitat. Prevalence and infection intensity of the chytrid were determined at all sites and for all factors using sensitive DNA-based RT-qPCR amplification. Amphibian populations at all elevations and stages of decline showed at least some degree of chytrid infection, and the chytrid was found on reptiles. In addition to presence of the pathogen, effects of the disease chytridiomycosis were variably seen at all elevations. Habitat and season did not seem to have a strong effect on infection prevalence and/or intensity, but frogs did appear to show greater infection at smaller anuran body sizes. All of the above results are suggestive of an enzootic pathogen and perhaps only the current epidemic of chytridiomycosis disease is novel. Since the infectionLe champignon pathogène chytrid, Batrachochytrium dendrobatidis, cause la diminution et l'extinction de nombreuses populations d'amphibiens tropicaux, principalement dans les regions à haute altitude. Si le champignon est endémique, il peut rester dans l'environnement après le passage d'une épidémie, contaminant les amphibiens des hautes et basses terres, ainsi que les autres organismes. Les sites de recherche étaient établis à diverses élévations et à différents stades de l'épidémie, à l'ouest du canal de Panama, où l'état des populations d'amphibiens pouvait être examiné. L'hypersensibilité différentielle des grenouilles à la maladie était adressée pour trois facteurs: la taille des grenouilles, la saison et l'habitat. La prévalence et l'intensité de l'infection étaient déterminées pour chaque facteur à tous les sites en utilisant la technique du RT-qPCR. Les amphibiens de toutes les élévations et de tous les stades de l'épidémie ont montré au moins un niveau d'infection, indiquant la présence d'un pathogène endémique. Le chytrid a aussi été trouvé sur les reptiles. En plus de la présense du champignon, les symptômes de la maladie chytridiomycosis ont même été remarqués sur les grenouilles des terres basses. La prévalence de l'infection est restée similaire pour les forêts et les ruisseaux, et aussi pour les deux saisons, et plus élevée pour les petites grenouilles que pour les plus grosses. Puisque l'infection peut rester dans les communautés amphibiennes à toutes altitudes, habitats et saisons, qu'elle peut persister pour longtemps (jusqu'à 11 ans), et qu'elle peut survivre sur d'autres organismes, la réintro
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Dimitrie, David Anthony. "Effects of Habitat Characteristics on Amphibian Use of Aquatic and Terrestrial Environments". Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1623333871708777.
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Hobbs, Michael T. "Amphibian mortality on roads| A case study in Santa Cruz long-toed salamander habitat". Thesis, San Jose State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1552258.
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Amphibian populations have been declining at higher rates than bird and mammal populations. Agriculture, urbanization, including roads, and resource extraction continue to put pressure on all species. Roads in particular, are major sources of mortality. The Santa Cruz long-toed salamander ( Ambystoma macrodactylum croceum), one of the most critically endangered species in the US, is one amphibian that is declining as a result of anthropogenic impacts, especially habitat loss and fragmentation due to urban development. Migration across roads puts these salamanders at risk from road-related death. This thesis quantified the rate of road mortality to these salamanders and other common amphibians during two A. m. croceum breeding-migration seasons in 2011–13 in a portion of the subspecies' range. Vehicular traffic was a major source of mortality to the salamander. Through traffic doubled the overall vehicle load on roads where the A. m. croceum migrated to and from breeding ponds. The Pacific chorus frog was also killed on the roads. This common species can be used as an indicator of road mortality risk for rarer amphibians. This study indicated that measures to reduce road mortality to the Santa Cruz long-toed salamander could include restricting vehicular traffic on roads adjacent to salamander ponds by limiting traffic to residential use only during breeding migrations, installing structures to protect A. m. croceum while crossing roads, and potentially assisting animals crossing roads at nighttime during the breeding migrations.
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Thompson, Danielle Kaye. "Amphibian and Reptile Species Survey and Habitat Assessment: Incorporating Environmental Education and Outreach". Miami University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=miami1208912407.
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Nunziata, Schyler O. "USING GENOMICS TO UNDERSTAND POPULATION DEMOGRAPHICS IN THE CONTEXT OF AMPHIBIAN CONSERVATION". UKnowledge, 2017. http://uknowledge.uky.edu/biology_etds/49.
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Understanding the demography of species over recent history (e.g., < 100 years) is critical in studies of ecology and evolution, but records of population history are rarely available. Large single nucleotide polymorphism datasets generated with restriction-site associated DNA sequencing (RADseq), in combination with demographic inference methods, are improving our ability to gain insights into the population history of both model and non-model species. However, to assess the performance of genetic methods it is important to compare their estimates of population history to known demography, in both simulation and empirical settings. Here, I used a simulation approach to examine the potential for RADseq datasets to accurately estimate effective population size (Ne) in Wright-Fisher populations over the course of stable and declining population trends, and distinguish stable from steadily declining populations over a contemporary time scale (20 generations). Overall, my results reveal that demographic inference using genome-wide data can be successfully applied to estimate Ne, and the detection of population-size declines. Next, I assess these methods in an empirical study from a wetland with 37 years of amphibian mark-recapture data to study the utility of genetically-based demographic inference on salamander species with documented population declines (Ambystoma talpoideum) and expansions (A. opacum). For both species, demographic model inference supported population size changes that corroborated mark-recapture data. To further validate these findings, I used individual-based population models of the pond-breeding salamander, Ambystoma opacum, with life-history parameters estimated from a long-term dataset, over a 50 year projection. My results demonstrate that genetically estimated Ne is positively correlated with census size in isolated and subdivided A. opacum populations. Finally, I investigated metapopulation patterns of genomic diversity in A. opacum and A. talpoideum and how migration may impact Ne estimation. I found strong patterns of subpopulation structuring, signatures of migration between subpopulations, and differences in Ne at the subpopulation level in both species. Overall, my findings suggest the ability of genomic data to reconstruct recent demographic changes, which can have important applications to conservation biology, and ultimately can help us elucidate the effects of environmental disturbances in the demography of endangered or declining species.
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Padgett-Flohr, Gretchen Elizabeth. "Batrachochytrium dendrobatidis in Central California". OpenSIUC, 2009. https://opensiuc.lib.siu.edu/dissertations/310.
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AN ABSTRACT OF THE DISSERTATION OF GRETCHEN ELIZABETH PADGETT-FLOHR for the Doctor of Philosophy degree in Zoology, presented on March 5, 2009 at Southern Illinois University of Carbondale. TITLE: BATRACHOCHYTRIUM DENDROBATIDIS IN CENTRAL CALIFORNIA AMPHIBIANS MAJOR PROFESSOR: Eric Schauber Amphibian chytridiomycosis has been identified as a disease responsible for the decline and extinction of many amphibian taxa world wide, but little research has been conducted on the disease in Mediterranean climates. To address this gap in the data I studied the amphibian assemblage present across a ~6,475 ha site in central California and investigated the occurrence of the etiological agent, Batrachochytrium dendrobatidis (BD) from organismal, community, landscape and historical perspectives. I initially tested the accuracy and reliability of a proposed diagnostic screening test for BD in four larval species that occur on the site. The screening test proposed by Fellers et al. (2001) and Vredenburg and Summers (2001) consisted of examining larval amphibian mouthparts for abnormalities and or defects, based on their hypothesis that mouthpart defects are clinical signs of BD infection. Sensitivity and specificity of the diagnostic screening test were 76% and 58%, respectively, indicating that the proposed screening test was not a reliable diagnostic test for BD infection for the four species I examined. I conducted controlled laboratory experiments to examine the consequences of BD infection in the two threatened California species that occur on my study site: Rana draytonii and Ambystoma californiense. Both species were susceptible to infection, but all infected animals survived the 18-month study. Infected A. californiense sloughed skin at three times the rate of uninfected salamanders, a pattern that may have long-term energetic costs potentially leading to population-level consequences of sublethal infection by BD. I conducted a retrospective survey of the California Academy of Sciences' (San Francisco, California, USA) amphibian collection, testing for BD in four amphibian species collected from central California between 1897 and 2005 to assess whether the pathogen is novel versus endemic. The earliest detection of BD was in two Rana catesbeiana collected in 1961, and the data support the hypothesis that BD was a novel pathogen introduced into central California prior to 1961 that spread geographically and taxonomically from at least one point of introduction and is now endemic throughout most of central California. I analyzed how environmental factors, amphibian community composition, land use practices, and landscape structure affect the dynamics of the pathogen's distribution on my study site in central California. The distribution of BD in ponds within the landscape varied markedly between years and increases were associated with precipitation, mean minimum and maximum temperatures, and presence of particular species. Pseudacris regilla infection patterns were highly indicative of overall patterns of pond BD status. Fourteen ponds were identified as BD hotpots (BD-positive three of four years). Occurrences of the pathogen within the landscape were spatially autocorrelated and ponds in close proximity to BD hotspots were more likely to test positive. Local land use, (presence/absence of grazing or recreational activity and developed lands), apparently did not influence BD status of a pond. My studies show that BD was likely a novel pathogen introduced into California ca. 1961 that has since become established as an endemic pathogen throughout most of central California. The listed amphibian species that occur in central California can be infected with BD but appear to be resistant to manifesting amphibian chytridiomycosis, and the data from the studies herein could support one of two hypotheses: that natural selection acting over the past 48 years has selected for those individuals that were resistant to the disease; or that the species on my site have always been resistant to BD. The research I conducted further supports the hypothesis that BD is locally vectored by native amphibians (e.g. P. regilla) moving between ponds and that local ecological constraints likely limit vectoring of BD by non-native species. These findings contribute substantially to elucidating and understanding the responses of amphibian populations to disease/pathogen introduction and lay groundwork for future investigations into the host-pathogen-environment relationship as it relates to declining amphibian populations.
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Thompson, Michelle E. "Recovery of Amphibian and Reptile Communities During Tropical Secondary Forest Succession". FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3701.
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The extensive clearing and modification of natural systems from anthropogenic activities is a pressing global concern. Forest habitats and animal communities within forests are among the most highly impacted, globally. Forest destruction has been repeatedly documented as a driver of biodiversity loss. However, little is known about how animal communities respond when altered landscapes are abandoned and left to regenerate into secondary forests. It is thought that the regrowth of secondary forests may help reverse biodiversity loss by restoring habitats to similar conditions as prior to land conversion. Of the forest cover that remains, over half is secondary forest, and in many countries secondary forest cover has been steadily increasing. Therefore, it is important to understand how and if faunal communities recover during secondary forest regeneration.
I combined meta-analytic, field-survey-based, and lab-based experimental techniques to determine how amphibians and reptiles respond to habitat change in general, and secondary forest regeneration on landscapes previously cleared for use as pasture. I addressed five specific questions: 1) what are the effects of habitat alteration on amphibians and reptiles?, 2) what are the effects of secondary forest succession on amphibians and reptiles?, 3) what is the relative importance of stochastic and deterministic effects on community assembly during secondary forest succession?, 4) how do amphibian and reptile species composition, probability of occurrence, and species richness change over the course of secondary forest succession?, and 5) is thermal quality of habitat an important mechanism of species response to secondary forest succession? I found that secondary forest has high conservation value for many amphibian and reptile species, environmental changes associated with secondary forest succession have a significant effect on shaping amphibian and reptile community composition, thermal quality is an important mechanism for species response and that strength of response is mediated by species-specific thermal biology. I also highlight the importance of riparian corridors in maintaining species diversity in modified habitats.
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Tran, Thi Anh Dao [Verfasser]. "Taxonomy and ecology of amphibian communities in Southern Vietnam : Linking morphology and bioacoustics / Thi Anh Dao Tran". Bonn : Universitäts- und Landesbibliothek Bonn, 2014. http://d-nb.info/1047145510/34.
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Smith, M. Alexander. "Spatial ecology of Bufo fowleri". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84844.
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The geographic isolation of populations can result in a metapopulation effect where regional dynamics of extinction and colonization are more important to population viability than local dynamics of individuals' birth or death. When this partial isolation is maintained for many generations genetic variability can be geographically structured. Populations of temperate-zone anuran amphibians are often considered to be geographically isolated on relatively small spatial scales due to the animals presumed high site fidelity and strict dependence on moisture for respiration and breeding. As a result, temperate, pond-breeding anuran amphibian populations are considered likely candidates to test hypotheses of metapopulation theory, movement and phylogeography. Using data from the Fowler's toad, (Bufo fowleri) I test the applicability of metapopulation theory, the likelihood of limited movement and the strength of phylogeographic structure. Specifically, I show that the generalization of the amphibians-as-metapopulations paradigm, due to their limited dispersal capabilities, is not supported (I). Bufo fowleri movement is well described by an inverse power function. Whereas most individuals do not move, some move long distances. There is no sex bias to this movement and I propose the hypothesis that the animals moving the longest distances are aided by the passive action of lake currents (II). B. fowleri juveniles are not a dispersal stage. They move neither farther nor faster than adults. The observation of predominantly juvenile contribution to a dispersal pool is due to their abundance---there are simply many more juveniles than adults (III). My observations of amphibian population turnover do not support the predictions of two specific metapopulation models when parameterized on a local (<10km) or regional scale (~300km) (IV). B. fowleri populations in Canada exhibit both shallow and deep phylogeographic structure. The shallow divisions are geo
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Rumschlag, Samantha Leigh. "The Influence of Environmental Factors on Responses on Amphibian Hosts Across Life Stages to an Infectious Fungal Pathogen". Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1468840914.
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Reider, Kelsey E. "Survival at the Summits: Amphibian Responses to Thermal Extremes, Disease, and Rapid Climate Change in the High Tropical Andes". FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3919.
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Understanding biological responses to climate change is a primary concern in conservation biology. Of the ecosystems being rapidly impacted by climate change, those in the high-elevation tropics are among the most poorly studied. The tropical Andean biosphere includes record elevations above 5000 meters, where extreme environmental conditions challenge many organisms. In the Cordillera Vilcanota of southern Peru, frogs including Pleurodema marmoratum and Telmatobius marmoratus have expanded their ranges to 5244 – 5400 m into habitats created by glacial recession, making them among the highest recorded amphibians on Earth. To understand how hydrologic alterations from loss of glacial meltwater and climatic fluctuations affect these amphibians, I conduct a 36-month field study of reproductive phenology and develop a method to distinguish glacial meltwater-fed ponds and precipitation-fed ponds utilizing natural variation in stable isotopes of water (18O, 2H, and d-excess). My results suggest that some ponds critical for breeding populations may have lost their connection to glacial runoff. Ongoing deglaciation may transform these ponds from permanent to ephemeral habitats, leading to the extirpation of the fully aquatic species, T. marmoratus. The 2015/2016 El Niño delayed the onset of the 2015 wet season and shortened the P. marmoratum breeding and tadpole development period in ephemeral ponds. I examine regional patterns of amphibian occupancy and prevalence of the deadly amphibian pathogen Batrachochytrium dendrobaditis in unexplored high-elevation zones that were until recent decades covered by permanent ice. Next, I examine adaptive strategies that allow these two frog species to persist in the harsh high-elevation environment. Pleurodema marmoratum withstands the daily freeze-thaw cycle by utilizing a wide thermal tolerance range (from below 0ºC to CTmax > 32ºC) and I report the first evidence of frost tolerance in a tropical frog. My research compares divergent strategies allowing two anuran species to persist through disease and variable, extreme conditions in high-mountain environments, providing a better understanding of responses to and consequences of climate change for some of the world's highest life forms.
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Queissada, Ingrid Carolline Soares Tiburcio [UNESP]. "Diversidade da herpetofauna de uma área de Mata Atlântica do estado de Alagoas: a reserva particular da usina Porto Rico, Campo Alegre". Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/99537.
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A Mata Atlântica é reconhecida internacionalmente como uma das 25 hotspots do planeta e engloba áreas com elevado endemismo, grande diversidade de espécies e fortes pressões antrópicas. É a segunda floresta mais ameaçada e abriga muitas espécies com risco de extinção. Os anfíbios e répteis constituem a chamada herpetofauna, formando um grupo que se destaca em quase todos os habitats terrestres e também são abundantes e importantes em ambientes aquáticos. No Brasil esse grupo está representado por 841 espécies de anfíbios, e 701 espécies de répteis. A maior diversidade desse grupo de animais ocorre em florestas tropicais úmidas, porém o frequente processo de fragmentação que estas florestas vêm sofrendo pode causar efeitos como a redução e até a extinção de populações. O presente estudo foi realizado na Reserva Particular da Usina Porto Rico e seu entorno, município de Campo Alegre, estado de Alagoas. O trabalho teve como principal objetivo conhecer a composição de espécies da herpetofauna na Reserva e comparar área de borda e área de interior de mata em relação à composição de espécies. Para as análises estatísticas só foram utilizados dados obtidos com o uso das armadilhas de interceptação e queda. Durante o período de junho de 2006 a agosto de 2007 foram registradas 29 espécies de anuros, 17 espécies de lagartos e 19 espécies de serpentes, capturados pelos métodos de busca ativa e de armadilhas de interceptação e queda e através de encontros acidentais. A composição herpetofaunística foi bastante similar quando comparados interior e borda de mata (coeficiente de Jaccard = 0,75862). Uma espécie típica de áreas abertas, Physalaemus cuvieri, foi a mais abundante tanto no interior da mata quanto na borda. Uma espécie considerada rara, Macrogenioglottus alipioi, foi encontrada na área de estudo enfatizando a importância da conservação desse remanescente florestal.
Atlantic Forest is internationally recognized as one of the 25 hotspots on the planet which embodies high endemism and high diversity areas over strong anthropic influence. This forest composing the second mort threatened forest, and representing an unique shelter for many endangered species. Amphibians and reptiles constitute what we named herpetofauna. This group to detach about all terrestrials habitats also is important and abundant in aquatics environments. In Brazil, the herpetofauna represent 841 amphibians species, and, 701 reptiles species. Its diversity occurs mainly within rain forests, but in these forests the frequent fragmentation processes may result on severe effects such as population reduction as extinct species. This study was developed at Usina Porto Rico Particular Reserve, Campo Alegre municipal district, Alagoas State. This aim of this work was to know the herpetofauna species composition in Reserve and to compare edge and interior of the forest. Only used data obtained about pittfall traps to statistical analyzes. From June 2006 to August 2007, 29 amphibians species, 17 lizards species and 19 snakes species were registered about pitfall traps and active look search and about accidental encounter. The herpetofauna composition was similar between edge and interior of the forest (Jaccard coefficient = 0,75862). One specie, Physalaemus cuvieri, typical of the open areas, was the most abundant in the edge as much as interior of the forest. One rare specie Macrogenioglottus alipioi was found within the studied área, pointing out the importance of this Forest remnant conservation.
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Farallo, Vincent R. "Notes from the Underground: Linking Microhabitat and Species Distributions of Plethodontid Salamanders". Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou148156741016879.
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Gallagher, Sarah Louise. "Influence of habitat associations and distance from low-order streams on amphibian and reptile communities on public lands in east-central Mississippi". Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11092007-100145.
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Puglis, Holly J. "Effects of Terrestrial Buffer Zones on Amphibians in Managed Green Spaces". Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1280773926.
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Ma, Chui-ying y 馬翠盈. "Assessment of the effects of agricultural practices on amphibian populations in Long Valley wetlands, Hong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48199461.
Texto completoResumen
Agricultural practices have altered natural wetland habitats for thousands of years in lowland areas of Southeast Asia, and currently these highly modified wetlands constitute some of the most important remaining habitats for amphibians. However, decreasing area of arable land and increased use of chemicals may affect the persistence of lowland amphibian populations that are now dependent on these habitats. I investigated how amphibians responded to different kinds of farming treatments in a large agricultural wetland in Hong Kong.
In the first part of the study, I assessed the occurrence of breeding amphibians in 53 farming plots in 2010 and 2011. Anuran call surveys were conducted at night at the plots once a week from March to August for two years. Environmental variables were measured and used to develop models to examine species presence, occupancy, and detection probabilities. Wet agricultural plots supported 10 species of amphibians and all had detection probabilities of < 1 that varied seasonally and yearly. Organically managed plots and shallow water plots yielded high species richness and particularly attracted the ornate pygmy frog (Microhyla fissipes) and the paddy frog (Fejervarya limnocharis). Air temperature and humidity were the relatively consistent predictors that influenced calling activity of the four most commonly detected species (M. fissipes; F. limnocharis; brown tree frog Polypedates megacephalus; and G?nther’s frog Hylarana guentheri).
For the second part of the study, I assessed the impacts of fertilizers on amphibians. Using mesocosm experiments in the field, I compared the effects of a chemical fertilizer (granular urea) and an organic fertilizer (peanut cake) on the survival and growth of hatchlings of Polypedates megacephalus, the marbled pygmy frog (Microhyla pulchra), Asian common toad (Duttaphrynus melanostictus) and Chinese bullfrog (Hoplobatrachus rugulosus). Fertilizers were applied at low, manufacturer-recommended, and high levels, and survival and snout-vent-length were measured after 21 days. No individuals survived in the chemical fertilizer treatment at the recommended application level. Conversely, survival was high for P. megacephalus (96%), M. pulchra (54%) and D. melanostictus (90%), but relatively low for H. rugulosus (18%), at the recommended level of the organic fertilizer. P. megacephalus and M. pulchra tadpoles showed increased growth in elevated concentrations of organic fertilizer. Polypedates megacephalus tadpoles were 1.6 times longer in the low concentration and almost double in length in the high concentration treatments. Similarly, increased growth in M. pulchra in all organic treatments resulted in abbreviated time to metamorphosis. Chemical fertilizers are clearly detrimental to early life stages of these amphibians, but organic fertilizers may confer benefits including a shorter time to, and larger size at, metamorphosis.
These results suggest that where amphibian conservation is a priority, shifts in the management of wet agricultural crops and limiting the use of chemical fertilizers may increase the suitability of breeding habitats and survival at early life stages.published_or_final_version
Biological Sciences
Master
Master of Philosophy
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Sharp, Colleen C. R. "Effects of copper and light exposure on the development and survival of the Wood Frog tadpole (Rana sylvatica)". University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1209657636.
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Queissada, Ingrid Carolline Soares Tiburcio. "Diversidade da herpetofauna de uma área de Mata Atlântica do estado de Alagoas : a reserva particular da usina Porto Rico, Campo Alegre /". Rio Claro : [s.n.], 2009. http://hdl.handle.net/11449/99537.
Texto completoResumen
Orientador: Hussam El Dine ZaherBanca: Gabriel Omar Skuk Sugliano
Banca: Otavio Augusto Vuolo Marques
Resumo: A Mata Atlântica é reconhecida internacionalmente como uma das 25 hotspots do planeta e engloba áreas com elevado endemismo, grande diversidade de espécies e fortes pressões antrópicas. É a segunda floresta mais ameaçada e abriga muitas espécies com risco de extinção. Os anfíbios e répteis constituem a chamada herpetofauna, formando um grupo que se destaca em quase todos os habitats terrestres e também são abundantes e importantes em ambientes aquáticos. No Brasil esse grupo está representado por 841 espécies de anfíbios, e 701 espécies de répteis. A maior diversidade desse grupo de animais ocorre em florestas tropicais úmidas, porém o frequente processo de fragmentação que estas florestas vêm sofrendo pode causar efeitos como a redução e até a extinção de populações. O presente estudo foi realizado na Reserva Particular da Usina Porto Rico e seu entorno, município de Campo Alegre, estado de Alagoas. O trabalho teve como principal objetivo conhecer a composição de espécies da herpetofauna na Reserva e comparar área de borda e área de interior de mata em relação à composição de espécies. Para as análises estatísticas só foram utilizados dados obtidos com o uso das armadilhas de interceptação e queda. Durante o período de junho de 2006 a agosto de 2007 foram registradas 29 espécies de anuros, 17 espécies de lagartos e 19 espécies de serpentes, capturados pelos métodos de busca ativa e de armadilhas de interceptação e queda e através de encontros acidentais. A composição herpetofaunística foi bastante similar quando comparados interior e borda de mata (coeficiente de Jaccard = 0,75862). Uma espécie típica de áreas abertas, Physalaemus cuvieri, foi a mais abundante tanto no interior da mata quanto na borda. Uma espécie considerada rara, Macrogenioglottus alipioi, foi encontrada na área de estudo enfatizando a importância da conservação desse remanescente florestal.
Abstract: Atlantic Forest is internationally recognized as one of the 25 hotspots on the planet which embodies high endemism and high diversity areas over strong anthropic influence. This forest composing the second mort threatened forest, and representing an unique shelter for many endangered species. Amphibians and reptiles constitute what we named herpetofauna. This group to detach about all terrestrials habitats also is important and abundant in aquatics environments. In Brazil, the herpetofauna represent 841 amphibians species, and, 701 reptiles species. Its diversity occurs mainly within rain forests, but in these forests the frequent fragmentation processes may result on severe effects such as population reduction as extinct species. This study was developed at Usina Porto Rico Particular Reserve, Campo Alegre municipal district, Alagoas State. This aim of this work was to know the herpetofauna species composition in Reserve and to compare edge and interior of the forest. Only used data obtained about pittfall traps to statistical analyzes. From June 2006 to August 2007, 29 amphibians species, 17 lizards species and 19 snakes species were registered about pitfall traps and active look search and about accidental encounter. The herpetofauna composition was similar between edge and interior of the forest (Jaccard coefficient = 0,75862). One specie, Physalaemus cuvieri, typical of the open areas, was the most abundant in the edge as much as interior of the forest. One rare specie Macrogenioglottus alipioi was found within the studied área, pointing out the importance of this Forest remnant conservation.
Mestre
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Greenwald, Katherine R. "Habitat fragmentation, functional landscape connectivity, and metapopulation processes in amphibians". Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1243366608.
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Miller, Courtney A. "Understanding the impacts of current and future environmental variation on central African amphibian biodiversity". ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2542.
Texto completoResumen
Global climate change is projected to impact multiple levels of biodiversity by imposing strong selection pressures on existing populations, triggering shifts in species distributions, and reorganizing entire communities. The Lower Guineo-Congolian region in central Africa, a reservoir for amphibian diversity, is predicted to be severely affected by future climate change through rising temperatures and greater variability in rainfall. Geospatial modelling can be used to assess how environmental variation shapes patterns of biological variation – from the genomic to the community level – and use these associations to predict patterns of biological change across space and time. The overall goal of this dissertation is to examine potential impacts of climate change on amphibian diversity in central Africa. Geospatial modeling is used to: 1) map the distribution of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd) in a biodiversity hotspot in Cameroon under current and future climate; 2) assess phenotypic and adaptive genomic variation in a widespread frog species, Phrynobatrachus auritus, in order to predict areas where populations may best adapt under climate change; 3) determine how amphibian community composition may shift with climate change and which areas may experience greatest loss of functional groups. Findings show that most Bd samples belong to a globally hypervirulent lineage. However, areas of highest predicted environmental suitability for Bd are predicted to shrink under warming temperatures. Within P. auritus, most phenotypic and genomic turnover occurred across known ecological gradients and are heavily influenced by seasonal precipitation. Current amphibian beta diversity is greatest throughout the Cameroonian highlands and forest-savanna ecotones flanking the central Congolian lowland forests. Greatest shifts in community composition under climate change are predicted to occur in coastal Cameroon and its eastern border whereas the greatest predicted loss of functional richness was in central Gabon. Overall, this dissertation shows that areas of elevated environmentally-associated phenotypic, genomic, and community turnover are associated with key ecological gradients. Regions predicted to experience high genomic mismatch, large shifts in community composition, and high loss of functional richness resulting from climate change may warrant conservation attention.
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Brom, Peta. "There might be a frog in McElligot's Pool: a study of the habitat characteristics and social factors associated with amphibian presence in urban residential gardens in a suburb in Cape Town". Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27525.
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This thesis engages with urban ecology through the lens of garden amphibians within a community in Cape Town. The study explores habitat and maintenance features associated with amphibian presence and the social processes underpinning attitudes towards amphibians, with the aim of strengthening knowledge underpinning the "what" (knowledge of natural requirements), "Why" (social drivers for urban landscape form and management), and the "how" (working with people, for garden biodiversity initiatives. To explore the "Why" component, a social survey was conducted with 192 members of the community. One‐way anova and correspondence analysis were used to explore the relationship between values, culture, knowledge and memories of early childhood experiences against a general attitude towards frogs and toads. The findings are consistent with the theoretical framework of Connectedness To Nature where positive attitudes are supported by normative values, cultural beliefs, knowledge and positive experiences with care‐givers and role‐models. The garden habitat component of the study sought to explore the technical questions of the "What" requirement for amphibian presence in gardens. It was loosely based on the BIMBY tool with adaptations for context and targeted species. 50 gardens were visited and surveyed. They were divided into two groups for comparison: Those in which residents reported amphibian presence, and those which did not. Results indicate that the cape river frog (A. fuscigula) and clicking stream frog (S. grayii), are attracted to gardens with moderate to dense vegetation at groundcover level. Gardens with moderately planted beds were more likely to report frogs if they had additional resources, in particular, ponds and mulch. The "How" question brought together the two themes in a discussion on citizen mobilization and ways in which community groups are successfully implementing urban ecology conservation and reconciliation strategies. This work is important for urban nature conservation which seeks to engage private land‐owners (garden enthusiasts) and community and citizen groups in implementing urban biodiversity projects.
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Rodrigues, Murilo Guimarães 1978. "Estimating vital rates with imperfect detection in amphibian and reptile populations = Estimando taxas vitais com detecção imperfeita em populações de anfíbios e répteis". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316218.
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Orientador: Ricardo Jannini SawayaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A ecologia de populações investiga os fatores que levam a variação das taxas vitais e, consequentemente, no número de indivíduos. Isso inclui testar hipóteses sobre aspectos da história de vida das espécies e entender os fatores que podem modular a dinâmica populacional. No entanto, a obtenção de dados para testar hipóteses pode ser difícil para populações que apresentam probabilidades de detecção < 1, como anfíbios e répteis. A marcação e recaptura é amplamente usada para estimar a detecção e inferir aspectos de dinâmica populacional e testar hipóteses ecológicas. Neste trabalho empregamos a teoria de marcação e recaptura para testar hipóteses relacionadas à ecologia e conservação de populações de anfíbios e répteis. Utilizamos o programa MARK para implementar modelos de populações abertas e fechadas incorporando a probabilidade de detecção dos indivíduos, para obter estimativas de sobrevivência, e outros parâmetros populacionais usando máxima verossimilhança. Organizamos esta tese em quatro capítulos. Iniciamos enfatizando a importância da probabilidade de detecção, além de simular cenários hipotéticos para demonstrar a relação entre esforço de campo, tamanho ótimo amostral e viés amostral. Em seguida comparamos o efeito de duas técnicas de marcação, o corte de artelhos e o implante de microchips, sobre a sobrevivência individual do sapo ferreiro, Hypsiboas faber. No terceiro capítulo estimamos a sobrevivência e o crescimento populacional da jararaca-ilhoa, Bothrops insularis incorporando emigração temporária aos modelos. Além do estudo de taxas vitais e de dinâmica nas populações, a alocação de energia e suas consequências na sobrevivência individual podem ser testadas com modelos de marcação e recaptura. Assim, no quarto e último capítulo consideramos dois caracteres sexuais presentes no sistema de acasalamento dos lagartos, o tamanho da mandíbula e a coloração chamativa, para comparar as estimativas de sobrevivência entre machos e fêmeas do lagarto cauda de chicote, Cnemidophorus cf. ocellifer. . De forma geral, observamos que a probabilidade de detecção individual nos sistemas estudados foi baixa e condizente com a detecção de vertebrados em ambientes tropicais. Além disso, a inclusão de covariáveis na investigação de parâmetros vitais e no processo de detecção é fundamental para o melhor entendimento dos fatores que explicam a dinâmica de uma população. Especificamente observamos que: (i) demonstramos que as taxas que não incorporam a detecção são enviesadas em relação às estimativas que consideram a detecção, (ii) as estimativas de sobrevivência foram similares em indivíduos de Hypsiboas faber marcados com ablação de artelhos e microchips , (iii) Bothrops insularis apresentou baixa probabilidade de sobrevivência anual e crescimento populacional anual negativo. Por fim, (iv) machos maiores do lagarto Cnemidophorus cf. ocellifer apresentaram sobrevivência mensal menor do que machos menores, mas o oposto foi observado para as fêmeas
Abstract: Population ecology aims to search for factors that lead to variation in vital rates and consequently, in the number of individuals. This includes testing hypotheses about natural history traits and threats to populations. However, obtaining data to test hypotheses is challenging because following individuals in the field can be difficult, especially for amphibians and reptiles, where detection probabilities are often < 1. Mark-recapture methods are widely used to estimate detection probabilities and to test ecological hypothesis. Here we used mark-recapture methods to test hypotheses related to ecology and conservation of amphibian and reptile populations. We implemented open- and closed-population models in Program MARK, to account for detection probabilities and to calculate survival estimates and other population parameters. We organized this dissertation into four chapters. In the first chapter we emphasize the importance of considering detection probabilities besides simulating hypothetical scenarios to show the relationship between field effort, sample size and precision. In the second chapter we used a Cormack-Jolly-Seber model to compare the effect of two amphibian marking techniques, toeclipping and PIT tagging, on survival in the blacksmith tree frog, Hypsiboas faber. In the third chapter our goal was to estimate survival and population growth of the golden lancehead, Bothrops insularis accounting for temporary emigration using Pollock's Robust Design. Besides the study of vital rates and population dynamics, energy allocation and its consequences for survival are testable with mark-recapture models. Thus, in the last chapter we used two traits from the lizard mating system, namely jaw size and courtship coloration, to compare survival estimates between males and females of the whiptail lizard, Cnemidophorus cf. ocellifer. In summary we observed that detection probability on the studied populations were low and similar to other vertebrate populations from the tropics. However, including covariates in estimation models of vital rates and detection is important to obtain more accurate results to explain population dynamics. Specifically we conclude that (i) return rates were biased low in relation to survival estimates that account for detectability, (ii) the estimates of survival were similar between toe-clipped and PIT tagged individuals of Hypsiboas faber, (iii) Bothrops insularis showed low survival probability and negative annual population growth. And (iv) larger Cnemidophorus cf. ocellifer males showed lower monthly survival probability than smaller males but the opposite was found for females
Doutorado
Ecologia
Doutor em Ecologia
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Distel, Christopher A. "Effects of an Insecticide on Competition in Anurans: Could Pesticide-Induced Competitive Exclusion be a Mechanism for Amphibian Declines?" Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1280363910.
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Haggerty, Christopher J. E. "Importance of Forest Structure for Amphibian Occupancy in North-Central Florida: Comparisons of Naturally Regenerated Forests with Planted Pine Stands". Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6509.
Texto completoResumen
Once dominant, longleaf pine forests of the southeastern United States have been modified by 97 percent, resulting in several animal species being listed as endangered and threatened. Pine plantation silviculture (tree plantings) now occupies half of the original longleaf range where several animal species of conservation concern have experienced recent local population declines. In North America, the accepted practice of pine plantations is to plant pines densely in rows for wood production. Given that land use is considered a primary local driver for the 30% of amphibian species currently at risk of extinction, and planted pine is predicted to expand coverage by 2020, sustainable land management will require integrating ecological and economic goals, including conservation objectives. To understand how amphibian species characteristic of longleaf pine forest are affected by planted pine forestry, it is necessary to understand how associated shifts in habitat structure associated with aging pine stands influence species composition across a wide geographic area, especially populations of rare species. The purpose of this dissertation is to examine how forest structure (natural regeneration vs plantation) affects amphibian species composition and occupancy of small isolated wetlands embedded within the forest. Particular emphasis is placed on assessing several potential causal mechanisms of regional declines in amphibian species. This study was performed on Florida public forests where active forest management is a potential conservation tool and historic populations of rare amphibians occur. Sites where occupancy was assessed included: Goethe State Forest, Ocala National Forest, Jennings State Forest, Saint Marks National Wildlife Refuge, and Apalachicola National Forest. Withlacoochee State Forest was used for examining potential causal mechanisms of amphibian declines because of close proximity of reference condition forest to planted pine.
Chapter One of this dissertation uses Objective Based Vegetation Monitoring (OBVM) metrics to quantify differences in forest habitat structure surrounding study sites (among planted pines and naturally regenerated second growth pine) and relationships between vegetation metrics. Increased basal area of planted pine resulted in decreased canopy openness and a significant decrease of ground cover, especially wiregrass. Serenoa repens petiole counts and percent cover of woody shrubs also significantly decreased wiregrass cover, and variance partitioning indicated that the effects of woody shrub invasion and pine basal area on wiregrass were independent on public forests. Absence of bare ground because of pine needle litter was a significant predictor of wiregrass absence in a zero-inflated negative binomial model (ZINB). ZINB predictions for wiregrass cover along a gradient of pine basal area and woody shrub abundance demonstrated the importance of habitat management for native groundcover on public forests. OBVM metrics were often positively correlated within the canopy, subcanopy, and groundcover categories.
Chapter Two presents the results of site occupancy modeling comparing the presence of 10 species of amphibians in planted pine and naturally regenerated forest, focusing on the influence of canopy and groundcover habitat structure on occupancy of individual amphibian species. Amphibian species of greatest conservation need (SGCN) in Florida adapted to xeric soils, i.e. the gopher frog (Lithobates capito) and striped newt (Notophthalmus perstriatus), were found where basal tree areas were below 10.3 m2/ha, and a mesic amphibian SGCN, the ornate chorus frog (Pseudacris ornata), was found at pine basal areas up to 13.1 sq. m2/ha. All SGCN were found at sites with average woody shrub cover below four percent, and litter cover below 80 percent. Wiregrass cover was higher than four and six percent per m2 at sites with L. capito and N. perstriatus, respectively. Of 33 site detections for SGCN, only three sites had < 2.5 m2 wiregrass cover. Only one species, the pinewoods treefrog (Hyla femoralis), was more common on planted pine stands, and both Lithobates sphenocephala and L. grylio had constant probability of occupancy regardless of forest type. Percent wiregrass cover was a significant predictor of occupancy for five species, particularly for State listed species L. capito and N. perstriatus, suggesting it may be a useful indicator of habitat quality for longleaf-dependent amphibians.
Chapter Three focuses on experimental release of juvenile southern toads into two types of terrestrial enclosures to independently determine if amphibian movement and desiccation is determined by forest management. Movement enclosures consisted of four 50 m x 2.5 m unidirectional runways joined at the center to determine movement rate, distance, and behavior among forests of varying habitat structure. Movement rates were relatively consistent among forest types and positively related to rainfall, which itself did not vary among forests. Canopy closure and ground slope were predictors of behavior as toads move preferentially toward canopy openings and negative slopes, particularly when in planted pine habitat. Ten desiccation enclosures, each 15 cm diameter by 45 cm tall, were used to determine water loss and survival of toads for up to 72 hours. The proportional water loss from toad bodies was significantly related to ambient soil moisture at enclosures, with moisture consistently less at planted pines sites in xeric soil, suggesting a potential source of mortality for species specialized to sandhills. Juvenile survival was particularly low at sandhills planted with pine where dry duff replaced native groundcover and likely prevented successful water conservation behavior.
The results of these studies suggest that land management decisions related to planted pine forests will determine the species composition at embedded isolated wetlands for both rare and common amphibians. As natural disturbance regimes that limit woody shrub invasion are replaced by plantation silviculture tree plantings that further decrease light transmittance, native groundcover is reduced to greater extent than stands allowed to naturally regenerate following past timber harvest. Current and predicted expansion of pine plantation will particularly limit occupancy for amphibian SGCN endemic to sandhills, where planting dense pines lowers ambient soil moisture and juvenile survival. The vegetation metrics presented will allow land managers to guide forests toward conservation goals, to predict suitability of forests for amphibian species, and enhance success when repatriation efforts are needed. The significant relationship of amphibian occupancy to sensitive herbaceous vegetation (wiregrass) highlights that greater emphasis on forest groundcover is needed where amphibian SGCN occur and that cumulative impacts of forest management on native groundcover should be considered.
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Krynak, Katherine L. "ENVIRONMENTAL INFLUENCES ONAMPHIBIAN INNATE IMMUNE DEFENSE TRAITS". Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1435590530.
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Larson, Danelle Marie. "The influence of fire and grazing on tallgrass prairie streams and herpetofauna". Diss., Kansas State University, 2014. http://hdl.handle.net/2097/17560.
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Doctor of PhilosophyDivision of Biology
Walter K. Dodds
Tallgrass prairie evolved with fire-grazer interactions. Fire and grazing are vital processes for maintaining grasslands and cattle production, and therefore will be continued as land management schemes. The effects of fire and grazers on prairie streams are understudied, but may significantly influence stream ecology. This dissertation examined how prescribed burning, bison grazing, and patch-burn grazing (by cattle) influence water quality, stream biota, and riparian amphibians and reptiles at Konza Prairie, Kansas, or Osage Prairie, Missouri. Using Global Positioning System, we monitored bison and cattle distribution throughout watersheds. The immediate effects of prescribed burning were examined at both Konza and Osage Prairies. The impacts of bison on water quality were determined by using a long-term dataset from Konza Prairie and compared watersheds with and without bison. Amphibian and reptile assemblages were monitored for two years at Osage, and assemblage data were analyzed using redundancy analysis, permuted analysis of variance, and occupancy modeling. A patch-burn grazing experiment occurred for 5 years at Osage (2 years pretreatment data and 3 years of treatments) and was analyzed using a before-after, control-impact design. Prescribed burning had minimal effects on water chemistry. At Konza Prairie, bison did not alter water quality likely because they spent negligible time (<5%) in streams. Contrarily, cattle at Osage Prairie significantly increased stream concentrations of total suspended solids, nutrients, Escherichia coli bacteria, algal biomass, and primary production. Unlike bison, cattle spent significant time (~21%) in streams if allowed access to riparian zones. In watersheds with cattle excluded from streams by riparian fencing, water quality contaminant concentrations increased significantly, but not to the magnitude of unfenced streams. Amphibian abundance and richness were not different among patch types; instead, they were restricted to specific basins. However, reptiles displayed preference for certain patch-types, and had the highest abundance and richness in watersheds with fire and grazing. These results have implications for natural resource management. Riparian fencing of cattle may be a useful practice in areas where water resource protection is the priority. However, overland flow may alter water quality in watersheds with grazers despite fencing. Land managers will need to define management objectives and accept trade-offs in water quality, amphibian and reptile habitat, and cattle production.
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Korfel, Chelsea Anne. "Distribution and environmental correlates between amphibians and the fungal pathogen, Batrachochytrium dendrobatidis". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1350573649.
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Porej, Deni. "Faunal aspects of wetland creation and restoration". Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1078327758.
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Thesis (Ph. D)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xii, 120 p.; also includes graphics. Available online via OhioLINK's ETD Center.
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Graziano, Michael Paul. "The Role of Forest Composition on Pool-breeding Amphibians: Colonization, Larval Communities, and Connectivity". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492685290070103.
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Bartoszek, Joseph E. "Genetic Differentiation in Ambystomatid Salamanders Across a Fragmented Landscape". Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1259031878.
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