Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 65-67).

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 52-54).

North American Giant Salamanders (Cryptobranchus alleganiensis), commonly known as hellbenders, have been experiencing a population decline for decades due to human influences, such as pollution and habitat destruction. Many efforts are underway to save the hellbender but their entire potential geographical range has not been well-studied. Currently, hellbender populations are delineated by county boundaries and are on the International Union for Conservation of Nature Red List. The Genetic Algorithm for Rule-set Production, an Ecological Niche Model, was used to model the current hellbender potential distribution at a macro-scale under two different environmental scenarios. Additionally, future potential distributions were projected under two different climate change scenarios (Representative Concentration Pathways) to predict where possible habitat loss and expansion may occur in coming decades. Niche modeling was also used to evaluate the influence of environmental parameters across geography and between two sub-species of hellbender, the Eastern hellbender and the Ozark hellbender. Results showed that vegetation indices had some influence on current distribution predictions, while future models revealed that potentially large areas of currently suitable habitat may be lost, especially in the Ozark Mountains and the Southern Appalachian Mountains. Habitat expansion was predicted for several areas in the New England region of the northern Appalachian Mountains. The most influential variables were the maximum temperature of the warmest month, temperature annual range, and annual precipitation, while slope and elevation were less influential. However, areas of very high slope and elevation were not suitable for hellbenders, confirming previous descriptive habitat analyses. Current and future modeled distributions will provide conservationists with a more specific, and quantified, geographical and ecological description of where environmentally suitable areas exist for hellbenders. Micro-scale, stream-based studies provide areas of future research.

Non-indigenous invasive species are a major threat to native species diversity and ecosystem function and have been called the single worst threat of natural disaster of this century. Eragrostis lehmanniana Nees (Lehmann lovegrass), a tufted perennial bunchgrass native to southern Africa, is one such problematic species in Arizona, USA. This dissertation research is a mix of predictive modeling and field experiments designed to inform management decisions based on greater understanding of this nonnative species, with emphasis on the potential for spread and the impacts of removal.The modeling studies in this dissertation aimed to predict the potential distribution of E. lehmanniana in the southwestern United States under current and potential future climate conditions. The first portion of study addressed a common assumption in predictive modeling of nonnative species: data from the species' native range are necessary to accurately predict the potential distribution in the invaded range. The second portion of this study predicted the distribution of E. lehmanniana under 28 different climate change scenarios. Results showed the distribution of E. lehmanniana progressively shrinking in the southeastern and northwestern portions of the state and increasing in the northeastern portion of the state with increasing temperatures and precipitation. Key shifts occurred under scenarios with increases in summer and winter precipitation of 30% or more, and increases in summer maximum and winter minimum temperatures of at least 2oC.The field experiment served as a pre-eradication assessment for E. lehmanniana and indicates how semi-desert grassland communities in southeastern Arizona may respond to the removal of this species. This study suggested that plant community response to removal of an introduced species is mediated by precipitation variability (timing and amount), local site history, and edaphic conditions. The response observed on a site previously farmed for decades was to subsequently become dominated by other nonnative annual species. However, the two other sites with histories of livestock grazing responded more predictably to the removal, with an increase in annual ruderal species (2 to 10 times the amount of annual cover recorded on control plots).

Invasive species are considered an agent of ecological change with more significant effects than global warming. Exotic plant invasions threaten biodiversity and ecosystem viability worldwide. Their effects in the Sonoran Desert ecosystems are a growing concern among ecologists and land managers. We hypothesized that highly dynamic desert environments are unstable, therefore more vulnerable to invasion by exotic plant species. To test this hypothesis we used a multidimensional approach to assess the spatial distribution of two exotic species: Brassica tournefortii (Saharan mustard) and Schismus arabicus (Arabian grass), in a portion of 'El Pinacate y Gran Desierto de Altar' Biosphere Reserve (PBR) in northwestern Sonora, Mexico. This approach combined genetic algorithms, geographic information systems, field methods, statistical analysis, and remote sensing modeling at multiple spatial and temporal scales to predict and test the current and potential distribution of the invasives over dynamic landscapes.Predicted probability of invasion was influenced strongly by human factors: Road networks were the strongest predictors of presence, revealing the potential importance of humans as vectors of invasiveness. Dynamic landscapes, associated mostly with vegetation losses, were detected spectrally in the eastern portion of the study area, very likely associated with past agricultural and current grazing activity. Combined models of high probability for invasion by B. tournefortii and S. arabicus over dynamic landscapes were tested against confirmed locations of the invasives and land cover types associated with invasion. Results confirmed the hypothesis of the study and suggest that more dynamic landscapes are more prone to invasion by these two exotic plants in the PBR. B. tournefortii was found associated mostly with landscapes occupied by microphyllous desert scrub and grassland, as well as sarcocaulescent desert scrub. S. arabicus was found more abundantly in the flat low lands occupied by microphyllous and crassicaulescent desert scrub. These relationships cannot, however, be conclusive and require further investigation due to the complex ecology of these invasives.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 87-91).

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La capacité des plantes à répondre aux stress de l'environnement, qu'ils soient de nature biotique ou abiotique, tient au fait qu'elles sont capables d'intégrer les signaux perçus grâce à des mécanismes de transduction du signal rapides et efficaces. La perception, le décodage et la mise en place de réponses biologiques adaptées font appel à de nombreux acteurs moléculaires tels que le calcium (Ca2+), second messager majeur de la signalisation Eucaryote. Parmi les "senseurs de calcium", la calmoduline (CaM) est la protéine la plus connue. Il existe des protéines apparentées à la CaM, spécifiques aux plantes, les Calmodulin-like (CMLs). Les CMLs sont très peu étudiées et la caractérisation de leurs rôles ouvre de larges perspectives sur l'identification des réseaux de régulation. L'objectif de ce travail de thèse a concerné un partenaire nucléaire d'une de ces CMLs, AtCML9, le Pseudo-Response Regulator 2 (PRR2), une protéine atypique contenant un domaine de liaison à l'ADN de type GARP et de fonction inconnue. Au cours de ce travail, des analyses moléculaires et biochimiques ont permis de caractériser le rôle de PRR2 dans l'immunité végétale, et en particulier en réponse à Pseudomonas syringae. L'étude de lignées perte ou gain de fonction a permis de mettre en évidence que PRR2 agit comme un régulateur positif des défenses lors de l'infection par la bactérie pathogène hémibiotrophe Pst DC3000 à travers la modulation de l'acide salicylique, de composés de défense tels que la protéine PR1 et la camalexine. Les analyses phénotypiques réalisées en réponse à différentes souches de Pseudomonas ont permis de préciser que PRR2 contribue à la mise en place des défenses à travers la signalisation dépendante de l'acide salicylique et de l'injection des effecteurs bactériens. Dans une deuxième partie, l'interaction entre PRR2 et des facteurs de transcription spécifiques aux plantes, les TCPs (Teosinte Branched 1, Cycloidea and PCF), a été étudié. Ces analyses ont montré une spécificité d'interaction entre PRR2 et TCP19 ou TCP20. Ces interactions stabilisent et relocalisent PRR2 dans des domaines nucléaires spécifiques. Ces données suggèrent une forte régulation post-traductionnelle de la protéine PRR2 qui pourrait s'avérer nécessaire à sa fonction biologique. / Plants are able to perceive and respond to diverse biotic or abiotic environmental cues. This ability relies on efficient signalling pathways that are ultimately associated with genetic reprograming. These responses involve various actors of the signalling pathways such as calcium (Ca2+) transients which act as a second messenger in eukaryotic cells. The variations in intracellular Ca2+ concentrations are perceived by calcium sensors. The calmodulin (CaM) is an ubiquitous Ca2+ sensor well studied both in animal and plant cells. Comparatively, plants also possess CaM-related proteins called Calmodulin-like (CMLs) which are less studied and their role in plant physiology are emerging. The objective of this PhD work was to perform the functional analysis of PRR2 (Pseudo-Response Regulator 2), a plant specific transcription factor (with a GARP DNA binding domain) previously identified as an AtCML9-interacting partner. Using diverse genetic tools, we were able to study the role of PRR2 in plant immunity using the model plant Arabidopsis thaliana and a phytopathogenic bacteria, Pseudomonas syringae. Our study has shown that PRR2 acts as a positive regulator of plant defenses upon bacterial infection. We show that PRR2 could act by modulating the biosynthesis of the salicylic acid (SA), and the production of defense-associated compounds such as PR1 and camalexin. Collectively our data indicate that PRR2 acts as a positive regulator of plant defense associated with SA. In the aim to better understand how PRR2 could be involved in different physiological responses, we search for PRR2-interacting partners. We have more precisely worked on the interactions between PRR2 and the TCPs (Teosinte branched 1, Cycloidea and PCF) which are also plant specific transcriptions factors involved in different biological processes. We showed that PRR2 specifically interact with TCP19 or TCP20. As consequences, these interactions stabilize PRR2 and relocalize the complex in specific nuclear subdomains.