Plant-herbivore interactions play a significant role in the structure and functioning of ecosystems. Co-evolutionary theory suggests that plant defenses evolved due to herbivores and herbivore pressure can shape the genetic composition of their food resources. We used interactions between North American porcupines (Erethizon dorsatum) and trembling aspens ( Populus tremuloides) as a system to investigate this theory's important assumption that herbivores select food sources based on genetically controlled traits. We confirmed that porcupines exhibit intra-specific food selection and that this is linked to the genetic composition of the aspens. We also demonstrated that variation in phenolic glycosides and condensed tannins are strong components of this selection, thereby creating an important link between genetics, plant chemistry, and mammalian herbivory. We investigated potential impacts of porcupine herbivory on aspen using fluctuating asymmetry, however we did not detect any stress on heavily eaten trees, thereby questioning the validity of this tool for this study system.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.A.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 85-90.

Different strains of rainbow trout (Salmo gairdneri), Ten Sleep, Sand Creek, Beitey, Shepherd-of-the-Hills, New Zealand, Fish Lake- Desmet, Desmet, were compared for survival to the creel, growth and catchability after being stocked in a fluctuating 80 ha Utah reservoir . Fish were stocked in the spring and fall as fingerlings and monitored by creel censusing, gill netting and electrofishing. Fish were tagged with coded wire snout tags prior to stocking . An angler opinion survey was conducted to determine angler satisfaction with numbers and size of fish caught. Regardless of strain, spring stocking was superior to fall stocking in survival to the creel. In the spring 78 stocking the Ten Sleep strain had the highest survival to the creel (33.7 percent), followed in order by Shepherd-of-the-Hills (11.0 percent), Beitey (5.5 percent), Sand Creek (5.4 percent), New Zealand (4.1 percent), and Fish Lake-Desmet (2 .9 percent). In the spring 79 stocking the Shepherd-of-the- Hills strain had the highest survival to the creel (7 .6 percent), followed in order by the Sand Creek (7.3 percent) and the Ten Sleep (6.5 percent). Similar trends in survival were found in gill netting and electrofishing samples. Migration out of the reservoir was negligible for each strain. There were no strain differences in catchability by different methods (shore, boat) or gear (bait, artificial lure). Differences in growth between the fastest growing strains (Ten Sleep, Sand Creek) and the slowest growing strains (New Zealand, Fish Lake-Desmet) averaged as great as 16 mm in length and 43 g in weight. Differences in growth and survival among strains were great enough to span the range of angler satisfaction with numbers caught and size of fish caught from satisfactory to unsatisfactory. Therefore, strain selection can be a useful tool to improve fingerling stocking programs and manipulate the number of anglers who are satisfied with the angling experience.

No description available.

The Wnt family of secreted proteins consists of 19 family members (in the mouse) and is known to signal through multiple pathways that regulate crucial processes in the development of almost all tissues. Dissecting the roles of individual Wnts has been hampered due to functional redundancy that exists between family members. We made use of a conditional allele of the acyltransferase, Porcupine (Porcn), that is required for the secretion of all Wnt ligands, and the Msx2Cre deleter to eliminate the secretion of all Wnt ligands from the ventral limb ectoderm, ventral abdominal ectoderm, and urogenital ectoderm. Phenotypically the limbs of these mice have several similarities with En1 mutant mice which have a double-dorsal phenotype. however, we show that appropriate dorsoventral limb pattern is maintained at the molecular level and that the observed defects are due to a failure to appropriately execute ventral pattern. Additionally, newborn mice lack ventral digital tendons and the most superficial musculature in the regions of strongest and earliest deletion. Molecular analysis indicates that tendons are lost downstream of the absent musculature and are initially patterned correctly. Thus we show a role for ectodermal Wnts in the development of underlying musculature. We additionally examine the role of limb mesenchymal Wnts in the development of deeper limb musculature utilizing the Prx1Cre deleter. The deep musculature of the autopod and zeugopod is reduced or absent in mutants and the development of superficial musculature appears to proceed normally. Hence we show that superficial muscles require only ectodermal Wnts and deeper muscles require only mesenchymal Wnts.

Cette étude documente la succession de phases de rift qui se sont formées le long d'une marge continentale dont l'évolution géologique a été particulièrement longue. Ce type d'évolution géologique est bien admise dans la littérature mais reste encore peu comprise en terme de processus géologiques. Ici, il est spécifiquement étudié comment ce type de rifts peut évoluer au cours du temps et il est tout particulièrement mis en évidence les processus de réactivation de failles et la formation des éléments géologiques associés dans l'évolution des bassins en extension. Cette étude résume les résultats principaux de deux projets de recherche menés sur(1) le Bassin de Porcupine (offshore irlandais) qui s'est formé pendant la propagation du système de rift nord-atlantique et (2) la région de la Mer de Corail (Papouasie Nouvelle Guinée) dont l'évolution en contexte de supra-subduction est liée à l'affrontement des plaques Pacifique et Australie. Ces deux projets de recherche discutent spécifiquement de l'enregistrement sédimentaire et de l'évolution des failles à partir de données sismiques corrélées à des données de puits, de magnétisme ou de gravimétrie.Les deux bassins ont évolué en bordure d'orogènes depuis le Paléozoïque supérieur. Il est démontré que l'extension s'est initiée au long de structures anciennes qui ont été réactivées lors de l'étalement orogénique mis en évidence par la migration de dépocentres. L'extension s'est ensuite développée de façon discontinue au cours de divers épisodes extensifs pulsés. Les premiers épisodes montrent en général des bassins étroits, plus ou moins discrets et qui sont remplis de dépôts continentaux qui passent progressivement à des environnements marins. L'extension est d'abord diffuse puis localisée le long de failles bordières qui accommodent l'ensemble de l'extension et le boudinage de la croûte. Au fur et à mesure que l'extension progresse, l'influence structurale de la croûte continentale diminue et la déformation évolue vers l'océan avant le stade ultime de déchirure continentale de façon très localisée. Le rifting se termine en général dès que les conditions aux limites changent, résultant en la production de bassins océaniques en propagateur qui sont transversaux aux bassins néoformés. Dans les marges classiques de type atlantique (p.ex. Bassin de Porcupine), ceci est lié à la propagation de croûte océanique dans des bassins plus ou moins perpendiculaires tels que le Golfe deGascogne dont l'ouverture stoppe la déformation extensive. Dans les zones en supra-subduction (par ex. Mer de Corail), la fin de l'extension est plutôt liée à un changement dans la dynamique de subduction qui peut contrôler l'ensemble de la propagation de l'océanisation.Ainsi, il apparait que l'extension migre progressivement depuis une zone initiale en réactivant d'anciennes structures orogéniques quelles que soit les conditions géodynamiques initiales. Ici, il est proposé qu'une phase de déformation souligne un mégacycle extensif durant lequel des grabens individuels, des bassins riftés ou des systèmes de rifts se forment successivement et surimposent les uns aux autres. Chaque mégacycle peut se définir sédimentologiquement et tectoniquement. La surimposition montre en général une déformation qui évolue progressivement vers l'océan par la réactivation spécifique de structures pré-existantes.L'initiation de l'extension et le passage d'un mégacycle à un autre est en général lié par un changement des conditions aux limites. / This study documents the succession of rifting phases that evolve along continental margins of longstanding history. This type of evolution, well admitted in the literature, remains poorly understood in terms of geological processes. Herein, the way rifts evolve through is specifically studied to highlight the fault reactivation processes and the formation of associated geological elements during the evolution of extensional basins. This study summarises some principal results of two research projects focussing on (1) the Porcupine Basin (offshore Ireland) that formed from the North-Atlantic rift propagation and (2) the Coral Sea region (Papua New Guinea) which the evolution within a supra-subduction context links to the convergence of the Pacific and Australian lithospheric plates. These two research projects specifically discuss the sedimentary record and the faulting evolution from seismic data correlated to wells, magnetism and gravimetry.Both basins evolved from the Late Palaeozoic on sides of orogens since the Late Palaeozoic. It is demonstrated that extension initiated along old structures that were reactivated during a general orogenic collapse evidenced by migration of depocentres. Then, extension discontinuously developed during several rifting events that are usually internally pulsed. The first rift events are usually very narrow and discreet, and evolve in a continental domain. Deformation progressively passes to localized normal faulting implying that major bounding faults progressively accommodate the extension. As long as extension progresses, the influence of continental structures tend to decrease and the deformation evolves oceanward prior continental tear. Extension generally stops once boundary conditions change, resulting in oceanic crust that may propagate transversally (oceanic propagators).Along classical Atlantic-type margins (e.g. Porcupine Basin), this links to the propagation of the oceanic crust but internal crosscutting oceanic basins (e.g. Bay of Biscay) stop the deformation prior to seafloor spreading that form the overall oceanic crust.In supra-subduction zones (e.g. Coral Sea), it is rather related to a change in the dynamics of the subduction which may control the overall direction of the spreading propagation.Thus, extension migrates progressively away from the initial deformation core by reactivating pre-existing structures, whatever geodynamic conditions are but with a general decrease in the influence of old continental fabrics. Herein, it is proposed herein that a deformation phase expresses as an extensional megacycle during which graben, basins or rift settings develop successively and overprint the ones another. Each extensional megacycle may be defined sedimentologically and tectonically. Their overlap generally shows an oceanward migration which reactivates specific pre-existing structures. The initiation of extension and the evolution from a megacycle another is generally linked associated to a variation of the boundary conditions.

Les veines sont parmi les structures les plus communes et les mieux développées le long des zones de cisaillement. Dans la ceinture de roches vertes de l'Abitibi (Canada), des systèmes de veines bien exposés le long de la zone de cisaillement Porcupine-Destor permettent d'étudier les conditions de contraintes dans lesquelles les veines se sont mises en place. Les systèmes de veines ont pu être caractérisés en examinant la texture, la géométrie, la distribution, l'espacement, l'épaisseur, et la longueur des veines, ce qui a permis de déterminer la surpression de fluide. La surpression de fluide moyenne pour l'un des systèmes de veines est estimée à 42 MPa, ce qui correspond à une profondeur de mise en place de 2.7 km. Ces estimations ont permis de modéliser l'état des contraintes lors de la phase de compression régionale. Les contrastes de compétence génèrent de fortes perturbations des contraintes le long de la zone de cisaillement. Dans la séquence de roches, la zone de cisaillement Porcupine-Destor agit comme une unité lithologique de faible compétence et génère une zone de faibles contraintes très favorable à la formation de veines. Vingt-cinq kilomètres plus à l'est, les veines se sont mises en place dans un contexte de faille-valve à fonctionnement cyclique; ceci indique que les veines résultent de la perturbation temporaire de l'état de contraintes lors de ruptures sismiques. Ces deux mécanismes de perturbation de la contrainte sont favorables à la formation de veines le long des zones de cisaillement. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Veines, Zones de cisaillement, Contraintes, Contraste de compétence, Abitibi.

No description available.

The Porcupine caribou herd is the focus of multiple stakeholder groups, all of which have different ways of understanding and valuing caribou. This thesis focuses on the knowledge and perspectives that the Teetł’it Gwich’in of Teetł’it Zheh (Fort McPherson, NWT) bring to Porcupine caribou co-management. This paper-based thesis has two major aims: first, to explore how the Teetł’it Gwich’in construct knowledge about caribou; and second, to explore Teetł’it Gwich’in rules-in-use with respect to caribou hunting. A comparison is made between Gwich’in methods of knowledge construction and rules-in-use with those of the Government of the Northwest Territories (GNWT), and the Porcupine Caribou Management Board (PCMB), with the intent of understanding difficulties in co-management. The thesis offers the concept of the Gwich’in Knowledge Complex, a knowledge complex created from multiple sources of information about caribou, including scientific information (mainly from the PCMB and the GNWT) as well as Traditional Knowledge. / Rural Sociology