Climate change and exotic plant invasions are significant anthropogenic threats to desert community structure and resilience . In the Mojave Desert, the invasive grass red brome (Bromusrubens L) is increasing fire frequency and extent in response to climatic factors. The resilience of this ecosystem will be affected by how plant and animal communities respond to fire. To better understand these dynamics, we studied the environmental factors underlying changes in invasive grass fire regimes in the Mojave Desert and its structural and functional effects on plant and animal communities. Following fire, reestablishment of native vegetation can be preempted by repeated burning associated with the abundant exotic grass red brome. Red brome density is correlated with various climate and landscape variables, but to establish causality, we experimentally assessed germination and growth of red brome. Red brome responded positively to fall precipitation, finer-textured soils, fertile-islands soils, and soils from burned landscapes. Red brome germination is maximized in wet fall periods when adequate water and optimal temperatures overlap . To evaluate landscape responses of pre- and post-fire plant communities and the potential for repeated burning we analyzed vegetation greenness (NDVI) data from 1985-2011 in response to temperature and precipitation. Landscape analysis indicated that the dominance of exotic grasses increases on post-fire landscapes. Following wet fall and winter seasons, high red brome productivity increases fire potential. Without mitigation, the establishment of an invasive-plant-driven fire regime is likely and may drive state transitions from arid shrublands to arid annual grasslands. Potential revegetation of post-fire landscapes will depend at least in part upon the physiological response of surviving vegetation to post-fire landscapes. Plant physiological responses to post-fire landscapes were generally neutral or positive, suggesting that revegetation of post-fire landscapes is not precluded by resource loss associated with fire and may even be enhanced by post-fire conditions. This will likely translate to increased reproductive potential of surviving plants. Alterations to small mammal populations will likely play a role in the reestablishment of vegetation (both native and exotics) as small mammals have strong top-down effects in arid ecosystems. Diversity and species richness responded negatively to burned landscapes as Merriam's kangaroo rat (Dipodomys merriami) increased in abundance while other species practically disappeared from burned landscapes. Merriam's kangaroo rat affects propagule sources through direct consumption, and seed dispersal. Increases in abundance and dominance of Merriam's kangaroo rat will likely alter plant recruitment.

This thesis is the culmination of a graduate research project involving a floristic survey of the lichens of the Spring Mountain National Recreation Area (SMNRA), Humboldt-Toiyabe National Forest, Nevada. The project was based on extensive collections made between 1997 and 2007 as part of an air pollution biomonitoring program and a baseline established by Larry St. Clair (BYU). The Spring Mountains are a sky island mountain range in the Mojave Desert located less than an hour northwest of Las Vegas. A floristic survey of the lichen communities in the Spring Mountains represents a major addition to our understanding of the lichen flora of the Mojave Desert, a poorly studied region in western North America. This thesis also compares the lichen flora of the SMNRA with other lichen floras of the Mojave Desert based on a literature survey of all the lichen studies conducted in the Mojave Desert. The SMNRA species list represents 58% of the 217 species in 68 genera reported for the Mojave Desert. This survey of all reported Mojave lichen species reveals several interesting interactions related to species diversity, substrate, and growth form distribution patterns. These interactions appear to be influenced by two general factors: Microhabitat conditions and available substrates – which are further defined by differences in geological substrates, occurrence and development of woody plant communities, and a combination of environmental factors – elevation, temperature, precipitation, and insolation. Drier and warmer habitats are generally dominated by crustose species with some, mostly smaller, foliose taxa in protected microhabitats usually with shaded or northern exposures. Fruticose species are generally lacking or sparse with smaller thalli when found in hot and dry habitats. All the fruticose species reported from the Mojave Desert sites were rare and had very small thalli. Many foliose and fruticose species, with larger, more complex thalli and thus greater surface area, are more susceptible to higher rates of water loss and therefore occur less frequently in extreme arid locations. The lichen communities in the Mojave Desert respond to sharp contrasts in microhabitat conditions with exposed, lower elevation sites having lower numbers of species along with more drought resistant growth forms – crustose and squamulose species. The Spring Mountains NRA, with high elevation mountains and well developed woody plant communities, accommodates a large variety of microhabitat conditions spread over a complex temperature and moisture gradient. These conditions have resulted in the highest species diversity (124 species in 48 genera) and the greatest number of foliose and corticolous species when compared with all of the other Mojave Desert lichen floras.

No description available.

Durch Parasiten stellen eine starke Gefährdung für die Aquakultur dar. Die durch diplomonaden Flagellaten bei der Regenbogenforelle Oncorhynchus mykiss verursachte Morbidität und Mortalität wurde bisher in Deutschland noch nicht gründlich untersucht. Ich habe diese Parasiten mittels SEM & TEM charakterisiert und wurde die Art Spironucleus salmonis bestimmt. Erstmals konnten die caudale Projektion, sich entleerende Vakuolen und verformbare Kernloben nachgewiesen werden. Ich untersuchte Mikrohabitatpräferenz von des Parasiten sowie pH-Profile in vier Darmabschnitten der Fische. Das Vorkommen und die Dichte von S. salmonis war in der Pylorusregion wesentlich höher als in anderen Bereichen. Das pH-Profil war bei infizierten und nicht infizierten Fischen gleich. Der optimale pH-Wert für S. salmonis war 7,1-7,5. Ich habe die Lebenszyklus der Diplomonaden mittels LM & SEM unter Kulturbedingungen untersucht. Die Enzystierung begann mit der Anheftung von Trophozoiten mit der Spitze der adhäsiven hinteren Flagellen aneinander oder an Fremdkörper. Die pyriformen Trophozoiten wurden kugelförmig, und die vorderen Flagellen inaktiv. Oberflächenbläschen produzierten eine lichtbrechende Zystenwand. Dies ist der erste Beschreibung der Multifunktionalität von Flagellen bei Diplomonaden. Ich untersuchte pathogene Mechanismen und sezierte die Pylorusregion sowie die Leber mittels H&E, PAS/AB. Bei infizierten Fischen trat eine signifikante Hypertrophie der Becherzellen auf. Zu erkennen war eine Hyperaktivität der Becherzellen, jedoch keine Hyperplasie. Ich entwickelte einen in vitro  Plasma-Inkubationstest zur Bestimmung der Suszeptibilität von Regenbogenforelle, Karpfen und Störe. Die unterschiedliche Resistenz von Stör, Karpfen und Regenbogenforelle gegen S. salmonis entsprechend zu den epizootiologischen Daten. Meine Untersuchungen führten zu einem neuen diagnostischen Hilfsmittel, Vorschlägen für neue Behandlungsmethoden, zu verbesserten in vitro-Kulturbedingungen und einem Modellsystem für die Multifunktionalität von Flagellen und flagellaren Signaltransduktion. / Parasitic diseases pose a significant threat to aquaculture. Diplomonad flagellates in rainbow trout Oncorhynchus mykiss are associated with morbidity and mortality; but in Germany has not been thoroughly studied. I characterised the species by SEM & TEM, which revealed Spironucleus salmonis, allowed its complete description including newly showing the caudal projection, discharging vacuoles, and deformable nuclear lobes; diagnostic keys were improved. The microhabitat preference of diplomonads was tested by recording occurrence and density of infection, and pH profile in 4 intestinal regions in fish. Occurrence and density of S. salmonis were significant higher in the pyloric region than elsewhere. The pH profile in uninfected and infected fish was similar; a causal relationship between microhabitat preference and pH was unlikely, and the optimal pH was between 7.1 – 7.5. I described life cycle and encystment using light and SEM. Encystment in culture began by trophozoites attaching at tip of adhesive posterior flagella to each other/debris. Pyriform trophozoites became sub-spherical, anterior flagella inactive, surface blebs produced a refractile cyst wall. Cysts clusters may exceed minimum infective dose for new infection; suggesting new treatment target. This is the first report of multi-functionality of flagella in diplomonads. I investigated pathogenic mechanism of diplomonads by sectioning and staining the pyloric region of the intestine and liver with H&E, and PAS/AB. There was significant hypertrophy of goblet cells in infected fish. The hyperactivity of goblet cells was seen, but no hyperplasia. This hyper-production of mucus may decrease nutrient absorption, underlying impaired growth in S. salmonis infected fish. I developed an in vitro plasma incubation test to predict host susceptibility of rainbow trout, carp, and sturgeon. The test showed the hierarchy of resistance of S. salmonis in sturgeon > carp > rainbow trout; this parallels epizootiological data. My research yielded new diagnostic tool, suggested new treatment target, improved in vitro conditions, and new model system for multi-functionality of flagella and flagellar signalling.

Nous avons étudié les mécanismes d'impact de l'algue envahissante Caulerpa taxifolia (Vahl) C. Agardh sur les poissons en Méditerranée, en particulier à l'aide d'une étude approfondie sur une espèce « modèle » : Symphodus ocellatus (Forsskål). Un suivi des peuplements de poissons ainsi que des expérimentations in situ ont été réalisés au niveau du département des Alpes-Maritimes, sur des milieux colonisés par l'algue et des milieux témoins. Caulerpa taxifolia qui forme des prairies de frondes très denses et hautes, de la fin de l'été jusqu'au début de l'hiver, représente une gêne physique pour l'accès à la nourriture benthique et aux microhabitats. Le suivi de deux récifs artificiels crées in situ a montré que l'envasement et l'obstruction de cavités par C. taxifolia diminuent la capacité d'accueil d'un milieu rocheux pour la faune ichtyologique. La raréfaction d'abris convenables mène à une augmentation de la mortalité des petits individus par prédation. L'étude de contenus digestifs ainsi que des acides gras corporels chez S. ocellatus montre un changement de régime alimentaire sur les milieux envahis (augmentation de la consommation de plancton au détriment des proies benthiques). En aquarium, nous avons montré que l'accessibilité aux proies benthiques diminue avec la densification de l'algue. Nous avons observé in situ que C. taxifolia pose également le problème de l'accès et de la détection des proies benthiques pour les rougets de roche Mullus surmuletus. Sur les milieux colonisés, le bilan énergétique global se traduit par des déficits de 21% dans le contenu lipidique corporel chez les jeunes S. ocellatus et de 59% dans les lipides de stockage du foie ainsi que par un déficit pondéral au niveau du foie et des ovaires chez les femelles reproductrices. Cependant, la qualité des œufs n'est pas affectée. Par ailleurs, in situ, les toxines de C. taxifolia n'ont pas d'influence sur le succès de développement embryonnaire de S. ocellatus.

Les acariens microprédateurs du genre Dermanyssus (espèces du groupe gallinae), inféodés aux oiseaux, représentent un modèle pour l'étude d'association lâche particulièrement intéressant : ces arthropodes aptères font partie intégrante du microécosystème du nid (repas de sang aussi rapide que celui du moustique) et leurs hôtes sont ailés. En outre, D. gallinae est une espèce d'importance économique, ce qui rend possible des comparaisons entre colonisation de milieux anthropisés et sauvages. Au début de l'étude, les espèces du groupe gallinae sont très mal délimitées. Les caractères morphologiques utilisés sont variables au sein de l'espèce, voire de la population, très chevauchants entre espèces. Afin de mieux comprendre les exigences écologiques du développement de D. gallinae et d'appréhender ses voies de dissémination, une investigation comparative basée sur des séquences d'ADN entre espèces du groupe gallinae a été adoptée. Un cheminement d'ordre taxinomique a permis de poser les bases nécessaires. Ensuite, l'exploration de certaines caractéristiques écologiques du groupe gallinae en relation avec sa phylogénie (spécificité d'hôte, flexibilité évolutive) a été menée à bien. Une espèce a été décrite, D. apodis, une lignée de D. gallinae constitue aussi une probable espèce inédite et D. longipes regroupe deux entités. Des différences écologiques marquées entre D. gallinae et les autres espèces semblent résulter non seulement de l'activité humaine, mais aussi de caractéristiques intrinsèques. Aujourd'hui, le rôle des flux commerciaux dans la dispersion de D. gallinae en élevage de pondeuses s'avère primordial, au moins en France, celui des oiseaux sauvages presque nul.

No description available.

The thesis addresses several aspects of ecology of lowland rainforest avifauna in Papua New Guinea. It describes spatial and temporal distributional patterns of abundance and diversity of bird community and different feeding guilds. More specifically, spatial patterns were explored in relation to topography, tree species composition, forest structure including vertical forest strata and inter-specific associations. The thesis also focuses on nest survival in continuous and fragmented forest, particularly in relation to nest predation.

Fundação de Amparo a Pesquisa do Estado de São Paulo / The oviposition site selection may influence both offspring development and female fitness. Females of the harvestman Bourguyia hamata exhibit maternal care and oviposit almost exclusively inside the epiphytic bromeliad Aechmea nudicaulis in the Cardoso Island, SP. In the present study, I examined whether the morphological structure of the individuals of A. nudicaulis influences B. hamata oviposition site selection in a sandy coastal forest at Cardoso Island, SP, Brazil. Data about the presence of the egg-batches inside the bromeliads, the length of the rosettes (which are tubular), the bromeliad angle in relation to the soil and the amount of debris inside the bromeliads were obtained along a 700 m transect from February 2005 to January 2006. Additionally, I used data collected in 2001 about water volume inside the rosettes, as well as the variation in the humidity inside bromeliads with long (30-32 mm) and short (18-20 mm) rosettes, as well as in the external environment. The frequency of egg-batches was greater in individuals with angles among 90º to 150º, for which the amount of debris accumulated inside the rosettes was smaller. Longer rosettes were preferred as oviposition site by the B. hamata females. Moreover, bromeliads with longer rosettes accumulated more water inside them, keeping the humidity variation inside the bromeliads lower than the external environment. Females of B. hamata selected a single bromeliad species and also chose morphological characteristics of A. nudicaulis individuals. Females oviposited predominantly in bromeliads that accumulate more water and have small amounts of debris inside the rosettes, probably because these characteristics may promote a more adequate microhabitat for offspring development. / A escolha do sítio de oviposição pode ter várias implicações no desenvolvimento da prole e na aptidão da fêmea. As fêmeas do opilião Bourguyia hamata exibem cuidado maternal e utilizam exclusivamente a bromélia Aechmea nudicaulis como sítio de oviposição na Ilha do Cardoso, SP. Neste estudo investigou-se se características arquiteturais de A. nudicaulis podem influenciar sua escolha como sítios de oviposição por B. hamata na restinga da Ilha do Cardoso, SP. Dados sobre a presença de desovas no interior das bromélias, o comprimento das rosetas (em forma tubular), o ângulo da inclinação das bromélias em relação ao solo e a quantidade de detritos acumulada no interior das bromélias foram obtidos ao longo de um transecto de 700 m entre fevereiro de 2005 a janeiro de 2006. Adicionalmente, foram usados dados coletados em 2001 sobre o volume de água no interior da roseta, assim como sobre a variação de umidade ao longo do dia no interior de bromélias grandes (30-32 mm) e pequenas (18-20 mm) e também no ambiente externo. A freqüência de desovas foi maior em indivíduos com inclinações entre 90º e 150º, para os quais a quantidade de detritos no interior da bromélia foi menor. Rosetas maiores foram mais usadas como sítio de oviposição por fêmeas de B. hamata. Além disso, bromélias maiores acumularam mais água no seu interior, de forma que a variação da umidade relativa foi menor dentro das bromélias grandes quando comparada com o ambiente externo. Fêmeas de B. hamata, além de escolherem apenas uma espécie de bromélia, conseguem acessar também características estruturais dos indivíduos de A. nudicaulis. As fêmeas ovipuseram predominantemente nos indivíduos que acumularam mais água e possuíam menos detritos nas rosetas, provavelmente porque essas características devem promover um microhabitat mais adequado para o desenvolvimento da prole. / Mestre em Ecologia e Conservação de Recursos Naturais

No description available.