O uso de animais de montaria em áreas naturais tem gerado grande preocupação, pois podem gerar impactos ambientais. Um dos problemas que precisa ser investigado é a relação entre animais de montaria e a presença de plantas exóticas em áreas de alto valor ecológico. Assim, o presente trabalho teve como objetivo testar um protocolo de germinação para sementes de duas espécies de gramíneas, braquiária (Urochloa decumbens) e capim gordura (Melinis minutiflora) que passaram pelo trato digestório de cavalos. As sementes foram ofertadas aos animais junto com a ração com posterior coleta das fezes. No experimento foram realizados três tratamento. No tratamento \"braquiária\" foram ofertadas sementes de Urochloa decumbens, no tratamento \"capim gordura\" foram ofertadas sementes de Melinis minutiflora e o \"sem tratamento\" foi ofertada apenas a ração. Parte das sementes foram retiradas das fezes e submetidas a testes de germinação e o material restante foi utilizado para testar a capacidade germinativa das sementes diretamente nas fezes em um ambiente controlado. Na germinadora verificou-se que as sementes que passaram pelo trato digestório dos cavalos tiveram uma menor taxa de germinação comparadas com as sementes com tratamento de quebra de dormência. No tratamento feito em casa de vegetação as sementes que foram retiradas das fezes e que germinaram foram identificadas. Não houve diferença na taxa de germinação entre os cavalos, o que ocorreu entre os tratamentos. No tratamento braquiária predominou a germinação de Urochloa decumbens, no tratamento capim gordura a maior taxa de germinação de Melinis minutiflora e no sem tratamento predominou o nascimento de outras espécies. As sementes estudas tem potencial de germinar, crescer e frutificar, porém não se sabe se as espécies podem formar uma população capaz de colonizar novas áreas. / The use of riding animals in natural areas has caused great concern because their use cause environmental impacts. One of the problems that needs to be investigated is the relationship between the use of riding animals and the presence of exotic plants in natural areas. This study aimed to test a germination protocol for the of two species Urochloa decumbens and Melinis minutiflora that has passed through the digestive tract of the horse. The seeds were offered to horses and their feces were collected. Tree treatments were set, in \"braquiaria\" treatment seeds Urochloa decumbens were offered to the horses, in the \"capim gordura\" treatment seeds of Melinis minutiflora offered and the untreated were offered only horse food. Part of the seeds were removed from the feces and undergo germination test and the remain of the feces were used to test in a green house. The germination rate of the seed from de horse dung was lower than germination rate of the dormancy breaking treatment seeds. The seeds that germinate on the greenhouse were identified. There were no difference between the germination rate between treatments, but there was between species in braquiaria treatment predominated the germination of Urochloa decumbens in the grass fat treatment most Melinis minutiflora germination rate and the untreated predominated the germination of other species. Seeds from horse dung has the potential to germinate, grow and bear fruit, but it is not known if this species can form a population able to colonize new areas.

Biological invasions threaten biodiversity globally, and degraded ecosystems increase the potential for invaders to compete with threatened native populations. In natural systems, niche partitioning minimizes interspecific competition, but introduced species may alter expected outcomes by competing with ecologically similar species for scarce resources. Where food production is highly variable, coexistence of native and invasive competitors may depend on dietary niche flexibility. Territorial species under invasion face additional challenges to maintain economically defendable territories. From 2011-2016, we conducted removal and behavior experiments to determine effects of non-territorial introduced Abert’s squirrels (Sciurus aberti) on diet, space use, and territoriality of endangered Mount Graham red squirrels (MGRS; Tamiasciurus fremonti grahamensis) in their declining habitat in the Pinaleño Mountains, Arizona. We collected comparative data from Arizona sites of natural syntopy between Abert’s and Fremont’s squirrels (T. fremonti). Stable isotope analysis revealed similar dietary partitioning among populations. Experimental removals did not appear to affect MGRS diet. Space use by MGRS responded inconsistently to removals; territory sizes increased after the first removal, but did not change following the second removal. Territory sizes and body mass of MGRS were sensitive to conspecific population density and food production. Behavioral experiments showed MGRS were more aggressive than other Fremont’s squirrels (hereafter, red squirrels). Dietary flexibility of Abert’s squirrels may have facilitated coexistence with MGRS, possibly due to coevolved resource partitioning with red squirrels. However, aggressive territoriality toward Abert’s squirrels may incur fitness costs for MGRS especially during poor food production years. Climate change may reduce the advantage of ecological specialist species globally, and where introduced species are better-adapted to novel environmental conditions, native species may ultimately be replaced.

Grasslands in the western United States face severe environmental threats including those brought about by climate change, such as changes in precipitation regimes and altered fire cycles; land-use conversion and development; and the introduction, establishment, and spread of non-native species. Lehmann’s lovegrass (Eragrostis lehmanniana) was introduced to the southwestern United States in the early 1900s. Since its introduction, it has become the dominant grass in the mid-elevation grasslands of southern Arizona, including the Santa Rita Experimental Range (SRER), where it has displaced native grasses including Arizona cottontop, three awns, and gramas. Like all plants in terrestrial ecosystems, this grass harbors fungal symbionts that can be important for its establishment and persistence. This thesis focuses on fungal symbionts of Lehmann’s lovegrass and has two components. First, the diversity and distributions of endophytes in Lehmann’s lovegrass are evaluated in the context of biotic and abiotic factors in the SRER. Culturing from roots and shoots of Lehmann’s lovegrass at points beneath and outside the canopy of native mesquites, which are encroaching on grasslands over time, provides insight into how a single plant species can exhibit local variation in the composition of its symbionts. Second, the thesis is used as the basis for engagement of students in science, technology, engineering, and mathematics (STEM) through the development and implementation of classroom- and field activities centered on endophytes, which help high school students address core learning aims while also gaining real research experience. Engaging students in important questions relevant to their local environment can catalyze interest in science and help students cross the threshold into research. The contributions of such approaches with respect to learning not only fulfills key next-generation science standards and common core objectives, but provides students with a meaningful introduction to the excitement, importance, and accessibility of science.

Conventional fish monitoring requires considerable investments of equipment and labour, and often harmful and potentially fatal techniques. Emerging methods allow detection of aquatic animals by collecting water and extracting DNA that has been shed to the environment (eDNA). Present knowledge gaps in the field include minimum densities necessary for consistent detection, and persistence of eDNA after a target species has left a site. I conducted three experiments at a salmon hatchery in British Columbia to address these knowledge gaps. Water samples were taken from flow-through tanks with juvenile Coho Salmon densities ranging from 38.0g/1000L to 0.6g/1000L. To simulate field surveys in recently abandoned habitats, I sampled water from tanks after removing fish, at flow-through volumes ranging from 20,000L to 1,000,000L. Post removal sampling occurred starting at one hour and ending after just over four days of flow-through time. Water samples from tanks containing one or more fish tested positive for Coho DNA at least 70% of the time, increasing at higher densities. Samples taken after removing the fish had detection probability of 75% at flow-through volume of 40,000L. Detection failed at flow-through volumes greater than 80,000L. In stream samples, all sites with Coho or salmonid presence confirmed by conventional trapping also tested positive for target species’ eDNA. Two sites tested positive for Coho eDNA where conventional methods failed, indicating a possible higher sensitivity of eDNA sampling. I also mapped the distribution of juvenile Coho Salmon through multiple tributaries of a productive salmon system with conventional and eDNA detections. This study improves on an emerging method with a new species by addressing existing uncertainties regarding eDNA detection threshold, and signal persistence through dilution in a simulated stream pool habitat. It also demonstrates that eDNA methods can be used to assess coastal streams for presence of juvenile and resident salmonid fishes. / Graduate

Invasive species are becoming more common as human interactions within coastal waters and the aquarium trade continues to increase. The establishment of the invasive lionfish complex Pterois volitans and P. miles from the Indo-Pacific to the Western Atlantic, Gulf of Mexico, and the Caribbean Sea has had significant negative effects on reef fish biodiversity and economically important species. Their rapid colonization and success has been attributed to their biological and ecological life history traits as well as their absence of predation. Past research has highlighted these characteristics; however, there is a knowledge gap in lionfish parasitism. This research explored the enemy release hypothesis as a key success factor in rapid establishment in the invaded range on a biogeographical scale. The diversity of lionfish parasitism was compared among 15 geographically diverse sites within the invaded range, incorporating the time of introduction at each site. Eight new parasites are described for the first time in the invasive lionfish: (1) a Cymothoid isopod: Rocinela stignata, (2) four nematodes: Raphidascais sp., Contraceacum sp., Paracuria adunca and Hysterothylaceum sp., (3) one digenean: Tergestia sp., (4) two acanthacephalans: Serracentis sp. and Dollfusentis sp., and (5) two cestodes: Nybelinia sp. and Tentacularia sp. Lionfish from the east coast of Florida exhibited the highest abundance in parasite fauna while other invaded areas yielded low abundance and diversity. Comparisons between lionfish parasitism from the past native range studies and the invaded range suggest that vectors of time, life history traits, and trophic interactions structure the lionfish parasite community. Lionfish in the Western Atlantic and Caribbean were found to be host for generalists parasite species within the coastal ecosystem. Consequently, lionfish have relatively low parasite abundance, supporting the enemy release hypothesis and its direct relation to their invasion success.

The simultaneous increase in biological invasions and habitat alteration through the building of coastal infrastructure is playing an important role in reshaping the composition and functioning of nearshore marine ecosystems. This thesis examined patterns of marine invasions across anthropogenic and natural habitats and explored some of the processes that influence establishment and spread of invaders. The goals of this thesis were four-fold. First, I examined the habitat distribution of marine nonindigenous species (NIS) spanning several taxonomic groups and geographical regions. Second, I conducted systematic subtidal surveys in anthropogenic and natural habitats and investigated the distribution of nonindigenous ascidians on Southern Vancouver Island, British Columbia, Canada. Third, I tested methods for in-situ larval inoculations and utilized these techniques to manipulate propagule supply and assess post-settlement mortality of ascidians across habitat types. Fourth, I investigated the role of biotic resistance, through predation by native species, on the survival of ascidian colonies in anthropogenic and natural habitats. Results from this research showed that anthropogenic habitats are hubs for marine invasions and may provide beachheads for the infiltration of nearby natural sites. Specifically, a literature review of global scope showed that most NIS are associated with anthropogenic habitats, but this pattern varied by taxonomic group. Most algal and mobile invertebrate NIS were reported from natural habitats, while most sessile NIS were reported from artificial structures. Subtidal field surveys across both anthropogenic and natural habitats showed that nonindigenous ascidians were restricted largely to artificial structures on Southern Vancouver Island and that this pattern is consistent across their global introduced ranges. Field manipulations using the ascidian Botrylloides violaceus as a model organism, showed that post-settlement mortality is high and that large numbers of larvae or frequent introduction events may be needed for successful initial invasion and successful infiltration of natural habitats. Experiments also showed that predation by native species can limit the survival of B. violaceus in anthropogenic and natural habitats. This dissertation contributes knowledge about the patterns and processes associated with habitat invisibility; provides insight into factors affecting colonization; and supplies valuable information for predicting and managing invasions. / Graduate / 0329

In 2006, a baseline survey for the UNEP/GEF-IAS Project was conducted in BFR to assess the status of IAS in the area. Findings indicated that extensive forest parts had severe S. spectabilis encroachment which appeared to interfere with the normal functioning and productivity of the forest. This study was motivated by the magnitude of S. spectabilis invasion in BFR, the level of public and government concern about the invasion, and the magnitude of the IAS problem across East Africa. This study was thus undertaken to address a specific need of the research and capacity building components of the UNEP/GEF-IAS Project. The study1 was carried out to assess the impacts of S. spectabilis invasion on the productivity of BFR and the socio-economic implications on the livelihoods of the dependent stakeholders (local resident population, timber suppliers and the tourism sector). The study used descriptive statistics to assess the levels of awareness of S. spectabilis invasion, perceptions and knowledge of the conservation values of BFR, knowledge on the benefits and costs of living with S. spectabilis and impacts of S. spectabilis on the flow of quantities and revenues from the benefits it generates. The impact on financial profitability and efficiency of timber firms was assessed using Gross margin analysis (GMA) and financial efficiency ratio analysis respectively. The impact on the population structure of chimpanzees was studied using mean differentials and focused group discussions. Results indicate that the level of awareness about S. spectabilis invasion and the knowledge of the conservation values of BFR were high among all the three stakeholder groups. GMA revealed that S. spectabilis invasion increases variable costs in timber production thus reducing profit margins and financial efficiency of timber firms. Alteration of habitat environment occasioned by S. spectabilis invasion was advanced, though with uncertainty, as a possible reason for the difference in chimpanzee numbers between the infested and non infested forest conditions. Like other IAS, S. spectabilis was found to have both benefits and costs though the distribution of the same differs. S. spectabilis can be considered a net benefit to the local dependent communities whereas it may be a net loss to both the timber and tourism sectors. Conflict of interest in S. spectabilis management is discussed and possible solutions suggested. It was recommended that the threat of invasive species should be tackled through a multisectoral approach. / Dissertation (MSc)--University of Pretoria, 2009. / Agricultural Economics, Extension and Rural Development / unrestricted

While there is increasing interest in the evolutionary consequences of species invasions on native plant communities, the connection between the phylogenetic relatedness of invaders and natives, and its evolutionary consequences, has not yet received much attention. One way to examine the role of relatedness on the impact of species invasions is through the use of meta-analytical techniques combined with a phylogenetic framework. I apply this technique and expand on a prior meta-analysis by Oduor (2013), in order to compare how native plant species that either have prior experience coexisting with an invasive (‘experienced’) or do not (‘naïve'), differ in terms of their growth and reproduction in the presence of the invasive for evidence of a phylogenetic signal in their response to plan invasions. My results suggest that the effects of a species invasion on native growth and reproductive traits may be greater when the native and invasive species are distantly related, and/or when the invasive species is allelopathic, but only in the presence on the invader. I also found that the negative effect of competition with an invader on native growth traits tended to be greatest when the native and invasive species were closely related, suggesting that the strength of competition and the evolutionary response of native plants to invasive plants may not be as closely associated as it is often assumed. Overall, my analysis suggests that future studies may benefit from integrating phylogenetic relatedness when exploring native evolutionary responses to invasions, but that considerable work need sot be done to tease apart the roles of relatedness and competition.

Invasive range expansion is correlated to life- history variation, boldness and dispersal behavior. The invasion of the African Jewelfish in Everglades National Park provides an opportunity to test life-history trait variation, boldness and dispersal behavior in the invasion success of this species. My study examined variation in somatic traits, boldness, and dispersal of jewelfish across their invaded range. Life histories were examined on wild individuals. Boldness and dispersal were tested in outdoor experimental tanks. Tested populations from the invasion front have higher somatic traits, but they were not bolder than longer established populations. Understanding the underlying mechanisms of invasions are key for the development of strategies looking to contain invaders and prevent their spread.

abstract: Needle steering is an extension of manually inserted needles that allows for maneuverability within the body in order to avoid anatomical obstacles and correct for undesired placement errors. Research into needle steering predominantly exploits interaction forces between a beveled tip and the medium, controlling the direction of forces by applying rotations at the base of the needle shaft in order to steer. These systems are either manually or robotically advanced, but have not achieved clinical relevance due to a multitude of limitations including compression effects in the shaft that cause undesired tissue slicing, torsional friction forces and deflection at tissue boundaries that create control difficulties, and a physical design that inherently restricts the workspace. While most improvements into these systems attempt to innovate the needle design or create tissue models to better understand interaction forces, this paper discusses a promising alternative: magnetic needle steering. Chapter 2 discusses an electromagnetic needle steering system that overcomes all aforementioned issues with traditional steering. The electromagnetic system advances the needle entirely magnetically so it does not encounter any compression or torsion effects, it can steer across tissue-interfaces at various angles of attack (90, 45, 22.5°) with root-mean-square error (RMSE) of 1.2 mm, achieve various radii of curvature as low as 10.2 mm with RMSE of 1.4 mm, and steer along complex 3D paths with RMSE as low as 0.4 mm. Although these results do effectively prove the viability of magnetic steering, the electromagnetic system is limited by a weak magnetic field and small 33mm cubic workspace. In order to overcome these limitations, the use of permanent magnets, which can achieve magnetic forces an order of magnitude larger than similarly sized electromagnetics, is investigated. The needle will be steered toward a permanent magnet configuration that is controlled by a 6 degree-of-freedom robotic manipulator. Three magnet configurations were investigated, two novel ideas that attempt to create local maximum points that stabilize the needle relative to the configuration, and one that pulls the needle toward a single magnet. Ultimately, the last design was found to be most viable to demonstrate the effectiveness of magnetic needle steering. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2020