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Habitat selection among fishes and shrimp in the pelagic Sargassum community: the role of habitat architectureUnknown Date (has links)
Pelagic Sargassum was used to determine the effects of habitat architecture for one species of shrimp (Leander tenuicornis) and two species of fish (Stephanolepis hispidus and Histrio histrio). Inter-thallus spacing (low, medium, and high) and depth (shallow versus deep) were manipulated independently to test whether the spatial components of habitat architecture. Two differing habitats (Sargassum versus seagrass species) were tested for the structural component of habitat architecture. There were no significant results for inter-thallus spacing experiments for L. tenuicornis and S. hispidus. H histrio selected habitats with medium inter-thallus spacing in two treatments. Large individual H. histrio contributed mostly to the significant effects. All three species selected habitats with a greater depth aspect. Finally, L. tenuicornis and H. histrio selected habitats with greater structural complexity (i.e., Sargassum). These results demonstrate clearly that habitat architecture of Sargassum influences habitat selection by these shrimp and fishes. / by Chelsea O. Bennice. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.
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Geospatial and genomic tools for conserving the Critically Endangered blue-eyed black lemur (Eulemur flavifrons) and the sportive lemurs (genus Lepilemur)Tinsman, Jen Casey January 2020 (has links)
Madagascar’s lemurs are the most endangered group of mammals in the world, with 94% of species threatened with extinction. Forest loss is one the greatest threat to these arboreal primates, but hunting, habitat degradation, and climate change also threaten their survival. Lemurs are a diverse group of more than 100 species; and their ecological traits shape how species respond to anthropogenic pressure. Incorporating knowledge of species’ ecological niches and evolutionary histories can contextualize threats and improve conservation assessments. In this dissertation, I investigate what constitutes suitable habitat for lemurs in light of the threats present, their sensitivity to forest fragmentation, their dispersal ability, and their ecological uniqueness.
I obtained data about lemur distributions in two ways. First, I conducted field surveys of the Critically Endangered blue-eyed black lemur (Eulemur flavifrons), which only occurs in the ecotone between eastern rainforest and western dry forest in the Sahamalaza region. I also surveyed the range of sister species, the black lemur (E. macaco), which inhabits nearby eastern rainforest in the Manogarivo region. I focused on areas that have not been surveyed recently and on the poorly studied boundary between the species to collect observations from the breadth of these species’ ecological ranges. I also documented threats, including incursions into protected areas, and collected fecal samples to test whether whole genomes could be obtained noninvasively for analyses of local adaptation in these species.
Second, I searched online databases and published literature for GPS localities for all species of lemur. I used these records, along with the ones collected in the field, to construct ecological niche models for nearly all species of lemur using Maxent. For the blue-eyed black lemur and the black lemur, I estimated the remaining area they can occupy based on these models and the threat survey data. Next, I examined the role of not just forest loss, but forest degradation, in determining where lemur species occur. I used high-resolution forest cover maps to determine lemurs’ tolerance for characteristics of degraded forest, including distance to the edge and mean patch size. I then limited species niche model to only intact, forested habitat. Lastly, using the sportive lemurs (genus Lepilemur) as an example, I evaluate how the inability to disperse across large rivers has influenced ecological niche diversity. I also examine what limited dispersal ability will mean for these species as climate change causes their ranges to shift.
Field surveys in the Sahamalaza and Manongarivo regions revealed extensive threats to blue-eyed black lemurs, from traps to cattle incursions and fire. I found no evidence of sympatry, but did locate an undocumented population of E. flavifrons north of the Andranomalaza River. Madagascar National Parks (MNP) managed protected areas appear to have less human incursion than NGO-managed protected areas. Further investigation of the ecological distinctiveness of these species is possible via non-invasive methods: I sequenced whole genomes at 2.3x coverage from eight of the fecal samples collected during this study. While SNPs indicating a loss of function did not reveal any patterns, sequencing additional samples could make studies of local adaptation and population genetic diversity possible.
At the regional scale, forest conversion is a grave threat to lemurs. When forest loss and degradation are considered in habitat models, lemur species have lost 51% of their habitat in the last 30 years. Proximity to a forest edge rendered more forested areas too degraded for lemurs than did mean patch size. This result is likely the influence of human contact nearer the forest edge. I recommend urgent support for reserves like Beanka, Tsimembo Forest, Ranobe PK 32, and Amoron’i Onilahy, which have highly suitable, intact forest for many lemur species. Spaces like these will be important for conserving the remarkable diversity within the sportive lemur clade. Though their distribution is largely explained by riverine barriers, I show a role for ecological niche divergence and local adaptation in accelerating allopatric speciation. These same rivers will limit their ability to track climatically suitable areas as climate change progresses: sportive lemurs as a group will lose nearly a quarter of their accessible habitat to climate change by the 2070s.
While my results are focused on the particulars of lemur conservation in Madagascar, the methods I have presented here are broadly applicable to other threatened species. Piggybacking fecal sample collection onto rapid field surveys is straightforward. The possibility of obtaining whole genomes from non-invasive samples presents a new way to answer questions about local adaptation without risking injury to other arboreal study subjects, like Neotropical monkeys, or for elusive species like big cats. For threatened species, their climatic niche only dictates part of their distribution. The habitat quantification pipeline presented here takes advantage of thirty-five years of research in Madagascar to estimate species’ tolerance for forest fragmentation. While these records are impressive for primates, they are dwarfed by those available for passerines, through scientific literature and online repositories like eBird. By integrating field surveys, ecological niche modeling, and non-invasive genomics, we can begin to understand the complex threats facing species like lemurs and the options for ensuring their survival.
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Use of native seed mixtures to improve erosion control and wildlife habitat on log landings following timber harvest in the Upper Elk Watershed of West VirginiaTager, Lisa R. January 1900 (has links)
Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains viii, 110 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references.
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Cost-effective land development with a spatially-realistic ecosystem constraint /Bauer, Dana Marie. January 2005 (has links)
Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 220-234).
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The nonbreeding season ecology of neotropical migratory birds in the dry zone of Puerto RicoBaltz, Michael E. January 2000 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.
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The role of habitat quality in shaping evolutionary dynamics, population dynamics, and conservation planning /Hoekstra, Jonathan M. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 119-134).
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Effects of an increasing harbor seal population on changes in sites used for pupping /Guldager, Nikolina, January 2001 (has links) (PDF)
Thesis (M.S.) in Wildlife Ecology--University of Maine, 2001. / Includes vita. Includes bibliographical references (leaves 78-82). Also available via Internet.
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Black rhinoceros (Diceros bicornis) habitat selection and movement analysis.Morgan, Simon. January 2010 (has links)
Many aspects of habitat selection have been largely ignored in conservation planning of large mammals, including variation between day and night movement patterns, inter-individual niche variation of conspecifics and translocated individual‟s responses to new environments in relation to the influence of ecogeographical variables. Being a solitary moving animal with a known tendency to move through the night, the black rhino Diceros bicornis is a perfect species to test theories about individual spatial and temporal variation in habitat utilisation. I tested the appropriateness of using carrying capacity (CC) estimates as a tool for population conservation planning, and as an indicator of habitat utilisation for black rhino. I found individual selection was not related to the value of the habitat according to modelled CC. I therefore do not recommend the use of a priori calculations of resource quality and abundance of habitats (CC estimates), which do not take into account the factors that influence an animal‟s selection of a habitat, as indicators of species habitat use. Secondly I tested whether current methods of analyzing mainly diurnal location data of animals result in accurate ecological or conservation conclusions. I found a circadian variation in habitat use for different behaviours, and that excluding nocturnal data from home and browsing range analyses would provide inaccurate results for black rhino habitat use. I then tested for inter-individual niche variation amongst two populations of black rhino at various scales of selection, ranging from habitat through to browse selection. I showed that black rhino, a selective browser, had a significant degree of inter-individual habitat and dietary niche variation. Consequently, pooling habitat location data and diet selection data for black rhino individuals in a population does not reflect the actual selection of any, or many, individuals. To clarify which ecogeographical variables might influence this selection I ran maximum entropy models on individual‟s diurnal locations across the landscape. I was then able to develop a habitat suitability model which was based on the individual rather than population, providing a more accurate prediction. I repeated the individual models in phases, from the initial post-release phase after the release of individuals onto a new reserve through to their „settled‟ phase, allowing me to explore the effect of habitat variables on different settling phases of translocated animals. The results indicate that all the rhinos‟ acclimation phase lasted no longer than 25 days and that to minimize disturbance to the settling process all individuals in a newly released cohort should be released within this period. This study as a whole provides conservation managers with a better ecological understanding of black rhino in conjunction with a number of management tools. This will enable conservation managers to better understand the way animals utilise and perceive their environment, allowing for better monitoring and analyses of animal movements. This will aid in the development of strategic management plans in the conservation of not only animal species but also the ecosystems that they reside in and the identification of suitable areas for future conservation of animal species. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.
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Determining the suitability of functional landscapes and wildlife corridors utilizing conservation GIS methods in Denton County, TexasSales, Joshua. Dong, Pinliang, January 2007 (has links)
Thesis (M.S.)--University of North Texas, Aug., 2007. / Title from title page display. Includes bibliographical references.
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An alternative futures analysis of Flathead County, Montana evaluating tradeoffs among economic growth, land use policy and land use change /Clark, Anthony S. January 2007 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on January 31, 2008) Vita. Includes bibliographical references.
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