Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 108 for “"rare species"”.
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Identifying, understanding, and conserving rare species
… biodiversité à l’échelle mondiale, les espèces rares méritent une attention particulière dans les efforts de conservation, car elles sont plus vulnérables à l'extinc-tion que les espèces communes. À la suite de l'adoption du Cadre mondial pour la biodiversité Kunming-Montréal en 2022, le Canada …
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Seed germination requirements and salt stress tolerance of coastal rare species in Sardinia
… that characterize coastal environments, plant species often require special physiological or metabolic adaptations to overcome environmental stresses. Stress may be physical (e.g. temperature) or chemical (e.g. salinity). Many communities comprise highly specialized species, which have …
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How Are Rare Species Maintained?: Reproductive Barriers Between Layia jonesii, a Rare Serpentine Endemic, and L. platyglossa
… barriers are vital to generating new species as well as maintaining distinct species. Investigating reproductive barriers between closely related plant taxa helps us to understand how these barriers are maintained, particularly between rare and widespread relatives. <em>Layia …
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The vascular flora and species distribution modeling of two rare species in Cloudland Canyon State Park, Dade and Walker Counties, Georgia
… records resulting in the documentation of 665 species and subspecific taxa, representing 361 genera in 122 families. The top three most represented families were Asteraceae (99 taxa; 14.9%), Poaceae (64; 9.6%), and Cyperaceae (52; 7.8%). Twenty-eight rare species were documented, including 10 …
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Developing a predictive geospatial habitat model for a rare species of salamander in Tennessee: a case study for the green salamander (Aneides aeneus)
… and Packard 1881) are a secretive and cryptic species of salamander that can be relatively difficult to detect, due to their occupation of arboreal habitats. The incorporation of geospatial tools is critical in developing models that can be used to predict undocumented locations in Tennessee …
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Increased phenotypic plasticity linked to broader geographic range size in sunflower (Helianthus) species
… biodiversity loss, particularly for vulnerable rare species. Plant species can respond to environmental changes via adaptation and/or acclimation or migration, yet limited genetic diversity and fitness in rare species can hinder these processes. Changes in light availability from human …
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The Effects of Fire on the Vernal Herbs of an Eastern Mesic Forest
… I studied the influence of prescribed fire on species richness, abundance of rare and common species, and density of exotics in the vernal herbaceous layer. To determine these effects, three sites in central Kentucky were surveyed prior to and following one of three treatments: spring burn, …
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Regional Rarity: Consequences of Dispersal Limitation and Strategies for Reintroduction
<p>Understanding factors that limit species distributions within restored habitats has been a longstanding goal of restoration ecology, particularly with respect to differences between rare and widespread species. Numerous mechanisms have been proposed to contribute to rarity, including species …
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Helitrons are enriched in lichenized fungi with long generation length and small distribution sizes
… comparative framework. We found that species with smaller distribution sizes and those with longer generation lengths had a higher genomic DNA transposon load, and that their genomes were enriched with Rolling Circle transposons, specifically, which contradicts broad patterns …
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Defining rarity and determining the mechanisms of rarity for North American freshwater fishes
Conserving rare species and protecting biodiversity depends on sound information on the nature of rarity. Rarity is multidimensional, presenting the need for a quantitative classification scheme by which to label species as rare or common. I defined rarity for freshwater fishes based on the range …
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Natural patterns and anthropogenic disturbance in north Adriatic marine benthic assemblages: descriptive and methodological studies
… benthic sedimentary characteristics and species distribution. The description of such spatial variability is required to understand the ecological processes behind them. However, in order to have a better estimate of spatial patterns, methods that take into account the complexity of the …
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The Effects of Invasive Plants on Biodiversity Across Spatial Scales
<p>Although introduced plant species are often considered to be one of the most notable anthropogenic threats to biodiversity, their influence on biodiversity remains controversial. Some studies have shown large declines in biodiversity in plant-invaded areas, whereas others have noted that plant …
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Tactical Escape Behavior and Performance of a Small Sceloporine Lizard in Two High Risk Habitats
… lizard (<em>Sceloporus woodi</em>) is a small, rare species endemic to two distinct and structurally complex environments in Florida, i.e. sand-pine scrub and longleaf pine-wiregrass sand-hills. The differing microhabitats of scrub and longleaf pine factor into the distribution and density of …
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The Impact of Neighborhood-Based Processes on Demography and a Decline in Species Diversity in a Temperate Deciduous Forest
Understanding the maintenance of species diversity is a central question in community ecology. Ecological processes explaining the maintenance of species diversity, including density-dependence, interspecific competition, and disturbance, should be able to elucidate not only the causes of the …
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A transdisciplinary study on developing knowledge based software tools for wildlife management in Namibia
… aimed to improve the management of selected rare and high value species in Namibia by building a knowledge base for better informed decision making. The knowledge base was required to encapsulate current knowledge and experience of conservation experts and specialists. To provide an …
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Spatial ecology of food webs : herbivore-parasitoid communities on the pedunculate oak
… and natural enemies form the largest and most species-rich communities on earth. But what forces structure such communities? Do they represent random collections of species, or are they assembled by given rules? To address these questions, food webs offer excellent tools. As a result of their …
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Captive propagation, reproductive biology, and early life history of Crystallaria cincotta (Diamond Darter), Etheostoma wapiti (Boulder Darter), E. vulneratum (Wounded Darter), and E. maculatum (Spotted Darter)
… be used for the management and conservation of rare species. During 2008--2012, a captive propagation study was conducted on Crystallaria cincotta (Diamond Darter), a rare species with a single extant population in the lower Elk River, WV. Also, captive propagation studies were conducting during …
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ECOLOGY AND CONSERVATION OF BUTTERFLIES IN A TRANSFORMED TROPICAL LANDSCAPE
… the past 25 years. Our long-term dataset of 281 species showed that mature forests are still key for butterflies, especially for rare species but forest fragments hold some habitat specialized species. In terms of flower use, we found that 43% of feeding observations by butterflies in forested …
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Recreational trail impacts on the plant communities of Castle and Castle Wildland Provincial Parks in southern Alberta
… the effect of recreational trails on plant species richness, community composition, and the presence of exotic and rare species in the Castle Provincial Parks of Alberta, Canada, by surveying 142 transects adjacent to or far from trails. I also characterized the habitat of species from the …
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