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 33 for “"Mutualisms"”.
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Evolutionary and ecological outcomes of tripartite mutualisms
… of costs and benefits in multiplayer mutualisms. Host investment in AMF also decreased when P was readily available in the soil. These negative effects were exacerbated when hosts were light limited suggesting that both costs and benefits play key roles in host interactions with each …
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Slippery Surfaces and the Biomechanics of Climbing in Macaranga-Ant Mutualisms
This thesis has three data-driven chapters, an introduction, a general methods section and a discussion. The first of the data chapters shows that claws are the essential attachment device used by wax runner ants to climb their host Macaranga trees. When wax runners had their claw tips ablated, …
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MULTI-PARTNER MUTUALISMS: INTERACTIONS AMONG THE MOUNTAIN PINE BEETLE AND TWO OPHIOSTOMATOID FUNGAL ASSOCIATES
I investigated interactions between the mountain pine beetle (Dendroctonus ponderosae) and its two main ophiostomatoid fungal associates,Grosmannia clavigera and Ophiostoma montium, as well as interactions between the two fungi. The main research questions were: What drives bark beetle fungal …
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MULTI-PARTNER MUTUALISMS: INTERACTIONS AMONG THE MOUNTAIN PINE BEETLE AND TWO OPHIOSTOMATOID FUNGAL ASSOCIATES
I investigated interactions between the mountain pine beetle (Dendroctonus ponderosae) and its two main ophiostomatoid fungal associates,Grosmannia clavigera and Ophiostoma montium, as well as interactions between the two fungi. The main research questions were: What drives bark beetle fungal …
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Vitamin B12-mediated physiology, mutualisms, and gene regulation studies in Chlamydomonas reinhardtii and Phaeodactylum tricornutum
… the physiology of newly B12 dependent algae and mutualisms with B12-producing bacteria. As well as the role of B12 as a cofactor, it also acts to repress gene expression. Most notably, METE shows rapid and robust repression in the presence of B12 in both C. reinhardtii and P. tricornutum. This …
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The effect of supplementary nectar feeders on bird-plant mutualisms in the Cape Fynbos, South Africa
Across the world, people feed birds to interact with nature. A variety of feeder types have been developed over the years to target a broad bird community. Attracting nectarivorous birds to gardens using supplementary nectar feeders is a popular human activity across the globe, but few studies have …
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Global change effects on ant-mediated seed dispersal
Seed dispersal mutualisms, including seed dispersal by ants, are critical to the assembly of communities and the function of ecosystems. However, the consequences of human-caused global change factors, such as habitat fragmentation and climate change, for the future of these mutualisms are not …
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An Experimental Test of Controls on Resource Exchange in an Ectomycorrhizal Mutualism
Models of resource exchange mutualisms utilize economic principles to explain how the costs and benefits of these interactions vary with environmental context. All of these models use a ratio of resource exchange (e.g., nitrogen: carbon) as the central variable, and it is unclear whether such …
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Genetic And Temporal Variation In Resource Exchange Between An Ectomycorrhizal Fungus, Rhizopogon Occidentalis, And Seedlings Of Pinus Radiata
… evolutionary persistence of resource exchange mutualisms such as mycorrhizae. The ratio of resources exchanged is an important variable comto all these models. Measuring resource exchange ratios is the first step in testing the hypotheses predicted by these models and will provide insight into …
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The role of cone volatiles and thermogenesis in the pollination of Encephalartos cycads with particular reference to E.villosus
… systems of cycads usually involve obligate mutualisms in which the cycad taxa depend on between one and three insect pollinators. Generally, the pollination periods of many cycad taxa are characterised by odour emissions in pollen shedding (male) and receptive (female) cones usually …
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Alfalfa Aphids From Pixel to Picture: Deciphering Symbiotic and Predatory Interactions Across Scales
… between the legume-rhizobia and aphid- Buchnera mutualisms. Both rhizobia and Buchnera transform nitrogen into forms that can be assimilated by their hosts and modulate the expression of host plant defense. Yet, the potential nutrient- or plant defense-mediated effects of rhizobia on Buchnera …
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Consequences of interaction between the native ant community and an invasive plant (Euphorbia esula)
Mutualisms, or mutually beneficial species interactions (+/+), play a key role in ecological community functioning, influencing community stability and biological diversity. Despite their importance in ecological processes, the study of mutualism has limitations. First, seemingly positive …
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The ecology, evolution and persistence of an obligate, one-on-one mutualism
… systems). Although obligate, one-on-one mutualisms may be common among intimate, endosymbiotic organisms, they are apparently uncommon between free-living or non-symbiotic organisms (Howe 1984). Many theories have been posulated to explain the rarity of obligate, one-on-one mutalisms but …
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Elephant fruit :The dispersal attributes of Balanites maughamii / Storme Viljoen
… plant species that have obligate dispersal mutualisms with megafauna are at risk of extinction because of the unique conservation threats associated with large animals. This study examines Balanites maughamii which appears to have similar dispersal attributes to Sclerocarya birrea and …
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Mutualism benefits and the evolution of an interspecific sentry call in associations between Sociable Weavers and Fork-tailed Drongos
Mutualisms, where organisms benefit from cooperation, are common in nature, but payoffs are dynamic and mutualists can incur costs as well as benefits from their association. Nevertheless, selection can favour the coevolution of behaviour that increases benefits. Such coevolution can potentially …
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How did governance in Acholi dovetail with violence?
… featuring varied forms of “facultative mutualisms” among two or more gangi agnates – with one gang as dominant in the realm. Gangi were kinship-based polities. Like kaka, gangi manifested autopoietic attributes and strong internal “fiduciary cultures”. Then in the 1900s, kaka as …
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How did governance in Acholi dovetail with violence?
… featuring varied forms of “facultative mutualisms” among two or more gangi agnates – with one gang as dominant in the realm. Gangi were kinship-based polities. Like kaka, gangi manifested autopoietic attributes and strong internal “fiduciary cultures”. Then in the 1900s, kaka as …
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The influence of long-term nitrogen fertilization on symbiosis and metabolism in the legume-rhizobium mutualism
Understanding how mutualisms evolve in response to a changing environment will be critical for predicting the long-term impacts of global changes, such as increased nitrogen (N) deposition. Bacterial mutualists in particular might evolve quickly, thanks to short generation times and the potential …
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Ecological genomics of mutualism decline in nitrogen-fixing bacteria
Mutualisms, cooperative partnerships between species, are among the most prevalent and economically important biological interactions. The fitness benefits of mutualism are well-known to depend on the context in which the interaction occurs, and recent evidence supports the hypothesis that …
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