Blar i tittel Mastergradsoppgaver i biologi
Viser treff 238-257 av 357
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Parallelism in parasite infections in two populations of polymorphic Arctic charr (Salvelinus alpinus L.) in northern Norway
(Master thesis; Mastergradsoppgave, 2014-05-15)The composition and structure of a component community can vary widely across host populations of the same host species. Revealing the causes and consequences of geographical variation in parasite community composition is of great importance in order to determine parasites role in an ecosystem. Divergence in parasite infections among sympatric polymorphic Arctic charr is commonly associated with ... -
Parasite communities of two three-spined stickleback (Gasterosteus aculeatus) populations : effects of a local-scale host introduction?
(Master thesis; Mastergradsoppgave, 2011-11)The introduction of new hosts into new habitats can bring along hitchhiking parasites, i.e. parasites being introduced with the host. This in particular can be an important dispersal mechanism for autogenic parasites that are otherwise restricted by the natural movement of their fish hosts. In this study, the effect of a local host introduction on the parasite communities of three-spined sticklebacks ... -
Parasites of Northeast Arctic cod (Gadus morhua) in the Barents Sea: effects on reproduction
(Master thesis; Mastergradsoppgave, 2017-07-15)Parasites play a key role in the biodiversity and dynamics of an ecosystem, either by affecting host mortality and/or host reproduction. Spawning comes with a great cost in time and energy, and in times of poor conditions this time and energy is better directed into growth and survival to increase future success. The phenomenon of skipped spawning, where sexually mature fish skip a reproductive ... -
"Parasitized by your own kind" : the life of the Svalbard Eider (Somateria mollissima)
(Master thesis; Mastergradsoppgave, 2008-11-15)Conspecific brood parasitism is a subtle reproduction tactic often performed by many species. The parasitizing females lay eggs in the nest of another female of the same species, and the hosting female then incubates and raises both her own and the parasite’s offspring. Is it highly discussed why the hosting females allow this parasitism, whether she is able to detect it, or if she receives more ... -
Parasitter som biologiske markører på interaktiv segregering mellom stasjonær sympatrisk ørret og røye
(Master thesis; Mastergradsoppgave, 2006)Allopatrisk ørret og røye i innsjøer er økologisk svært like med hensyn på nærings- og habitatpreferanser. I allopatri foretrekker begge artene å beite bunndyr i de littorale delene av innsjøen. I sympatri observeres ofte en segregering i nærings- og habitatvalg mellom ørret og røye, der røya skifter fra det prefererte habitatet, og går over til å beite mer zooplankton i de pelagiale delene av ... -
A patch of Calanus finmarchicus in the Lofoten-Vesterålen Region. Characteristics and determining factors
(Master thesis; Mastergradsoppgave, 2019-05-16)Zooplankton patchiness has been documented in many shelf areas and is of vital importance for understanding predator-prey relationships in pelagic marine systems. By combining hydrographic, acoustic and net data collected in spring 2017, we present a detailed understanding of the extent of this phenomenon in the Lofoten-Vesterålen region. Such patches are of potential interest not only for zooplankton ... -
Pathogen exposure surveillance in Southern Ocean pinnipeds
(Master thesis; Mastergradsoppgave, 2019-05-15)An increased pressure of human activities that can introduce new infectious agents and therefore alter host-pathogen interactions, resulting in epizootics and biodiversity loss, challenges the Southern Ocean. Health status information and the potential effect of disease outbreaks in the Southern Ocean fauna is scare and evaluating the susceptibility to new infectious agents is decisive for its ... -
Perception and Appreciation of Plant Biodiversity, An assessment of human perception and appreciation of plant biodiversity using photography of artificial plant communities
(Master thesis; Mastergradsoppgave, 2017-07-31)Anthropogenically caused global biodiversity declines and other human drivers point to the possibility of local plant diversity changes. The well-studied effects of local plant diversity on ecosystem processes implicate consequences to human well-being in the form of altered ecosystem services (including cultural services). Public awareness (knowledge and correct perception) about these changes ... -
Peripheral heterothermia in reindeer (Rangifer tarandus tarandus)
(Master thesis; Mastergradsoppgave, 2011-05-16)Reindeer (Rangifer tarandus tarandus) inhabit the Arctic and have evolved adaptions to meet the climatic challenges in this region. Peripheral heterothermia, which is a heat conserving mechanism in homeotherms during cold exposure, is well documented in the reindeer and manifests itself in tissue temperatures in the extremities well below 10°C. It is, however, unknown whether peripheral heteothermia ... -
Phylogeny of Somniosus sleeper sharks: insights from newly sequenced mitochondrial genomes
(Master thesis; Mastergradsoppgave, 2022-05-16)Mitochondrial DNA (mtDNA) has been extensively used to explore phylogenetics since the its use became available. This science is considered useful in discerning relationships and evolutionary histories that are not possible with morphological studies alone. The sleeper sharks (genus: Somniosus) are a group of poorly understood, long-lived, iconic species whose taxonomic status within the genus have ... -
The pineal gland of Arctic charr (Salvelinus alpinus L.): a survey of seasonal melatonin production and gland ultrastructure
(Master thesis; Mastergradsoppgave, 2009-11)The pineal gland is part of the endocrine system involved with rhythmic activity in e.g. fish. The main product of the pineal gland is the indole hormone melatonin, synthesised from the amino acid tryptophan. Melatonin is mainly synthesized when it is dark, as light inhibit the production. For this reason melatonin is thought to be strongly involved in biological rhythms. Arctic charr (Salvelinus ... -
Plant-Soil Feedback: Alpine Grassland Plants in Home and Away soil
(Master thesis; Mastergradsoppgave, 2021-12-16)For the grassland, plant soil feedback (PSF) has been the focus of much recent research to understand plant species dynamics. Experimental methods are very important in the plant soil feedback (PSF) analysis, and it has been observed that various PSF experimental approaches yield in different feedback values. More field type experiments are required to understand the role of PSFs in plant communities ... -
Plastic occurrence in six different species of Arctic seabirds - Harmonizing methods and closing knowledge gaps on plastic occurrence and polymer identity
(Master thesis; Mastergradsoppgave, 2021-05-18)The once pristine Arctic is now facing negative alterations with a rapidly changing climate, increasing human activity, and plastic pollution. Seabirds are intrinsic to the marine ecosystems, and in recent years, plastic ingestion by seabirds has been of increasing concern because of the potential negative impact on individual and population levels. The aim of this study was to investigate the plastic ... -
Populasjonsstruktur og morfologi hos kongsnegl Buccinum undatum L. på to lokaliteter i Balsfjorden, Nord-Norge
(Master thesis; Mastergradsoppgave, 2007-11-16)To lokaliteter i Balsfjorden, Nord-Norge ble sammenlignet med hensyn på fangstmengde, populasjonsstruktur og morfologi til kongsnegl (Buccinum undatum). Til innsamling ble det benyttet walisiske snegleteiner som var egnet med fisk/sild og haneskjell i kombinasjon eller kun fisk/sild. Fangst foregikk månedlig fra mars til og med juni 2004, på 15, 30 og 45 m dyp. Fangsttiden var på 1 døgn. Antall og ... -
Populasjonsstruktur, kjønnsmodning og variasjon i fekunditet hos kongekrabbe (Paralithodes camtschaticus) i Porsangerfjorden, Finnmark : et litteratur- og feltbasert studium
(Master thesis; Mastergradsoppgave, 2012-11-22)Russiske forskere introduserte kongekrabben, Paralithodes camtschaticus, til Barentshavet på 1960 og 1970-tallet for å gi lokale fiskere en ny art å høste av. Det var antatt at spredning til norske farvann var lite sannsynlig. Artens etablering ble en suksess sett fra russisk side. Kongekrabben har nå spredt seg over hele kysten av Finnmark fylke, og Porsangerfjorden er den siste av fjordene ... -
Population dynamics, diet and trophic positioning of three small demersal fish species within Porsangerfjord, Norway
(Master thesis; Mastergradsoppgave, 2012-11-15)In today’s society, one often stumbles over the quote “you are what you eat”. Diet is closely related to fish size and physical conditions, so in order to understand the food web one must first understand the population dynamics of the fish. Three demersal species in the northern hemisphere are; Artediellus atlanticus, Myoxocephalus scorpius and Leptagonus decagonus. The study was undertaken in ... -
Potential effects of two stressors on morphological traits of Northern Goshawk (Accipiter gentilis) nestlings
(Master thesis; Mastergradsoppgave, 2009-01)Anthropogenic and natural stressors can affect ecosystems negatively and it is therefore important to have a clear understanding of the responses of organisms to stressors. The Northern Goshawk (Accipiter gentilis) is a common raptor species of the boreal forest ecosystem and its location at the top of its food chain makes it a special target for two important stressors; endoparasitism and environmental ... -
Predation on artificial ground nests in a subarctic ecosystem
(Master thesis; Mastergradsoppgave, 2008-05-15)Studies of gallinaceous bird species stress the importance of high nest losses as a factor influencing life histories and populations. Accordingly knowledge of the mechanisms affecting nest losses is essential for understanding the population dynamics. The aim of this one year study was to estimate predation rates on artificial ground nests in ptarmigan habitats, along a landscape gradient which ... -
Predator aversion in resident generalist birds. A ghost of evolutionary past?
(Master thesis; Mastergradsoppgave, 2018-05-14)Predator aversion is an important adaptation that can significantly lower the mortality rate among prey animals, but avoiding a predator requires knowing and recognizing them. The predator aversion of Common gulls and Mallard ducks at Prestvannet Lake, Tromsø, Northern Norway was tested in an experiment by placing differing objects resembling snakes next to bread during the summer and autumn of 2017. ... -
Predictive state-space modelling of lemming population outbreaks on the Fennoscandian tundra: Are determinants of spatial variation in outbreak amplitude temporally consistent?
(Master thesis; Mastergradsoppgave, 2015-11-13)Lemmings are famous for their spectacular population cycles that causes waves of biomass through the arctic tundra. Both climate variability and the interaction with the sympatric grey-sided vole have been shown to effect lemming outbreaks. However little is known about the transferability of these effects between peaks. I analyzed the spatial variability using snap-trapping data from two ...