Search results for "I.5.0"
showing 10 items of 65 documents
Trophic state changes can affect the importance of methane-derived carbon in aquatic food webs
2017
Methane-derived carbon, incorporated by methane-oxidizing bacteria, has been identified as a significant source of carbon in food webs of many lakes. By measuring the stable carbon isotopic composition (δ13C values) of particulate organic matter, Chironomidae andDaphniaspp. and their resting eggs (ephippia), we show that methane-derived carbon presently plays a relevant role in the food web of hypertrophic Lake De Waay, The Netherlands. Sediment geochemistry, diatom analyses and δ13C measurements of chironomid andDaphniaremains in the lake sediments indicate that oligotrophication and re-eutrophication of the lake during the twentieth century had a strong impact on in-lake oxygen availabili…
Why aren't warning signals everywhere? : On the prevalence of aposematism and mimicry in communities
2021
Warning signals are a striking example of natural selection present in almost every ecological community - from Nordic meadows to tropical rainforests, defended prey species and their mimics ward off potential predators before they attack. Yet despite the wide distribution of warning signals, they are relatively scarce as a proportion of the total prey available, and more so in some biomes than others. Classically, warning signals are thought to be governed by positive density-dependent selection, i.e. they succeed better when they are more common. Therefore, after surmounting this initial barrier to their evolution, it is puzzling that they remain uncommon on the scale of the community. He…
Soil fungi invest into asexual sporulation under resource scarcity, but trait spaces of individual isolates are unique
2022
During the last few decades, a plethora of sequencing studies provided insight into fungal community composition under various environmental conditions. Still, the mechanisms of species assembly and fungal spread in soil remain largely unknown. While mycelial growth patterns are studied extensively, the abundant formation of asexual spores is often overlooked, though representing a substantial part of the fungal life cycle relevant for survival and dispersal. Here, we explore asexual sporulation (spore abundance, size and shape) in 32 co-occurring soil fungal isolates under varying resource conditions, to answer the question whether resource limitation triggers or inhibits fungal investment…
Feeding Ecology of Harbour Seals (Phoca vitulina) in Southern Norway
2017
Master's thesis Aquatic Ecology BIO500 - University of Agder 2017 In order to understand ecosystem dynamics and functions it is vital to have knowledge about relationships between predator and prey. Harbour seals (Phoca vitulina) are piscivorous marine mammals found at or near the top of marine food webs. Being mainly piscivores, harbour seals have the potential to come into conflict with fishermen and fisheries. Recently, as the Skagerrak and Kattegat population of harbour seals has increased, claims that seals are depleting the cod population have surfaced. Using scat sampling and otolith identification, harbour seal diet was estimated in four separate locations along the coast of souther…
Natural selection against offshore Atlantic cod (Gadus morhua) in Skagerrak fjords?
2016
Master's thesis Aquatic Ecology BIO500 - University of Agder 2016 The marine environment was previously presumed to be demographically “open”, and marineorganisms were thought to have pronounced gene flow over vast areas due to their potentialof dispersal during early life stages. However, recent studies have suggested a degree of selfrecruitmentwithin segments of coastal and offshore areas for several marine species. Two ofthe forces acting on this structuring are retention of early life stages and homing of adultindividuals. This study looks at the distribution of early life stages of the Atlantic cod (Gadusmorhua) in two Norwegian fjords divided into inshore-offshore transects, and study…
Analysering av miljø-DNA for kartlegging av marin fiskefauna
2016
Masteroppgave akvatisk økologi BIO500 - Universitetet i Agder 2016 Marine ecosystems worldwide are currently threatened due to overfishing and other humanimpacts. To monitor marine fish, which represents a main component in present monitoring ofmarine ecosystem health, one is mainly depending on invasive and selective methods. Thesemethods are also dependent on physical identification of species, which in many cases can bedifficult, or in some cases, impossible. Such limitations of traditional surveillance methodshave created a demand for alternative methods. One such alternative is the environment-DNAmethod, i.e. analysis of genetic material from a sample collected in the environment.In th…
Genome-wide meta-analysis increases to 71 the number of confirmed Crohn's disease susceptibility loci
2010
We undertook a meta-analysis of six Crohn's disease genome-wide association studies (GWAS) comprising 6,333 affected individuals (cases) and 15,056 controls and followed up the top association signals in 15,694 cases, 14,026 controls and 414 parent-offspring trios. We identified 30 new susceptibility loci meeting genome-wide significance (P < 5 x 10(-8)). A series of in silico analyses highlighted particular genes within these loci and, together with manual curation, implicated functionally interesting candidate genes including SMAD3, ERAP2, IL10, IL2RA, TYK2, FUT2, DNMT3A, DENND1B, BACH2 and TAGAP. Combined with previously confirmed loci, these results identify 71 distinct loci with gen…
Absolute and relative quantification of RNA modifications via biosynthetic isotopomers
2014
In the resurging field of RNA modifications, quantification is a bottleneck blocking many exciting avenues. With currently over 150 known nucleoside alterations, detection and quantification methods must encompass multiple modifications for a comprehensive profile. LC-MS/MS approaches offer a perspective for comprehensive parallel quantification of all the various modifications found in total RNA of a given organism. By feeding (13)C-glucose as sole carbon source, we have generated a stable isotope-labeled internal standard (SIL-IS) for bacterial RNA, which facilitates relative comparison of all modifications. While conventional SIL-IS approaches require the chemical synthesis of single mod…
El Terç del Cartoixà de Joan Roís de Corella. Edició i estudi
2016
La tesi doctoral "El Terç del Cartoixà de Joan Roís de Corella. Edició i estudi" fixa el text d'aquest incunable i el compara a doble columna amb el text del qual és deutor, la Vita Christi de Ludolf de Saxònia. La datació de l'obra, entre febrer i març de 1495, i l'atribució a un taller, el de Hagenbach-Hutz a la ciutat de València, es realitza per mitjà de l'anàlisi de dades codicològiques i d'història de la impremta en aquesta ciutat. Aquesta anàlisi permet també situar adequadament el projecte d'edició dels quatre volums que conformen el Cartoixà de Corella a finals del segle XV. La comparació del text català amb el llatí permet descobrir les diferents tècniques usades per l'autor valen…
Expanding the Active Inference Landscape: More Intrinsic Motivations in the Perception-Action Loop
2018
Active inference is an ambitious theory that treats perception, inference and action selection of autonomous agents under the heading of a single principle. It suggests biologically plausible explanations for many cognitive phenomena, including consciousness. In active inference, action selection is driven by an objective function that evaluates possible future actions with respect to current, inferred beliefs about the world. Active inference at its core is independent from extrinsic rewards, resulting in a high level of robustness across e.g.\ different environments or agent morphologies. In the literature, paradigms that share this independence have been summarised under the notion of in…