| 1. |
- Johansson, Anders, 1972-
(författare)
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Biopolitics and Reflexivity : A Study of GMO Policymaking in the European Union
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The political discourse that has emerged as a consequence of establishing a European regulatory framework for GMOs has not been without problems. This dissertation addresses the political and regulatory challenges created by the development and use of genetically modified organisms (GMOs) in the EU. The underlying hypothesis in the dissertation is that the emergence of a European policy in the field of GMOs has appeared through new reflexive forms of governance. The aim of this research is to understand how these reflexive forms of regulation have emerged and operate within the EU, with a particular focus on the two GMO directives 90/220/EEC and 2001/18/EC. However, the study scrutinises the regulatory regimes from the 1970s onwards by investigating how the regulatory framework regarding GMOs has been developed and implemented in the EU. This is done through an analysis of the notion of ‘risk’ and the ‘precautionary principle’ since these concepts have been at the forefront of the GMO regulation debate. The empirical approach focuses on how the European Commission, the European Parliament and the European Council as well as other actors and institutions articulate ambivalence, interpretations and uncertainties in the decision-making processes regarding regulative measures for GMOs, with an accent on risk and the precautionary principle. The main empirical material has been documents concerning the inter-institutional process involved in the regulatory process of making the two directives. The analysis indicates that during the process of implementing GMO regulations, new steering strategies have appeared within the EU’s decision-making institutions when the objective of the regulation has taken centre stage in political and scientific controversies.
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| 2. |
- Johansson, Jenny, 1977-
(författare)
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Drivers of polymorphism dynamics in pygmy grasshoppers
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, I used colour polymorphism in pygmy grasshoppers as a model system to study the influence of selection, developmental plasticity, mating behaviour and gene flow on patterns of phenotypic and genetic diversity within and among populations in changing environments.Data for more than 5,000 individuals collected from natural populations showed that the incidence of black (melanic) pygmy grasshoppers was higher in burnt than in non-burnt areas, and rapidly declined over time within populations in post-fire environments. A common garden experiment confirmed that differences among populations were genetically determined. A split brood experiment further uncovered no developmental plasticity in response to rearing substrate, but a high resemblance between mothers and their offspring thus indicating that colour morphs are under strong genetic control.To investigate the role of polyandry, I experimentally mated virgin females to multiple males; genotyped families using microsatellite markers developed for this purpose, and demonstrated that polyandrous females can produce offspring sired by different males. Analysis of families produced by females collected from a natural population confirmed that multiple paternities can increase colour morph diversity among half-siblings in the wild. Analysis of 130 AFLP (Amplified Fragment Length Polymorphism) markers in individuals from 5 localities uncovered two distinct gene clusters, as well as high genetic diversity within and significant divergence among populations within each cluster.My studies of colour polymorphism dynamics demonstrate an important role of population differentiation and rapid adaptive evolution in response to selection in heterogeneous environments, indicate limited effects of plasticity and gene flow, and implicate multiple mating as promoting diversity within populations in this pygmy grasshopper system.
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| 3. |
- Johansson, Jacob
(författare)
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Evolving ecological communities in changing environments
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of theoretical studies of the evolutionary consequences of environmental change in ecological communities. Paper I and II are concerned with the origin of diversity, i.e. how a single lineage can split into two, under the influence of selection induced by competitive interactions (evolutionary branching). In paper I we find that environmental fluctuations may affect the likelihood of such a split. In particular, if correlation in species environment decreases quickly during divergence, stochastic fluctuations can impede or delay the branching process. In paper II we study this process more in detail in a scenario where population fluctuations are derived mechanistically from environmental fluctuations affecting prey growth rates. We find that high autocorrelation in combination with low or negative correlation in environmental fluctuations can block the branching process. The fluctuating environment may also cause cycles of branching and extinction. In paper III I study the role of competition for adaptation in a changing environment. The environmental change is envisioned as gradual shifts of the resource landscape. I find that competitive interactions decrease the rate of adaptation considerably due to an ecological effect of the environmental change (an increase in population size of the species favoured by the change). As a result a coalition of two species can only adapt to a slowly changing resource landscape, whereas a single species can adapt to much more variable environments. In paper IV we investigate the long term effects of extinctions on ecological communities, and especially if inherent evolutionary dynamics, i.e. gradual evolution in combination with evolutionary branching can restore an ecological community after extinctions of constituent species. Interestingly, even if an ESS can be constructed, or attained, from a single precursor species it is not certain that evolution will lead back to it after extinctions. We discuss how such irreversible evolution may lead to Humpty-Dumpty effects and community closure on an evolutionary time scale. In sum, the findings illustrate that if ecological feedback is taken into account for evolutionary responses to environmental changes and extinctions, rather complex patterns of community evolution can be anticipated. With very few assumptions in the description of the ecological and evolutionary model, environmental perturbations may cause delays in community radiation, evolutionarily driven extinctions, patterns of repeated branching and shifts of ESS impeding restoration. The inclusion of ecological feedback also reveals how evolutionary responses to a changing environment can be modified and slowed down by interactions which even may lead to patterns of stasis and mass extinctions.
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| 4. |
- Lindh, Magnus, 1973-
(författare)
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Evolution of Plants : a mathematical perspective
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Earth harbors around 300 000 plant species. The rich and complex environment provided by plants is considered a key factor for the extraordinary diversity of the terrestrial fauna by, for example, providing food and shelter. This thesis contributes to the understanding of these questions by investigating how the interplay of physiology, demography, and evolution gives rise to variation and diversity in fundamental plant traits. This will help us answer questions such as: How has this amazing diversity of plant species emerged? Which mechanisms maintain diversity? How are plant strategies and plant diversity influenced by variations in the environment?A plant faces multiple problems to survive and reproduce successfully. These problems can be modeled by considering traits, trade-offs and a fitness measure. For example: How to maximize growth rate, while maximizing structural stability? I will investigate four plant models in order to understand the function of plants, and mechanisms promoting diversity. Paper I: We study how annual plants with and without growth constraints should optimize their flowering time when productivity or season length changes. With a dynamic ontogenetic growth model and optimal control theory we prove that a bang-bang reproductive control is optimal under constrained growth and constant mortality rate. We find that growth constraints can flip the direction of optimal phenological response for increasing productivity. The reason is that the growth rate of vegetative mass saturates at high productivity and therefore it is better to flower earlier and take advantage of a longer reproductive period. If season length extends equally both in the beginning and the end of the season, growth constraints control the direction of the optimal response as well. Our theory can help explaining phenological patterns along productivity gradients, and can be linked to empirical observations made on a calendar scale.Paper II: We introduce a new measure of tree crown-rise efficiency based on the loss of biomass of the tree during growth. The more mass the tree looses during growth, the less crown-rise efficient it is. Top-heavy shapes loose more biomass than bottom-heavy shapes. Light-use efficiency is defined as the mean light assimilation of the leaves in the crown times the ratio of leaf mass and total mass. We then study the trade-off between light-use efficiency to crown-rise efficiency for tree crown shapes. We assume that the total tree mass is constant, and a constant vertical light gradient represent the shading from a surrounding forest. We find large differences in crown shapes at intermediate vertical light gradient, when both self-shading and mean-field shading are important, suggesting light-use vs crown-rise efficiency as a new trade-off that can explain tree diversity. Our crown-rise efficiency measure could easily be integrated into existing forest models.Paper III: We extend an evolutionary tree crown model, where trees with different heights compete for light, with drought-induced mortality rates depending on ground-water availability and the depth of an optional taproot. The model does not include competition for ground water. Our model explains how ground-water availability can shape plant communities, when taproot and non-taproot strategies can coexist, and when only one of these strategies can persist. We investigate how emerging plant diversity varies with water table depth, soil water gradient and drought-induced mortality rate. The taproot enables plants to reach deep water, thus reducing mortality, but also carries a construction cost, thus inducing a trade-off. We find that taproots maintain plant diversity under increasing drought mortality, and that taproots evolve when groundwater is accessible at low depths. There are no viable strategies at high drought mortality and deep water table. Red Queen evolutionary dynamics appear at intermediate drought mortality in mixed communities with and without taproots, as the community never reaches a final evolutionarily stable composition.Paper IV: We extend a size-structured plant model, with self-shading and two evolving traits, crown top-heaviness and crown width-to-height ratio. The model allows us to identify salient trade-offs for the crown shape. The most important trade-off for top-heaviness is light-use efficiency vs crownrise efficiency, and the most important trade-off for width-to-height ratio is self-shading vs branch costs. We find that when the two traits coevolve; the outcome is a single common evolutionarily stable strategy (ESS), far away from the highest net primary production (NPP). When only sun angle is decreasing with increasing latitude both the crown width-to-height ratio and crown top-heaviness decrease. However, when light response in addition to the sun angle decreases with increasing latitude, the crown width-to-height ratio is nearly invariant of latitude except at low site productivity when the ratio decreases with latitude. Top-heaviness is always decreasing with increasing latitude. Finally, we find that crown top-heaviness increases with the NPP or leaf-area index (LAI) at ESS, but crown width-to-height ratio is maximal at an intermediate NPP or LAI.
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| 5. |
- Nordmark, Johanna, 1968-
(författare)
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Aspects of Induced Hypothermia following Cardiopulmonary Resuscitation : Cerebral and Cardiovascular Effects
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hypothermia treatment with cooling to a body temperature of 32-34°C has been shown to be an effective way of improving neurological outcome and survival in unconscious patients successfully resuscitated after cardiac arrest (CA). The method is used clinically but there are still many questions on the biological mechanisms and on how the treatment is best performed. This thesis focuses on cerebral and haemodynamic effects of hypothermia and rewarming. A porcine model of CA was used. To shorten time to reach target temperature, induction of hypothermia, by means of infusion of 4°C cold fluid, was started already during ongoing cardiopulmonary resuscitation. The temperature was satisfactorily reduced without obvious haemodynamic disturbances. Cerebral effects of hypothermia and rewarming were studied. Microdialysis monitoring showed signs of cerebral energy failure (increased lactate/pyruvate-ratio) and excitotoxicity (increased glutamate) immediately after CA. There was a risk of secondary energy failure that was reduced by hypothermia. Intracranial pressure (ICP) increased gradually after CA irrespectively of if hypothermia was used or not. There were no indications of increasing cerebral disturbances during rewarming. Haemodynamic effects of hypothermia treatment and rewarming were examined in a study of patients successfully resuscitated after CA. Hypothermia was induced by means of cold intravenous infusion. No negative effects on the cardiovascular system were revealed. There were indications of decreased intravascular volume in spite of a positive fluid balance. Cerebral microdialysis and ICP recording were performed in four patients. All patients had signs of energy failure and excitotoxicity following CA. ICP was only exceptionally above 20 mmHg. In contrast to the experimental study indications of increasing ischemia were seen during rewarming. Glycerol had a biphasic pattern, perhaps due to an overspill of metabolites from the general circulation. As most patients become extensively anti-coagulated following CA, intracranial monitoring is not suitable to be used in routine care.
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