Sexual signals and preferences play a central role in mate choice, sexual selection, and reproductive isolation. However, when such traits are learned rather than genetically fixed, maintaining their accuracy and alignment becomes a major challenge. Learning introduces variation across individuals that can accumulate into mismatches between signallers and receivers, raising the question of how learned mating traits remain sufficiently stable to function in communication and reproduction. Birdsong is one such trait. In songbirds, songs are acquired through vocal learning, and successful song development depends on young individuals attending to, discriminating, and learning from appropriate acoustic models. Understanding how early song responses arise, what shapes tutor related biases, and whether adult song reliably reflects broader aspects of male quality is therefore important for explaining the development and evolution of learned sexual signals.

In this thesis, I investigate these questions in the pied flycatcher (Ficedula hypoleuca), focusing on early song discrimination and the information content of adult song. In Chapter I, I examine whether nestlings discriminate between their social father's song and that of an unfamiliar local male. I show that 13-day-old nestlings respond more strongly to their social father's song, indicating that nestlings can distinguish socially familiar from unfamiliar conspecific songs at an early age.

In Chapter II, I test whether nestlings respond differently to simplified short songs and longer complex songs played back from either their social father or an unfamiliar local male. Since males sing shorter songs after pairing, nestlings are typically exposed to simplified rather than complex paternal song, raising the question of how song length shapes early responsiveness. Nestlings showed stronger postural begging responses to shorter songs regardless of familiarity, suggesting that both early auditory experience and intrinsic acoustic salience contribute to early song responsiveness.

In Chapter III, I investigate whether early discrimination of paternal song reflects inherited predispositions or early auditory experience using an embryonic cross-fostering experiment in the wild. Nestlings reared by either genetic or foster parents were exposed to songs of their social father, genetic father, and an unfamiliar local male, but showed no differential begging responses to the three treatments. Because begging was strongly influenced by nestling condition, these results suggest that behavioural assays may fail to reveal auditory discrimination when nestling motivation is low, and the data remain inconclusive about the relative contributions of experience and predisposition.

In Chapter IV, I shift to adult sexual signalling and test whether song complexity predicts cognitive ability in breeding males, using a novel foraging task and a detour reaching task. Contrary to the hypothesis that preferred song traits signal cognitive quality, I find no consistent positive relationship between song complexity and cognitive performance. The traits most strongly linked to female preference were either unrelated or negatively related to task performance, suggesting that song complexity is unlikely to serve as a straightforward indicator of cognition.

Together, these findings shed new light on how learned sexual signals emerge, are shaped during development, and are maintained in natural populations.

Since the early 2000s, pro-European secessionist parties have pursued “independence in the EU” while becoming increasingly mainstream in European politics. This suggests that the process of European integration might sustain rather than hamper the quest for independence among non-sovereign regions in the EU. This development is puzzling since EU representatives have consistently argued in public that independence is an “internal matter” and that regions of EU member states would automatically lose EU membership upon secession. Previous research has so far overwhelmingly focused on pro-European secessionist parties at the national level, even though mobilization in the European Parliament (EP) has been a consistent component of their strategy. As a result, few studies have focused on how and to what extent the EP is used as a political arena in secessionist parties’ independence strategies.

This thesis examines how pro‑European secessionist parties advance their independence agendas in the EP and explores the role of European integration in contemporary secessionist politics. Although the EU has not delivered on secessionist parties’ wishes and expectations, these parties have continued to mobilize electoral support to secure representation in the EP, raising the question of how Europe matters in their pursuit of independence. The thesis addresses two research questions: how have pro-European secessionist parties used Europe in their independence strategies in the EP between 1999 and 2024, and what contextual factors help understand differences in how Europe is used in secessionist parties’ independence strategies? The thesis adopts a strategic constructivist perspective and develops a new conceptual framework based on the concept of “usage of Europe”, originally established by Sophie Jacquot and Cornelia Woll. The framework is used to structure a comparative study of three secessionist parties from Scotland and Catalonia: Scottish National Party (SNP); Esquerra Republicana de Catalunya (ERC) and Convergència i Unió/Partit Demòcrata Europeu Català/Junts per Catalunya (CiU/PDeCAT/Junts). 

The thesis combines qualitative content analysis of a novel dataset of EP text data with semi-structured interviews with Members of the European Parliament. The findings show that pro‑European secessionist parties have continuously used the EP to address independence, albeit the SNP has used Europe primarily pragmatically, whereas the Catalan parties have used it more idealistically, making Europe more central to their independence strategies. While the different usages of Europe are shaped by contextual factors, the study also shows that all parties engage in practices aiming at normalizing both themselves and their independence claims within the EP. Taken together, the findings suggests that despite the EU’s formal reluctance to facilitate secession,European integration still offers secessionist parties institutional and discursive resources and is therefore not perceived by them as a closed opportunity structure. The thesis thus makes both theoretical and empirical contributions to the study of secessionist politics in Europe.

This thesis is based on three papers which focus on representations of Grothendieck toposes as localic groupoids, localic stacks, and categories of points equipped with convergence data.

In Paper I, we analyse various localic covering theorems and localic groupoid representations for toposes given in the literature. We note that each of these arises from a minimal, concrete object: a locale equipped with a suitable 'amorphous' sheaf. With this definition in hand, we abstract the standard recipe for covering theorems, describe and compare the amorphous sheaves associated to standard covering constructions from the literature, and give a general logical characterisation of amorphous objects.

In Paper II, we show that the 2-category of locales is dense in that of toposes, and that toposes can faithfully be represented as stacks over locales. This is achieved by the combination of an original technical result about the 2-localisation induced by a 2-site, and the key observation that open surjections are of lax descent type in toposes.

In Paper III, we build on the recent development that toposes with enough points can be represented as categories equipped with ultraconvergence data, using it to characterise the surjection–embedding and hyperconnected–localic factorisation systems in terms of points. We introduce analogous classes of functors between abstract categories equipped with ultraconvergence data; provide a new characterisation of separating families of points of a topos; and apply it to show preservation and reflection results between these classes of functors and geometric morphisms.

In this thesis we explore several strategies for the valorization of forestry residues, which account for 30% of lignocellulosic biomass from forestry operations and are currently incinerated, due to the lack of feasible methods of fractionation of the complex feedstock. To address this challenge, chemical conversion methods capable of processing different components have been developed.

In the first chapter, valorization of spruce wood from tops and branches (T&B) was investigated. A fast fractionation method was applied to obtain three main fractions from spruce T&B: solid residue, organic, and aqueous fractions. The solid residue, comprised mainly cellulose, lignin, and small amounts of hemicellulose was converted to textile fibers. The organic fraction, rich in lignin, was converted into hydrocarbons. The environmental sustainability of the process was studied by life-cycle assessment (LCA) and demonstrated better scores in four out of five footprint categories benchmarked to cotton production. 

In the second chapter, conversion of spruce bark into different high-value compounds, such as starch, lipophilic extractives, lignin, tannins, and cellulosic pulp is presented. Pulping under alkaline conditions was chosen as a methodology to delignify bark and obtain cellulosic pulp. To enhance the efficiency of extractions and soda pulping process, a flow-through system was used. The flow-through system demonstrated tunability in the pulping step to achieve either high yields of lignin or pulp depending on the applied temperature. The process also allowed for the mechanical separation of condensed tannins from the cellulosic pulp. LCA showed that conversion of bark into valuable products is more climate-beneficial than combustion.

In the third chapter, the possibility of fractionating a mixture consisting of birch bark and wood, that represents T&B was demonstrated. Two different catalytic approaches allowed us to sequentially isolate monophenols, suberin and yield a cellulose-rich pulp, showing that valorization of complex mixtures could offer a more resource-efficient alternative to incineration. 

Overall, chemical conversion approaches for efficient fractionation of barks and T&B to a variety of compounds that can substitute fossil-based products on the market, was investigated in this thesis.

Postmating prezygotic isolation can reduce gene flow early in divergence, but the reproductive traits and postmating processes that generate these barriers are often challenging to identify. This is especially true in internally fertilizing animals, where fertilization depends on interactions between male ejaculates and the female reproductive tract, and where reduced fertilization can arise through several distinct postmating steps. In this dissertation, I investigate how divergence in interacting reproductive traits translates into postmating prezygotic isolation in Drosophila montana, with a particular focus on sperm length, female sperm storage, and female-mediated postmating processes.

In Chapter I, I test whether divergence in sperm length and seminal receptacle length predicts fertilization success across populations and genotypes. I show that these traits co-diverge and together form a major compatibility axis, such that fertilization success is best predicted by the sperm to seminal receptacle length gap. Fertilization is lowest when sperm are relatively short for a given seminal receptacle. I further show that both traits have substantial additive genetic variance and a polygenic basis, and that their QTL intervals overlap in several genomic regions, identifying candidate regions that may have facilitated coordinated divergence.

In Chapter II, I ask whether this compatibility relationship is fixed or modifiable by developmental condition. I show that seminal receptacle length is condition-dependent in the population with the longest seminal receptacles and sperm, whereas sperm length remains largely insensitive to developmental condition. I further show that female condition can alter fertilization success, both through general female effects and by amplifying sperm to storage mismatch in the cross-direction that already shows the strongest barrier.

In Chapter III, I examine whether divergence in female sperm management helps explain the postmating prezygotic barrier. Using Rhodamine B-labelled ejaculates and organ-specific sperm storage assays across time, I show that sperm management differs between female populations and between storage organs. Heteropopulation effects are female-population dependent, with reduced persistence of heteropopulation sperm in the seminal receptacle in one population and increased early spermathecal occupancy in the other, while complete sperm depletion is generally higher in one female population across the same postmating window regardless of male population origin.

Together, these results show that postmating prezygotic isolation in D. montana is not explained by a single reproductive failure. Instead, it emerges through divergence in interacting reproductive traits and female-mediated postmating processes. More broadly, this dissertation identifies a quantitative speciation phenotype linking sperm and sperm storage divergence to asymmetric reproductive isolation, shows that its expression can be modified by condition-dependence, and helps narrow the postmating mechanisms through which early reproductive barriers arise during speciation.

This compilation thesis consists of four studies examining how individuals and institutions respond to changes in economic conditions and information environments. The first three papers focus on contemporary Africa and study how technological and income shocks affect demographic outcomes and social norms, while the fourth paper examines how political and economic incentives influence institutional change in a historical setting.

The first paper studies the impact of mobile broadband expansion on fertility and child health. Using individual-level data and the staggered rollout of 3G networks, the paper finds that improved connectivity increases fertility, particularly among older and more educated women, but is associated with adverse child health outcomes. The evidence is consistent with two complementary forces: the marginal pregnancies induced by 3G are intrinsically higher-risk, and the maternal health system does not expand to meet rising demand.

The second paper investigates how the expansion of mobile and fixed internet affects attitudes toward intimate partner violence. Exploiting the rollout of submarine cables and 3G coverage across Africa, the study finds that different technologies have contrasting effects on gender norms, with mobile internet improving women's attitudes while male attitudes become more regressive.

The third paper examines how agricultural income shocks affect fertility and child outcomes. Using variation in global commodity price movements interacted with local crop suitability, the study shows that increases in cash crop income raise fertility, primarily through higher-order births, and alter the timing of family formation.

The fourth paper analyses the determinants of franchise expansion in nineteenth-century Britain. Using data on parliamentary voting behaviour, the study shows that political elites' support for democratization depends on electoral incentives, inequality, and the heterogeneity of voter interests, highlighting how strategic considerations shape institutional change.

Trapped ions are one of the leading platforms for quantum technologies due to their excellent control over their internal electronic and external motional degrees of freedom. Many techniques and interesting effects rely on the coupling of the ions to their motion, which makes precise control of them paramount.

In this work, two novel techniques for motional state detection are presented. They allow the probing of certain motional states with a single measurement, without affecting the motion of the measured ion. These techniques are employed to generate and detect a highly entangled state between two motional modes in a novel manner. Furthermore, we harness the rich and intricate dynamics arising from the coupling of the ion's motion to its electronic degrees of freedom to study the emergence of interference. Theoretical predictions, describing interference both in the quantum and the classical regimes, are verified, offering a new and more intuitive description of interference, not just for trapped ions, but for a variety of systems that can be described in a similar way.

On the other hand, Rydberg excitation with trapped ions enables new interaction mechanisms and makes them extremely sensitive to their surroundings. This thesis presents advances towards Rydberg experiments with longer ion strings and concludes with a first demonstration of coherent population transfer between Rydberg states in trapped ions. The methods developed significantly increase the toolbox for trapped Rydberg ions, enabling more sophisticated experiments, especially when multiple different Rydberg states are involved, and allow more flexibility when using longer ion strings.

Developmental gene regulation depends on the coordinated action of transcription factors, chromatin regulators, and histone modifications that establish and maintain cell-type-specific transcriptional states. In this thesis, I investigate how activating and repressive chromatin factors shape lineage specification in Drosophila melanogaster embryogenesis, with a particular focus on the histone acetyltransferase CREB-binding protein (CBP) and Polycomb-mediated repression. Using genomic, genetic, and single-cell approaches, this work addresses how chromatin states are established during zygotic genome activation (ZGA), how CBP controls distinct steps of transcription, and how active and repressive histone modifications together define developmental trajectories.

The first paper examines the regulation of dorsoventral patterning genes. We demonstrated that RNA polymerase II is recruited to their promoters independently of whether the gene is expressed. Chromatin profiling revealed that H3K27ac closely correlates with gene and enhancer activity, while CBP occupancy at promoters remains invariant. These results identify promoter-proximal pausing as a central regulatory step in early developmental patterning and suggest that inactive CBP can remain associated with silent but poised promoters.

The second paper of the thesis dissects the catalytic and non-catalytic functions of CBP during ZGA. By combining catalytic inactivation and targeted protein degradation, we show that CBP has separable roles in transcriptional elongation and initiation. Its catalytic activity is required for pause release, whereas its non-catalytic activity supports pre-initiation complex stability and RNA polymerase II recruitment. CBP is dispensable for chromatin opening itself and therefore acts downstream of pioneer factors such as Zelda. 

The third paper addresses how CBP activity is regulated across the genome. We show that CBP activity enhances its own recruitment and affects transcription factor binding at regions pioneered by the transcription factor Zelda. Catalytic functions of CBP are shown to be crucial for proper expression of early patterning genes in the Drosophila embryo. Inactive CBP persists at a subset of paused promoters primed by the pioneer factor GAF, and may contribute to Polycomb-associated repression. Together, these results establish CBP as a transcription factor-dependent regulator whose catalytic and non-catalytic functions differently contribute to early development.

The final part of the thesis extends this analysis to later embryogenesis using single-cell nanoCUT&Tag to co-profile H3K27ac and H3K27me3 in individual nuclei. We suggest a new way for epigenetic potential visualization, and found genes where Polycomb repression and gene activity co-occur in one cell lineage. The data distinguishes between two repressive states: active Polycomb-mediated repression and passive chromatin inaccessibility. H3K27me3 associates with genes exposed to activation cues rather than with all silent developmental genes. We further corroborate this conclusion by showing preferential upregulation of lineage-matching genes when H3K27me3 was partially depleted in a mesoderm lineage. 

Together, the studies in this thesis show that developmental epigenetic regulation occurs by the controlled and context-dependent action of co-activators, co-repressors, and pioneer factors that together ensure lineage commitment and maintain robust boundaries between cell identities.

This doctoral thesis examines how participation in a queer mainstream fan culture contributes to meaning-making in the everyday lives of young people. The study is based on ten months of ethnographic fieldwork with fans aged 15–35, the majority of whom were 15–26. The empirical material consists of interviews, participant observations, and fan-created artworks. Through an ethnographic and queer theoretical approach, the dissertation foregrounds the participants’ own perspectives, with particular attention of time, emotion and everyday life. Across four empirical chapters, the dissertation analyzes different temporal and  affective dimensions of fandom.

The first chapter ”enchantment,” examines how fans orient themselves towards enchanting cultural experiences.  If queerness in everyday life has been associated with vulnerability and pain, engaging with queer fan cultures offers a new optic through which queerness appears in a different light. Within the enchanted framework, queerness is not only linked to suffering but also to beauty and possibility. The chapter further highlights how a foundational aspect of being a fan, lays in meeting like-minded others and creating a community. The orientation towards enchantment becomes meaningful when experienced collectively with other fans.

The second chapter, ”Ecstasy,” examines how enchantment is intensified through collective ecstatic states. Drawing on empirical material describing fans waiting for a pop concert to begin, the chapter illustrates how playful and seemingly ­ ”silly” forms of joy, generates a shared emotional intensity. Interpreted through queer temporal perspectives, these moments are conceptualized as forms of micro-ecstasy. 

The third chapter, ”Escapism,” shifts attention from the intensity of ecstasy to quieter practices characterized by withdrawal, waiting and seclusion. The chapter sheds light on the ”insivible” fans that are less drawn to the social dimensions of fan cultures. They engage with fandom in more private ways. These fans create meningful experiences of enjoyment and emotional attachment in solitude. The findings suggest that escapism becomes significant by providing secluded spaces for comfort, rest and pleasure.  

The fourth chapter ”The hangover,” explores the processes through which enchantment transforms to disenchantment. Here, toxic community dynamics, algorithmic platform logics and emotional exhaustion lead fans to renegotiate their sense of belonging within fan communities. This chapter therefor examines the ambivalent and at times painful dimensions of fan culture. Experiences of disenchantment also raise questions concerning future participation and how fans manage their ”personal archives” of fan engagement. Decisions to leave a fan community often involve practices of archiving, erasing or preserving traces of participation. These negeotations are analyzed through queer theocratical perspectives on everyday archiving. 

The final chapter ties together the thesis’ main arguments and reflects further upon how ideas of queer temporality can contribute to the field of youth culture studies.