The genetics and evolutionary dynamics of sexually antagonistic polymorphisms in Drosophila melanogaster

The evolution of sexual dimorphism is constrained by a shared genome between males and females. This constraint can lead to ‘sexual antagonism’ where segregating alleles at given genetic loci have opposing fitness effects in each sex. Despite its wide taxonomic incidence, little is known about the identity, genomic location and evolutionary dynamics of sexually antagonistic polymorphisms. This is a major knowledge gap, since a better understanding of antagonistic polymorphisms can shed light on two fundamental questions: (i) how does the genome evolve to accommodate divergent and often contradictory selective pressures, and (ii) what evolutionary forces maintain genetic variation for fitness? In this thesis, I describe the genetics and evolutionary dynamics of sexually antagonistic polymorphisms. I first highlight the limitations of previous genetic studies of sexual antagonism (Chapter 2). Specifically, I re-analyse a prominent study of antagonistic gene expression and show that inferences of antagonistic selection were driven by non-random population structure in the sample of genomes considered, rendering previous conclusions unreliable. I then present the first genome-wide association study of sex-specific fitness and sexual antagonism in a laboratory-adapted population of D. melanogaster (Chapter 3). I show that antagonistic variation disproportionately accumulates in coding regions but not on the X chromosome. I proceed to test whether sexually antagonistic selection maintains population genetic variation (Chapter 4), as has long been proposed but never tested. Consistent with this hypothesis, I find multiple signatures of balancing selection associated with antagonistic loci across populations of D. melanogaster separated over 10,000 years, and possibly across species boundaries. Finally, I present experimental work testing whether a specific candidate gene—fruitless—is under antagonistic selection (Chapter 5). The results presented are consistent with balancing but not antagonistic selection. Overall, this thesis underscores the fundamental difficulty of evolving genetic mechanisms that accommodate the divergent evolutionary interests of each sex

The volatility of a half-cooked bouillabaisse. Rebel-military integration and conflict dynamics in eastern DRC

In early 2012, Congolese army deserters formed the M23 rebel movement. This article analyses the insurgency and other armed group activity in the eastern DRC in the light of the politics of rebel-military integration. It argues that military integration processes have fuelled militarization in three main ways. First, by creating incentive structures promoting army desertion and insurgent violence; second, by fuelling inter- and intra-community conflicts; and third, by the further unmaking of an already unmade army. We argue that this is not merely the product of a ‘lack of political will’ on behalf of the DRC government, but must be understood in the light of the intricacies of Big Man politics and Kinshasa’s weak grip over both the fragmented political-military landscape in the east and its own coercive arm. Demonstrating the link between military integration and militarization, the article concludes that these problems arise from the context and implementation of integration, rather than from the principle of military power-sharing itself. It thus highlights the crucial agency of political¬–military entrepreneurs, as shaped by national-level policies, in the production of ‘local violence’

Reverse engineering of force integration during mitosis in the Drosophila embryo

The mitotic spindle is a complex macromolecular machine that coordinates accurate chromosome segregation. The spindle accomplishes its function using forces generated by microtubules (MTs) and multiple molecular motors, but how these forces are integrated remains unclear, since the temporal activation profiles and the mechanical characteristics of the relevant motors are largely unknown. Here, we developed a computational search algorithm that uses experimental measurements to ‘reverse engineer' molecular mechanical machines. Our algorithm uses measurements of length time series for wild-type and experimentally perturbed spindles to identify mechanistic models for coordination of the mitotic force generators in Drosophila embryo spindles. The search eliminated thousands of possible models and identified six distinct strategies for MT–motor integration that agree with available data. Many features of these six predicted strategies are conserved, including a persistent kinesin-5-driven sliding filament mechanism combined with the anaphase B-specific inhibition of a kinesin-13 MT depolymerase on spindle poles. Such conserved features allow predictions of force–velocity characteristics and activation–deactivation profiles of key mitotic motors. Identified differences among the six predicted strategies regarding the mechanisms of prometaphase and anaphase spindle elongation suggest future experiments

Introducing biological realism into the study of developmental plasticity in behaviour

There is increasing attention for integrating mechanistic and functional approaches to the study of (behavioural) development. As environments are mostly unstable, it is now often assumed that genetic parental information is in many cases not sufficient for offspring to become optimally adapted to the environment and that early environmental cues, either indirectly via the parents or from direct experience, are necessary to prepare them for a specific environment later in life. To study whether these early developmental processes are adaptive and through which mechanism, not only the early environmental cues but also how they impinge on the later-life environmental context has therefore to be taken into account when measuring the animal's performance. We first discuss at the conceptual level six ways in which interactions between influences of different time windows during development may act (consolidation, cumulative information gathering and priming, compensation, buffering, matching and mismatching, context dependent trait expression). In addition we discuss how different environmental factors during the same time window may interact in shaping the phenotype during development. Next we discuss the pros and cons of several experimental designs for testing these interaction effects, highlighting the necessity for full, reciprocal designs and the importance of adjusting the nature and time of manipulation to the animal's adaptive capacity. We then review support for the interaction effects from both theoretical models and animal experiments in different taxa. This demonstrates indeed the existence of interactions at multiple levels, including different environmental factors, different time windows and between generations. As a consequence, development is a life-long, environment-dependent process and therefore manipulating only the early environment without taking interaction effects with other and later environmental influences into account may lead to wrong conclusions and may also explain inconsistent results in the literature.</p

Chapter 4 Choreographing Love

This chapter examines Sasha Waltz’s choreographic staging of Berlioz’s Roméo et Juliette for the Paris Opera Ballet from 2007. Waltz’s production reimagines one of the most canonical stories in the classical ballet repertoire through the abstract and fragmentary lens of contemporary dance. I trace how Waltz appropriates the post-modern principles of Contact Improvisation for purposes of balletic storytelling. Drawing from recent affect-focussed criticism in dance studies, I explore how Waltz uses the non-narrative relationality of Contact Improvisation to transform Shakespeare’s poetic constellations of affect into abstract, yet dramatically expressive choreographic embodiments of affect, especially in the Pas de deux during the “Scène d’amour”

Elucidating the Targets and Function of the MLR Compass-Like Complex During Development

MLR COMPASS-like complexes are highly-conserved epigenetic regulators required for enhancer establishment and subsequent reprogramming during differentiation and development. Mutation of MLR complex subunits in humans is associated with cancer and developmental disorder, yet much remains to be determined concerning both the healthy and disease-altered functions of these complexes. Using the developmental model Drosophila melanogaster, I further elucidate the functions of the MLR complex during in vivo organ development as well as stress response. I characterize the miRNa bantam as a regulatory target of the complex, required for proper tissue patterning during wing and compound eye formation. in the same systems I confirm in vitro evidence that the MLR complex is required to establish enhancers for regulatory activity cell generations before reprogramming, and further demonstrate a protective role against apoptosis in undifferentiated tissue. Using the fat body as a model of metabolic activity and stress response, I demonstrate that the depletion rate of triglyceride stores during nutrient stress is sensitive to MLR complex activity, and suggest that this is an indirect effect of the regulation of stress response signaling pathways. Through these investigations I demonstrate that the MLR complex may function to either promote or suppress the activity of a single transcriptional effector or the transcription of a single regulatory target, depending on the contexts of development and cell fate