Does social context influence male mating tactics in Drosophila melanogaster?

Social context, such as mate availability and perceived competition, can influence a male’s mating tactics. In Drosophila melanogaster most research has investigated how physical interactions and the perceived levels of sperm competition alter mating behaviour. I wanted to know if males would respond to the perceived social environments without the presence of physical interaction. Using a unique apparatus, I altered focal males’ social context by separating them physically from a social environment using a screen. Focal males were either in: (i) the presence of rival males and mates, (ii) the presence of potential mates only, (iii) isolation, or (iv) the presence of rival males only. I also manipulated the period the focal male was conditioned to a social environment to assess if the timing of cues is important. My findings suggest that the duration of acclimation alters male mating tactics. Regardless of social environment, the duration a male was conditioned influenced copulation latency. Males that were conditioned to their social environment for the duration of the experiment had differing copulation latencies between environments. Males held in isolation took longer to successfully court females, and transferred less sperm during mating then experimental males in the presence of rival males. Additionally, copulation duration correlated with the number of sperm transferred. Overall, my results suggest that the social environment and the perceived competition level affect mating strategies even without physical interactions. Since this apparatus may trick flies into believing they are a part of a social group, while controlling the male mating status, future work could examine behavioural, genetic and physiological phenotype effects of the social environment for both sexes.

Haptic information stabilizes and destabilizes coordination dynamics

Goal-directed, coordinated movements in humans emerge from a variety of constraints that range from 'high-level' cognitive strategies based oil perception of the task to 'low-level' neuromuscular-skeletal factors such as differential contributions to coordination from flexor and extensor muscles. There has been a tendency in the literature to dichotomize these sources of constraint, favouring one or the other rather than recognizing and understanding their mutual interplay. In this experiment, subjects were required to coordinate rhythmic flexion and extension movements with an auditory metronome, the rate of which was systematically increased. When subjects started in extension on the beat of the metronome, there was a small tendency to switch to flexion at higher rates, but not vice versa. When subjects: were asked to contact a physical stop, the location of which was either coincident with or counterphase to the auditor) stimulus, two effects occurred. When haptic contact was coincident with sound, coordination was stabilized for both flexion and extension. When haptic contact was counterphase to the metronome, coordination was actually destabilized, with transitions occurring from both extension to flexion on the beat and from flexion to extension on the beat. These results reveal the complementary nature of strategic and neuromuscular factors in sensorimotor coordination. They also suggest the presence of a multimodal neural integration process-which is parametrizable by rate and context - in which intentional movement, touch and sound are bound into a single, coherent unit.

Predictable Pathways? Negotiating Risk in the Context of Marginalisation and Social Exclusion

This article is based on ethnographic research with young people living in an area of multiple deprivation in the North-east of England. The young people in this study experience many risk factors associated with social exclusion and future offending. Through in-depth examination of crime within the context of their lives, it will be argued that recent theorisations of youth crime and criminal careers do not fully capture the nature of their offending, the contextual circumstances surrounding it and the differential impact of similar risk factors on their lives. The article concludes by suggesting that not only do such theories detract from the situations of poverty and social exclusion in which young people live but that youth policies informed by them potentially add to their experiences of exclusion and marginalisation.

A Context-Dependent Algorithm for Merging Uncertain Information in Possibility Theory

The need to merge multiple sources of uncertaininformation is an important issue in many application areas,especially when there is potential for contradictions betweensources. Possibility theory offers a flexible framework to represent,and reason with, uncertain information, and there isa range of merging operators, such as the conjunctive anddisjunctive operators, for combining information. However, withthe proposals to date, the context of the information to be mergedis largely ignored during the process of selecting which mergingoperators to use. To address this shortcoming, in this paper,we propose an adaptive merging algorithm which selects largelypartially maximal consistent subsets (LPMCSs) of sources, thatcan be merged through relaxation of the conjunctive operator, byassessing the coherence of the information in each subset. In thisway, a fusion process can integrate both conjunctive and disjunctiveoperators in a more flexible manner and thereby be morecontext dependent. A comparison with related merging methodsshows how our algorithm can produce a more consensual result.