Sexual selection hinders adaptation in experimental populations of yeast

Sexual selection, the suite of processes that lead to differential mating success among individuals, probably influences the evolutionary trajectory of populations. Because sexual selection often shifts traits away from their survival optima, strong sexual selection pressures are thought to increase potential for population extinction, especially during environmental change. Sexual selection pressures may also increase the opportunity for speciation by accelerating the generation of pre-zygotic isolation among populations. These relationships remain largely untested experimentally. Here, we allow populations of baker\u27s yeast, Saccharomyces cerevisiae, to evolve for approximately 250 generations with altered sex ratios in order to test the effect of the strength of sexual selection on the fate of populations. We find that populations experiencing stronger sexual selection are less able to adapt to a novel environment compared with populations experiencing weaker sexual selection or no sex, and that strong sexual selection erases the benefits of sexual reproduction. This pattern persists when fitness is assayed in a closely related environment. We also identify a trend that may suggest the beginning of pre-zygotic isolation between populations experiencing stronger sexual selection, though this is not statistically significant. These results highlight the importance of sexual selection in shaping macroevolutionary patterns and biodiversity

Unsung heroes: Constituency election agents in British general elections

Despite their central role in the electoral process, constituency agents have been largely overlooked by political scientists and this article seeks to rectify the omission. It sketches the origins and development of the role of agent from the late 19th century and suggests that a serious rethink of the role took place in the 1990s. Survey-based evidence about the social characteristics of agents is presented confirming that they are largely middle-aged, middle-class, well-educated men. They are also becoming more experienced, offer realistic assessments of the impact of constituency campaigning and, arguably, many take a long-term view of how their party's support can be maximised

Field testing an acoustic lighthouse : Combined acoustic and visual cues provide a multimodal solution that reduces avian collision risk with tall human-made structures

Billions of birds fatally collide with human-made structures each year. These mortalities have consequences for population viability and conservation of endangered species. This source of human-wildlife conflict also places constraints on various industries. Furthermore, with continued increases in urbanization, the incidence of collisions continues to increase. Efforts to reduce collisions have largely focused on making structures more visible to birds through visual stimuli but have shown limited success. We investigated the efficacy of a multimodal combination of acoustic signals with visual cues to reduce avian collisions with tall structures in open airspace. Previous work has demonstrated that a combination of acoustic and visual cues can decrease collision risk of birds in captive flight trials. Extending to field tests, we predicted that novel acoustic signals would combine with the visual cues of tall communication towers to reduce collision risk for birds. We broadcast two audible frequency ranges (4 to 6 and 6 to 8 kHz) in front of tall communication towers at locations in the Atlantic migratory flyway of Virginia during annual migration and observed birds’ flight trajectories around the towers. We recorded an overall 12–16% lower rate of general bird activity surrounding towers during sound treatment conditions, compared with control (no broadcast sound) conditions. Furthermore, in 145 tracked “at-risk” flights, birds reduced flight velocity and deflected flight trajectories to a greater extent when exposed to the acoustic stimuli near the towers. In particular, the 4 to 6 kHz stimulus produced the greater effect sizes, with birds altering flight direction earlier in their trajectories and at larger distances from the towers, perhaps indicating that frequency range is more clearly audible to flying birds. This “acoustic lighthouse” concept reduces the risk of collision for birds in the field and could be applied to reduce collision risk associated with many human-made structures, such as wind turbines and tall buildings

Ultraviolet-reflective film applied to windows reduces the likelihood of collisions for two species of songbird

Perhaps a billion birds die annually from colliding with residential and commercial windows. Therefore, there is a societal need to develop technologies that reduce window collisions by birds. Many current window films that are applied to the external surface of windows have human-visible patterns that are not esthetically preferable. BirdShades have developed a short wavelength (ultraviolet) reflective film that appears as a slight tint to the human eye but should be highly visible to many bird species that see in this spectral range. We performed flight tunnel tests of whether the BirdShades external window film reduced the likelihood that two species of song bird (zebra finch, Taeniopygia guttata and brown-headed cowbird, Molothrus ater) collide with windows during daylight. We paid particular attention to simulate the lighting conditions that birds will experience while flying during the day. Our results indicate a 75–90% reduction in the likelihood of collision with BirdShades-treated compared with control windows, in forced choice trials. In more ecologically relevant comparison between trials where all windows were either treated or control windows, the estimated reduction in probability of collision was 30–50%. Further, both bird species slow their flight by approximately 25% when approaching windows treated with the BirdShades film, thereby reducing the force of collisions if they were to happen. Therefore, we conclude that the BirdShades external window film will be effective in reducing the risk of and damage caused to populations and property by birds’ collision with windows. As this ultraviolet-reflective film has no human-visible patterning to it, the product might be an esthetically more acceptable low cost solution to reducing bird-window collisions. Further, we call for testing of other mitigation technologies in lighting and ecological conditions that are more similar to what birds experience in real human-built environments and make suggestions for testing standards to assess collision-reducing technologies

One dimensional Confinement of Electric Field and Humidity Dependent DNA Conductivity

The dependence of DNA assemblies conductance on relative humidity is investigated theoretically. Following earlier suggestions, we consider the ionic conductivity through the layers of water adsorbed by DNA molecules. The increase in humidity results in a growing water layer. The binding energy of ions depends on the thickness of the water layer due to change in water polarization. This dependence is very strong at smaller thicknesses of water layers due to the low-dimensional confinement of an electric field in water. We show that the associated change in ion concentration can explain the six orders of magnitude increase in conductivity, with relative humidity growing from 0.05 to 0.95Comment: 16 pages, 5 figures, published in Journal of Chemical Physic

The analysis of facial beauty: an emerging area of research in pattern analysis

Much research presented recently supports the idea that the human perception of attractiveness is data-driven and largely irrespective of the perceiver. This suggests using pattern analysis techniques for beauty analysis. Several scientific papers on this subject are appearing in image processing, computer vision and pattern analysis contexts, or use techniques of these areas. In this paper, we will survey the recent studies on automatic analysis of facial beauty, and discuss research lines and practical application

A generation apart? Youth and political participation in Britain

Conventional wisdom holds that young people in Britain are alienated from politics, with some claiming that this reflects a wider crisis of legitimacy that should be met by initiatives to increase citizenship. This article addresses these areas, presenting both panel survey and focus group data from first-time voters. It concludes that, contrary to the findings from many predominantly quantitative studies of political participation, young people are interested in political matters, and do support the democratic process. However they feel a sense of anti-climax having voted for the first time, and are critical of those who have been elected to positions of political power. If they are a generation apart, this is less to do with apathy, and more to do with their engaged scepticism about ‘formal’ politics in Britain

Passerine Birds Breeding under Chronic Noise Experience Reduced Fitness

Background Fitness in birds has been shown to be negatively associated with anthropogenic noise, but the underlying mechanisms remain obscure. It is however crucial to understand the mechanisms of how urban noise impinges on fitness to obtain a better understanding of the role of chronic noise in urban ecology. Here, we examine three hypotheses on how noise might reduce reproductive output in passerine birds: (H1) by impairing mate choice, (H2) by reducing territory quality and (H3) by impeding chick development. Methodology/Principal Findings We used long-term data from an island population of house sparrows, Passer domesticus, in which we can precisely estimate fitness. We found that nests in an area affected by the noise from large generators produced fewer young, of lower body mass, and fewer recruits, even when we corrected statistically for parental genetic quality using a cross-fostering set-up, supporting H3. Also, individual females provided their young with food less often when they bred in the noisy area compared to breeding attempts by the same females elsewhere. Furthermore, we show that females reacted flexibly to increased noise levels by adjusting their provisioning rate in the short term, which suggests that noise may be a causal factor that reduces reproductive output. We rejected H1 and H2 because nestbox occupancy, parental body mass, age and reproductive investment did not differ significantly between noisy and quiet areas. Conclusions/Significance Our results suggest a previously undescribed mechanism to explain how environmental noise can reduce fitness in passerine birds: by acoustically masking parent–offspring communication. More importantly, using a cross-fostering set-up, our results demonstrate that birds breeding in a noisy environment experience significant fitness costs. Chronic noise is omnipresent around human habitation and may produces similar fitness consequences in a wide range of urban bird species