The heritability of mating behaviour in a fly and its plasticity in response to the threat of sperm competition.

Phenotypic plasticity is a key mechanism by which animals can cope with rapidly changeable environments, but the evolutionary lability of such plasticity remains unclear. The socio-sexual environment can fluctuate very rapidly, affecting both the frequency of mating opportunities and the level of competition males may face. Males of many species show plastic behavioural responses to changes in social environment, in particular the presence of rival males. For example, Drosophila pseudoobscura males respond to rivals by extending mating duration and increasing ejaculate size. Whilst such responses are predicted to be adaptive, the extent to which the magnitude of response is heritable, and hence selectable, is unknown. We investigated this using isofemale lines of the fruit fly D. pseudoobscura, estimating heritability of mating duration in males exposed or not to a rival, and any genetic basis to the change in this trait between these environments (i.e. degree of plasticity). The two populations differed in population sex ratio, and the presence of a sex ratio distorting selfish chromosome. We find that mating duration is heritable, but no evidence of population differences. We find no significant heritability of plasticity in mating duration in one population, but borderline significant heritability of plasticity in the second. This difference between populations might be related to the presence of the sex ratio distorting selfish gene in the latter population, but this will require investigation in additional populations to draw any conclusions. We suggest that there is scope for selection to produce an evolutionary response in the plasticity of mating duration in response to rivals in D. pseudoobscura, at least in some populations

Listening to music reduces eye movements

Listening to music can change the way that people visually experience the environment, probably as a result of an inwardly directed shift of attention. We investigated whether this attentional shift can be demonstrated by reduced eye movement activity, and if so, whether that reduction depends on absorption. Participants listened to their preferred music, to unknown neutral music, or to no music while viewing a visual stimulus (a picture or a film clip). Preference and absorption were significantly higher for the preferred music than for the unknown music. Participants exhibited longer fixations, fewer saccades, and more blinks when they listened to music than when they sat in silence. However, no differences emerged between the preferred music condition and the neutral music condition. Thus, music significantly reduces eye movement activity, but an attentional shift from the outer to the inner world (i.e., to the emotions and memories evoked by the music) emerged as only one potential explanation. Other explanations, such as a shift of attention from visual to auditory input, are discussed

Probabilistic Study on the Geotechnical Behavior of Fiber Reinforced Soil

Expansive soils which are considered extremely problematic due to their potential to create swell and shrinkage-related distresses. In order to satisfy the geotechnical requirements, these soils are fiber reinforced to sustain dynamic loads as a subgrade material. Polypropylene fiber materials when amended with soil medium, have proven functionality in the long run. Usually, a binder is required to ensure proper bonding between discrete/random fiber elements and the clay particulates. In the current study, lime is a proposed binder and its dosage is fixed at 6% satisfying initial lime consumption and optimum lime requirements. Two types of fiber materials (Fiber Cast® and Fiber Mesh®) at varying dosages (0.2, 0.4, and 0.6% by weight of soil) and having different lengths (6 and 12 mm) are considered for the present study and its inclusion effect on the hydraulic conductivity, unconfined compression strength behavior and California bearing ratio behavior has been studied. The focus of this paper is in determining the optimum fiber reinforcement parameters (fiber type, length, dosage, etc.) for the stabilization of selected expansive Al-Ghat soil. Probabilistic analysis has been performed to correlate the targeted properties with aspect parameters (i.e., dosage and length) for fiber-reinforced soil. In addition to this, reliability analysis has been performed to examine the applicability of this fiber-reinforced soil in municipal solid waste (MSW) landfills for waste containment. The probabilistic analysis revealed that both aspect parameters play a crucial role in fiber-reinforced soils. Further, it is concluded that the target reliability approach (TRA) gives a valuable insight with regards to choosing optimum aspect parameters for effective soil stabilization practice