410 research outputs found

    The role of condition on sexual selection in the seed bug Lygaeus simulans

    Get PDF
    Funding: VLB was funded by a University of St Andrews PhD Apprenticeship. MKC's internship was funded by the School of Biology, University of St Andrews.Organism condition plays an important role in sexual selection. Sexual ornaments and displays can be condition-dependent, reflecting either underlying genetic quality, experience of environmental stressors, or both. As such, the phenotypic expression of such traits, and the resulting patterns of mate choice acting on them, may be shaped by intrinsic genetic quality and the environment. Moreover, condition may also influence the choosing individual in mate choice, influencing their ability to invest in mate discrimination, or changing what traits of the chosen, including resources, are most preferred. Here we consider sexual selection and condition in the seed bug Lygaeus simulans, a species characterised by strong post-copulatory sexual selection, but rather limited pre-copulatory discrimination. We manipulated short-term condition in both males and females by restricting access to water for 24 hours. Water is particularly important in these bugs, given their feeding ecology and physiology. We found that water-deprived males proved less likely to mate, whilst copulation duration with water-deprived females was significantly reduced. Given the importance of copulation duration for the successful transfer of sperm by males to females, the data suggest cryptic male choice acting against water-deprived females. These data add to those suggesting that cryptic male choice for fecund females plays an important role in sexual selection in this species. More generally, our results support the widespread importance of condition in terms of mating dynamics and sexual selection.Peer reviewe

    The niche construction perspective: a critical appraisal

    Get PDF
    Niche construction refers to the activities of organisms that bring about changes in their environments, many of which are evolutionarily and ecologically consequential. Advocates of niche construction theory (NCT) believe that standard evolutionary theory fails to recognize the full importance of niche construction, and consequently propose a novel view of evolution, in which niche construction and its legacy over time (ecological inheritance) are described as evolutionary processes, equivalent in importance to natural selection. Here, we subject NCT to critical evaluation, in the form of a collaboration between one prominent advocate of NCT, and a team of skeptics. We discuss whether niche construction is an evolutionary process, whether NCT obscures or clarifies how natural selection leads to organismal adaptation, and whether niche construction and natural selection are of equivalent explanatory importance.We also consider whether the literature that promotes NCT overstates the significance of niche construction, whether it is internally coherent, and whether it accurately portrays standard evolutionary theory. Our disagreements reflect a wider dispute within evolutionary theory over whether the neo-Darwinian synthesis is in need of reformulation, as well as different usages of some key terms (e.g., evolutionary process)

    Cylindrical vector beams for rapid polarization-dependent measurements in atomic systems

    Full text link
    We demonstrate the use of cylindrical vector beams - beams with spatially varying polarization - for detecting and preparing the spin of a warm rubidium vapor in a spatially dependent manner. We show that a modified probe vector beam can serve as an atomic spin analyzer for an optically pumped medium, which spatially modulates absorption of the beam. We also demonstrate space-variant atomic spin by optical pumping with the vector beams. The beams are thus beneficial for making singleshot polarization-dependent measurements, as well as for providing a means of preparing samples with position-dependent spin.Comment: 8 pages, 5 figures. Accepted in Optics Expres

    Recombination and its impact on the genome of the haplodiploid parasitoid wasp Nasonia

    Get PDF
    Homologous meiotic recombination occurs in most sexually reproducing organisms, yet its evolutionary advantages are elusive. Previous research explored recombination in the honeybee, a eusocial hymenopteran with an exceptionally high genome-wide recombination rate. A comparable study in a non-social member of the Hymenoptera that would disentangle the impact of sociality from Hymenoptera-specific features such as haplodiploidy on the evolution of the high genome-wide recombination rate in social Hymenoptera is missing. Utilizing single-nucleotide polymorphisms (SNPs) between two Nasonia parasitoid wasp genomes, we developed a SNP genotyping microarray to infer a high-density linkage map for Nasonia. The map comprises 1,255 markers with an average distance of 0.3 cM. The mapped markers enabled us to arrange 265 scaffolds of the Nasonia genome assembly 1.0 on the linkage map, representing 63.6% of the assembled N. vitripennis genome. We estimated a genome-wide recombination rate of 1.4-1.5 cM/Mb for Nasonia, which is less than one tenth of the rate reported for the honeybee. The local recombination rate in Nasonia is positively correlated with the distance to the center of the linkage groups, GC content, and the proportion of simple repeats. In contrast to the honeybee genome, gene density in the parasitoid wasp genome is positively associated with the recombination rate; regions of low recombination are characterized by fewer genes with larger introns and by a greater distance between genes. Finally, we found that genes in regions of the genome with a low recombination frequency tend to have a higher ratio of non-synonymous to synonymous substitutions, likely due to the accumulation of slightly deleterious non-synonymous substitutions. These findings are consistent with the hypothesis that recombination reduces interference between linked sites and thereby facilitates adaptive evolution and the purging of deleterious mutations. Our results imply that the genomes of haplodiploid and of diploid higher eukaryotes do not differ systematically in their recombination rates and associated parameters.Publisher PDFPeer reviewe

    Threshold and non-linear behavior of lasers of Ξ›\Lambda and V - configurations

    Full text link
    Dynamic properties of closed three level laser systems are investigated. Two schemes of pumping - Ξ›\Lambda and V - are considered. It is shown that the non-linear behavior of the photon number as a function of pump both near and far above threshold is crucially different for these two configurations. In particular, it is found that in the high pump regime laser can turn off in a phase-transition-like manner in both Ξ›\Lambda and V schemes.Comment: 9 pages, 5 figure

    Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective

    Get PDF
    This Report has a number of inter-related general purposes. One is to explore the extent to which food, nutrition, physical activity, and body composition modify the risk of cancer, and to specify which factors are most important. To the extent that environmental factors such as food, nutrition, and physical activity influence the risk of cancer, it is a preventable disease. The Report specifies recommendations based on solid evidence which, when followed, will be expected to reduce the incidence of cancer

    Effect of the Congenital Heart Disease on Growth and Nutritional State of Children

    Get PDF
    Background:This study will show the most likely congenital heart disease that affect on growth parameters which re- arrange our information for rapid referring of such patient to solving their problems and maintains the life of child and decrease burden on salary of family. Objective: To assess nutritional status and factors that predicts nutritional changes in children with congenital heart disease. Patients and Methods: Cross-sectional study, of 110 patients with congenital heart diseases, performed in Al-Hilla and Baghdad cities in Iraq. Children were divided into three groups according to the age. Cardiac diagnosis was made on basis of clinical history, examination, electrocardiography and echocardiography.Β  acute malnutrition assessed by weight/length ratio, chronic malnutrition assessed by length/age ratio, while poor nutritional status and acute deterioration of health status assessed by weight/age ratio. Results: 110 patient; Wasted or severely wasted (60.9%) according to weight/length, and Stunted or severely stunted (61.8%) according to length for age measure; and wasted or severely wasted was (42.7%) according to BMI . There was significant association between acute malnutrition and child age, p value <0.002. Acute malnutrition (Wasted or severely wasted) more with left side volume overload (62.7%) and (60.2%) those with chronic malnutrition (Stunted or severely stunted) have complex heart disease. There was significant association between malnutrition assessed by weight for height and presence of mild, moderate and Severe PHT, absence or presence of treatment, type of feeding and syndromatic type of CHD. There was significant association between chronic malnutrition assessed by height for age and cyanosis, pulmonary hypertension and type of feeding. There was significant association between acute malnutrition assessed by BMI for age and pulmonary hypertension, absence or presence of treatment and type of feeding. There was significant association between malnutrition assessed by Weight for height and history of abortion. Conclusion: Congenital heart disease can affect the growth of children so need resolve these problems by correcting the cardiac abnormality whether by cardiac catheterization of surgical intervention

    Elimination, reversal, and directional bias of optical diffraction

    Full text link
    We experimentally demonstrate the manipulation of optical diffraction, utilizing the atomic thermal motion in a hot vapor medium of electromagnetically-induced transparency (EIT). By properly tuning the EIT parameters, the refraction induced by the atomic motion may completely counterbalance the paraxial free-space diffraction and by that eliminates the effect of diffraction for arbitrary images. By further manipulation, the diffraction can be doubled, biased asymmetrically to induced deflection, or even reversed. The latter allows an experimental implementation of an analogy to a negative-index lens

    The Effect of Neutral Atoms on Capillary Discharge Z-pinch

    Get PDF
    We study the effect of neutral atoms on the dynamics of a capillary discharge Z-pinch, in a regime for which a large soft-x-ray amplification has been demonstrated. We extended the commonly used one-fluid magneto-hydrodynamics (MHD) model by separating out the neutral atoms as a second fluid. Numerical calculations using this extended model yield new predictions for the dynamics of the pinch collapse, and better agreement with known measured data.Comment: 4 pages, 4 postscript figures, to be published in Phys. Rev. Let

    Co‐foundress confinement elicits kinship effects in a naturally sub‐social parasitoid

    Get PDF
    Kinship among interacting individuals is often associated with sociality and also with sex ratio effects. Parasitoids in the bethylid genus Goniozus are sub-social, with single foundress females exhibiting post-ovipositional maternal care via short-term aggressive host and brood defence against conspecific females. Due to local mate competition (LMC) and broods normally being produced by a single foundress, sex ratios are female biased. Contests between adult females are, however, not normally fatal and aggression is reduced when competing females are kin, raising the possibility of multi-foundress reproduction on some hosts. Here we screen for further life-history effects of kinship by varying the numbers and relatedness of foundresses confined together with a host resource and also by varying the size of host. We confined groups of 1 to 8 Goniozus nephantidis females together with a host for 5+ days. Multi-foundress groups were either all siblings or all non-siblings. Our chief expectations included that that competition for resources would be more intense among larger foundress groups but diminished by both larger host size and closer foundress relatedness, affecting both foundress mortality and reproductive output. From classical LMC theory, we expected that offspring group sex ratios would be less female biased when there were more foundresses and from extended LMC theory we expected that sex ratios would be more female biased when foundresses were close kin. We found that confinement led to the death of some females (11% overall) but only when host resources were most limiting. Mortality of foundresses was less common when foundresses were siblings. Developmental mortality among offspring was considerably higher in multi-foundress clutches but was unaffected by foundress relatedness. Groups of sibling foundresses collectively produced similar numbers of offspring to non-sibling groups. There was little advantage for individual females to reproduce in multi-foundress groups: single foundresses suppressed even the largest hosts presented and had the highest per capita production of adult offspring. Despite single-foundress reproduction being the norm, G. nephantidis females in multi-foundress groups appear to attune sex allocation according to both foundress number and foundress relatedness: broods produced by sibling foundresses had sex ratios similar to broods produced by single foundresses (ca. 11% males) whereas the sex ratios of broods produced by non-sibling females were approximately 20% higher and broadly increased with foundress number. We conclude that relatedness and host size may combine to reduce selection against communal reproduction on hosts and that, unlike other studied parasitoids, G. nephantidis sex ratios conform to predictions of both classical and extended LMC theor
    • …
    corecore