Male genital morphology influences paternity success in the millipede <Emphasis Type="Italic">Antichiropus variabilis</Emphasis>

The genitalia of internally fertilizing animals are among the most diverse of all sexual characters. It is currently argued that genitalia evolve rapidly and divergently due to intense post-copulatory sexual selection. If true, male genital morphology should be subject to directional selection, whereby males with particular genital morphologies achieve greater paternity success. There is mounting evidence that male genital morphology can influence competitive fertilization success; however, the form of selection acting on genitalia has rarely been explored. We conducted competitive fertilization experiments using Antichiropus variabilis millipedes. Using microsatellite loci, we determined the paternity of offspring following double matings. The last male to mate had a significant paternity advantage. While no aspect of the behavior of last males was correlated with paternity success, variation in genital morphology did account for variation in last male paternity. Male genitalia were subject to nonlinear selection, with both convex (stabilizing) selection and concave (disruptive) selection acting on genital shape. This is the first study to provide evidence for sperm precedence in a millipede and only the second to document the form of post-copulatory sexual selection operating on male genital morphology. We discuss the implications of our results for the evolution of genitalia in A. variabilis and, more broadly, how our findings relate to alternative theories of genital evolution.     

The effects of subsampling and sampling frequency on the use of surface-floating pupal exuviae to measure Chironomidae (Diptera) communities in wadeable temperate streams

Community, diversity, and biological index metrics for chironomid surface-floating pupal exuviae (SFPE) were assessed at different subsample sizes and sampling frequencies from wadeable streams in Minnesota (USA). Timed collections of SFPE were made using a biweekly sampling interval in groundwater-dominated (GWD) and surface-water-dominated (SWD) streams. These two types of stream were sampled because they support different Chironomidae communities with different phenologies which could necessitate sampling methodologies specific to each stream type. A subsample size of 300 individuals was sufficient to collect on average 85% of total taxa richness and to estimate most metrics with an error of about 1% relative to 1,000 count samples. SWD streams required larger subsample sizes to achieve similar estimates of taxa richness and metric error compared to GWD streams, but these differences were not large enough to recommend different subsampling methods for these stream types. Analysis of sample timing determined that 97% of emergence occurred from April through September. We recommend in studies where estimation of winter emergence is not important that sampling be limited to this period. Sampling frequency also affected the proportion of the community collected. To maximize the portion of the community, collected samples should be taken across seasons although no specific sampling interval is recommended. Subsampling and sampling frequency was also assessed simultaneously. When using a 300-count subsample, a 4-week sampling interval from April through September was required to collect on average 71% of the community. Due to differences in elements of the chironomid community evaluated by different studies (e.g., biological condition, phenology, and taxonomic composition), richness estimates are documented for five sampling intervals (2, 4, 6, 8, 10, and 12 weeks) and five subsample sizes (100, 200, 300, 500, and 1,000 counts). This research will enhance future studies by providing guidelines for tailoring SFPE methods to study specific goals and resources.     

Micrometeorological measurements of N2O and CH4 emissions from a municipal solid waste landfill.

Micrometeorological measurements of methane (CH4) and nitrous oxide (N2O) emissions were made at the decommissioned Park Road Landfill in Grimsby, Ontario, Canada between June and August 2002. The influence of precipitation, air temperature, wind speed and barometric pressure on the temporal variability of landfill biogas emissions was assessed. Gas flux measurements were obtained using a micrometeorological mass balance measurement technique [integrated horizontal flux (IHF)] in conjunction with two tunable diode laser trace gas analyser (TDLTGA) systems. This method allows for continuous, non-intrusive measurements of gas flux at high temporal resolution. Mean fluxes of N2O were negligible over the duration of the study (-0.23 to 0.02 microg m(-2) s(-1)). In contrast, mean emissions of CH4 were much greater (80.4 to 450.8 microg m(-2) s(-1)) and varied both spatially and temporally. Spatial variations in CH4 fluxes were observed between grass kill areas (biogas 'hot spots') and the densely grass-covered areas of the landfill. Temporal variations in CH4 fluxes were also observed, due at least in part to barometric pressure, wind speed and precipitation effects.     

Brood-provisioning strategies in Dawson's burrowing bee, Amegilla dawsoni (Hymenoptera: Anthophorini)

Males of Dawson's burrowing bee are dimorphic in size. Although large (major) males defeat smaller ones in competition for emerging females and therefore are more likely to mate, majors are greatly outnumbered by half-sized (minor) males. Nesting females might produce many minor males, despite their low reproductive value, because female behaviour is governed by a mixed evolutionarily stable strategy (ESS), in which case the ratio of majors to minors should not be affected by changes in female condition. In contrast, a conditional-strategy hypothesis predicts that older, wing-worn or stressed females unable to forage efficiently should be especially likely to produce minor offspring, which require less brood provisions. To test these alternative hypotheses, we manipulated the condition of nesting female bees by the addition of weights and the removal of their wing margins. These manipulations, done early in the flight season, failed to increase the production of minor males, a result consistent with the mixed-ESS hypothesis. However, unmanipulated females were far more likely to produce minor males if they were small or if they were nesting late in the season, when foraging conditions had deteriorated, findings that are consistent with a conditional provisioning strategy. Thus it appears that the abundance of minor males is the result of a conditional provisioning strategy of nesting females, which may be superimposed on a fixed tendency to produce large offspring early in the season and small ones later.     

A further examination of managerial burnout: Toward an integrated model

A model of managerial burnout was examined among 148 human service supervisors and managers. The findings suggest that emotional exhaustion plays a central mediating role in the burnout process. Social support and direct control were associated with exhaustion through role stress. Job and life satisfaction, and time spent with clients and subordinates were also related to exhaustion. In turn, exhaustion was related to depersonalization, professional commitment, and turnover intentions. An expected reciprocal relation between exhaustion and helplessness was not found, as the former had only a weak impact on the latter. Implications for stress coping are discussed.     

Development of a field well head safety system for use with radiation generating devices

This paper discusses the design, testing and application of a new interlock system for field use with neutron generating bore hole probes at the Idaho National Engineering and Environmental Laboratory. Such probes produce 14 MeV neutrons at a yield up to 3×10⁸ neutrons/s, and present an ionizing radiation hazard to personnel particularly when operated in an unshielded configuration. This interlock system prevents personnel from being exposed to the relatively high radiation fields caused by an unsafe condition when an operating neutron generator probe is withdrawn from a well in the ground. An electromechanical interlock prototype system has been designed, built and tested, and has been found to be effective at preventing this event. The design is simple, is effective in mitigating the hazard, and can be installed in minutes. The system could be modified to interlock radiation-generating devices other than neutron generators that are used in similar environments.     

The Ethics of Food for Tomorrow: On the Viability of Agrarianism—How Far can it Go? Comments on Paul Thompson’s Agrarian Vision

I consider Paul Thompson’s Agrarian Vision from the perspective of the philosophy of technology, especially as it relates to certain questions about public engagement and deliberative democracy around food issues. Is it able to promote an attitudinal shift or reorientation in values to overcome the view of “food as device” so that conscientious engagement in the food system by consumers can become more the norm? Next, I consider briefly, some questions to which it must face up in order to move closer in dismantling the barriers that inhibit the capacity for virtuous caretaking of the food system at various levels. Lastly, and more deeply, how successful might agrarianism be in inculcating citizenship values (ones that go beyond food ethics as a private affair), for the democratization of agricultural technologies? Might the Jeffersonian foundation to which the agrarianism (a la) Thompson appeals need something like a contemporary theory of justice in order to facilitate the reconstitution of our politico-moral selves? How can it help guide appropriate ruminations on the intra and intergenerational question, “What do we want the shape of our current and future social and political institutions to look like in relation to food?”     

Effects of Topographic Heterogeneity on Coarse Resolution Grid-Based Runoff Simulation—Assessment for Three River Basins in Peninsular Malaysia

This paper investigates the effects of topographic heterogeneity on the runoff response simulated by a 0.05 degree (approximately 5.5 km) spatial resolution distributed hydrological model for the Pahang, Kelantan, and Muda river basins (25,600, 11,900, and 4010 km², respectively) in Peninsular Malaysia. Daily simulations were carried out and assessed against observed streamflow for the period 1999–2004. Topographic structure was characterized by means of subgrid terrain slope to guide the decomposition of hydrological parameters over the model grid. The results show improved simulation skill for all three basins compared to a traditional runoff production parameterization scheme that does not take into account the subgrid topographic variability. However, other factors related to morphological heterogeneity and variability in physical terrain conditions should be considered in future work in order to characterize the hydrological heterogeneity. The present methodology may be of potential for further development of large-scale, coarse resolution grid-based hydrological models without adding structural model complexity and without affecting parameter parsimony.