Love bites: male fang use during coercive mating in wolf spiders

Evolutionary conflicts of interest between the sexes are common, as mating tactics and strategies that increase fitness benefits for one sex may incur costs for the other. As a consequence, antagonistic coevolution between the sexes often results in a complex arms race between male persistence and female resistance. Coercive mating (e.g., forced copulation) likely benefits males by increasing the probability of mating; however, costs to females may be high, including injury or even death. Here, we report on a study of the use of fangs by males of the wolf spider Schizocosa ocreata (Hentz) during forcible mating with resistant females, which results in hemolymph loss and scar tissue formation in females. Microscopic inspection revealed that fang wounds (evidenced by scar tissue) were absent on unmated (virgin) females but were found on mated females and were significantly more frequent in coercively mated females. Experimental fang immobilization studies found no difference in copulation success between experimental (fangs immobilized) and control (sham manipulation) males. However, males that had use of their fangs had significantly longer copulation duration. These findings represent a previously unknown male mating tactic in spiders and an unrecognized potential cost of mating for female spiders.     

Scale-dependent responses of plant biodiversity to nitrogen enrichment

Experimental studies demonstrating that nitrogen (N) enrichment reduces plant diversity within individual plots have led to the conclusion that anthropogenic N enrichment is a threat to global biodiversity. These conclusions overlook the influence of spatial scale, however, as N enrichment may alter beta diversity (i.e., how similar plots are in their species composition), which would likely alter the degree to which N-induced changes in diversity within localities translate to changes in diversity at larger scales that are relevant to policy and management. Currently, it is unclear how N enrichment affects biodiversity at scales larger than a small plot. We synthesized data from 18 N-enrichment experiments across North America to examine the effects of N enrichment on plant species diversity at three spatial scales: small (within plots), intermediate (among plots), and large (within and among plots). We found that N enrichment reduced plant diversity within plots by an average of 25% (ranging from a reduction of 61% to an increase of 5%) and frequently enhanced beta diversity. The extent to which N enrichment altered beta diversity, however, varied substantially among sites (from a 22% increase to an 18% reduction) and was contingent on site productivity. Specifically, N enrichment enhanced beta diversity at low-productivity sites but reduced beta diversity at high-productivity sites. N-induced changes in beta diversity generally reduced the extent of species loss at larger scales to an average of 22% (ranging from a reduction of 54% to an increase of 18%). Our results demonstrate that N enrichment often reduces biodiversity at both local and regional scales, but that a focus on the effects of N enrichment on biodiversity at small spatial scales may often overestimate (and sometimes underestimate) declines in regional biodiversity by failing to recognize the effects of N on beta diversity.     

Modeling transit bus fuel consumption on the basis of cycle properties

A method exists to predict heavy-duty vehicle fuel economy and emissions over an "unseen" cycle or during unseen on-road activity on the basis of fuel consumption and emissions data from measured chassis dynamometer test cycles and properties (statistical parameters) of those cycles. No regression is required for the method, which relies solely on the linear association of vehicle performance with cycle properties. This method has been advanced and examined using previously published heavy-duty truck data gathered using the West Virginia University heavy-duty chassis dynamometer with the trucks exercised over limited test cycles. In this study, data were available from a Washington Metropolitan Area Transit Authority emission testing program conducted in 2006. Chassis dynamometer data from two conventional diesel buses, two compressed natural gas buses, and one hybrid diesel bus were evaluated using an expanded driving cycle set of 16 or 17 different driving cycles. Cycle properties and vehicle fuel consumption measurements from three baseline cycles were selected to generate a linear model and then to predict unseen fuel consumption over the remaining 13 or 14 cycles. Average velocity, average positive acceleration, and number of stops per distance were found to be the desired cycle properties for use in the model. The methodology allowed for the prediction of fuel consumption with an average error of 8.5% from vehicles operating on a diverse set of chassis dynamometer cycles on the basis of relatively few experimental measurements. It was found that the data used for prediction should be acquired from a set that must include an idle cycle along with a relatively slow transient cycle and a relatively high speed cycle. The method was also applied to oxides of nitrogen prediction and was found to have less predictive capability than for fuel consumption with an average error of 20.4%.     

Reporting central tendencies of chamber measured surface emission and oxidation

Methane emissions, concentrations, and oxidation were measured on eleven MSW landfills in eleven states spanning from California to Pennsylvania during the three year study. The flux measurements were performed using a static chamber technique. Initial concentration samples were collected immediately after placement of the flux chamber. Oxidation of the emitted methane was evaluated using stable isotope techniques. When reporting overall surface emissions and percent oxidation for a landfill cover, central tendencies are typically used to report “averages” of the collected data. The objective of this study was to determine the best way to determine and report central tendencies. Results showed that 89% of the data sets of collected surface flux have lognormal distributions, 83% of the surface concentration data sets are also lognormal. Sixty seven percent (67%) of the isotope measured percent oxidation data sets are normally distributed. The distribution of data for all eleven landfills provides insight of the central tendencies of emissions, concentrations, and percent oxidation. When reporting the “average” measurement for both flux and concentration data collected at the surface of a landfill, statistical analyses provided insight supporting the use of the geometric mean. But the arithmetic mean can accurately represent the percent oxidation, as measured with the stable isotope technique. We examined correlations between surface CH₄ emissions and surface air CH₄ concentrations. Correlation of the concentration and flux values using the geometric mean proved to be a good fit (R² = 0.86), indicating that surface scans are a good way of identifying locations of high emissions.     

Environmental pollutants and type 2 diabetes: a review of human studies

The incidence of diabetes has increased dramatically in recent decades and become one of the leading health problems worldwide. Lifestyle and dietary changes alone cannot account for the dramatic rise of diabetes, while an increasing number of publications have reported the possible relationships between exposure to environmental pollutants and risk of diabetes. In the present review, our objective was to summarize the human studies on environmental pollutants, which includes persistent organic pollutants, pesticides (not on the Stockholm Convention list), bisphenol A, and phthalates, and the risk of diabetes. Currently published results suggest a positive relationship between certain persistent organic pollutants (dichlorodiphenyldichloroethene, dichlorodiphenyltrichloroethane, hexachlorobenzene, and polychlorinated biphenyls) and bisphenol A exposure and risk of diabetes. For pyrethroids, organophosphates, carbamates, and phthalates, there are insufficient studies to reach conclusions and therefore more studies, especially prospective studies, are needed along with in vivo and in vitro studies to understand the underlying mechanisms.     

Influence of prairie restoration on CT-measured soil pore characteristics

Restored prairies are expected to improve soil physical properties, yet little is known about the extent of change to soil properties and how rapidly these changes take place. The objective of this study was to compare effects of prairie restoration on computed tomography (CT)-measured pore parameters. Undisturbed soil cores (76 mm diam. by 76 mm long) from native prairie (NP), restored prairie (RP), conservation reserve program (CRP), and no-till corn (Zea mays L.)-soybean (Glycine max (L.) Merr.; CS) sites were collected with six replicates from the 0- to 40-cm depth in 10-cm increments. Five CT images were acquired from each soil core using a medical CT scanner with 0.2 by 0.2 mm pixel resolution with 0.5 mm slice thickness, and then images were analyzed. Soil bulk density and hydraulic conductivity (K(sat)) were also measured. Soils under NP, RP, CRP, and CS areas had 83, 43, 48, and 26 pores on a 2500 mm(2) area, respectively, for the 0- to 40-cm depth. The number of pores, number of macropores (>1000 microm diam.), macroporosity, mesoporosity (200-1000 microm diam.), and fractal dimension were significantly higher and pore circularity was lower for NP, RP, and CRP than the CS treatment. The CT-measured mesoporosity and macroporosity of the CS treatment were 20 and 18% of the values for the NP site. CT-measured number of pores and macropores explained 43 and 40% of the variation for K(sat). The study showed that prairie restoration improves CT-measured soil pore parameters and decreases bulk density which are related to soil water infiltration.     

Unprecedented bleaching-induced mortality in Porites spp. at Rangiroa Atoll, French Polynesia

In April-May 1998, mass coral bleaching was observed in the lagoon of Rangiroa Atoll, Tuamotu Archipelago, French Polynesia. Six months later, the extent of bleaching-induced coral mortality was assessed at three sites. Corals in the fast-growing genus Pocillopora had experienced >99% mortality. Many large colonies of the slow-growing genus Porites (mean horizontal cross-sectional area 5.8 m²) had also died - a phenomenon not previously observed in French Polynesia and virtually unprecedented world-wide. At one site, 25% of colonies, or 44% of the pre-bleaching cover of living Porites, experienced whole-colony mortality. At the two other sites, recently dead Porites accounted for 41% and 82% of the pre-bleaching live cover. Mortality in Porites was negatively correlated with depth between 1.5 and 5 m. Using a 50-year dataset of mean monthly sea surface temperature (SST), derived from ship- and satellite-borne instruments, we show that bleaching occurred during a period of exceptionally high summer SST. 1998 was the first year in which mean monthly SSTs exceeded the 1961-1990 upper 95% confidence limit (29.4°C) for a period of three consecutive months. We suggest that the sustained 3-month anomaly in local summer SST was a major cause of coral mortality, but do not discount the synergistic effect of solar radiation. Recovery of the size-frequency distribution of Porites colonies to pre-bleaching levels may take at least 100 years.     

Assessment of GM Crops in Commercial Agriculture

The caliber of recent discourse regarding geneticallymodified organisms (GMOs) has suffered from a lack of consensuson terminology, from the scarcity of evidence upon which toassess risk to health and to the environment, and from valuedifferences between proponents and opponents of GMOs. Towardsaddressing these issues, we present the thesis that GM should bedefined as the forcible insertion of DNA into a host genome,irrespective of the source of the DNA, and exclusive ofconventional or mutation breeding.Some defenders of the commercial use of GMOs have referred to thescientific work of GMO critics as ``junk science.' Such a claim isfalse and misleading, given that many papers critical of both theutility and safety of GMOs have been published in peer reviewedjournals by respected scientists. In contrast, there is a dearthof peer reviewed work to substantiate the frequently heardassertions of either safety or utility in GMOs. The polarity,which now characterizes much of the public discourse on GMOs,reflects not simply scientific disagreement, but alsodisagreement in underlying value assumptions. Value differencesstrongly affect the assessment of both benefit and harm fromGMOs.The concept of substantial equivalence occupies a pivotalposition in the GMO risk assessment process that is used in bothCanada and the US. A GMO judged to be substantially equivalent toa conventional product – as have all submissions to date – ispresumed to be safe enough for commercialization. The conclusionof safety – from both human health and environmental perspectives– should be based on scientific evidence, corroborated by actualexperimentation. However, regulators infer safety largely fromassumptions-based reasoning, with little or no experimentalvalidation. The judgement of safety because of substantialequivalence is a dubious argument by analogy.     

Vivianite precipitation and phosphate sorption following iron reduction in anoxic soils

Phosphorus retention in lowland soils depends on redox conditions. The aim of this study was to evaluate how the Fe(III) reduction degree affects phosphate adsorption and precipitation. Two similarly P-saturated, ferric Fe-rich lowland soils, a sandy and a peat soil, were incubated under anaerobic conditions. M?ssbauer spectroscopy demonstrated that Fe(III) in the sandy soil was present as goethite and phyllosilicates, whereas Fe(III) in the peat soil was mainly present as polynuclear, Fe-humic complexes. Following anoxic incubation, extensive formation of Fe(II) in the solids occurred. After 100 d, the Fe(II) production reached its maximum and 34% of the citrate-bicarbonate-dithionite extractable Fe (Fe(CBD)) was reduced to Fe(II) in the sandy soil. The peat soil showed a much faster reduction of Fe(III) and the maximum reduction of 89% of Fe(CBD) was reached after 200 d. Neoformation of a metavivianite/vivianite phase under anoxic conditions was identified by X-ray diffraction in the peat. The sandy soil exhibited small changes in the point of zero net sorption (EPC?) and P(i) desorption with increasing Fe(III) reduction, whereas in the peat soil P desorption increased from 80 to 3100 μmol kg?1 and EPC? increased from 1.7 to 83 μM, after 322 d of anoxic incubation. The fast Fe(III) reduction made the peat soils particularly vulnerable to changes in redox conditions. However, the precipitation of vivianite/metavivianite minerals may control soluble P(i) concentrations to between 2 and 3 μM in the long term if the soil is not disturbed.