Length polymorphism at the avpr1a locus is correlated with male reproductive behavior in a natural population of prairie voles (Microtus ochrogaster)

Laboratory studies have shown that vasopressin can influence sociosexual behavior through its action on the vasopressin 1a receptor (V1aR). There is substantial evidence that the length of a microsatellite in the gene (avpr1a) encoding for the V1aR can affect social attachment to females and paternal behavior in male prairie voles under laboratory conditions. However, previous field studies of prairie voles have failed to detect a strong effect of the length of a male’s avpr1a allele on their sociosexual behavior, but these studies are typically much shorter than the average prairie vole breeding lifespan. We examined the relationship between male avpr1a microsatellite allele length and sociosexual behavior in a natural population of prairie voles for 15 weeks, closer to the lifespan of prairie voles in nature. Contrary to predictions, we found that males with the longest avpr1a microsatellite alleles were significantly more likely to sire offspring with more than one female and to sire offspring that survived until trappable age than males with the shortest avpr1a microsatellite allele lengths. This relationship was the strongest for males with the longest tenure on the study site. As in previous field studies, we did not find evidence of a relationship between a male’s avpr1a genotype and any index of social behavior including male residency status or the number of females with which males associate. This is the first study to support the hypothesis that a male’s avpr1a genotype is a factor underlying variation in the genetic mating system of prairie voles under natural conditions.     

Removal of Remazol Brilliant Violet-5R dye using periwinkle shells

The purpose of this research is to obtain optimal processing conditions for the adsorption of Remazol Brilliant Violet-5R (RBV-5R) dye onto activated carbon prepared from periwinkle shells (PSAC) by chemical activation with KOH using response surface methodology. Central composite design (CCD) was used to determine the effects of three preparation variables; CO₂ activation temperature, CO₂ activation time and KOH:char impregnation ratio (IR) on two responses; percentage RBV-5R dye removal and PSAC yield. Based on the CCD, two quadratic models were developed for percentage RBV-5R dye removal and PSAC yield, respectively. The most influential factor on each experimental design response was identified from the analysis of variance (ANOVA). The optimum conditions for the adsorption of RBV-5R dye onto PSAC were CO₂ activation temperature of 811 °C, CO₂ activation time of 1.70 h and IR of 3.0, resulting in 81.28% RBV-5R dye removal and 28.18% PSAC yield. PSAC prepared under optimum conditions was mesoporous with a Brunauer–Emmett–Teller surface area of 1894 m²·g^?1, total pore volume of 1.107 cm³·g^?1 and average pore diameter of 2.32 nm. The surface morphology and functional groups of the activated carbon were respectively determined from the scanning electron microscopy and Fourier transform infrared analysis.     

Speciation and long- and short-term molecular-level dynamics of soil organic sulfur studied by X-ray absorption near-edge structure spectroscopy

We investigated speciation, oxidative state changes, and long- and short-term molecular-level dynamics of organic S after 365 d of aerobic incubation with and without the addition of sugarcane residue using XANES spectroscopy. Soil samples were collected from the upper 15 cm of undisturbed grasslands since 1880, from undisturbed grasslands since 1931, and from cultivated fields since 1880 in the western United States. We found three distinct groups of organosulfur compounds in these grassland-derived soils: (i) strongly reduced (S to S) organic S that encompasses thiols, monosulfides, disulfides, polysulfides, and thiophenes; (ii) organic S in intermediate oxidation (S to S) states, which include sulfoxides and sulfonates; and (iii) strongly oxidized (S) organic S, which comprises ester-SO-S. The first two groups represent S directly linked to C and accounted for 80% of the total organic S detected by XANES from the undisturbed soils. Aerobic incubation without the addition of sugarcane residue led to a 21% decline in organanosulfur compounds directly linked to C and to up to an 82% increase inorganic S directly bonded to O. Among the C-bonded S compounds, low-valence thiols, sulfides, thiophenic S, and intermediate-valence sulfoxide S seem to be highly susceptible to microbial attack and may represent the most reactive components of organic S pool in these grassland soils. Sulfonate S exhibited a much lower short-term reactivity. The incorporation of sugarcane residue resulted in an increase in organosulfur compounds directly bonded to C at the early stage of incubation. However, similar to soils incubated without residue addition, the proportion of organic S directly linked to C continued to decline with increasing duration of aerobic incubation, whereas the proportion of organic S directly bonded to O showed a steady rise.     

Mitigating energy production-based carbon dioxide emissions in Argentina: the roles of renewable energy and economic globalization

Environmental Science and Pollution Research - The energy sector of Argentina is predominantly reliant on fossil fuels. Consequently, such fossil fuel dependency within the nation’s power...     

Quantitative approaches to the analysis of stable isotope food web data

Ecologists use stable isotopes (delta13C, delta15N) to better understand food webs and explore trophic interactions in ecosystems. Traditionally, delta13C vs. delta15N bi-plots have been used to describe food web structure for a single time period or ecosystem. Comparisons of food webs across time and space are increasing, but development of statistical approaches for testing hypotheses regarding food web change has lagged behind. Here we present statistical methodologies for quantitatively comparing stable isotope food web data. We demonstrate the utility of circular statistics and hypothesis tests for quantifying directional food web differences using two case studies: an arthropod salt marsh community across a habitat gradient and a freshwater fish community from Lake Tahoe, USA, over a 120-year time period. We calculated magnitude and mean angle of change (theta) for each species in food web space using mean delta13C and delta15N of each species as the x, y coordinates. In the coastal salt marsh, arthropod consumers exhibited a significant shift toward dependence on Spartina, progressing from a habitat invaded by Phragmites to a restored Spartina habitat. In Lake Tahoe, we found that all species from the freshwater fish community shifted in the same direction in food web space toward more pelagic-based production with the introduction of nonnative Mysis relicta and onset of cultural eutrophication. Using circular statistics to quantitatively analyze stable isotope food web data, we were able to gain significant insight into patterns and changes in food web structure that were not evident from qualitative comparisons. As more ecologists incorporate a food web perspective into ecosystem analysis, these statistical tools can provide a basis for quantifying directional food web differences from standard isotope data.     

Exposure of homeowners and bystanders to 2,4-dichlorophenoxyacetic acid (2,4-D).

Total body dose received in home gardeners applying 2,4-D and bystanders living within the household, but not applying the pesticide was measured. Levels of 2,4-D were monitored in air samples both inside the home and downwind of the application site. Homeowners were divided into protective and non-protective apparel groups and applied both a granular and liquid formulation of 2,4-D on two separate dates. Analyses of urine collected from homeowners for 96 hours following applications found total body doses ranging from non-detectable to 0.0071 mg/kg of body weight. The highest exposures occurred in the non-protected group and were consistently associated with spills of the liquid concentrate or excessive contact with the dilute mixture on the hands or forearms. Residues of 2,4-D were not detected in urine samples supplied by bystanders to home applicators. Residues of 2,4-D were detected in five of the 76 air samples taken during the home applications. Two of these air samples coincided with measurable applicator exposure but it is unlikely that this was a major route of exposure.     

Forest dynamics in Oregon landscapes: evaluation and application of an individual-based model.

The FORCLIM model of forest dynamics was tested against field survey data for its ability to simulate basal area and composition of old forests across broad climatic gradients in western Oregon, USA. The model was also tested for its ability to capture successional trends in ecoregions of the west Cascade Range. It was then applied to simulate present and future (1990-2050) forest landscape dynamics of a watershed in the west Cascades. Various regimes of climate change and harvesting in the watershed were considered in the landscape application. The model was able to capture much of the variation in forest basal area and composition in western Oregon even though temperature and precipitation were the only inputs that were varied among simulated sites. The measured decline in total basal area from tall coastal forests eastward to interior steppe was matched by simulations. Changes in simulated forest dominants also approximated those in the actual data. Simulated abundances of a few minor species did not match actual abundances, however. Subsequent projections of climate change and harvest effects in a west Cascades landscape indicated no change in forest dominance as of 2050. Yet, climate-driven shifts in the distributions of some species were projected. The simulation of both stand-replacing and partial-stand disturbances across western Oregon improved agreement between simulated and actual data. Simulations with fire as an agent of partial disturbance suggested that frequent fires of low severity can alter forest composition and structure as much or more than severe fires at historic frequencies.     

Costs and benefits of communal rearing to female prairie voles (<Emphasis Type="Italic">Microtus ochrogaster</Emphasis>)

Communal rearing of offspring may help mothers maximize their investment in offspring at a reduced cost to their own bodily condition, thus maximizing their potential for reproductive success. The objective of this study was to quantify the costs and benefits of communal rearing to prairie vole (Microtus ochrogaster) pups and mothers. Mothers were assigned to one of three social units: solitary mothers, singularly breeding groups (i.e. one mother and one non-reproductive sister) and plurally breeding groups (i.e. two lactating sisters). For each type of social unit, some replicates were provided with food ad libitum, while others were provided with limited food. The body mass of focal mothers (i.e. the first mother to produce a litter) was a significant predictor of pup growth. Regardless of food availability, litters of focal mothers in plurally breeding groups gained more weight than litters reared by solitary mothers. Pups reared in singularly breeding groups were intermediate in weight gain, but did not gain significantly more weight than solitary offspring. There was no difference in the body mass of focal mothers from each type of social unit, regardless of food availability. Within plurally breeding groups, the weight gain of the two litters and body mass of focal and second mothers did not differ. However, focal mothers from plurally breeding groups nursed fewer pups than solitary mothers and also fewer pups than their nestmates when food was limited. Our results suggest that plural breeding results in greater fitness to mothers than solitary and singular breeding.Communicated by E. Korpimäki     

Spatial distribution of polybrominated diphenyl ethers and polybrominated biphenyls in lake trout from the Laurentian Great Lakes

Concentrations of two types of brominated flame-retardants (BFRs); polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) were determined in a single age class of lake trout (Salvelinus namaycush) collected from the Laurentian Great Lakes in 1997. Mean concentrations of total PBDE were highest in samples from Lake Ontario at 95+/-22 ng/g wet weight (ww) or 434+/-100 ng/g lipid weight (lw) while the lowest concentrations were observed in Lake Erie lake trout (27+/-8.6 ng/g ww, 117+/-37 ng/g lw). In all samples, the predominant PBDE congeners were 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), and 2,2',4,4', 6-pentabromodiphenyl ether (BDE-100), which are the primary components of the commonly used penta-BDE formulation flame retardant. Lake trout collected from Lake Huron had the highest concentrations of PBBs (3.1+/-1.7 ng/g ww, 15+/-8.5 ng/g lw), while the lowest levels were detected in fish from Lake Superior (0.25+/-0.13 ng/g ww, 1.7+/-0.89 ng/g lw). In all lake trout samples, 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), a major constituent of the flame-retardant FireMaster BP-6, was the predominant PBB congener.     

The effect of two applications of atrazine on the water quality of freshwater enclosures

To simulate runoff from agricultural lands, atrazine was applied to aquatic enclosures (112 m(3)) on 1 June 1983 at a concentration of 0.1 mg litre(-1). Thirty-five days later the nominal concentration was increased to 0.155 mg litre(-1). Treated enclosures became clearer with Secchi disc readings of 3.6 m compared to non-treated controls (2.9 m). Less than 5% of the first atrazine addition disappeared during the first 35 days and little effect on biological activity was observed. However, with the second enrichment the rate of loss of atrazine was rapid (t(1/2) = 150 days), ammonium, calcium, dissolved inorganic carbon and nitrate levels were higher, while oxygen, chlorophyll, dissolved organic carbon and particulate organic carbon concentrations were lower in the treated enclosures. These water quality changes cannot be explained by herbicide-water chemistry interactions alone, thereby suggesting an indirect effect as a consequence of atrazine inhibition on photosynthesis and possibly other microbial processes.