Can We Accurately Characterize Wildlife Resource Use When Telemetry Data Are Imprecise?

ABSTRACT Telemetry data have been widely used to quantify wildlife habitat relationships despite the fact that these data are inherently imprecise. All telemetry data have positional error, and failure to account for that error can lead to incorrect predictions of wildlife resource use. Several techniques have been used to account for positional error in wildlife studies. These techniques have been described in the literature, but their ability to accurately characterize wildlife resource use has never been tested. We evaluated the performance of techniques commonly used for incorporating telemetry error into studies of wildlife resource use. Our evaluation was based on imprecise telemetry data (mean telemetry error = 174 m, SD = 130 m) typical of field-based studies. We tested 5 techniques in 10 virtual environments and in one real-world environment for categorical (i.e., habitat types) and continuous (i.e., distances or elevations) rasters. Technique accuracy varied by patch size for the categorical rasters, with higher accuracy as patch size increased. At the smallest patch size (1 ha), the technique that ignores error performed best on categorical data (0.31 and 0.30 accuracy for virtual and real data, respectively); however, as patch size increased the bivariate-weighted technique performed better (0.56 accuracy at patch sizes >31 ha) and achieved complete accuracy (i.e., 1.00 accuracy) at smaller patch sizes (472 ha and 1,522 ha for virtual and real data, respectively) than any other technique. We quantified the accuracy of the continuous covariates using the mean absolute difference (MAD) in covariate value between true and estimated locations. We found that average MAD varied between 104 m (ignore telemetry error) and 140 m (rescale the covariate data) for our continuous covariate surfaces across virtual and real data sets. Techniques that rescale continuous covariate data or use a zonal mean on values within a telemetry error polygon were significantly less accurate than other techniques. Although the technique that ignored telemetry error performed best on categorical rasters with smaller average patch sizes (i.e., ≤31 ha) and on continuous rasters in our study, accuracy was so low that the utility of using point-based approaches for quantifying resource use is questionable when telemetry data are imprecise, particularly for small-patch habitat relationships.     

Inactivation of recombinant plasmid DNA from a human erythropoietin-producing mouse cell line grown on a large scale

Summary Experiments were carried out to assess the survival of recombinant plasmid DNA during large-scale production of recombinant human erythropoietin (rhuEPO) in a fermentation pilot plant. The analyses revealed DNA-degrading activities in the fermentation broth and in the waste-water, leading to rapid destruction of plasmid DNA added to medium or waste-water. The capability of the plasmid-DNA-spiked samples to transform competent bacteria was drastically reduced. The DNA-degrading activity in the waste-waters could be blocked by addition of EDTA or by boiling, indicating the presence of DNA-degrading enzymes (DNases). No plasmid-specific DNA sequences were detected in waste-water samples by in-vitro amplification with Taqpolymerase. Genomic DNA preparations of cell debris collected from waste-water samples only contained degraded plasmid DNA. Furthermore, it was shown that intact plasmid DNA could be degraded to fragments of less than 1000 bp by incubation at 121°C for 20 min, leading to a decrease in the plasmid-specific transforming capacity by a factor of 10³ per minute. Thus, DNA from the rhuEPO production pilot plant was efficiently inactivated at three different levels: (i) in the fermentation medium (DNase), (ii) in the waste-water container (DNase), and (iii) by heat inactivation for 20 min at 120°C. These results indicate that the probability of delivery of recombinant DNA into the environment is extremely low in such biotechnological production processes. Offprint requests to: M. R. Fibi     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

The function of innervated kidneys during stimulation of the carotid chemoreceptors under constant renal perfusion pressure]

The carotid chemoreceptors of narcotized, vagotomized and spontaneously breathing hydropenic cats in hypertonic mannite diuresis were stimulated by perfusion with venous blood penic cats in hypertonic mannite diuresis were stimulated by perfusion with venous blood for 70 min. Elevation of blood pressure at the innervated kidneys was prevented by an automatically controlled balloon located within the aorta. Stimulation of the chemoreceptors intensified respiration and raised the arterial systemic pressure. With the renal arteries at constant pressure, the effective renal plasma flow and the glomerular filtration rate significantly declined. The filtration fraction remained unchanged. The absolute urinary and sodium excretion did not change significantly, whereas the fractional time-volume, fractional sodium excretion, and the fractional osmotic excretion significantly increased. The fractional tubular reabsorption of osmotically free water was significantly enhanced. These reactions subsided during subsequent perfusion of the glomerula carotici with arterial blood. The results suggest that tubular sodium reabsorption is inhibited by stimulation of the carotid chemoreceptors, although re-adjustment of renal perfusion and filtrate volume cannot be excluded.     

Effects of Wild Pig Disturbance on Forest Vegetation and Soils

In North America, wild pigs (Sus scrofa; feral pigs, feral swine, wild boars) are a widespread exotic species capable of creating large-scale biotic and abiotic landscape perturbations. Quantification of wild pig environmental effects has been particularly problematic in northern climates, where they occur only recently as localized populations at low densities. Between 2016 and 2017, we assessed short-term (within ~2 yrs of disturbance) effects of a low-density wild pig population on forest features in the central Lower Peninsula of Michigan, USA. We identified 16 8-ha sites using global positioning system locations from 7 radio-collared wild pigs for sampling. Within each site, we conducted fine-scale assessments at 81 plots and quantified potential disturbance by wild pigs. We defined disturbance as exposure of overturned soil, often resulting from rooting behavior by wild pigs. We quantified ground cover of plants within paired 1-m² frames at each plot, determined effects to tree regeneration using point-centered quarter sampling, and collected soil cores from each plot. We observed less percent ground cover of native herbaceous plants and lower species diversity, particularly for plants with a coefficient of conservatism ≥5, in plots disturbed by wild pigs. We did not observe an increase in colonization of exotic plants following disturbance, though the observed prevalence of exotic plants was low. Wild pigs did not select for tree species when rooting, and we did not detect any differences in regeneration of light- and heavy-seeded tree species between disturbed or undisturbed plots. Magnesium and ammonium content in soils were lower in disturbed plots, suggesting soil disturbance accelerated leaching of macronutrients, potentially altering nitrogen transformation. Our study suggested that disturbances by wild pigs, even at low densities, alters short-term native herbaceous plant diversity and soil chemistry. Thus, small-scale exclusion of wild pigs from vulnerable and rare plant communities may be warranted. © 2020 The Wildlife Society.     

Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.