Morphological variation in the short-tailed fruit bat (Carollia) in Ecuador,with comments on the practical and philosophical aspects of boundaries among species

The mechanisms for the morphological delimitation of species in Carollia remain poorly understood. This is the first study to assess variation in size and shape from strictly geometric terms. Both factors are assessed by statistical perspectives of distribution, overlap and relative distances. Despite its overlap, the size of the skull seems to be the most influential character for the discrimination of species, with shape playing a much smaller role. The smallest species seems to be the most distinct in shape, not only in terms of distance among centroids in morphometric space, but also in the overall trend and direction of variation. Contrary to previous studies, sexual dimorphism is not given by size but by distinct shapes of the skull. Characters such as the shape of the maxilla, previously described qualitatively as discrete with sharp boundaries, appear to be truly continuous with fuzzy borders among species. Because morphometric space is a gamut of continuous variation and overlap, the taxonomic error rate for size characters seems to be substantial for the medium-sized species (Carollia brevicauda Schinz, 1821), with approximately 30–40% of individuals erroneously assigned to a different species after a jackknifed discriminant function. This taxonomic error is higher for shape characters. Morphological, systematic and ecological consequences of the observed patterns of shape and size variation are commented within the context of previously proposed arguments and hypotheses.     

Assessing wild bees in perennial bioenergy landscapes: effects of bioenergy crop composition,landscape configuration,and bioenergy crop area

Context

Wild bee populations are currently under threat, which has led to recent efforts to increase pollinator habitat in North America. Simultaneously, U.S. federal energy policies are beginning to encourage perennial bioenergy cropping (PBC) systems, which have the potential to support native bees.

Objectives

Our objective was to explore the potentially interactive effects of crop composition, total PBC area, and PBC patches in different landscape configurations.

Methods

Using a spatially-explicit modeling approach, the Lonsdorf model, we simulated the impacts of three perennial bioenergy crops (PBC: willow, switchgrass, and prairie), three scenarios with different total PBC area (11.7, 23.5 and 28.8% of agricultural land converted to PBC) and two types of landscape configurations (PBC in clustered landscape patterns that represent realistic future configurations or in dispersed neutral landscape models) on a nest abundance index in an Illinois landscape.

Results

Our modeling results suggest that crop composition and PBC area are particularly important for bee nest abundance, whereas landscape configuration is associated with bee nest abundance at the local scale but less so at the regional scale.

Conclusions

Strategies to enhance wild bee habitat should therefore emphasize the crop composition and amount of PBC.

     

Herd Health and Production Management in Dairy Practice: Wagenin Pers: 1996

Veterinary Research Communications -     

Swine trichinosis in mid-atlantic slaughterhouses: Possible relationship to hog marketing systems

Digests of diaphragms from 33 482 hogs slaughtered in the mid-atlantic states were examined for the presence of Trichinella spiralis larvae. The samples were obtained from 7 slaughterhouses, ranging in slaughter capacity from less than 50 per day to more than 4000 per day. The sources of the hogs varied from “backyard” operations, raising hogs for home use, to commercial farms. The means by which hogs were brought to the slaughterhouse also differed; the larger slaughterhouses often purchased directly from the producer while the smaller slaughterhouses (1000 hogs per day or less) usually purchased through dealers or brokers. Infected hogs were detected more frequently than was expected from previously-published prevalence studies; overall, 0.58% of samples examined contained T. spiralis larvae. All of the infected hogs were marketed through the smaller slaughterhouses (less than 1000 per day) and nearly all were marketed through brokers. The mean number of larvae per gram of diaphragm, determined by slaugterhouses type, ranged from 0.5 to 74.6; most infections were light although 5 had counts of 1000–2480.Most of the positive samples were obtained from one slaughterhouse, the data from which exhibited marked differences in the frequency of infection by day of the week; 128 positive samples of the total of 190 found were obtained on Fridays, although only 10% of all samples were obtained on that day. Analysis of the geographic origin of shipments containing infected hogs revealed that most originated in New Jersey and Pennsylvania, although the hogs shipped from the latter state might originated in New England or Maryland. Attempts to trace back infected hogs for further epidemiological investigation were largely futile, owing to the absence of an identification system.     

Effect of creep feeding on structural and functional changes of the gut of early weaned pigs

Dose-dependent hypersensitivity responses mounted against antigenic constituents of creep feeds have been previously implicated in intestinal damage, digestive disorders and impaired performance of early weaned pigs. In the present study biochemical and histological investigations of the small intestine were undertaken to determine the putative relationship between creep feed level and hypersensitivity response in pigs weaned at 14 days. Creep feed was administered by gastric intubation and weaned pigs received the same diet by gastric intubation for five days. Mucosal structure and function at weaning were not affected by creep feeding regimen. Villus height decreased and crypt depth increased in weaned compared to suckled pigs, but morphology was unaffected by prior exposure to creep. Xylose absorption was not influenced by either creep feed level or weaning. Intraepithelial lymphocyte numbers increased during weaning but were not affected by the creep feeding regimen. Mucosal carbohydrase activity in weaned pigs was not significantly affected by preweaning treatment. The results do not support the hypothesis that post weaning changes in structure and function of the gut are related to creep feed level or to immune responses to dietary antigens.