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321.
Carl N. Keiser Devin K. Jones Andreas P. Modlmeier Jonathan N. Pruitt 《Behavioral ecology and sociobiology》2014,68(5):839-850
Social animals are extraordinarily diverse and ecologically abundant. In understanding the success of complex animal societies, task differentiation has been identified as a central mechanism underlying the emergence and performance of adaptive collective behaviors. In this study, we explore how individual differences in behavior and body size determine task allocation in the social spider Stegodyphus dumicola. We found that individuals with high body condition indices were less likely to participate in prey capture, and individuals’ tendency to engage in prey capture was not associated with either their behavioral traits or body size. No traits were associated with individuals’ propensity to participation in web repair, but small individuals were more likely to engage in standard web-building. We also discovered consistent, differences among colonies in their collective behavior (i.e., colony-level personality). At the colony level, within-colony variation in behavior (aggressiveness) and body size were positively associated with aggressive foraging behavior. Together, our findings reveal a subtly complex relationship between individual variation and collective behavior in this species. We close by comparing the relationship between individual variation and social organization in nine species of social spider. We conclude that intraspecific variation is a major force behind the social organization of multiple independently derived lineages of social spider. 相似文献
322.
Andreas P. Modlmeier Carl N. Keiser Taylor A. Shearer Jonathan N. Pruitt 《Behavioral ecology and sociobiology》2014,68(12):1929-1937
The success of a social group is often driven by its collective characteristics and the traits of its individuals. Thus, understanding how collective behavior is influenced by the behavioral composition of group members is an important first step to understand the ecology of collective personalities. Here, we investigated how the efficiency of several group behaviors is influenced by the aggressiveness of its members in two species of Temnothorax ants. In our manipulation of group composition, we created two experimentally reconstituted groups in a split-colony design, i.e., each colony was split into an aggressive and a docile group of equal sizes. We found strong species-specific differences in how collective behaviors were influenced by its group members. In Temnothorax longispinosus, having more aggressive individuals improved colony defense and nest relocation efficiency. In addition, source colony identity strongly influenced group behavior in T. longispinosus, highlighting that manipulations of group compositions must control for the origin of the chosen individuals. In contrast, group composition and source colony did not influence collective behaviors in Temnothorax curvispinosus. This suggests that the mechanisms regulating collective behaviors via individual differences in behavior might differ among even closely related species. 相似文献
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325.
Environmental risk assessment of heavy metals in soil frequently involves testing of freshly spiked soils kept under stable humidity conditions, but it has been questioned whether these assessments are representative of the field situation. Furthermore, the poor correspondence that is often found between total metal content and metal toxicity calls for integrated chemical and biological analysis. The aim of this work was to determine time- and moisture-dependent changes in total water-extractable Cu as well as bioavailable Cu in soil water extracts. Measurements of total water-extractable copper ([Cu]tot) were performed using furnace atomic absorption spectrometry. An in vitro assay employing a Cu-specific Pseudomonas fluorescens reporter strain was used to estimate Cu that was biologically available to the reporter strain. We refer to this copper fraction as "bioavailable," [Cu]bio. We found a time-dependent decrease in [Cu]tot and [Cu]bio during incubation for up to 220 d at field capacity. Hence the [Cu]bio was reduced to between 32 and 40% of the initial values. Furthermore, the [Cu]bio to [Cu]tot ratio correlated positively with the amount of added Cu and tended to increase with time. The moisture content of the soil was important for Cu retention. Dry soil had higher [Cu]tot concentrations than humid soil, but the [Cu]bio to [Cu]tot, ratio was lower in the dry soil. Alternating drying and wetting did not lead to a more rapid Cu retention than observed under constant humid conditions. Our observations underline the need for considering both time and moisture effects when interpreting short-term toxicity studies and when making predictions concerning possible long-term effects of Cu in the soil environment. 相似文献
326.
327.
Lawrence Busch 《Journal of Agricultural and Environmental Ethics》2003,16(5):459-477
Some 2000 years ago, Virgil wroteThe Georgics, a political tract on Romanagriculture in the form of a poem. Today, as aresult of rising global trade in food andagricultural products, growing economicconcentration, the merging of food andpharmacy, chronic obesity in the midst ofhunger, and new disease and pest vectors, weare in need of a new Georgics that addressesthe two key issues of our time: vigilance andvoice. On the one hand, vigilance must becentral to a new Georgics. Enforceablestandards for food safety, food quality,environmental protection, worker health andsafety, sanitary and phytosanitaryrequirements, animal welfare, and appellationsmust be addressed. On the other hand, a newGeorgics must increase the range of persons whohave voice in the democratic governance of anew global agrifood system. New organizationsand institutions will be needed to accomplishthis task. 相似文献
328.
Lawrence Busch 《Journal of Agricultural and Environmental Ethics》2002,15(1):17-29
Today there is considerable disagreement between the US and the EU with respect to food safety standards. Issues include GMOs, beef hormones, unpasteurized cheese, etc. In general, it is usually asserted that Europeans argue for the precautionary principle (with exceptions such as the Sanitary and Phytosanitary Agreement where ``substantial equivalence,' a form of familiarity, is used) while Americans defend risk analysis or what is sometimes described as the familiarityprinciple. This is not to suggest that EUmember countries agree on how the precautionaryprinciple should be applied; considerabledifferences exist among nations as will benoted below.In this paper I review both positionsarguing that they are best understood asvariants of the homiletics of risk rather thanas differing scientific positions. I concludethat while science must necessarily enter intothe formulation of food and agriculturalstandards, state policy, private economicinterests, and the interface between the two(e.g., when democratic states are successfullylobbied to support particular privateinterests), play important roles in determininghow particular risks will be treated. Moreover,I argue that the role of science mustnecessarily be limited if its credibility is tobe preserved. 相似文献
329.
Jan M. Pestka Florian Barvencik Frank T. Beil Robert P. Marshall Eilin Jopp Arndt F. Schilling Andreas Bauerochse Mamoun Fansa Klaus Püschel Michael Amling 《Die Naturwissenschaften》2010,97(4):393-402
Although numerous bodies were deposited in Western European bogs in the past centuries, few were found and underwent archeological
analysis. No studies comparing skeletal structure and mineralization of bog bodies from different ages have been performed
to this day. Therefore, the aim of this study was to analyze and compare skeletal features and specifics of the human remains
of three bog bodies from the Iron and Middle Ages found in Northern European peat bogs. Demineralization due to the acidic
environment in peat bogs was comparably pronounced in all three bodies. Still, the macroscopic state of skeletal preservation
was excellent. In addition to contact radiography, we used peripheral quantitative computed tomography to measure cortical
bone mineral density. The conservation of skeletal three-dimensional microstructural elements was assessed by high-resolution
microcomputed tomography analysis. These techniques revealed severe differences in bone mineral density and enabled us to
determine handedness in all three bodies. Additionally, unique skeletal features like intravital bone lesions, immobilization
osteoporosis, and Harris lines were found. A deformity of the left femoral head was observed which had the typical appearance
of an advanced stage of Legg–Calve–Perthes disease. This study gives detailed insight into the skeletal microstructure and
microarchitecture of 800- to 2,700-year-old bog bodies. Skeletal analysis enables us to draw conclusions not only concerning
changes in the acidic environment of the bog, but also serves as a diagnostic tool to unravel life circumstances and diseases
suffered by humans in the Iron and Middle Ages. 相似文献
330.
Effects of methyl-, phenyl-, ethylmercury and mercurychlorid on immune cells of harbor seals (Phoca vitulina) 总被引:1,自引:0,他引:1
Antje Kakuschke Elizabeth Valentine-Thon Sonja Fonfar Katharina Kramer Andreas Prange 《环境科学学报(英文版)》2009,21(12):1716-1721
Mercury (Hg) is present in the marine environment as a natural metal often enhanced through human activities. Depending on its
chemical form, Hg can cause a wide range of immunotoxic e ects. In this study, the influence of methyl-, ethyl- and phenylmercury as
well as mercurychloride on immune functions was evaluated. Two parameters of cellular immunity, proliferation and mRNA cytokine
expression of interleukin-2, -4, and transforming growth factor , were investigated in harbor seal lymphocytes after in vitro exposure
to Hg compounds. While all Hg compounds had a suppressive e ect on proliferation, di erences between juvenile and adult seals
were found. Lymphocytes from juveniles showed a higher susceptibility to the toxic e ect compared to lymphocytes from adults.
Furthermore, the degree of inhibition of proliferation varied among the four Hg compounds. The organic compounds seem to be
more immunotoxic than the inorganic compound. Finally, for the cytokine expression of methylmercury-incubated lymphocytes, timedependent
changes were observed, but no dose-dependency was found. Marine mammals of the North Sea are burdened with Hg, and
lymphocytes of harbor seals may be functionally impaired by this metal. The present in vitro study provides baseline information for
future studies on the immunotoxic e ects of Hg on cellular immunity of harbor seals. 相似文献