375 research outputs found

    Cyanogenesis and the feeding preference of Acraea horta (L.) (Lepidoptera : Acraeinae)

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    Bibliography: pages 47-55.The statement that similar sorts of plants often have similar medicinal properties (Le. contain similar chemicals) is at least 300 years old, while the concept probably dates back several thousand years (Stace, 1980). Indeed, a knowledge of the secondary chemicals produced by different plant species has played an important role since the early stages of man's cultural, and probably evolutionary, development (e.g. Leopold and Ardrey, 1972). Until recently, however, the biological role of this large group of compounds has remained largely obscure, with many plant physiologists regarding them as waste products and of no possible survival value to plants (Harborne, 1982). In recent years a tremendous increase in attention paid to these compounds has led to the suggestion that plant secondary substances evolved as herbivore deterrents, and diversified with the plants producing them as herbivores evolved various means of coping with their toxicity. In what follows I present an overview of events leading to the establishment of this theory, and a history of the discovery that some insect herbivores have turned the toxicity of plant secondary compounds to their own advantage, thereby becoming exclusively associated with toxic food plants. It will be seen that although this theory of plant-herbivore coevolution has become generally accepted, it has yet to be tested for a wide range of herbivores and chemical types. From this view I have taken a detailed look at a specific group of herbivores and plant toxins: Lepidoptera feeding on cyanide-producing plants

    The geometry of human nutrition

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    What We Know about the Public’s Level of Concern for Farm Animal Welfare in Food Production in Developed Countries

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    Population growth and rising consumption of meat, dairy, eggs and fish are forcing the world to face the intersecting challenges of how to sustainably feed a population expected to exceed 9 billion by 2050, while also controlling the impact of food production on the planet, on people and on animals. This review acknowledges the absence of a globally accepted definition of animal welfare and then explores the literature regarding different levels of concern for animal welfare in food production by such stakeholders as veterinarians, farmers, and the general public. It focuses on the evidence that the general public’s level of concern for animal welfare is linked to various demographic and personal characteristics, such as age, gender, religion, location, meat eating, and knowledge of animal welfare. Certain animals have characteristics that influence concern for their welfare, with those species that are considered more intelligent being afforded more concern. There is compelling evidence that the general public’s understanding of animal welfare in food production is poor. Acknowledging that public concern can be a driving force to change current production methods, the authors suggest widespread consciousness raising to redefine socially acceptable methods of food production from animals and to ensure that it remains in step with societal concerns

    Vorticity generation by short-crested wave breaking

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    Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 39 (2012): L24604, doi:10.1029/2012GL054034.Eddies and vortices associated with breaking waves rapidly disperse pollution, nutrients, and terrestrial material along the coast. Although theory and numerical models suggest that vorticity is generated near the ends of a breaking wave crest, this hypothesis has not been tested in the field. Here we report the first observations of wave-generated vertical vorticity (e.g., horizontal eddies), and find that individual short-crested breaking waves generate significant vorticity [O(0.01 s−1)] in the surfzone. Left- and right-handed wave ends generate vorticity of opposite sign, consistent with theory. In contrast to theory, the observed vorticity also increases inside the breaking crest, possibly owing to onshore advection of vorticity generated at previous stages of breaking or from the shape of the breaking region. Short-crested breaking transferred energy from incident waves to lower frequency rotational motions that are a primary mechanism for dispersion near the shoreline.Funding was provided by a National Security Science and Engineering Faculty Fellowship, the Office of Naval Research, and a Woods Hole Oceanographic Institution Postdoctoral Fellowship.2013-06-2

    Extremely low frequency (0.1 to 1.0 mHz) surf zone currents.

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    Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 46(3), (2019):1531-1536, doi:10.1029/2018GL081106.Low‐frequency surf zone eddies disperse material between the shoreline and the continental shelf, and velocity fluctuations with frequencies as low as a few mHz have been observed previously on several beaches. Here spectral estimates of surf zone currents are extended to an order of magnitude lower frequency, resolving an extremely low frequency peak of approximately 0.5 mHz that is observed for a range of beaches and wave conditions. The magnitude of the 0.5‐mHz peak increases with increasing wave energy and with spatial inhomogeneity of bathymetry or currents. The 0.5‐mHz peak may indicate the frequency for which nonlinear energy transfers from higher‐frequency, smaller‐scale motions are balanced by dissipative processes and thus may be the low‐frequency limit of the hypothesized 2‐D cascade of energy from breaking waves to lower frequency motions.We thank R. Guza, T. Herbers, and T. Lippmann for their leadership roles during the SandyDuck and NCEX projects and the CCS (SIO), PVLAB (WHOI), and FRF (USACE) field teams for deploying, maintaining, and recovering sensors in harsh conditions over many years. Funding was provided by ASD(R&E), NSF, and ONR. The data can be obtained via https://chlthredds.erdc.dren.mil/thredds/catalog/frf/catalog.html and https://pv‐lab.org.2019-07-0

    30 Days in the life: daily nutrient balancing in a wild chacma baboon

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    For most animals, the ability to regulate intake of specific nutrients is vital to fitness. Recent studies have demonstrated nutrient regulation in nonhuman primates over periods of one observation day, though studies of humans indicate that such regulation extends to longer time frames. Little is known about longer-term regulation in nonhuman primates, however, due to the challenges of multiple-day focal follows. Here we present the first detailed study of nutrient intake across multiple days in a wild nonhuman primate. We conducted 30 consecutive all day follows on one female chacma baboon ( Papio hamadryas ursinus ) in the Cape Peninsula of South Africa. We documented dietary composition, compared the nutritional contribution of natural and human-derived foods to the diet, and quantified nutrient intake using the geometric framework of nutrition. Our focus on a single subject over consecutive days allowed us to examine daily dietary regulation within an individual over time. While the amounts varied daily, our subject maintained a strikingly consistent balance of protein to non-protein (fat and carbohydrate) energy across the month. Human-derived foods, while contributing a minority of the diet, were higher in fat and lower in fiber than naturally-derived foods. Our results demonstrate nutrient regulation on a daily basis in our subject, and demonstrate that she was able to maintain a diet with a constant proportional protein content despite wide variation in the composition of component foods. From a methodological perspective, the results of this study suggest that nutrient intake is best estimated over at least an entire day, with longer-term regulatory patterns (e.g., during development and reproduction) possibly requiring even longer sampling. From a management and conservation perspective, it is notable that nearly half the subject's daily energy intake derived from exotic foods, including those currently being eradicated from the study area for replacement by indigenous vegetation
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