821 research outputs found

    Welcome to Journal of Ethnobiology and Ethnomedicine

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    Ethnobiology is a multidisciplinary field of study that draws on approaches and methods from both the social and biological sciences. Ethnobiology aims at investigating culturally based biological and environmental knowledge, cultural perception and cognition of the natural world, and associated behaviours and practices. Ethnomedicine is concerned with the cultural interpretations of health, disease and illness and also addresses the health care seeking process and healing practices. Research interest and activities in the areas of ethnobiology and ethnomedicine have increased tremendously in the last decade. Since the inception of the disciplines, scientific research in ethnobiology and ethnomedicine has made important contributions to understanding traditional subsistence and medical knowledge and practice. The Journal of Ethnobiology and Ethnomedicine (JEE) invites manuscripts and reviews based on original interdisciplinary research from around the world on the inextricable relationships between human cultures and nature, on Traditional Environmental Knowledge (TEK), folk and traditional medical knowledge, as well as on the relevance of the above for Primary Health Care (PHC) policies in developing countries

    «Великий перелом» 1920 – 30-x рр. у контексті регіональної історії

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    (uk) Розглядається регіональна політика більшовиків щодо селянства у 1920 – 30-х роках, висвітлюється опір селянства насильницькій колективізації в Центральній Україні.(en) The regional policy of bolshevists in relation to peasantry in 1920 – 30 is examined – х years, is lighted resistance of peasantry to violent collectivization in Central Ukraine

    Detection vs selection: integration of genetic, epigenetic and environmental cues in fluctuating environments

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    ArticleThere are many inputs during development that influence an organism's fit to current or upcoming environments. These include genetic effects, transgenerational epigenetic influences, environmental cues and developmental noise, which are rarely investigated in the same formal framework. We study an analytically tractable evolutionary model, in which cues are integrated to determine mature phenotypes in fluctuating environments. Environmental cues received during development and by the mother as an adult act as detection-based (individually observed) cues. The mother's phenotype and a quantitative genetic effect act as selection-based cues (they correlate with environmental states after selection). We specify when such cues are complementary and tend to be used together, and when using the most informative cue will predominate. Thus, we extend recent analyses of the evolutionary implications of subsets of these effects by providing a general diagnosis of the conditions under which detection and selection-based influences on development are likely to evolve and coexist.This work was supported by a Leverhulme Trust International Network Grant to the four authors and by a grant from the Swedish Research Council (621-2010-5437) to O.L

    Evolutionarily stable defence and signalling of that defence

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    We examine the evolution and maintenance of defence and conspicuousness in prey species using a game theoretic model. In contrast to previous works, predators can raise as well as lower their attack probabilities as a consequence of encountering moderately defended prey. Our model predicts four distinct possibilities for evolutionarily stable strategies (ESSs) featuring maximum crypsis. Namely that such a solution can exist with (1) zero toxicity, (2) a non-zero but non-aversive level of toxicity, (3) a high, aversive level of toxicity or (4) that no such maximally cryptic solution exists. Maximally cryptic prey may still invest in toxins, because of the increased chance of surviving an attack (should they be discovered) that comes from having toxins. The toxin load of maximally cryptic prey may be sufficiently strong that the predators will find them aversive, and seek to avoid similar looking prey in future. However, this aversiveness does not always necessarily trigger aposematic signalling, and highly toxic prey can still be maximally cryptic, because the increased initial rate of attack from becoming more conspicuous is not necessarily always compensated for by increased avoidance of aversive prey by predators. In other circumstances, the optimal toxin load may be insufficient to generate aversion but still be non-zero (because it increases survival), and in yet other circumstances, it is optimal to make no investment in toxins at all. The model also predicts ESSs where the prey are highly defended and aversive and where this defence is advertised at a cost of increased conspicuousness to predators. In many circumstances there is an infinite array of these aposematic ESSs, where the precise appearance is unimportant as long as it is highly visible and shared by all members of the population. Yet another class of solutions is possible where there is strong between-individual variation in appearance between conspicuous, poorly defended prey

    How Gaussian competition leads to lumpy or uniform species distributions

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    A central model in theoretical ecology considers the competition of a range of species for a broad spectrum of resources. Recent studies have shown that essentially two different outcomes are possible. Either the species surviving competition are more or less uniformly distributed over the resource spectrum, or their distribution is 'lumped' (or 'clumped'), consisting of clusters of species with similar resource use that are separated by gaps in resource space. Which of these outcomes will occur crucially depends on the competition kernel, which reflects the shape of the resource utilization pattern of the competing species. Most models considered in the literature assume a Gaussian competition kernel. This is unfortunate, since predictions based on such a Gaussian assumption are not robust. In fact, Gaussian kernels are a border case scenario, and slight deviations from this function can lead to either uniform or lumped species distributions. Here we illustrate the non-robustness of the Gaussian assumption by simulating different implementations of the standard competition model with constant carrying capacity. In this scenario, lumped species distributions can come about by secondary ecological or evolutionary mechanisms or by details of the numerical implementation of the model. We analyze the origin of this sensitivity and discuss it in the context of recent applications of the model.Comment: 11 pages, 3 figures, revised versio

    PROBLEMA DE INVERSIÓN ÓPTIMA EN MERCADOS CON LIQUIDEZ LIMITADA

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    En esta tesis abordamos el problema de selección de portafolio óptimo para un modelo de inversión en un activo que presenta cierto riesgo de liquidez. Para modelar el precio del activo, utilizamos un proceso continuo y positivo S el cual es una estructura de tipo Ito-Lévy con algunas condiciones de regularidad e integrabilidad. El aspecto de poca liquidez se ve reflejado en restricciones en los tiempos de transacción, los cuales corresponden a tiempos aleatorios y discretos siguiendo una ley Poisson. La metodología que hemos utilizado para encontrar una estrategia de inversión óptima es plantear una ecuación de programación dinámica y después de encontrar una solución, comprobar mediante argumentos de verificación, que dicha solución corresponde a la función de valor para el problema de optimización

    Ecological genetic conflict: Genetic architecture can shift the balance between local adaptation and plasticity

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    This is the author accepted manuscript. The final version is available from University of Chicago Press via the DOI in this record.Genetic polymorphism can contribute to local adaptation in heterogeneous habitats, for instance as a single locus with alleles adapted to different habitats. Phenotypic plasticity can also contribute to trait variation across habitats, through developmental responses to habitat-specific cues. We show that the genetic architecture of genetically polymorphic and plasticity loci may influence the balance between local adaptation and phenotypic plasticity. These effects of genetic architecture are instances of ecological genetic conflict. A reduced effective migration rate for genes tightly linked to a genetic polymorphism provides an explanation for the effects, and they can occur both for a single trait and for a syndrome of co-adapted traits. Using individualbased simulations and numerical analysis, we investigate how among-habitat genetic polymorphism and phenotypic plasticity depend on genetic architecture. We also study the evolution of genetic architecture itself, in the form of rates of recombination between genetically polymorphic loci and plasticity loci. Our main result is that for plasticity genes that are unlinked to loci with between-habitat genetic polymorphism, the slope of a reaction norm is steeper in comparison with the slope favored by plasticity genes that are tightly linked to genes for local adaptation.This work was supported by grants from the Carl Trygger Foundation (CTS 15292) to OL and by a Leverhulme Trust International Network Grant to SRXD, PH, OL, and JMM

    Adaptation to fluctuating environments in a selection experiment with Drosophila melanogaster

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    A fundamental question in life-history evolution is how organisms cope with fluctuating environments, including variation between stressful and benign conditions. For short-lived organisms, environments commonly vary between generations. Using a novel experimental design, we exposed wild-derived Drosophila melanogaster to three different selection regimes: one where generations alternated between starvation and benign conditions, and starvation was always preceded by early exposure to cold; another where starvation and benign conditions alternated in the same way, but cold shock sometimes preceded starvation and sometimes benign conditions; and a third where conditions were always benign. Using six replicate populations per selection regime, we found that selected flies increased their starvation resistance, most strongly for the regime where cold and starvation were reliably combined, and this occurred without decreased fecundity or extended developmental time. The selected flies became stress resistant, displayed a pronounced increase in early life food intake and resource storage. In contrast to previous experiments selecting for increased starvation resistance in D. melanogaster, we did not find increased storage of lipids as the main response, but instead that, in particular for females, storage of carbohydrates was more pronounced. We argue that faster mobilization of carbohydrates is advantageous in fluctuating environments and conclude that the phenotype that evolved in our experiment corresponds to a compromise between the requirements of stressful and benign environments

    The emergence of reciprocally beneficial cooperation

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    We offer a new and robust model of the emergence and persistence of cooperation when interactions are anonymous, the population is well-mixed, and evolution selects strategies according to material payoffs. The model has a Prisoner’s Dilemma structure, but with an outside option of non-participation. The payoff to mutual cooperation is stochastic; with positive probability, it exceeds that from cheating against a cooperator. Under mild conditions, mutually beneficial cooperation occurs in equilibrium. This is possible because the non-participation option holds down the equilibrium frequency of cheating. Dynamic properties of the model are investigated theoretically and through simulations based on replicator dynamics
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