237 research outputs found

    Simulating Species Richness Using Agents with Evolving Niches, with an Example of Galápagos Plants

    Get PDF
    I sought to evolve plant species richness patterns on 22 Galápagos Islands, Ecuador, as an exploration of the utility of evolutionary computation and an agent-based approach in biogeography research. The simulation was spatially explicit, where agents were plant monocultures defined by three niche dimensions, lava (yes or no), elevation, and slope. Niches were represented as standard normal curves subjected to selection pressure, where neighboring plants bred if their niches overlapped sufficiently, and were considered the same species, otherwise they were different species. Plants that bred produced seeds with mutated niches. Seeds dispersed locally and longer distances, and established if the habitat was appropriate given the seed's niche. From a single species colonizing a random location, hundreds of species evolved to fill the islands. Evolved plant species richness agreed very well with observed plant species richness. I review potential uses of an agent-based representation of evolving niches in biogeography research

    Adjustment and Sensitivity Analyses of a Beta Global Rangeland Model

    Get PDF
    G-Range is a global model that simulates generalized changes in rangelands through time, created with support from the International Livestock Research Institute. Spatial data and a set of parameters that control plant growth and other ecological attributes in landscape units combine with computer code to represent ecological process such as soil nutrient and water dynamics, vegetation growth, fire, and wild and domestic animal offtake. The model is spatial, with areas of the world divided into square cells

    La evolución de la legislación sobre menores de edad delincuentes en la dictadura militar brasileña

    Get PDF
    La dictadura brasileña (1964-1985) desarrolló diversos mecanismos para el cuidado de la infancia y adolescencia marginal, como era denominada por el discurso oficial. Dentro de ese grupo de «menores» sinónimo de niños pobres- este artículo se propone aproximarse a los conocidos como menores delincuentes, y analizar cómo la normativa, el tratamiento y la ideología proyectados sobre esos muchachos y muchachas evolucionaron a lo largo de los años dictatoriales, como parte de las estrategias de consolidación y supervivencia del Régimen autoritario.-1. Introducción. -2. Los inicios del Derecho de Menores en Brasil. -3. Dictadura militar, Fundación de Bienestar del Menor y marginalidad social. -4. La normativa menorista y el progresivo endurecimiento del sistema dictatorial. -5. La década de 1970 y el aumento de la violencia contra los niños y niñas marginales. -6.El Código de Menores de 1979. El paradigma de la situación irregular. -7. De la Dictadura a la Democracia: ¿cambios en la consideración de la infancia delincuente? 8. Conclusiones. -Bibliografía

    Glycine max and Glycine soja are capable of cold acclimation

    Get PDF
    Soybean has been considered a cold intolerant species; based largely upon seed germination and soil emergent evaluations. This study reports a distinct acquisition of cold tolerance, in seedlings, following short acclimation periods. Diversity in cold responses was assessed in eight cultivars of Glycine max and six accessions of G. soja. All varieties of soybean significantly increased in freezing tolerance following acclimation. This study indicates soybean seedlings are indeed capable of sensing cold and acquiring cold tolerance. Germination rates after cold imbibition were negatively correlated with maturity group, but positively correlated with cold acclimation potential in G. soja. Seed fatty acid composition was varied between the species, with Glycine soja accessions containing about 2-times more linolenic acid (18:3) than G. max. Furthermore, high levels of linoleic acid (18:2) in seeds were positively correlated with germination rates following cold imbibition in G. soja only. We suggest that domestication has not impacted the overall ability of soybean to cold acclimate at the seedling stage and that there is little variation within the domesticated species for ability to cold acclimate. Thus, this brief comparative study reduces the enthusiasm for the “wild” species as an additional source of genetic diversity for cold tolerance

    Climate Change Impacts on Livestock

    Get PDF
    This Working Paper summarizes projected climate change impacts on livestock across Africa, using a combination of literature review and some new results on the projected impacts of climate change on the rangelands of Africa. Findings show that there are many options that can help livestock keepers adapt, but there appear to be no options that are widely applicable which do not have constraints to their adoption. An enabling technical and policy environment will thus be needed to ensure livestock keepers can adapt to climate change and enhance their livelihoods and food security

    Linking Animals Aloft with the Terrestrial Landscape

    Get PDF
    Despite using the aerosphere for many facets of their life, most flying animals (i.e., birds, bats, some insects) are still bound to terrestrial habitats for resting, feeding, and reproduction. Comprehensive broad-scale observations by weather surveillance radars of animals as they leave terrestrial habitats for migration or feeding flights can be used to map their terrestrial distributions either as point locations (e.g., communal roosts) or as continuous surface layers (e.g., animal densities in habitats across a landscape). We discuss some of the technical challenges to reducing measurement biases related to how radars sample the aerosphere and the flight behavior of animals. We highlight a recently developed methodological approach that precisely and quantitatively links the horizontal spatial structure of birds aloft to their terrestrial distributions and provides novel insights into avian ecology and conservation across broad landscapes. Specifically, we present case studies that (1) elucidate how migrating birds contend with crossing ecological barriers and extreme weather events, (2) identify important stopover areas and habitat use patterns of birds along their migration routes, and (3) assess waterfowl response to wetland habitat management and restoration. These studies aid our understanding of how anthropogenic modification of the terrestrial landscape (e.g., urbanization, habitat management), natural geographic features, and weather (e.g., hurricanes) can affect the terrestrial distributions of flying animals

    Linking Animals Aloft with the Terrestrial Landscape

    Get PDF
    Despite using the aerosphere for many facets of their life, most flying animals (i.e., birds, bats, some insects) are still bound to terrestrial habitats for resting, feeding, and reproduction. Comprehensive broad-scale observations by weather surveillance radars of animals as they leave terrestrial habitats for migration or feeding flights can be used to map their terrestrial distributions either as point locations (e.g., communal roosts) or as continuous surface layers (e.g., animal densities in habitats across a landscape). We discuss some of the technical challenges to reducing measurement biases related to how radars sample the aerosphere and the flight behavior of animals. We highlight a recently developed methodological approach that precisely and quantitatively links the horizontal spatial structure of birds aloft to their terrestrial distributions and provides novel insights into avian ecology and conservation across broad landscapes. Specifically, we present case studies that (1) elucidate how migrating birds contend with crossing ecological barriers and extreme weather events, (2) identify important stopover areas and habitat use patterns of birds along their migration routes, and (3) assess waterfowl response to wetland habitat management and restoration. These studies aid our understanding of how anthropogenic modification of the terrestrial landscape (e.g., urbanization, habitat management), natural geographic features, and weather (e.g., hurricanes) can affect the terrestrial distributions of flying animals

    Impact of climate change on African agriculture: focus on pests and diseases

    Get PDF
    According to the IPCC’s Fifth Assessment Report, changes in the climate over the last 30 years have already reduced global agricultural production by 1 – 5 % per decade relative to a baseline without climate change. In addition, recent studies indicate that even a 2 degrees increase in global temperature will affect agricultural productivity, particularly in the tropics, and this impact will rise with increases in temperature. In this context, this Info Note presents recent evidence on the implications for crops, livestock, and fisheries production, and their associated pests and diseases in Africa
    corecore