3,071 research outputs found

    The evolutionary ecology of interactive synchronism: The illusion of the optimal phenotype

    Get PDF
    In this article, we discuss some ecological-evolutionary strategies that allow synchronization of organisms, resources, and conditions. Survival and reproduction require synchronization of life cycles of organisms with favourable environmental and ecological features and conditions. This interactive synchronization can occur directly, through pairwise or diffuse co-evolution, or indirectly, for example, as a result of actions of ecosystem engineers and facilitator species. Observations of specific interactions, especially those which have coevolved, may give the false impression that evolution results in optimal genotypes or phenotypes. However, some phenotypes may arise under evolutionary constraints, such as simultaneous evolution of multiple traits, lack of a chain of fit transitional forms leading to an optimal phenotype, or by limits inherent in the process of selection, set by the number of selective deaths and by interference between linked variants. Although there are no optimal phenotypes, optimization models applied to particular species may be useful for a better understanding of the nature of adaptations. The evolution of adaptive strategies results in variable life histories. These strategies can minimize adverse impacts on the fitness of extreme or severe environmental conditions on survival and reproduction, and may include reproductive strategies such as semelparity and iteroparity, or morphological, physiological, or behavioural traits such as diapause, seasonal polyphenism, migration, or bet-hedging. However, natural selection cannot indefinitely maintain intra-population variation, and lack of variation can ultimately extinguish populations

    The empirics of the Solow growth model: Long-term evidence

    Get PDF
    In this paper we reassess the standard Solow growth model, using a dynamic panel data approach. A new methodology is chosen to deal with this problem. First, unit root tests for individual country time series were run. Second, panel data unit root and cointegration tests were performed. Finally, the panel cointegration dynamics is estimated by (DOLS) method. The resulting evidence supports roughly one-third capital share in income, a.Economic growth, panel data, unit root, cointegration and convergence

    A review of techniques for spatial modeling in geographical, conservation and landscape genetics

    Get PDF
    Most evolutionary processes occur in a spatial context and several spatial analysis techniques have been employed in an exploratory context. However, the existence of autocorrelation can also perturb significance tests when data is analyzed using standard correlation and regression techniques on modeling genetic data as a function of explanatory variables. In this case, more complex models incorporating the effects of autocorrelation must be used. Here we review those models and compared their relative performances in a simple simulation, in which spatial patterns in allele frequencies were generated by a balance between random variation within populations and spatially-structured gene flow. Notwithstanding the somewhat idiosyncratic behavior of the techniques evaluated, it is clear that spatial autocorrelation affects Type I errors and that standard linear regression does not provide minimum variance estimators. Due to its flexibility, we stress that principal coordinate of neighbor matrices (PCNM) and related eigenvector mapping techniques seem to be the best approaches to spatial regression. In general, we hope that our review of commonly used spatial regression techniques in biology and ecology may aid population geneticists towards providing better explanations for population structures dealing with more complex regression problems throughout geographic space

    Transformações capitalistas na avicultura brasileira: do campesinato à pequena burguesia rural

    Get PDF
    Este trabalho tem por finalidade ampliar o debate sobre a questão camponesa no Brasil a partir da análise do complexo agroindustrial avícola. Baseou-se, metodologicamente, em discussões teóricas a partir de análise bibliográfica. Discute-se a produção familiar de base camponesa e as transformações nesse modelo produtivo a partir das leituras clássicas (Chayanov, Kautsky e Lênin) sobre o campesinato e o avanço do capitalismo no campo, bem como a sua correlação com as transformações, produtivas e sociais, ocorridas no espaço rural brasileiro a partir do processo de modernização da agricultura. Transformações que, por sua vez, podem estar conduzindo a uma redefinição no perfil do avicultor integrado e conduzindo a uma gradual expulsão da produção familiar camponesa da avicultura

    Modeling body size evolution in Felidae under alternative phylogenetic hypotheses

    Get PDF
    The use of phylogenetic comparative methods in ecological research has advanced during the last twenty years, mainly due to accurate phylogenetic reconstructions based on molecular data and computational and statistical advances. We used phylogenetic correlograms and phylogenetic eigenvector regression (PVR) to model body size evolution in 35 worldwide Felidae (Mammalia, Carnivora) species using two alternative phylogenies and published body size data. The purpose was not to contrast the phylogenetic hypotheses but to evaluate how analyses of body size evolution patterns can be affected by the phylogeny used for comparative analyses (CA). Both phylogenies produced a strong phylogenetic pattern, with closely related species having similar body sizes and the similarity decreasing with increasing distances in time. The PVR explained 65% to 67% of body size variation and all Moran's I values for the PVR residuals were non-significant, indicating that both these models explained phylogenetic structures in trait variation. Even though our results did not suggest that any phylogeny can be used for CA with the same power, or that “good” phylogenies are unnecessary for the correct interpretation of the evolutionary dynamics of ecological, biogeographical, physiological or behavioral patterns, it does suggest that developments in CA can, and indeed should, proceed without waiting for perfect and fully resolved phylogenies

    PROJETO PARQUE CAPIBARIBE, RECIFE: REINVENTANDO A CIDADE A PARTIR DO RIO

    Get PDF
    Recife is an amphibious city whose urban development does not value its rivers. In the past, the city’s main watercourse, the river Capibaribe, was understood to play a key role in structuring urban spaces and providing connectivity. Since then, this understanding has dwindled, and the resulting situation is a cause of great concern. Recife City has turned its back on the banks of its rivers and neglected both their capacity to smooth and shape urban space, and their potential to create a coherent image of the city. Recife is one of those cities in the world that are most vulnerable to climate change, ranking 16th in the list of world hotspots. In order to confront these challenges and rethink the role of the river that runs in the heart of Recife, researchers, architects, engineers, and sociologists from Research and Innovation for Cities — Universidade Federal de Pernambuco (INCITI-UFPE) were invited by the Recife City Hall to draw up plans for a park stretching along the river’s banks. Capibaribe Park Project attempts to answer one key question: How can we use the river to transform the city? The park project is based on a structural approach to landscape and is guided by the precepts of sustainability and regeneration of public spaces, in line with the emerging paradigm that combines a cross-disciplinary and cross-sector approach with water-sensitive design and social participation. The present article presents an overview of the main characteristics and development of this project, its theoretical and methodological underpinnings, its contribution to society, and the results achieved so far. It shows how, in addition to the planned park, the project also envisages the installation of a much more extensive system of parks, as a first stage towards the creation of park-city by the 500th anniversary of the foundation of Recife, in 2037.Cidade anfĂ­bia, o Recife nĂŁo valoriza seus rios em seu ordenamento territorial. Principal curso d’água da cidade, o Capibaribe chegou a receber atenção correspondente ao seu papel de articulador e estruturador dos espaços urbanos no passado. Desde entĂŁo, esse interesse reflui, resultando em um quadro preocupante: o Recife deu as costas ao rio, desprezando tanto sua função de organização e amenização dos espaços urbanos, quanto seu potencial de dar coesĂŁo Ă  imagem da cidade. Frente ao processo de mudanças climáticas, a cidade Ă© uma das mais vulneráveis, ocupando o 16Âş lugar na lista de pontos de acesso mundiais. Para enfrentar essas problemáticas e revalorizar o papel no rio que atravessa o coração da cidade, pesquisadores, arquitetos, engenheiros e sociĂłlogos do Pesquisa e Inovação para as Cidades - Universidade Federal de Pernambuco (INCITI‑UFPE) foram convidados pela Prefeitura da Cidade do Recife para projetar um parque linear Ă s suas margens. O objetivo do Projeto Parque Capibaribe era responder Ă  uma questĂŁo chave: como transformar a cidade a partir do rio? Fundado em uma abordagem estrutural da paisagem e guiado por preceitos como a sustentabilidade e a requalificação de espaços pĂşblicos, o projeto alinha-se com um paradigma em formação, associando aspectos como a integração setorial e disciplinar, a sensibilidade para com as águas e a participação social para efetivação do parque. Este artigo resume o desenvolvimento desse projeto, seus referenciais teĂłrico‑metodolĂłgicos e resultados, sua natureza e contribuições. Revela-se que, alĂ©m do projeto de um parque, consolidou-se a perspectiva de estruturação de um sistema de parques, primeiro passo rumo Ă  concepção de uma cidade parque no ano de 2037, ano em que o Recife festeja seus 500 anos

    Do passivo passado ao ativo presente.

    Get PDF
    Programa de P?s-Gradua??o em Sustentabilidade Socioecon?mica e Ambiental. N?cleo de Pesquisas e P?s-Gradua??o em Recursos H?dricos, Escola de Minas, Universidade Federal de Ouro Preto.A minera??o e todas as atividades a ela aliadas s?o, ainda, consideradas uma das maiores respons?veis pela degrada??o do meio ambiente. As atividades explorat?rias de min?rio de ferro na regi?o da Serra das Farofas, tamb?m conhecida como Serra do Itatiaiu?u, localizada no Quadril?tero Ferr?fero, estado de Minas Gerais, v?m sendo desenvolvidas desde a d?cada de 30 e, frequentemente, foram executadas sem nenhum controle de ordem ambiental, o que culminou por transformar extensas ?reas degradadas em passivos ambientais. Neste contexto, este estudo destaca a ?rea da Mina Esperan?a situada nos munic?pios de Brumadinho e S?o Joaquim de Bicas, considerada um dos maiores passivos ambientais do Quadril?tero Ferr?fero, tendo em vista o estado de abandono e degrada??o em que se encontrava essa antiga ?rea de explota??o de min?rio de ferro. Com a aquisi??o da Mina Esperan?a pela Ferrous Resources do Brasil S/A no ano de 2007, iniciou-se um relevante trabalho de recupera??o ambiental na ?rea, demonstrando que as atividades explorat?rias podem e devem caminhar paralelamente com as atividades de recupera??o das ?reas degradadas por empresas engajadas e comprometidas com a responsabilidade ambiental.Mining and all associated activities continue to be considered a main source of environmental degradation. Exploratory iron ore mining has been ongoing in the Serra das Farofas, also known as Serra do Itatiaiu?u, of the Quadril?tero Ferr?fero, State of Minas Gerais, since the 1930s, and has been frequently executed without any control. This has culminated in the transformation of large degraded areas into environmental liabilities. In this context, the former iron ore exploitation area of the Esperan?a Mine, located in the municipalities of Brumadinho and S?o Joaquin de Bicas, considered one of the greatest environmental liabilities of the Quadril?tero Ferr?fero, due to its state of abandonment and degradation. With the purchase of the Esperan?a Mine by Ferrous Resources do Brasil S.A. in 2007, an important environmental recovery began in the area. This recovery demonstrated that exploratory activities can and should be carried out in parallel with remediation activities in degraded areas, by companies engaged and committed to environmental responsibility
    • …
    corecore