937 resultados para spatial dynamics
Resumo:
Spatial disease ecology is emerging as a new field that requires the integration of complementary approaches to address how the distribution and movements of hosts and parasites may condition the dynamics of their interactions. In this context, migration, the seasonal movement of animals to different zones of their distribution, is assumed to play a key role in the broad scale circulation of parasites and pathogens. Nevertheless, migration is not the only type of host movement that can influence the spatial ecology, evolution, and epidemiology of infectious diseases. Dispersal, the movement of individuals between the location where they were born or bred to a location where they breed, has attracted attention as another important type of movement for the spatial dynamics of infectious diseases. Host dispersal has notably been identified as a key factor for the evolution of host-parasite interactions as it implies gene flow among local host populations and thus can alter patterns of coevolution with infectious agents across spatial scales. However, not all movements between host populations lead to dispersal per se. One type of host movement that has been neglected, but that may also play a role in parasite spread is prospecting, i.e., movements targeted at selecting and securing new habitat for future breeding. Prospecting movements, which have been studied in detail in certain social species, could result in the dispersal of infectious agents among different host populations without necessarily involving host dispersal. In this article, we outline how these various types of host movements might influence the circulation of infectious disease agents and discuss methodological approaches that could be used to assess their importance. We specifically focus on examples from work on colonial seabirds, ticks, and tick-borne infectious agents. These are convenient biological models because they are strongly spatially structured and involve relatively simple communities of interacting species. Overall, this review emphasizes that explicit consideration of the behavioral and population ecology of hosts and parasites is required to disentangle the relative roles of different types of movement for the spread of infectious diseases.
Resumo:
Dietary studies of marine species constitute an important key to improve the understanding of its biology and of its role in the ecosystem. Thus, prey-predator relationships structure and determine population dynamics and the trophic network at the ecosystem scale. Among the major study sites, the marine ecosystem is submitted to natural and anthropogenic constraints. In the North-Eastern part of the Atlantic Ocean, the Bay of Biscay is a large open area surrounded South by Spain and East by France. This bay is an historic place of intense fishery activities for which the main small pelagic species targeted are the pilchard, Sardina pilchardus and the anchovy, Engraulis encrasicolus. The aim of this work is to analyze the trophic ecology of these two small pelagic fish in spring in the Bay of Biscay. To do this, a first section is devoted to their prey composed by the mesozooplanktonic compartment, through a two-fold approach: the characterization of their spatio-temporal dynamics during the decade 2003-2013 and the measurement of their energetic content in spring. For this season, it appears that all prey types are not worth energetically and that the Bay of Biscay represents a mosaic of dietary habitat. Moreover, the spring mesozooplankton community presents a strong spatial structuration, a temporal evolution marked by a major change in abundance and a control by the microphytoplankton biomass. The second section of this work is relative to a methodological approach of the trophic ecology of S. pilchardus and E. encrasicolus. Three different trophic tracers have been used: isotopic ratios of carbon and nitrogen, parasitological fauna and mercury contamination levels. To improve the use of the first of these trophic tracers, an experimental approach has been conducted with S. pilchardus to determine a trophic discrimination factor. Finally, it appears that the use of these three trophic tracers has always been permitted to highlight a temporal variability of the relative trophic ecology of these fish. However, no spatial dynamics could be identified through these three trophic tracers.
Resumo:
This dissertation is about the spatial configuration in Natal and processes in the Ponta Negra neighborhood today. Ponta Negra has undergone a number of critical social and spatial changes due to tourism development after the 1990s. It is of special interest to consider the intensification of real estate investment after 2000, when the new airport terminal, located in the neighboring municipality of Parnamirim, was in use. Ponta Negra is the place where most tourists go to, so attracting considerable public investments. New agents of transformation have produced change in the neighborhood as well. The present study aims at analysing the spatial processes in this part of the city. Here, the spatial configuration that resulted from extended real estate investments, both public and private, in recent years, is analysed in detail. The study identifies the multually differentiated, however internally homogenous areas. The concepts of production of space, contemporanean urban development and spatial dynamics are discussed. The research is based on document analysis and field work. Results were plotted to maps and tables. A detailed analysis of the spatial processes in the Ponta Negra neighborhood is undertaken as a conclusion, considering the contemporanean global scenario
Resumo:
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Economia, Administração e Contabilidade, Programa de Pós-Graduação em Administração, Mestrado Profissional em Administração Pública, 2015.
Resumo:
El orgullo brasileño estalló en el año 2007, cuando Brasil fue elegido sede del mundial FIFA 2014. Esto se debe a que Brasil en ese momento gozaba de un creciente prestigio internacional por cuenta de su condición de Potencia Emergente, miembro de los BRICS, aspirante a un puesto permanente en el Consejo de Seguridad y contar con la selección de fútbol más exitosa de la historia. No obstante, en su afán por incrementar su visibilidad y proyección internacional acudió al ejercicio del Poder Blando, a través de la Diplomacia Cultural, concretamente se decidió por la Organización de Mega Eventos deportivos, al tiempo que debía enfrentar varios problemas en el ámbito interno (desigualdad, corrupción, pobreza). Así, esta estrategia de aplicación del Poder Blando resultó de cierta manera contraproducente, debido a que la política exterior y su éxito no suele estar disociada de la realidad interna.
Resumo:
In recent years, haying has extended to Iberian Mediterranean dry grasslands potentially threatening grassland birds. We evaluate the between and within-year effects of haying on grassland birds in Alentejo region, Portugal. Our main goals were: (1) to investigate variations on bird abundance and species richness in the fields hayed, with respect to past haying events occurred in a field and its surroundings and (2) to investigate the shifts in bird abundance, species richness and spatial dynamics resulting from haying a field and its surrounding area in a given year. We conducted grassland bird censuses during the breeding season through point counts from 2012 to 2015. The relationship between bird abundance/richness and past haying events was investigated using Generalized Linear Models whereas within-year effects of haying were analysed using Generalized Additive Models. Bird abundance in a field was positively related with the surface hayed in the vicinity of that field in the previous year. However, contrasting yearly effects were found for non passerines. Also, some species prefer fields with less haying events or surface hayed, whereas others occur mostly in fields frequently managed for haying. Haying a field leads, in the short term, to its abandonment by birds, and thus to a decrease in bird abundance and, for some species, to spatial concentration in surrounding fields offering suitable habitat. We conclude that within-year effects of haying have higher impact on grassland birds than between-year effects. Maintaining haying at low levels by rotating haying yearly through the different fields in each farm and using partial haying may be an adequate way to ensure an effective management of grassland bird populations.
Resumo:
Reduced economic circumstances havemoved management goals towards higher profit, rather than maximum sustainable yields in several Australian fisheries. The eastern king prawn is one such fishery, for which we have developed new methodology for stock dynamics, calculation of model-based and data-based reference points and management strategy evaluation. The fishery is notable for the northward movement of prawns in eastern Australian waters, from the State jurisdiction of New South Wales to that of Queensland, as they grow to spawning size, so that vessels fishing in the northern deeper waters harvest more large prawns. Bioeconomic fishing data were standardized for calibrating a length-structured spatial operating model. Model simulations identified that reduced boat numbers and fishing effort could improve profitability while retaining viable fishing in each jurisdiction. Simulations also identified catch rate levels that were effective for monitoring in simple within-year effort-control rules. However, favourable performance of catch rate indicators was achieved only when a meaningful upper limit was placed on total allowed fishing effort. Themethods and findings will allow improved measures for monitoring fisheries and inform decision makers on the uncertainty and assumptions affecting economic indicators.
Resumo:
Long-running datasets from aerial surveys of kangaroos (Macropus giganteus, Macropus [uliginosus, Macropus robustus and Macropus rufus) across Queensland, New South Wales and South Australia have been analysed, seeking better predictors of rates of increase which would allow aerial surveys to be undertaken less frequently than annually. Early models of changes in kangaroo numbers in response to rainfall had shown great promise, but much variability. We used normalised difference vegetation index (NDVI) instead, reasoning that changes in pasture condition would provide a better predictor than rainfall. However, except at a fine scale, NDVI proved no better; although two linked periods of rainfall proved useful predictors of rates of increase, this was only in some areas for some species. The good correlations reported in earlier studies were a consequence of data dominated by large droughtinduced adult mortality, whereas over a longer time frame and where changes between years are less dramatic, juvenile survival has the strongest influence on dynamics. Further, harvesting, density dependence and competition with domestic stock are additional and important influences and it is now clear that kangaroo movement has a greater influence on population dynamics than had been assumed. Accordingly, previous conclusions about kangaroo populations as simple systems driven by rainfall need to be reassessed. Examination of this large dataset has permitted descriptions of shifts in distribution of three species across eastern Australia, changes in dispersion in response to rainfall, and an evaluation of using harvest statistics as an index of density and harvest rate. These results have been combined into a risk assessment and decision theory framework to identify optimal monitoring strategies.
Resumo:
Reduced economic circumstances have moved management goals towards higher profit, rather than maximum sustainable yields in several Australian fisheries. The eastern king prawn is one such fishery, for which we have developed new methodology for stock dynamics, calculation of model-based and data-based reference points and management strategy evaluation. The fishery is notable for the northward movement of prawns in eastern Australian waters, from the State jurisdiction of New South Wales to that of Queensland, as they grow to spawning size, so that vessels fishing in the northern deeper waters harvest more large prawns. Bio-economic fishing data were standardized for calibrating a length-structured spatial operating model. Model simulations identified that reduced boat numbers and fishing effort could improve profitability while retaining viable fishing in each jurisdiction. Simulations also identified catch-rate levels that were effective for monitoring in simple within-year effort-control rules. However, favourable performance of catch-rate indicators was achieved only when a meaningful upper limit was placed on total allowed fishing effort. The methods and findings will allow improved measures for monitoring fisheries and inform decision makers on the uncertainty and assumptions affecting economic indicators.
Resumo:
Urbanisation is a dynamic complex phenomenon involving large scale changes in the land uses at local levels. Analyses of changes in land uses in urban environments provide a historical perspective of land use and give an opportunity to assess the spatial patterns, correlation, trends, rate and impacts of the change, which would help in better regional planning and good governance of the region. Main objective of this research is to quantify the urban dynamics using temporal remote sensing data with the help of well-established landscape metrics. Bangalore being one of the rapidly urbanising landscapes in India has been chosen for this investigation. Complex process of urban sprawl was modelled using spatio temporal analysis. Land use analyses show 584% growth in built-up area during the last four decades with the decline of vegetation by 66% and water bodies by 74%. Analyses of the temporal data reveals an increase in urban built up area of 342.83% (during 1973-1992), 129.56% (during 1992-1999), 106.7% (1999-2002), 114.51% (2002-2006) and 126.19% from 2006 to 2010. The Study area was divided into four zones and each zone is further divided into 17 concentric circles of 1 km incrementing radius to understand the patterns and extent of the urbanisation at local levels. The urban density gradient illustrates radial pattern of urbanisation for the period 1973-2010. Bangalore grew radially from 1973 to 2010 indicating that the urbanisation is intensifying from the central core and has reached the periphery of the Greater Bangalore. Shannon's entropy, alpha and beta population densities were computed to understand the level of urbanisation at local levels. Shannon's entropy values of recent time confirms dispersed haphazard urban growth in the city, particularly in the outskirts of the city. This also illustrates the extent of influence of drivers of urbanisation in various directions. Landscape metrics provided in depth knowledge about the sprawl. Principal component analysis helped in prioritizing the metrics for detailed analyses. The results clearly indicates that whole landscape is aggregating to a large patch in 2010 as compared to earlier years which was dominated by several small patches. The large scale conversion of small patches to large single patch can be seen from 2006 to 2010. In the year 2010 patches are maximally aggregated indicating that the city is becoming more compact and more urbanised in recent years. Bangalore was the most sought after destination for its climatic condition and the availability of various facilities (land availability, economy, political factors) compared to other cities. The growth into a single urban patch can be attributed to rapid urbanisation coupled with the industrialisation. Monitoring of growth through landscape metrics helps to maintain and manage the natural resources. (C) 2012 Elsevier B.V. All rights reserved.