Este trabajo discute la secuencia de desarrollo histórico prehispánico en el Norte Semiárido de Chile a partir del estudio de las dinámicas espaciales y temporales de las ocupaciones humanas en la cuenca hidrográfica del río Limarí. A partir del estudio de asentamientos, materiales depositados en colecciones y arte rupestre se observa una secuencia de transformaciones y desarrollo desde el Arcaico Temprano hasta el período Incaico que diverge de lo tradicionalmente planteado para la región, reconociéndose ritmos de cambios sociales diferenciales dentro de la misma zona, especialmente en relación con la tradicional asociación entre incorporación de cerámica y la constitución de un modo de vida agrícola. La incorporación del arte rupestre permite articular sus características espaciales y representacionales con procesos más amplios, discutiéndose las relaciones establecidas entre dinámi-cas y cambios sociales con los flujos de información que producen las representaciones rupestres y sus respectivas audiencias.Palabras claves: norte semiárido, cuenca hidrográfica del río Limarí, secuencia histórica, patrón de asentamiento, arte rupestre. This paper discusses the pre-Hispanic sequence of historical development in the semiarid north of Chile through the study of spatial and temporal dynamics of human occupation in the
Enzyme electrophoresis was employed to assess genetic diversity within and divergence among four species of Robinsonia (R. evenia, R. gayana, R. gracilis, R. thurifera), a genus endemic to the Juan Fernandez Islands, Chile. The genus consists of treelike perennial plants, and all species are dioecious. Morphological diversity within the genus is reflected by recognition of two subgenera, with three sections in one subgenus. Total gene diversity is highest in the two species (R. gayana and R. gracilis) that are most common and have the largest population sizes. Robinsonia evenia has only half and the rare R. thurifera only 20% of the diversity detected in the other two species. The diversity measured in R. gayana and R. gracilis is comparable to the values typical of continental species of flowering plants with similar life history attributes. The genetic identities between species range from 0.560 to 0.706, which is similar to or below many values for congeneric species, but much lower than most reports for congeners on oceanic islands. The higher diversity within and divergence among species of Robinsonia compared to many insular endemics may result from several factors. The genus probably arose from selfincompatible plants of the genus Senecio, which means that several to perhaps many colonizers carried considerable allozymic variation to the Islands. Large population sizes and obligate outcrossing are additional factors that would account for higher diversity. Sorting of alleles during radiation and the process of mutation probably combined to produce divergence among the species. Estimated divergence times calculated for the species from allozyme data range from 1.7 to 5.5 million years depending on the assumptions made in the calculations; the age of the island (Masatierra) on which these four species are confined is approximately 4.0 million years. The electrophoretic data suggest that Robinsonia arrived early in the archipelago, and radiated and speciated rapidly after colonization.
A regional network in experimental mode over the last two years monitors environmental variables and develops scientifically based forecasts with easy-to-use oceanographic, meteorological, and hydrological products for decision makers in the six collaborating countries.T he Andean countries are located in the western and northern regions of South America. Most of them lie in the tropical strip, where complex atmospheric dynamics and the lack of a comprehensive understanding of mesoscale and microphysical phenomena lead to difficult forecasting challenges. More than 7,000 km long, typically 200 km wide, and with about a 4,000-m average height, the Andean Mountain chain includes complex topographic features, with substantial repercussions on the meteorological and climatological behavior of the atmosphere in the region. The climate in this area shows large variability (Garreaud 2009;Garreaud et al. 2009), depending on altitude, location, and proximity to the sea and to the Amazon region.The ground observational network of the six Andean countries is neither homogeneously distributed nor dense enough, and only a few national weather services (NWSs) have weather radars or radiosounding stations working on a regular basis. Satellite products are the most common and useful tools for nowcasting tasks in the region, while the Global Forecast System (GFS; Kalnay et al. 1990) is the most frequently used model for operational forecasting.Until 2006, efforts for building a regional and collaborative climate watch system for the Andean countries have been scarce. In 2007, Centro Internacional para la Investigación del Fenómeno "El Niño" (CIIFEN) received the approval and funding support from the Inter-American Development Bank An EnvironmEntAl WAtch SyStEm for thE AndEAn countriESEl Observatorio Andino by Ángel g. Muñoz, Patricio lóPez, raMón VelÁsquez, luis Monterrey, gloria león, Franklyn ruiz, cristina recalde, JaiMe cadena, raúl MeJía, Marcos Paredes, Juan bazo, carMen reyes, gualberto carrasco, yaruska castellón, claudia Villarroel, Juan quintana, and aVel urdaneta AffiliAtions: Muñoz-centro de modelado científico, la universidad del Zulia, maracaibo, venezuela, and centro internacional para la investigación del fenómeno El niño, Guayaquil, Ecuador; lóPez-Agencia Estatal de meteorología (AEmEt), madrid, Spain; VelÁsquez and Monterrey-Servicio de meteorología de la fuerza Aérea venezolana (SEmEtfAv), maracay, venezuela; león and ruiz-instituto de hidrología, meteorología y Estudios Ambientales (idEAm), Bagotá, colombia; recalde, cadena, and MeJía-instituto nacional de meteorología e hidrología (inAmhi), Guayaquil, Ecuador; Paredes, bazo, and reyes-Servicio nacional de meteorología e hidrología (SEnAmhi), lima, Peru; carrasco and castellón-Servicio nacional de meteorología e hidrología (SEnAmhi),
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