999 resultados para Bosque secundario
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Anthropogenic changes in the reproductive population density can affect the mating system and result in an increase in selfing and correlated matings. This study investigated the mating system in small fragmented populations of the insect pollinated tropical tree species Copaifera langsdorffii, using microsatellite loci and the mixed and correlated mating models. Open-pollinated seeds were collected from 15 seed-trees located in a small forest fragment (4.8 ha), denominated Bosque and from 14 other seed-trees located in other small forest fragments of the north-western region of São Paulo State. No significant differences were observed between the seed-trees from Bosque (tm=0.933±0.028) and other fragments (tm=0.971±0.032), although these estimates were significantly different from 1.0, suggesting that selfing was occurring. Differences between multilocus and unilocus outcrossing rate were significantly high in both seed-trees of Bosque (tm -ts=0.478±0.05) and other forest fragments (tm -ts=0.475±0.018), suggesting a spatial genetic structure in those stands. The results also showed high rates of correlated mating in the samples, indicating that a good part of the offspring were full-sibs. As a consequence of selfing, mating among relatives and correlated matings, the coancestry within families was equally high in the seed-trees of Bosque ((Θ=0.237) and in the seed-trees of the other forest fragments (Θ=0.241) and the effective population size was lower than expected in panmitic populations (Ne<4). The results were discussed, focusing on the sample size of seed-trees to collect seeds for genetic conservation and enviromental reforestation.
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El desarrollo economico de la Republica Dominicana ha experimentado cambios sustanciales desde la decada del 50. La estructura productiva se diversifico, ganando importancia los sectores secundario y terciario, en desmedro del agropecuario. No obstante el crecimiento ha mostrado fluctuaciones primero debido a la inestabilidad politica del pais y despues por la crisis de los 80; a esto se agregan evidentes desequilibrios socio-espaciales. Por otra parte, el crecimiento no estuvo acompanado por una expansion sustantiva de los programas sociales. El desempleo, subempleo y una muy desigual distribucion del ingreso continuan siendo problemas de magnitud. En este marco el pais ha experimentado un continuo descenso de la mortalidad y una rapida baja en la fecundidad. En el periodo 1950-80 la esperanza de vida aumento 16 anos y la TGF disminuyo de 7.4 a 4.7 (p54).
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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