983 resultados para Forest Cover Zones
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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 (Zoologia) - IBRC
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Pós-graduação em Ciências Biológicas (Zoologia) - IBRC
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Population genetics theory predicts loss in genetic variability because of drift and inbreeding in isolated plant populations; however, it has been argued that long-distance pollination and seed dispersal may be able to maintain gene flow, even in highly fragmented landscapes. We tested how historical effective population size, historical migration and contemporary landscape structure, such as forest cover, patch isolation and matrix resistance, affect genetic variability and differentiation of seedlings in a tropical palm (Euterpe edulis) in a human-modified rainforest. We sampled 16 sites within five landscapes in the Brazilian Atlantic forest and assessed genetic variability and differentiation using eight microsatellite loci. Using a model selection approach, none of the covariates explained the variation observed in inbreeding coefficients among populations. The variation in genetic diversity among sites was best explained by historical effective population size. Allelic richness was best explained by historical effective population size and matrix resistance, whereas genetic differentiation was explained by matrix resistance. Coalescence analysis revealed high historical migration between sites within landscapes and constant historical population sizes, showing that the genetic differentiation is most likely due to recent changes caused by habitat loss and fragmentation. Overall, recent landscape changes have a greater influence on among-population genetic variation than historical gene flow process. As immediate restoration actions in landscapes with low forest amount, the development of more permeable matrices to allow the movement of pollinators and seed dispersers may be an effective strategy to maintain microevolutionary processes.
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The major Neotropical malaria vector, Anopheles darlingi, was reintroduced into the Iquitos, Loreto, Peru area during the early 1990s, where it displaced other anophelines and caused a major malaria epidemic. Since then, case numbers in Loreto have fluctuated, but annual increases have been reported since 2012. The population genetic structure of An. darlingi sampled before and after the introduction of long-lasting insecticidal nets (LLINs) was investigated to test the hypothesis of temporal population change (2006 vs. 2012). Current samples of An. darlingi were used to test the hypothesis of ecological adaptation to human modified (highway) compared with wild (riverine) habitat, linked to forest cover. In total, 693 An. darlingi from nine localities in Loreto, Peru area were genotyped using 13 microsatellite loci. To test the hypothesis of habitat differentiation in An. darlingi biting time patterns, HBR and EIR, four collections of An. darlingi from five localities (two riverine and three highway) were analysed. Analyses of microsatellite loci from seven (2006) and nine settlements (2012-2014) in the Iquitos area detected two distinctive populations with little overlap, although it is unclear whether this population replacement event is associated with LLIN distribution or climate. Within the 2012-2014 population two admixed subpopulations, A and B, were differentiated by habitat, with B significantly overrepresented in highway, and both in near-equal proportions in riverine. Both subpopulations had a signature of expansion and there was moderate genetic differentiation between them. Habitat and forest cover level had significant effects on HBR, such that Plasmodium transmission risk, as measured by EIR, in peridomestic riverine settlements was threefold higher than in peridomestic highway settlements. HBR was directly associated with available host biomass rather than forest cover. A population replacement event occurred between 2006 and 2012-2014, concurrently with LLIN distribution and a moderate El Niño event, and prior to an increase in malaria incidence. The likely drivers of this replacement cannot be determined with current data. The present-day An. darlingi population is composed of two highly admixed subpopulations, which appear to be in an early stage of differentiation, triggered by anthropogenic alterations to local habitat.
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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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Deer-vehicle collisions (DVCs) impact the economic and social well being of humans. We examined large-scale patterns behind DVCs across 3 ecoregions: Southern Lower Peninsula (SLP), Northern Lower Peninsula (NLP), and Upper Peninsula (UP) in Michigan. A 3 component conceptual model of DVCs with drivers, deer, and a landscape was the framework of analysis. The conceptual model was parameterized into a parsimonious mathematical model. The dependent variable was DVCs by county by ecoregion and the independent variables were percent forest cover, percent crop cover, mean annual vehicle miles traveled (VMT), and mean deer density index (DDI) by county. A discriminant function analysis of the 4 independent variables by counties by ecoregion indicated low misclassification, and provided support to the groupings by ecoregions. The global model and all sub-models were run for the 3 ecoregions and evaluated using information-theoretic approaches. Adjusted R2 values for the global model increased substantially from the SLP (0.21) to the NLP (0.54) to the UP (0.72). VMT and DDI were important variables across all 3 ecoregions. Percent crop cover played an important role in DVCs in the SLP and UP. The scale at which causal factors of DVCs operate appear to be finer in southern Michigan than in northern Michigan. Reduction of DVCs will likely occur only through a reduction in deer density, a reduction in traffic volume, or in modification of sitespecific factors, such as driver behavior, sight distance, highway features, or speed limits.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The creation of new legally protected areas brings many conflicts that distance the real landscape from the expected according to environmental law or conservation researchers. In this study, we mapped and compared the changes in Serra da Japi (Sao Paulo State, Brazil) throughout 40 years with scenarios of legal protection and scientific expectation on forest conservation, to evaluate the distance between them. This may allow us to infer the direction of historical changes and assist in the debate among decision makers. The results showed that most legal requirements on forest protection in the current landscape have been met. The 1960s was the period when the forest cover was closest to the desirable conservation stage. Although the Serra do Japi has maintained large areas of forests during the entire study period, human interference increased with the expansion of reforestation and urban areas, and access roads were identified as a primary potential driving forces of change. In addition, habitat loss was observed in the landscape, which can represent the first phase of a sequence of modifications detrimental to the environmental conservation of this protected area, including decision changes to land use. In conclusion, the changes evolved toward conservation expectations, but not toward the forest configuration of scientific expectation.
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Communities in fragmented landscapes are often assumed to be structured by species extinction due to habitat loss, which has led to extensive use of the species-area relationship (SAR) in fragmentation studies. However, the use of the SAR presupposes that habitat loss leads species to extinction but does not allow for extinction to be offset by colonization of disturbed-habitat specialists. Moreover, the use of SAR assumes that species richness is a good proxy of community changes in fragmented landscapes. Here, we assessed how communities dwelling in fragmented landscapes are influenced by habitat loss at multiple scales; then we estimated the ability of models ruled by SAR and by species turnover in successfully predicting changes in community composition, and asked whether species richness is indeed an informative community metric. To address these issues, we used a data set consisting of 140 bird species sampled in 65 patches, from six landscapes with different proportions of forest cover in the Atlantic Forest of Brazil. We compared empirical patterns against simulations of over 8 million communities structured by different magnitudes of the power-law SAR and with species-specific rules to assign species to sites. Empirical results showed that, while bird community composition was strongly influenced by habitat loss at the patch and landscape scale, species richness remained largely unaffected. Modeling results revealed that the compositional changes observed in the Atlantic Forest bird metacommunity were only matched by models with either unrealistic magnitudes of the SAR or by models ruled by species turnover, akin to what would be observed along natural gradients. We show that, in the presence of such compositional turnover, species richness is poorly correlated with species extinction, and z values of the SAR strongly underestimate the effects of habitat loss. We suggest that the observed compositional changes are driven by each species reaching its individual extinction threshold: either a threshold of forest cover for species that disappear with habitat loss, or of matrix cover for species that benefit from habitat loss.
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Premise of the study: Vellozia hirsuta forms a complex presenting wide morphological and anatomical variation, resulting in five specific names and 14 morpho-anatomical patterns occurring in disjunct populations. We carried out a phylogeographical study to investigate the existence of correlation among the genetic and morphological patterns within this complex, and to determine whether it is composed of various species or should be treated as an ochlospecies, a species having widely polymorphic and weakly polytypic complex variation, with morphological characteristics varying independently. Methods: We carried out phylogeographical analyses using cpDNA rpl32F-trnL intergenic region. Key results: We found 20 haplotypes in 23 populations sampled. The populations are genetically structured (Phi(ST) = 0.818) into four phylogeographical groups demonstrating geographical structuring but with no correlation with morpho-anatomical patterns. Our analyses do not support recognizing any of the species now synonymized under Vellozia hirsuta. The northern populations were the most genetically differentiated and could be considered a distinct taxon, as they are also morphologically different. Conclusions: It is recommended that Vellozia hirsuta be considered a single enormously variable species. The patterns of variation within V. hirsuta probably are related to climatic changes that occurred during the Pleistocene Epoch in tropical Brazil when reductions in forest cover favored the expansion of V. hirsuta populations into extensive lowland areas. The expansion of forest cover at the end of the glaciations would have again restricted the occurrence of campos rupestres vegetation to high elevations, which constitute the current centers of diversity of this species.
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The effects of habitat configuration on species persistence are predicted to be most apparent when remaining habitat cover is below 30%. We tested this prediction by comparing vertebrate communities in 21 landscapes located in the southern Amazonia, including 7 control landscapes (similar to 100% of forest cover) and 14 fragmented landscapes (4 x 4 km). The fragmented landscapes retained similar proportions of forest (similar to 25%), but had contrasting configurations, resulting from two different deforestation patterns: the "fish-bone pattern" common in small properties, and the large-property pattern generally used by large ranchers. Vertebrates were surveyed in all landscapes in February-July 2009 with interviews (n = 150). We found a significant difference in reported species richness among the fish-bone, large-property, and control areas (mean = 29.3, 38.8 and 43.5 respectively). Control areas and large-properties tended to have a higher number of specialist species (mean = 13.7, and 11.7, respectively), when compared with the fish-bone pattern (5.1). Vertebrate community composition in the control and large-properties was more similar to one another than to those of the fish-bone landscapes. The number of fragments was the main factor affecting the persistence of species, being negatively associated with specialist species richness. Species richness was also positively related with the size of the largest fragment structurally connected to the studied landscapes (i.e., a regional scale effect). Our results demonstrated that the large-property pattern, which results in less fragmented landscapes, can maintain a more diverse community of large vertebrates, including top predators, which are considered fundamental for maintaining ecosystem integrity. These results support the hypothesis that landscape configuration contributes to the persistence and/or extirpation of species.