923 resultados para Native parasitoids


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Latin America, a region rich in both energy resources and native heritage, faces a rising politico-social confrontation that has been growing for over two decades. While resources like oil and gas are exploited to enhance the state’s economic growth, indigenous groups feel threatened because the operations related to this exploitation are infringing on their homelands. Furthermore, they believe that the potential resource wealth found in these environmentally-sensitive regions is provoking an “intrusion” in their ancestral territory of either government agencies or corporations allowed by governmental decree. Indigenous groups, which have achieved greater political voice over the past decade, are protesting against government violations. These protests have reached the media and received international attention, leading the discourse on topics such as civil and human rights violations. When this happens, the State finds itself “between a rock and a hard place”: In a debate between indigenous groups’ rights and economic sustainability.

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The Indian Gaming Regulatory Act of 1988 was intended to provide a statutory basis for the growth of Indian gaming. This article explains that the intentions of the act, when coupled with court decisions and a competitive economic environment, may be the basis for federal intervention in the gaming industry, specifically for Native American gaming. The author reviews the history of programs and promises, the magnitude of the total gaming industry, and the role of Native American gaming.

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The authors describe a project undertaken at the School of Hotel and Restaurant Management at Northern Arizona University in which the internet is used to present Native American tribes in Arizona with customer service training. It discusses why the project was instigated looks at its development and funding, and highlights the educational and technological challenges that had to be overcome. This is the second in a series of articles on the uses of the internet in educating non-university student constituencies interested in hospitality management.'

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Short-hydroperiod Everglades wetlands have been disproportionately affected by reductions in freshwater inflows, land conversion and biotic invasions. Severe hydroperiod reductions in these habitats, including the Rocky Glades, coupled with proximity to canals that act as sources of invasions, may limit their ability to support high levels of aquatic production. We examined whether karst solution holes function as dry-down refuges for fishes, providing a source of marsh colonists upon reflooding, by tracking fish abundance, nonnative composition, and survival in solution holes throughout the dry season. We paired field surveys with an in situ nonnative predation experiment that tested the effects of predation by the recent invader, African jewelfish (Hemichromis letourneuxi) on native fishes. Over the 3 years surveyed, a large number of the solution holes dried before the onset of the wet season, while those retaining water had low survivorship and were dominated by nonnatives. In the experiment, mortality of eastern mosquitofish (Gambusia holbrooki) in the presence of African jewelfish was greater than that associated with deteriorating water quality. Under current water management, findings suggest that solution holes are largely sinks for native fishes, given the high frequency of drydown, extensive period of fish residence, and predation by nonnative fishes.

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The purpose of this study was to examine the hypothesis that no differences existed in the upper division performance of academically excellent community college transfer students when compared to native university students. The relationship of enrollment patterns such as skipped terms, dropped terms, summer session utilization, college of major, credits attempted, credits received, test scores, and current status were also studied.^ The data were collected through a hand analysis of 673 student transcripts which provided the information for a database designed specifically for this study. The subjects were 229 transfers from Miami-Dade Community College and 444 natives from Florida International University. The students all began their studies in the lower division in the Fall term of 1982, 1983 or 1984 and eventually transferred to the upper division at FIU. This longitudinal study followed the upper division performance and enrollment patterns through the Spring term of 1991.^ Data analysis included chi-square for all categorical and numerical variables; t-tests were performed for the numerical variables. Correlation coefficients, Two-Way Analysis of Variance and Three-Way Crosstabulations were also used when indicated. There were significant differences among the upper division performance of community college transfer students and native university students for the graduation rate and the GPA range. A significant difference was also found between the math and essay CLAST scores, number of summer terms utilized, number of terms to graduation, current enrollment status, and credits attempted and received for the groups. ^

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The Maya of the Yucatan region have a long history of keeping the native stingless bees (subfamily Meliponinae). However, market forces in the last few decades have driven the Maya to favor the use of invasive Africanized honey bees (Apis mellifera scutellata) for producing large quantities of high quality honey that has an international market. Furthermore, the native bees traditionally used by the Maya are now disappearing, along with the practice of keeping them. ^ An interdisciplinary approach was taken in order to determine the social factors behind the decrease in stingless beekeeping and the ecological driving forces behind their disappearance from the wild. Social research methods included participant observation with stingless beekeepers, Apis beekeepers, and marketing intermediaries. Ecological research methods included point observations of commonly known melliferous and polliniferous plants along transects in three communities with different degrees of human induced ecosystem disturbance. ^ The stingless bee species most important to the Maya, Melipona beecheii, has become extremely rare, and this has caused a breakdown of stingless beekeeping tradition, compounded with the pressure of the market economy, which fuels Apis beekeeping and has lessened the influence of traditional practices. The community with the heaviest amount of human induced ecosystem disturbance also had the highest degree of dominance of Apis mellifera, while the area with the most intact ecosystem had the highest diversity of stingless bees, though Apis mellifera was still the dominant species. Aggressive competitive behavior involving physical attacks by Apis mellifera against stingless bees was observed on several occasions, and this is a new observation previously unreported by science. ^

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Angadenia berteroi is a tropical perennial subshrub of the pine rocklands with large yellow flowers that set very few fruits. My dissertation seeks to elucidate the factors that affect the reproductive fitness of Angadenia berteroi a native species of the south Florida pine rocklands. I provide novel information on the pollination biology of this native species. I also assess the effects of herbivory on growth and the reproductive success of A. berteroi. Finally, I elucidate how habitat fragmentation and quality are correlated with reproductive fitness of this native perennial plant. Using a novel experimental approach, I determined the most effective pollinator group. I used nylon fishing line of widths corresponding to proboscis diameter of the major groups of visitors to examine pollen removal and deposition. In the field, I estimated visitation frequency and efficacy of each pollinator type. Using potted plants, I exposed flowers to single visit from different types of pollinators to measure fruit set. I performed artificial defoliation with scissors on plants growing in the greenhouse to assess the effects of defoliation before flowering as well as during flowering. Additionally, I used structural equation modelling (SEM) to elucidate how A. berteroi reproductive fitness was affected by habitat fragmentation and quality. My experiments provide evidence that Angadenia berteroi is specialized for bee pollination; though butterflies, skippers and others also visit its flowers, A. berteroi is exclusively pollinated by two native bees of the South Florida pine rocklands . This research also demonstrated that herbivory by the oleander moth may have direct and indirect effects on Angadenia berteroi growth and reproductive success. The SEM results suggested that habitat quality (litter depth and subcanopy cover) may favor reproduction in native species of the South Florida pine rocklands that are properly maintained by periodic fires and exotic control. Insights from this threatened and charismatic species may provide impetus to properly manage remaining pine rocklands in South Florida for this and other endemic understory species.

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Invasive plant species are major threats to the biodiversity and ecosystem stability. The purpose of this study is to understand the impacts of invasive plants on soil nutrient cycling and ecological functions. Soil samples were collected from rhizosphere and non-rhizosphere of both native and exotic plants from three genera, Lantana, Ficus and Schinus, at Tree Tops Park in South Florida, USA. Experimental results showed that the cultivable bacterial population in the soil under Brazilian pepper (invasive Schinus) was approximately ten times greater than all other plants. Also, Brazilian pepper lived under conditions of significantly lower available phosphorus but higher phosphatase activities than other sampled sites. Moreover, the respiration rates and soil macronutrients in rhizosphere soils of exotic plants were significantly higher than those of the natives (Phosphorus, p=0.034; Total Nitrogen, p=0.0067; Total Carbon, p=0.0243). Overall, the soil biogeochemical status under invasive plants was different from those of the natives.

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The recent invasion of the European green crab (Carcinus maenas) populations in Placentia Bay, Newfoundland and Labrador (NL) raises great concern about potential impacts on local fisheries and native biodiversity. Green crab are highly adaptable and in both native and invaded areas, green crab are well established predators that can outcompete other similarly sized decapods. The main objectives of this thesis were to: 1) identify the native species that green crab compete with for resources; 2) determine the depths and substrate types in which these interactions likely occur; 3) assess the indirect effects of green crab on native crustaceans and their changes in behavior; 4) assess the impacts of green crab on benthic community structure; 5) compare the NL population with other Atlantic Canadian populations in terms of competitive abilities; and 6) compare morphological features of the NL population with other Atlantic Canadian populations. I found that green crab overlap in space and diet with both rock crab (Cancer irroratus) and American lobster (Homarus americanus), potentially leading to a shift in habitat. Laboratory studies on naïve juvenile lobster also suggested shifts in behavior related to green crab, in that lobster decreased foraging activity and increased shelter use in the presence of green crab. Benthic community analyses showed fewer species in mud, sand, and eelgrass sites heavily populated by green crab compared to sites without green crab, although results depended on the taxa involved and I could not eliminate environmental differences through a short term caging study. Foraging ability of green crab varied in intraspecific competition experiments, with populations from NL and Prince Edward Island dominating longer-established populations from Nova Scotia and New Brunswick. Additional studies excluded claw size as a factor driving these results and behavioral differences likely reflected differences in invasion time and population genetics. Overall, green crab in Placentia Bay appear to be altering community structure of benthic invertebrates through predation and they also appear to indirectly impact native crustaceans through competition.

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Composition, structure and occurrence of native aluminium in bottom sediments of the Northeast Pacific at Station DM9-647 are reported.

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Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organisms. A major challenge has been to monitor oxygen binding characteristics and concomitant pH changes as they occur in vivo, in limited sample volumes. Here we report a technique allowing highly resolved and simultaneous monitoring of pH and blood pigment saturation in minute blood volumes. We equipped a gas diffusion chamber with a broad range fibre optic spectrophotometer and a micro-pH optode and recorded changes of pigment oxygenation along PO2 and pH gradients to test the setup. Oxygen binding parameters derived from measurements in only 15 µl of haemolymph from the cephalopod Octopus vulgaris showed low instrumental error (0.93%) and good agreement with published data. Broad range spectra, each resolving 2048 data points, provided detailed insight into the complex absorbance characteristics of diverse blood types. After consideration of photobleaching and intrinsic fluorescence, pH optodes yielded accurate recordings and resolved a sigmoidal shift of 0.03 pH units in response to changing PO2 from 0-21 kPa. Highly resolved continuous recordings along pH gradients conformed to stepwise measurements at low rates of pH changes. In this study we showed that a diffusion chamber upgraded with a broad range spectrophotometer and an optical pH sensor accurately characterizes oxygen binding with minimal sample consumption and manipulation. We conclude that the modified diffusion chamber is highly suitable for experimental biologists who demand high flexibility, detailed insight into oxygen binding as well as experimental and biological accuracy combined in a single set up.

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General note: Title and date provided by Bettye Lane.

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General note: Title and date provided by Bettye Lane.

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General note: Title and date provided by Bettye Lane.