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General Prediction (general + prediction)
Selected AbstractsDietary absorption efficiencies and toxicokinetics of polychlorinated biphenyls in ring doves following exposure to aroclor® mixturesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Ken G. Drouillard Abstract Ring doves (Streptotpelia risoria) were fed a meal of pellets spiked with an Aroclor® mixture. Feces were collected from birds after fasting 31 h postexposure and dietary absorption efficiencies (AbE) of polychlorinated biphenyls (PCBs) were determined by mass balance. Polychlorinated biphenyl AbEs ranged from 0.86 to 0.97 for individual congeners and were similar to the lipid AbE of 0.90. The AbEs exhibited a declining trend with increasing chemical hydrophobicity. The toxicokinetics of PCBs and dietary lipids in blood plasma were also followed in the exposed birds for 25 h after feeding the contaminated meal. Despite decreasing trends in net AbEs with increasing chemical hydrophobicity, all PCBs exhibited similar blood toxicokinetics as observed for dietary lipids. The PCB plasma uptake rate constants exhibited a positive correlation with chemical hydrophobicity such that the most hydrophobic congener PCB 180 approached the plasma uptake rate constant measured for dietary lipids. Trends in assimilation kinetics of PCBs in blood were not consistent with the general prediction that solubility limitations of chemicals in the unstirred water layer (UWL) contribute to declines in net AbEs for highly hydrophobic chemicals. The data are consistent with a micelle-mediated diffusion model, which indicates that dietary lipids and hydrophobic contaminants can cross the UWL and enter intestinal tissues at equivalent rates; however, solubility limitations of highly hydrophobic chemicals in mixed micelles may contribute to decline in net AbEs. [source] Landscape influences on aluminium and dissolved organic carbon in streams draining the Hubbard Brook valley, New Hampshire, USAHYDROLOGICAL PROCESSES, Issue 9 2005Sheila M. Palmer Abstract Concentrations of both aluminium (Al) and dissolved organic carbon (DOC) in stream waters are likely to be regulated by factors that influence water flowpaths and residence times, and by the nature of the soil horizons through which waters flow. In order to investigate landscape-scale spatial patterns in streamwater Al and DOC, we sampled seven streams draining the Hubbard Brook valley in central New Hampshire. We observed considerable variation in stream chemistry both within and between headwater watersheds. Across the valley, concentrations of total monomeric aluminium (Alm) ranged from below detection limits (<0·7 µmol l,1) to 22·3 µmol l,1. In general, concentrations of Alm decreased as pH increased downslope. There was a strong relationship between organic monomeric aluminium (Alo) and DOC concentrations (R2 = 0·92). We observed the highest Alm concentrations in: (i) a watershed characterized by a steep narrow drainage basin and shallow soils and (ii) a watershed characterized by exceptionally deep forest floor soils and high concentrations of DOC. Forest floor depth and drainage area together explained much of the variation in ln Alm (R2 = 0·79; N = 45) and ln DOC (R2 = 0·87; N = 45). Linear regression models were moderately successful in predicting ln Alm and ln DOC in streams that were not included in model building. However, when back-transformed, predicted DOC concentrations were as much as 72% adrift from observed DOC concentrations and Alm concentrations were up to 51% off. This geographic approach to modelling Al and DOC is useful for general prediction, but for more detailed predictions, process-level biogeochemical models are required. Copyright © 2005 John Wiley & Sons, Ltd. [source] How two different host species influence the performance of a gregarious parasitoid: host size is not equal to host qualityJOURNAL OF ANIMAL ECOLOGY, Issue 2 2007JOHANNA HÄCKERMANN Summary 1Hyssopus pallidus Askew (Hymenoptera, Eulophidae) is a gregarious ectoparasitoid of the two tortricid moths species Cydia molesta Busck and C. pomonella L. (Lepidoptera, Tortricidae). It paralyses and parasitizes different larval instars of both species inside the apple fruit, which leads to the death of the caterpillar. 2We assessed the influence of host species characteristics and host food on the performance of the parasitoid female in terms of clutch size decisions and fitness of the F1 generation. 3A comparison of clutch size revealed that female parasitoids deposited similar numbers of eggs on the comparatively smaller C. molesta hosts as on the larger C. pomonella hosts. The number of parasitoid offspring produced per weight unit of host larva was significantly higher in C. molesta than in C. pomonella, which is contrary to the general prediction that smaller hosts yield less parasitoid offspring. However, the sex ratio was not influenced by host species that differed considerably in size. 4Despite the fact that less host resources were available per parasitoid larva feeding on C. molesta caterpillars, the mean weight of emerging female wasps was higher in the parasitoids reared on C. molesta. Furthermore, longevity of these female wasps was neither influenced by host species nor by the food their host had consumed. In addition we did not find a positive relationship between adult female weight and longevity. 5Parasitoid females proved to be able to assess accurately the nutritional quality of an encountered host and adjust clutch size accordingly. These findings indicate that host size is not equal to host quality. Thus host size is not the only parameter to explain the nutritional quality of a given host and to predict fitness gain in the subsequent generation. [source] Role of host identity in effects of phytogenic mounds on plant assemblages and species richness on coastal arid dunesJOURNAL OF VEGETATION SCIENCE, Issue 5 2007Magdy I. El-Bana Abstract Question: Phytogenic mounds (nebkhas) - the natural accumulation of wind-blown sediments within or around the canopies of plants - have been proposed as important structures for locally maintaining high species richness in coastal and arid ecosystems. Nebkhas are assumed to increase habitat heterogeneity, but what is the importance of the nebkha host species relative to other nebkha characteristics in determining the associated plant assemblages? Are some host species more effective in creating diversity hotspots, or does a single species-area relationship apply to all nebkhas, regardless of host species? Can the influence of the host be ascribed to its indirect effects on abiotic attributes of the nebkha complex? Methods and location: We investigated plant species richness and composition on nebkhas around six psammophytic species on Mediterranean coastal dunes of the Sinai Peninsula. Results: Plant species richness was significantly related to nebkha size by the single power function according to the general prediction of island biogeography theory, but this relationship was modified - though to a limited degree - by nebkha host species identity. Canonical Correspondence Analysis revealed that nebkha host species identity and nebkha environmental and non-environmental factors significantly explained species composition on the nebkhas, but host species identity did so to a greater extent. The latter might reflect differences in seed trapping ability or free space for colonization between host species. Conclusion: Differences in community composition and richness among nebkhas formed by different host species represent a key factor in the maintenance of plant diversity on arid coastal dunes. [source] EVOLUTION OF MOUTHBROODING AND LIFE-HISTORY CORRELATES IN THE FIGHTING FISH GENUS BETTAEVOLUTION, Issue 4 2004Lukas Rüber Abstract The origin of and evolutionary transitions among the extraordinary diverse forms of parental care in teleost fish remain largely unknown. The "safe harbor" hypothesis predicts that the evolution from a "guarding" to a "brooding" form of care in teleost fish is associated with shifts in reproductive and life-history features such as reduced fecundity, and increased egg volume with higher parental investment. Robust phylogenetic hypotheses may help to identify evolutionary changes in key traits associated with differences in the form of parental care. Here, we used reconstruction of ancestral character states to study the evolution of the two forms of parental care, bubble nesting and mouthbrooding in the fighting fish genus Betta. We also applied a comparative analysis using the phylogenetic generalized least-squares method to test the "safe harbor" hypothesis by evaluating differences between the two forms of parental care in standard length, life-history traits, and three habitat variables. Evolutionary hypotheses were derived from the first molecular phylogeny (nuclear and mitochondrial DNA sequence data; 4448 bp) of this speciose group. Ancestral character state reconstructions of the evolution of the form of parental care in the genus Betta, using the methods of unweighted parsimony and maximum likelihood, are uncertain and further indicate a high rate of evolutionary transitions. Applying different weights for the suspected directionality of changes, based on the consistent phenotypic and behavioral differences found between bubble nesters and mouthbrooders, recurrent origin of mouthbrooding in the genus Betta is favored using parsimony. Our comparative analyses further demonstrate that bubble nesters and mouthbrooders do not have a consistent set of life-history correlates. The form of parental care in Betta is correlated only with offspring size, with mouthbrooders having significantly bigger offspring than bubble nesters, but is not correlated with egg volume, clutch size, and broodcare duration, nor with any of the three habitat variables tested. Our results thus challenge the general predictions of the "safe harbor" hypothesis for the evolution of alternative brood care forms in the fighting fish genus Betta. [source] The impacts of non-native species on UK biodiversity and the effectiveness of controlJOURNAL OF APPLIED ECOLOGY, Issue 5 2000Sarah J. Manchester 1.,The introduction of non-native species continues to cause ecological concern globally, but there have been no published reviews of their effects in the UK. Impacts in the UK are therefore reviewed, along with current legislation and guidelines relating to the introduction and control of such species. 2.,A large number of non-native species have been introduced to the UK, both deliberately and accidentally, but only a small number of introduced non-native species have established and caused detrimental ecological impacts. However, general declines in UK biodiversity, and the potential effects of future climate change, may increase the susceptibility of ecosystems to invasions. 3.,Detrimental impacts of non-native species on native biota have occurred through competition, predation, herbivory, habitat alteration, disease and genetic effects (i.e. hybridization). There are potential effects on genetic biodiversity as well as species biodiversity. 4.,Several high profile examples highlight the technical difficulties, and financial implications, of removing an introduced species once it is established. Few UK control or eradication programmes have been successful. 5.,Control might be more feasible if ,problem' species could be identified at an earlier stage of establishment. However, the poor success of attempts to characterize invasive species and predict which will have negative impacts highlight the individual and unpredictable nature of invasions. The difficulties of making general predictions suggest that every proposed species introduction should be subject to rigorous ecological characterization and risk assessment prior to introduction. 6.,The plethora of UK legislation and guidelines developed to reduce impacts of non-native species only go part of the way towards ameliorating impact. Many species already established in the wild might cause future problems. Illegal releases and escapes of non-native species may augment feral populations or establish new colonies. While regulation of imports and releases is important, further enforcement of existing legislation and action against unlicensed releases is necessary. [source] The future of psychotherapy for mentally ill children and adolescentsTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 1-2 2009John S. March Objective:, Given striking advances in translational developmental neuroscience and its convergence with developmental psychopathology and developmental epidemiology, it is now clear that mental illnesses are best thought of as neurodevelopmental disorders. This simple fact has enormous implications for the nature and organization of psychotherapy for mentally ill children, adolescents and adults. Method:, This article reviews the ,trajectory' of psychosocial interventions in pediatric psychiatry, and makes some general predictions about where this field is heading over the next several decades. Results:, Driven largely by scientific advances in molecular, cellular and systems neuroscience, psychotherapy in the future will focus less on personal narratives and more on the developing brain. In place of disorders as intervention targets, modularized psychosocial treatment components derived from current cognitive-behavior therapies will target corresponding central nervous system (CNS) information processes and their functional behavioral consequences. Either preventive or rehabilitative, the goal of psychotherapy will be to promote development along typical developmental trajectories. In place of guilds, psychotherapy will be organized professionally much as physical therapy is organized today. As with other forms of increasingly personalized health care, internet-based delivery of psychotherapy will become commonplace. Conclusion:, Informed by the new field of translational developmental neuroscience, psychotherapy in the future will take aim at the developing brain in a service delivery model that closely resembles the place and role of psychosocial interventions in the rest of medicine. Getting there will be, as they say, interesting. [source] Population structure in the catfish Trichogenes longipinnis: drift offset by asymmetrical migration in a tiny geographic rangeBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2009KELLY R. ZAMUDIO Based on population genetic theory and empirical studies of small populations, we expect that species with very small ranges (narrow endemics) will exhibit reduced genetic diversity, increasing their susceptibility to the negative effects of genetic homogeneity. Although this pattern of reduced diversity applies to most narrow endemics, conservation biologists have yet to identify a general pattern for the degree of spatial population genetic structure expected in species with very small ranges. In part, this is because the degree of population structure within narrow endemics will be highly variable depending on the equilibrium between the homogenizing effects of dispersal and the diversifying effects of drift and local selection in small populations, thus precluding general predictions about the relative importance of small range, small population sizes, and habitat patchiness for maintaining genetic diversity in narrowly-distributed species. We document a striking example of high population structure in the tiny geographic range of a stream-dwelling catfish, Trichogenes longipinnis, endemic to the Atlantic Forest of Brazil. The maintenance of this diversity results from a combination of asymmetrical and limited dispersal, and drift in small populations. Our results highlight the need to understand population structure, and not only overall genetic diversity, of narrowly-distributed species for their conservation planning. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 259,274. [source] | ||||||||||