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We investigated the phylogenetic relationships among different size groups of the pelagic microcopepod Oncaea venusta Philippi, 1843, by comparing the patterns of genetic variation of specimens collected at five locations of the Indo-West Pacific Ocean. Phylogenetic analyses were based on sequence data obtained from two DNA markers: A 310 bp fragment of the mitochondrial cytochrome b (cyt b) gene and a 480 bp fragment of the nuclear internal transcribed spacer 1 (ITS1). The cyt b sequences showed a much higher level of variation than those from ITS1, but the conclusion from both genes was concordant. Four genetic clades could be differentiated. A small- and a large-size group were unambiguously assigned to two distinct clades or lineages. Unexpectedly, the medium-sized individuals could be divided into another two different genetic clades. All four lineages were supported by high bootstrap values. The high levels of sequence divergence under sympatric conditions indicated that at least the two main groups, the large and the small one, may be assigned to different species. For the medium-size group additional morphological studies and more sensitive nuclear markers are required to clarify their taxonomic status. 相似文献
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The Science of Nature - 相似文献
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The Science of Nature - 相似文献
176.
Ruth?SalwayEmail author Jonathan?Wakefield 《Environmental and Ecological Statistics》2005,12(3):321-347
Ecological studies investigate relationships at the level of the group, rather than at the level of the individual. Although
such studies are a common design in epidemiology, it is well-known that estimates may be subject to ecological bias. Most
discussion of ecological bias has focused on rare disease events, where the tractability of the loglinear model allows some
characterization of the nature of different biases. This paper concentrates on non-rare events, where the Poisson approximation
to the binomial distribution is not appropriate. We limit the discussion to bias that arises from within-area variability
in exposures and confounders. Our aims are to investigate the likely sizes and directions of bias and, where possible, to
suggest methods for controlling the bias or for addressing the sensitivity of inference to assumptions on the nature of the
bias. We illustrate that for non-rare events it is much more difficult to characterize the direction of bias than in the rare
case. A series of simple numerical examples based on a chronic study of respiratory health illustrate the ideas of the paper. 相似文献
177.
Dickey CA Heal KV Cape JN Stidson RT Reeves NM Heal MR 《Journal of environmental monitoring : JEM》2005,7(2):137-144
Soil is an important compartment in the environmental cycling of trichloroacetic acid (TCA), but soil TCA concentration is a methodologically defined quantity; analytical methods either quantify TCA in an aqueous extract of the soil, or thermally decarboxylate TCA to chloroform in the whole soil sample. The former may underestimate the total soil TCA, whereas the latter may overestimate TCA if other soil components (e.g. humic material) liberate chloroform under the decarboxylation conditions. The aim of this work was to show that extraction and decarboxylation methods yield different TCA concentrations because the decarboxylation method can also determine "bound" TCA. Experiments with commercial humic acid solutions showed there was no additional chloroform formation under decarboxylation conditions, and that all TCA in a TCA-humic acid mixture could be quantitatively determined (108 +/- 13%). Anion exchange resin was used as a provider of solid-phase TCA binding; only 5 +/- 1% of a TCA solution mixed with the resin was present in the aqueous extract subsequently separated from the resin, yet the decarboxylation method yielded mass balance (123 +/- 22%) with TCA remaining in the resin. In aqueous extraction of a range of soil samples (with or without added TCA spike), the decarboxylation method was able to satisfactorily account for TCA in the extractant + residue post-extraction, compared with whole-soil TCA (+ spike) pre-extraction: e.g. mass balances for unspiked soil from Sikta spruce and larch forest were 99 +/- 8% and 93 +/- 6%, respectively, and for TCA-spiked forest and agricultural soils were 114 +/- 13% and 102 +/- 2%. In each case recovery of TCA in the extractant was substantially less than 100%(<20% for unspiked soils, <55% for spiked soils). Extraction efficiencies were generally lower in more organic soils. The results suggest that analytical methods which utilise aqueous extraction may underestimate whole-soil TCA concentrations. Application of both methodologies together may enhance insight into TCA behaviour in soil. 相似文献
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Environmental reporting requirements under the EU: eco-management and audit scheme (EMAS) 总被引:1,自引:1,他引:0
Ruth Hillary 《The Environmentalist》1995,15(4):293-299
The fifth Action Programme on the Environment: Towards Sustainability, defines European Union (EU) environmental policy until the year 2000 and emphasises the need for greater disclosure of environmental information. This paper discusses the Eco-management and audit scheme (EMAS), and EU market based instrument designed to bring more industrial environmental performance data into the public domain. The paper discusses the purpose of the Regulation's environmental statement identifying the potential audiences and their requirements. Using six corporate environmental reports, the paper analyzes how these meet the Regulation's reporting requirements and what modifications would be needed in current reporting trends. The paper concludes that existing reporting requirements will need to change to satisfy EMAS requirements and the increasing public demands for industrial environmental performance information.Ruth Hillary successfully completed a MSc in Environmental Technology at Imperial College, University of London, and is currently undertaking a doctorate to continue her research into the fields of environmental auditing and environmental management. She was placed at the European Commission's Industry and Environment Division of DG XI where she worked on the draft Eco-management and audit Regulation during its progress towards adoption and application. She is the Series Editor for the Business and the Environment Practitioner Series, a series of practical business reports addressing current and emerging environmental topics of importance to companies, and has recently published a reportThe Eco-management and audit Scheme-A Practical Guide. She has also published many papers on the subjects of environmental auditing and the EU Eco-management and audit scheme. 相似文献