Towards the solution of urban transport problems in China

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Microscale genetic differentiation in a sessile invertebrate with cloned larvae: investigating the role of polyembryony

Microscale genetic differentiation of sessile organisms can arise from restricted dispersal of sexual propagules, leading to isolation by distance, or from localised cloning. Cyclostome bryozoans offer a possible combination of both: the localised transfer of spermatozoa between mates with limited dispersal of the resulting larvae, in association with the splitting of each sexually produced embryo into many clonal copies (polyembryony). We spatially sampled 157 colonies of Crisia denticulata from subtidal rock overhangs from one shore in Devon, England at a geographic scale of ca. 0.05 to 130 m plus a further 21 colonies from Pembrokeshire, Wales as an outgroup. Analysis of molecular variance (AMOVA) revealed that the majority (67%) of genetic variation was distributed among individuals within single rock overhangs, with only 16% of variation among different overhangs within each shore and 17% of variation between the ingroup and outgroup shores. Despite local genetic variation, pairwise genetic similarity analysed by spatial autocorrelation was greatest at the smallest inter-individual distance we tested (5 cm) and remained significant and positive across generally within-overhang comparisons (<4 m). Spatial autocorrelation and AMOVA analyses both indicated that patches of C. denticulata located on different rock overhangs tended to be genetically distinct, with the switch from positive to negative autocorrelation, which is often considered to be the distance within which individuals reproduce with their close relatives or the radius of a patch, occurring at the 4–8 m distance class. Rerunning analyses with twenty data sets that only included one individual of each multilocus genotype (n = 97) or the single data set that contained just the unique genotypes (n = 67) revealed that the presence of repeat genotypes had an impact on genetic structuring (PhiPT values were reduced when shared genotypes were removed from the dataset) but that it was not great and only statistically evident at distances between individuals of 1–2 m. Comparisons to a further 20 randomisations of the data set that were performed irrespective of genotype (n = 97) suggested that this conclusion is not an artefact of reduced sample size. A resampling procedure using kinship coefficients, implemented by the software package GENCLONE gave broadly similar results but the greater statistical power allowed small but significant impacts of repeat genotypes on genetic structure to be also detected at 0.125–0.5 and 4–16 m. Although we predict that a proportion of the repeat multilocus genotypes are shared by chance, such generally within-overhang distances may represent a common distance of cloned larval dispersal. These results suggests that closely situated potential mates include a significant proportion of the available genetic diversity within a population, making it unlikely that, as previously hypothesised, the potential disadvantage of producing clonal broods through polyembryony is offset by genetic uniformity within the mating neighbourhood. We also report an error in the published primer note of Craig et al. (Mol Ecol Notes 1:281–282, 2001): loci Cd5 and Cd6 appear to be the same microsatellite. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A note on Prudencio's experimental tests of the coase propositions

The purpose of this note is to review Prudencio's recent experimental test of the Coasian propositions of neutrality and efficiency. His conclusion that the propositions are statistically supported by the experimental results is not substantiated. A careful examination of the design and methodology of the experiment leads to the conclusion that the experimental bargaining cannot be considered voluntary, and that the results are likely to be influenced by hypothetical bias. Other problems with the representativeness of Prudencio's participants are also discussed.     

The relationship between adaptation and mitigation in managing climate change risks: a regional response from North Central Victoria,Australia

This two-part paper considers the complementarity between adaptation and mitigation in managing the risks associated with the enhanced greenhouse effect. Part one reviews the application of risk management methods to climate change assessments. Formal investigations of the enhanced greenhouse effect have produced three generations of risk assessment. The first led to the United Nations Intergovernmental Panel on Climate Change (IPCC), First Assessment Report and subsequent drafting of the United Nations Framework Convention on Climate Change. The second investigated the impacts of unmitigated climate change in the Second and Third IPCC Assessment Reports. The third generation, currently underway, is investigating how risk management options can be prioritised and implemented. Mitigation and adaptation have two main areas of complementarity. Firstly, they each manage different components of future climate-related risk. Mitigation reduces the number and magnitude of potential climate hazards, reducing the most severe changes first. Adaptation increases the ability to cope with climate hazards by reducing system sensitivity or by reducing the consequent level of harm. Secondly, they manage risks at different extremes of the potential range of future climate change. Adaptation works best with changes of lesser magnitude at the lower end of the potential range. Where there is sufficient adaptive capacity, adaptation improves the ability of a system to cope with increasingly larger changes over time. By moving from uncontrolled emissions towards stabilisation of greenhouse gases in the atmosphere, mitigation limits the upper part of the range. Different activities have various blends of adaptive and mitigative capacity. In some cases, high sensitivity and low adaptive capacity may lead to large residual climate risks; in other cases, a large adaptive capacity may mean that residual risks are small or non-existent. Mitigative and adaptive capacity do not share the same scale: adaptive capacity is expressed locally, whereas mitigative capacity is different for each activity and location but needs to be aggregated at the global scale to properly assess its potential benefits in reducing climate hazards. This can be seen as a demand for mitigation, which can be exercised at the local scale through exercising mitigative capacity. Part two of the paper deals with the situation where regional bodies aim to maximise the benefits of managing climate risks by integrating adaptation and mitigation measures at their various scales of operation. In north central Victoria, Australia, adaptation and mitigation are being jointly managed by a greenhouse consortium and a catchment management authority. Several related studies investigating large-scale revegetation are used to show how climate change impacts and sequestration measures affect soil, salt and carbon fluxes in the landscape. These studies show that trade-offs between these interactions will have to be carefully managed to maximise their relative benefits. The paper concludes that when managing climate change risks, there are many instances where adaptation and mitigation can be integrated at the operational level. However, significant gaps between our understanding of the benefits of adaptation and mitigation between local and global scales remain. Some of these may be addressed by matching demands for mitigation (for activities and locations where adaptive capacity will be exceeded) with the ability to supply that demand through localised mitigative capacity by means of globally integrated mechanisms.     

Scaling Uncertainties in Estimating Canopy Foliar Maintenance Respiration for Black Spruce Ecosystems in Alaska

A major challenge confronting the scientific community is to understand both patterns of and controls over spatial and temporal variability of carbon exchange between boreal forest ecosystems and the atmosphere. An understanding of the sources of variability of carbon processes at fine scales and how these contribute to uncertainties in estimating carbon fluxes is relevant to representing these processes at coarse scales. To explore some of the challenges and uncertainties in estimating carbon fluxes at fine to coarse scales, we conducted a modeling analysis of canopy foliar maintenance respiration for black spruce ecosystems of Alaska by scaling empirical hourly models of foliar maintenance respiration (R_m) to estimate canopy foliar R_m for individual stands. We used variation in foliar N concentration among stands to develop hourly stand-specific models and then developed an hourly pooled model. An uncertainty analysis identified that the most important parameter affecting estimates of canopy foliar R_m was one that describes R_m at 0 ^∘C per g N, which explained more than 55% of variance in annual estimates of canopy foliar R_m. The comparison of simulated annual canopy foliar R_m identified significant differences between stand-specific and pooled models for each stand. This result indicates that control over foliar N concentration should be considered in models that estimate canopy foliar R_m of black spruce stands across the landscape. In this study, we also temporally scaled the hourly stand-level models to estimate canopy foliar R_m of black spruce stands using mean monthly temperature data. Comparisons of monthly R_m between the hourly and monthly versions of the models indicated that there was very little difference between the estimates of hourly and monthly models, suggesting that hourly models can be aggregated to use monthly input data with little loss of precision. We conclude that uncertainties in the use of a coarse-scale model for estimating canopy foliar R_m at regional scales depend on uncertainties in representing needle-level respiration and on uncertainties in representing the spatial variability of canopy foliar N across a region. The development of spatial data sets of canopy foliar N represents a major challenge in estimating canopy foliar maintenance respiration at regional scales.     

Prenatal diagnosis of klippel—trénaunay—weber syndrome by ultrasound

Ultrasound examination due to an elevated maternal serum alpha-fetoprotein level showed lower extremity asymmetry. The findings were felt to be consistent with Klippel—Trénaunay—Weber syndrome. The pregnancy was terminated based on these findings. The ultrasound findings, confirming post-mortem examination, and counselling issues are discussed.     

A TRADE-OFF ANALYSIS OF ALTERNATIVE WATER USES1

ABSTRACT: In the western United States, hydropower and agriculture often cempete for surface waters. Since water markets are imperfect, allocations are often made through institutional arrangements and policy The purpose of this paper is to compare the gross water returns from agriculture with hydropower in terms of water use in Idaho. For the year 1986, returns from agriculture averaged $200 per acre-foot, and returns from hydropower averaged $8.00 per acre-foot.     

International renegotiations: the case of the Dominican Republic and Falconbridge

In 1969, Falconbridge Ltd agreed to expand greatly the facilities operated by its subsidiary in the Dominican Republic. Over the succeeding years, the company mined, processed and exported a large proportion of the country's nickel reserves. Due to worldwide market conditions, however, the company made losses rather than profits, and the Dominican government received little financial benefit from the company's operations. Matters came to a head in November 1987 when President Balaguer of the Dominican Republic unilaterally imposed taxes on company imports and exports. This action was significant because under a long-standing agreement with the Dominican government, Falconbridge was only obligated to pay income taxes and had an exemption in perpetuity from all other taxes. When the company refused to pay the new taxes, the government began to curtail nickel exports. Meanwhile, on world markets, the price of nickel soared. This paper briefly describes how the world nickel market has evolved, and then focuses attention on the relationship between Falconbridge and the Dominican Republic. It outlines the issues that arose, describes the renegotiation process itself and analyses how matters were resolved.     

IDENTIFICATION AND ANALYSIS OF OUTDOOR RECREATION HABITATS: THE RECREATION HABITAT ANALYSIS METHOD1

ABSTRACT: This paper describes a concept for identification and ranking of outdoor recreation habitats using principles of ecology as a guide. The Habitat Evaluation Procedures (HEP) is a commonly used technique for assessment of human impacts on the vigor of wildlife species, and serves as the model for the Recreation Habitat Analysis Method (RHAM). Recreation activities are dependent on habitat attributes for their success just as are wildlife species. A sample model is described for recreation activities at large, multipurpose lakes. RHAM could be applied to recreation experiences in a variety of settings including smaller water bodies and riparian and terrestrial ecosystems.     

The multidonor approach in large river and lake basin development in Africa

From the outset of its efforts to promote the socio-economic development of river and lake basins in developing countries, UNDP took the position that in most cases the river basin was the appropriate geographical entity for development. However, the amount of technical Assistance required to evaluate the potentialities of a large river or lake basin is beyond the capabilities of any single donor of assistance. Similarly, the capital investment required to implement a basin development programme, ranging from US $ several hundred million to possibly US $ several thousand million, is usually beyond the capabilities of any single financial institution. On the basis of the experience gained in the development of the Mekong River and the Senegal River, UNDP advocates concerted and coordinated cooperation among donors interested in different aspects of one given large river or lake basin development, for which it coined the phrase 'multidonor approach'.