Egg size and laying order in relation to offspring sex in the extreme sexually size dimorphic brown songlark,<Emphasis Type="Italic"> Cinclorhamphus cruralis</Emphasis>

In some bird species, mothers can advantage the offspring of one sex either by elevating them in the laying order to promote earlier hatching or by allocating greater resources to eggs of the preferred sex. In size dimorphic species, the predictions as to which sex should benefit most from such pre-laying adjustments are ambiguous. The smaller sex would benefit from an initial size advantage to help compensate for the faster growth rate of the larger sex. However, an early advantage to offspring of the larger sex might have a greater effect on their lifetime reproductive success than an equivalent advantage to offspring of the smaller sex. We investigated these hypotheses in the polygynous brown songlark, Cinclorhamphus cruralis, which is one of the most sexually size dimorphic birds known. We conducted within-clutch comparisons and found that females hatched from larger eggs and were initially heavier (but not structurally larger) than their brothers. This may afford females an early competitive advantage, as egg volume remained correlated with chick mass until at least 5 days of age. Similarly, we found that hatch order was still positively associated with nestling mass and size when the brood was 10 days of age, but there was no clear relationship between offspring sex and hatching order. During this study, food was plentiful and there were few obvious cases of nestling starvation. When food is limited, we suggest that the greater nutrient reserves of female hatchlings could not only help compensate for their slower growth, but could also give them a survival advantage over their brothers early in the nestling period. Consequently, egg size dimorphism may be an adaptation that facilitates an early shift in brood sex-ratio towards cheaper daughters in conditions of low food availability.     

Constitutive and herbivore‐induced volatiles in pear,alder and hawthorn trees

Summary. Qualitative and quantitative differences among pear cultivars were found in constitutive and Cacopsylla-induced volatiles, depending on experimental treatment of the trees (i.e., uninfested and partly or completely infested by psyllids). Blend differences were also found between pear cultivars and wild-type pear, alder and hawthorn–the latter trees are frequently present in pear orchard hedgerows. ?Interesting differences were found in the presence of methyl salicylate and (E,E)-α-farnesene, two compounds previously found to mediate attraction of predatory bugs towards psyllid-infested pear trees. Methyl salicylate is expressed constitutively and is induced systemically by infestation in the whole plant of all four cultivars. (E,E)-α-farnesene on the other hand showed also systemic induction in Bartlett, NY10355 and Beurré Hardy, but in partially infested Conference trees it was induced locally, only in herbivore-damaged leaves. No methyl salicylate or (E,E)-α-farnesene were identified in honeydew. In field collected headspace samples of alder leaves infested by aphids and leaf beetles we found methyl salicylate but no (E,E)-α-farnesene, whereas in uninfested hawthorn neither were identified. Insight in the variability of damage-related pear volatiles will have important implications for integrated pest management in the field. Received 27 August 2002; accepted 28 November 2002 R1D=" Correspondence to: Petru Scutareanu, e-mail:scuterea@science.uva.nl     

Animal Burrowing Attributes Affecting Hazardous Waste Management

/ Animal burrowing is critical to the formation of soils and contributes to the interface between geological materials and organic life. It also influences the management of hazardous materials at nuclear waste facilities and elsewhere. For example, residues and waste products from the production of nuclear weapons are released onto the ground surface and within engineered burial structures. Soil bioturbation has exposed radionuclides and other hazardous materials to wind and rain, thereby risking inhalation and injury to humans and wildlife on and off site. Soil bioturbation can expand soil depths and spatial distributions of the source term of hazardous waste, potentially increasing chronic exposures to wildlife and humans over the long term. Ample evidence indicates that some of the large quantities of hazardous materials around the world have been released from soil repositories, where they have also contaminated and harmed biota. Key burrowing parameters influencing these outcomes include the catalog of resident species, and their abundance, typical burrow volumes (void space created by soil displacement), burrow depth profiles, maximum depth of excavation, constituents and structural qualities of excavated soil mounds, and proportion of the ground covered by excavated soil. Other important parameters include rate of mound construction, depth of den chambers, and volume of burrow backfill. Soil bioturbation compromised the integrity of some hazardous waste management systems using soil, but the environmental impact remains largely unknown. Designers and operators of waste management facilities, as well as risk assessors, need to understand how burrowing animals influence hazardous waste storage.KEY WORDS: Burrowing; Environmental impact; Radioactivity; Risk; Soil bioturbation; Hazardous waste     

粮食生产系统中的镉:对敏感人群的健康威胁

本文概述了瑞典农业系统中镉的状况以及镉的人类暴露状况.农业土壤(耕层)中的镉每年增加0.03%～0.05%.饲料是当地农业系统中镉增加的重要原因.当前暴露水平下已经有一些测量表明人体肾功能受到影响.如果粮食中的水平达到欧盟允许的最大限度,那么10%～25%的瑞典人群暴露的镉水平将超过暂时可容忍的每周摄入量(PTWI,7μg Cd/kg体重).人群中的敏感者是那些低铁状况(主要是女性)和肾紊乱的个体.最近的研究表明镉对骨质疏松症有影响,但还需要进一步的研究来辨别镉是否在早期发展阶段毒害神经.必须采取坚决行动来阻止农业土壤中镉含量进一步增加.本文给出了预防及采取措施的建议.     

汽车修配厂含油废水处理工程分析

研究了汽车修配厂含油废水的处理技术，提出了隔油－混凝－澄清－过滤处理工艺；根据该工艺设计的汽车修配厂含油废水的处理工程；运行的实际测定结果表明，其处理后的废水，ＣＯＤｃｒ可降到３５ｍｇ／Ｌ，油可降到８ｍｇ／Ｌ，ＳＳ可降到２０ｍｇ／Ｌ，色度可降到１０度，处理后的水可达到广州市的废水处理排放标准，并可回收再利用。     

Contents Volume 7

Volume Contents

Contents Volume 7     

Prenatal identification of an isochromosome for the short arm of the Y i(Yp), by cytogenetic and Molecular analyses

A case of 45,X/46,X,+mar mosaicism was detected in a male fetus (27 weeks' gestation) referred for karyotype analysis following the observation of a short femur at the ultrasound scan. Analysis of 12 Y-chromosome loci by fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR) demonstrated that the marker chromosome is of Y origin and corresponds to an authentic isochromosome for the short arm of the Y chromosome, i(Yp). The breakpoint on this marker is in YQ11·1 close to the centromere. The present report illustrates the importance of FISH and PCR techniques as a complement to cytogenetic methods for accurate identification and characterization of chromosome rearrangements in prenatal diagnosis.     

Analysing countries’ contribution to climate change: scientific and policy-related choices

This paper evaluates the influence of different policy-related and scientific choices on the calculated regional contributions to global climate change (the “Brazilian Proposal”). Policy-related choices include the time period of emissions, the mix of greenhouse gases and different indicators of climate change impacts. The scientific choices include historical emissions and model representations of the climate system. We generated and compared results of several simple climate models. We find that the relative contributions of different nations to global climate change—from emissions of greenhouse gases alone—are quite robust, despite the varying model complexity and differences in calculated absolute changes. For the default calculations, the average calculated contributions to the global mean surface temperature increase in 2000 are about 40% from OECD, 14% from Eastern Europe and Former Soviet Union, 24% from Asia and 22% from Africa and Latin America. Policy-related choices, such as time period of emissions, climate change indicator and gas mix generally have larger influence on the results than scientific choices. More specifically, choosing a later attribution start date (1990 instead of 1890) for historical emissions, decreases the contributions of regions that started emitting early, such as the OECD countries by 6 percentage points, whereas it increases the contribution of late emitters such as Asia by 8 percentage points. However, only including the fossil CO₂ emissions instead of the emissions of all Kyoto gases (fossil and land use change), increases the OECD contributions by 21 percentage points and decreases the contribution of Asia by 14 percentage points.     

Margins of agricultural fields as habitats for pollinating insects

The occurrence of pollinating insects in field margins with different vegetation was studied in field experiments. Some margins were widened and vegetation was established by sowing of leguminous plants or was allowed to invade spontaneously. The communities of pollinating insects in reclaimed field margins were compared with those of a margin with a naturally diverse flora and an adjacent pasture. A beehive was placed in the area and the collection of pollen by the honey-bees was followed over the season in order to compare the bees' preferences with the supply of flowering plants available in the different experimental field margins. The sown leguminous plants were very attractive to most insect groups, especially bees and bumble-bees, and their pollen constituted an important part of the bees' total catch. The vegetation established by spontaneous succession especially attracted Syrphidae and other groups of Diptera. Butterflies were found in all vegetation types. It is concluded that small areas with flowering plants can give highly positive effects. The key question is how to avoid weed problems and keep the most attractive plant species with a minimum of cost and effort.