Begging affects parental effort in the pied flycatcher, Ficedula hypoleuca

It has been suggested that nestlings use begging to increase their share of parental resources at the expense of current or future siblings. There is ample evidence that siblings compete over food with nestmates by begging, but only short-term effects of begging on parental provisioning rates have been shown. In this study, we use a new experimental design to demonstrate that pied flycatcher (Ficedula hypoleuca) nestlings that beg more are able to increase parental provisioning rates over the major part of the nestling period, thus potentially competing with future siblings. Parents were marked with microchips so that additional begging sounds could be played back when one of the parents visited the nest. By playing back begging sounds consistently at either male or female visits, a sex difference in provisioning rate that lasted for the major part of the nestling period was induced. If each parent independently adjusts its effort to the begging intensity of nestlings, begging may also be the proximate control mechanism for the sexual division of labour. Received: 24 January 1997 / Accepted after revision: 30 August 1997     

Asymmetric sibling rivalry and nestling growth in red-winged blackbirds (Agelaius phoeniceus)

Many birds hatch their offspring asynchronously, and the adaptive significance of this trait, if any, is controversial. David Lack suggested long ago that by facilitating brood reduction when resources are scarce, hatching asynchrony provides relief from the effects of overcrowding. Some field workers interpret this to mean that the growth and survival of survivors should rise following partial brood loss. Here we show in a 6-year study of red-winged blackbirds (Agelaius phoeniceus) that the presence or absence of marginal offspring in experimentally manipulated broods had virtually no effect upon the growth of core offspring, whereas alterations of the size of core brood had strong and significant effects. Nestling growth was, not surprisingly, slower in broods with partial brood loss. Intriguingly, marginal offspring showed significantly greater variation in mass. Core offspring are less sensitive to, but not exempt from, the inimical effects of resource shortfall than are marginal offspring. The phenotypic handicap appears to marginal offspring a caste of high-variance progeny whose fitness prospects rest upon levels of parental input (stochastic resources) and the size of the core brood (stochastic development). Received: 21 June 1999 / Revised: 5 June 2000 / Accepted: 25 June 2000     

Male-male competition ensures honest signaling of male parental ability in the three-spined stickleback (Gasterosteus aculeatus)

The importance of socially imposed costs for the evolution and maintenance of honest sexual signals has received less attention than other costs. Here I show that male-male competition can increase the honesty of sexual signaling in relation to male parental ability in a species with flexible signaling. When four three-spined stickleback (Gasterosteus aculeatus) males were allowed to court a female first separately and then in competition, red nuptial coloration under competition reflected male parental ability more accurately than red coloration when separated. Parental ability was determined as the ability of the male to raise a clutch of eggs to the hatching stage under interaction with other breeding and non-breeding males. The increased honesty under competition was probably due to subordinate males of poor parental ability decreasing their color expression under interaction to reduce the risk of fights with superior males. However, socially imposed costs of signaling were probably not the main factors maintaining honest signaling, as red coloration reflected male parental ability also in the absence of competition, although less accurately. Nevertheless, the small-scale differences that male-male competition induced can significantly facilitate adaptive female choice and have large impacts on sexual selection. Received: 7 July 2000 / Revised: 31 August 2000 / Accepted: 4 September 2000     

Non-adaptive adoptions of nestlings in the colonial lesser kestrel: proximate causes and fitness consequences

We examined the causes, costs and benefits of adoption in the altricial lesser kestrel Falco naumanni. Specifically, we tested the intergenerational conflict hypothesis, proposed to explain adoption in some birds. Adoptions involved 76% of the nests and 51% of the nestlings at a mean age of 25 days (12 days before fledging). Nest-switching nestlings were not in poorer body condition, more parasitized or younger than their siblings, and body condition and prey delivery rates of their parents did not differ from those of other parents. In the foster nest, adopted nestlings did not benefit from higher feeding rates or a prolongation of the nestling period. They did not have fewer nest-mates or achieve higher rank within the new brood. Thus, adopted nestlings did not improve their body condition and survival. Adult lesser kestrels seemed unable to finely discriminate beween their own and alien chicks. Foster parents bore the cost of an increase of prey delivery rates, although it did not affect their survival or subsequent reproductive performance. Therefore, our results do not support the intergenerational conflict hypothesis, and suggest that adoption in this species is non-adaptive. Traditionally, the lesser kestrel bred in cliffs where movement among nest-sites was restricted. Nowadays, about half of the colonies are in tiled roofs which facilitate nest-switching by nestlings. The high rate of adoptions may thus be explained as reproductive errors associated with the recent occupation of a new breeding habitat. Received: 3 May 1996 / Accepted after revision: 19 January 1997     

Modelling the impact of thermal adaptation of soil microorganisms and crop system on the dynamics of organic matter in a tropical soil under a climate change scenario

No consensus currently exists about how climate change should affect the status of soil organic matter (SOM) in the tropics. In this study, we analyse the impact of climate change on the underlying mechanisms controlling SOM dynamics in a ferralsol under two contrasting tropical crops: maize (C4 plant) and banana (C3 plant). We model the effect of microbial thermal adaptation on carbon (C) mineralisation at the crop system scale and introduce it in the model STICS, which was previously calibrated for the soil-crop systems tested in this study. Microbial thermal adaptation modelling is based on a reported theory for thermal acclimation of plant and soil respiration. The climate is simulated from 1950 to 2099 for the tropical humid conditions of Guadeloupe (French Antilles), using the ARPEGE model and the IPCC emission scenario A1B. The model predicts increases of 3.4 °C for air temperature and 1100 mm yr⁻¹ for rainfall as a response to an increase of 375 ppm for atmospheric carbon dioxide concentration in the 2090-2099 decade compared with the 1950-1959 decade. The results of the STICS model indicate that the crop affects the response of SOM to climate change by controlling the change in several variables involved in C dynamics: C input, soil temperature and soil moisture. SOM content varies little until 2020, and then it decreases faster for maize than for banana. The decrease is weakened under the hypothesis of thermal adaptation, and this effect is greater for maize (−180 kg C ha⁻¹ yr⁻¹ without adaptation and −140 kg C ha⁻¹ yr⁻¹ with adaptation) than for banana (−60 kg C ha⁻¹ yr⁻¹ and −40 kg C ha⁻¹ yr⁻¹, respectively). The greater SOM loss in maize is mainly due to the negative effect of warming on maize growth decreasing C input from residues. Climate change has a small effect on banana growth, and SOM loss is linked to its effect on C mineralisation. For both crops, annual C mineralisation increases until 2040, and then it decreases continuously. Thermal adaptation reduces the initial increase in mineralisation, but its effect is lower on the final decrease, which is mainly controlled by substrate limitation. No stabilisation in SOM status is attained at the end of the analysed period because C mineralisation is always greater than C input. Model predictions indicate that microbial thermal adaptation modifies, but does not fundamentally change the temporal pattern of SOM dynamics. The vegetation type (C3 or C4) plays a major role in SOM dynamics in this tropical soil because of the different impact of climate change on crop growth and then on C inputs.     

参数完全不确定系统在未知输入下的损伤识别

由于各种因素的影响,实际结构系统与计算模型有着不小的差异。本文针对结构系统参数及基底输入完全未知情况下的损伤识别问题,构造了与质量无关的结构规格化刚度参数和阻尼参数,提出了关于结构规格化参数和层间质量比的非线性最小二乘迭代优化识别方法,并给出了用规格化参数进行识别损伤和地震动反演的公式。算例表明本方法是有效的。     

基于EFQM的建筑企业安全投入绩效评估SEM

为解决目前我国建筑业安全生产事故频发,安全投入不足及其绩效产出低下的现状,通过探索性因子分析,从建筑企业安全投入22项组成内容中提炼出6项要素;借鉴欧洲质量卓越(EFQM)模型,建立建筑企业安全投入绩效评估结构方程模型(SEM),实证分析安全投入构成要素之间的复杂交互影响关系:领导分别对人员、资源设施、政策战略具有正向直接影响;人员与资源受到政策战略的正向直接影响,并对生产过程与事故损失产生正向直接与间接影响。因此,在加强领导投入以提升整体安全投入绩效的前提下,提高政策战略对于人员、资源与设施的约束性,将最终保障安全生产与减少事故损失。     

A comparative study of countries’ responsibilities for carbon dioxide emission in an open economy

In an open economy, embodied carbon dioxide emissions in international trade should be taken into consideration to scientifically define each country’s emissions responsibility. In this study, a multiregional input–output model is constructed to calculate the embodied carbon dioxide emissions of 25 World Trade Organization members, including China, according to the producer–consumer shared responsibility principle. The study indicates that: it is fairer and more efficient to identify each country’s carbon dioxide emissions responsibility according to the shared responsibility principle; China’s producer responsibility is 1.4 times that of the USA, while China’s consumer responsibility is only one-tenth that of the USA; according to the producer responsibility principle, China shoulders the greatest responsibility. According to the producer–consumer shared responsibility principle, China’s responsibility shows a large decrease. Resource endowment, economic development stage, and trade structure account for the abovementioned changes in China’s emissions responsibility.     

基于Windows DEA模型的我国自然灾害应急公共投入绩效研究

为提升自然灾害应急公共投入绩效评价的精准性、科学性,运用动态绩效评价Windows DEA模型,结合应急处置结果,对我国近年来自然灾害领域的应急公共投入绩效进行全面系统评价,研究结果表明:我国应急公共投入效率不高且有较大改善空间;应急公共投入效率较高的省（区、市）未能产生辐射效应;我国应急公共投入效率呈现“滞后性”,即当年投入的应急公共投入在当年未得到相应产出。