Showing papers by "International Institute for Applied Systems Analysis published in 1999"

On the origin of species by sympatric speciation

Abstract: Understanding speciation is a fundamental biological problem. It is believed that many species originated through allopatric divergence, where new species arise from geographically isolated populations of the same ancestral species. In contrast, the possibility of sympatric speciation (in which new species arise without geographical isolation) has often been dismissed, partly because of theoretical difficulties. Most previous models analysing sympatric speciation concentrated on particular aspects of the problem while neglecting others. Here we present a model that integrates a novel combination of different features and show that sympatric speciation is a likely outcome of competition for resources. We use multilocus genetics to describe sexual reproduction in an individual-based model, and we consider the evolution of assortative mating (where individuals mate preferentially with like individuals) depending either on an ecological character affecting resource use or on a selectively neutral marker trait. In both cases, evolution of assortative mating often leads to reproductive isolation between ecologically diverging subpopulations. When assortative mating depends on a marker trait, and is therefore not directly linked to resource competition, speciation occurs when genetic drift breaks the linkage equilibrium between the marker and the ecological trait. Our theory conforms well with mounting empirical evidence for the sympatric origin of many species.

Climate change and world food security: a new assessment

Abstract: Building on previous work quantitative estimates of climate change impacts on global food production have been made for the UK Hadley Centre's HadCM2 greenhouse gas only ensemble experiment and the more recent HadCM3 experiment (Hulme et al., 1999). The consequences for world food prices and the number of people at risk of hunger as defined by the Food and Agriculture Organisation (FAO, 1988) have also been assessed. Climate change is expected to increase yields at high and mid-latitudes, and lead to decreases at lower latitudes. This pattern becomes more pronounced as time progresses. The food system may be expected to accommodate such regional variations at the global level, with production, prices and the risk of hunger being relatively unaffected by the additional stress of climate change. By the 2080s the additional number of people at risk of hunger due to climate change is about 80 million people (±10 million depending on which of the four HadCM2 ensemble members is selected). However, some regions (particularly the arid and sub-humid tropics) will be adversely affected. A particular example is Africa, which is expected to experience marked reductions in yield, decreases in production, and increases in the risk of hunger as a result of climate change. The continent can expect to have between 55 and 65 million extra people at risk of hunger by the 2080s under the HadCM2 climate scenario. Under the HadCM3 climate scenario the effect is even more severe, producing an estimated additional 70+ million people at risk of hunger in Africa.

WWW-based negotiation support: design, implementation, and use

Abstract: Support for international negotiations requires integration of decision-theoretic approaches with communication facilities, and different visualization modes. In addition, negotiation support systems (NSS) should also be tailored to different cultural and educational backgrounds of their users. While there have been studies on cross-cultural negotiations involving simple game or economic models, there have been no experiments with NSS in international and cross-cultural contexts. At the same time the emergence and quickly spreading use of the World Wide Web (WWW) and electronic commerce indicates the potential of NSS supporting commercial transactions across borders. This paper presents INSPIRE, the first Web-based NSS that has been tested and used in teaching and training in several countries. Developed in the context of a cross-cultural study of decision making and negotiation, it has been primarily used to conduct and study negotiation via WWW as well as in teaching and training. The architecture of INSPIRE, which relies heavily on the net-centric computing paradigm and object oriented design, is also discussed.

The evolutionary ecology of dispersal

Abstract: Dispersal is a life-history trait that has profound consequences for populations. Viewed from an ecological perspective, dispersal influences the dynamics and persistence of populations, the distribution and abundance of species, and community structure. From an evolutionary perspective, dispersal determines the level of gene flow between populations and affects processes such as local adaptation, speciation, and the evolution of life-history traits. In fact, it is difficult to imagine any ecological or evolutionary problem that would not be affected by dispersal. The various consequences of dispersal are extensively discussed in the ecological and evolutionary literature (a search in the Science Citation Index gave more than 1000 occurrences of 'dispersal' in the abstract or title of papers for the year 1997 alone). Surprisingly, however, the question of why particular dispersal strategies evolved has received much less attention. Part of the problem is that many of the mechanisms proposed to affect the evolution of dispersal (Box 1) are notoriously difficult to test in the field. Consequently, there exists a serious gap between theory and data, and our understanding why particular organisms disperse in specific ways is still limited. A recent workshop in Finland provided an opportunity to survey the state of the field.

How Should We Define Fitness in Structured Metapopulation Models? Including an Application to the Calculation of Evolutionarily Stable Dispersal Strategies

Abstract: We define a fitness concept applicable to structured metapopulations consisting of infinitely many equally coupled patches, and provide means for calculating its numerical value. In addition we introduce a more easily calculated quantity RM that relates to fitness in the same manner as RO relates to fitness in ordinary population dynamics: RM of a mutant is only defined when the resident population dynamics converges to an equilibrium, and RM is larger (smaller) than one if and only if mutant fitness is positive (negative). RM corresponds to the average number of newborn dispersers resulting from the (on average less than one) local colony founded by a newborn disperser. As an example of the usefulness of these concepts we calculate the ES conditional dispersal strategy for individuals that can account for the local population density in their dispersal decisions.

Norms as emergent properties of adaptive learning: The case of economic routines

Abstract: Interaction among autonomous decision-makers is usually modelled in economics in game-theoretic terms or within the framework of General Equilibrium. Game-theoretic and General Equilibrium models deal almost exclusively with the existence of equilibria and do not analyse the processes which might lead to them. Even when existence proofs can be given, two questions are still open. The first concerns the possibility of multiple equilibria, which game theory has shown to be the case even in very simple models and which makes the outcome of interaction unpredictable. The second relates to the computability and complexity of the decision procedures which agents should adopt and questions the possibility of reaching an equilibrium by means of an algorithmically implementable strategy. Some theorems have recently proved that in many economically relevant problems equilibria are not computable. A different approach to the problem of strategic interaction is a “constructivist” one. Such a perspective, instead of being based upon an axiomatic view of human behaviour grounded on the principle of optimisation, focuses on algorithmically implementable “satisfycing” decision procedures. Once the axiomatic approach has been abandoned, decision procedures cannot be deduced from rationality assumptions, but must be the evolving outcome of a process of learning and adaptation to the particular environment in which the decision must be made. This paper considers one of the most recently proposed adaptive learning models: Genetic Programming and applies it to one the mostly studied and still controversial economic interaction environment, that of oligopolistic markets. Genetic Programming evolves decision procedures, represented by elements in the space of functions, balancing the exploitation of knowledge previously obtained with the search of more productive procedures. The results obtained are consistent with the evidence from the observation of the behaviour of real economic agents.

Ecology and adaptation of stunted growth in fish

Abstract: Dwarf individuals are observed in many species of freshwater fish. This paper studies the potential causes of such stunted growth. We present a model which describes the effect of growth conditions on the age- and size-structure of fish populations. The model parameters are chosen to characterize a Eurasian perch population. Two possible causes of stunting are identified: resource limitation and size- or age-dependent survival probabilities. While the former mechanism often arises from intraspecific density dependence, the latter is of particular relevance in the context of interspecific interactions and fishing. After evaluating the immediate ecological consequences of these factors, we examine the potential for life-history adaptations in stunted fish populations. Interactions between the ecological and adaptive mechanisms of stunting are shown to be intricate: not only does the age at maturity of individuals affect their growth trajectories, but, in addition, alterations in growth conditions can result in different adaptively stable ages at maturity. We show that such adaptive responses can either alleviate or amplify stunting caused by ecological factors. Life-history adaptation may also lead to the persistence of stunting when ecological factors alone would allow for normal growth. An appreciation of the interplay between ecological and adaptive factors therefore is critical for understanding the causes and mechanisms of stunted growth.

Do Power Consumption Data Tell the Story? - Electricity Intensity and Hidden Economy in Post-Socialist Countries

Abstract: The paper disputes the frequently presented and quoted statement that in post-socialist economies data on power consumption are better indicators for aggregate output changes than data on official GDP. Attempt is made to show that the variation of electricity intensities in post-socialist countries does not necessarily reflect the growth of the hidden parts of the economy. Statistical and econometric analysis of data for 18 post-socialist economies show that in this region, the differences in measured and registered structural changes are more important factors explaining the differences in the changes of electricity intensity than the changing size of the unofficial economy.

Universal Power Laws Govern Intermittent Rarity in Communities of Interacting Species

Abstract: The temporal dynamics of many natural populations involve intermittent rarity, that is, the alternation over variable periods of time of phases of extremely low abundance and short outbreaks. In this paper, we show that intermittent rarity can arise in simple community models as a result of competitive interactions within and between species. Intermittently rare species are typified as weak invaders in fluctuating communities. Although the dynamics of intermittent rarity are highly irregular, the distribution of time spent in phases of rarity (“rarity times”) involves strong regularity. Specifically, intermittent rarity is governed by a well-defined power law. The scaling exponent (−3/2) is a universal feature of intermittent rarity: it does not depend on species demographic parameters; it is insensitive to environmental stochasticity; and the same exponent is found in very different models of nonstructured populations. The distribution of rarity times implies that the dynamics of rarity have no characteristic time scale. Yet, in practice, the universal scaling law offers a general form of prediction, in which one can calculate the frequency of occurrence of rarity phases of any given duration. Data on marine fish communities support the prediction of a −3/2 power law underlying the dynamics of intermittently rare species. The scale-free dynamics reported here place intermittent rarity in the same class as the critical states of other nonlinear dynamical systems in the physical sciences. At a critical state, general laws govern the systems’ dynamics, irrespective to the specific details of the interactions between constituents.

Cost benefit analysis of European air quality targets for sulphur dioxide, nitrogen dioxide and fine and suspended particulate matter in cities

Abstract: The European Commission has proposed air quality standards for NO2, SO2 and PM10 to be in force by 2010. The present paper presents a study that gauged their costs and benefits. An analysis of the expected emissions for 2010 (reference emission scenario), using simplified air quality models, showed that non-compliance with these standards will occur in cities only, not in rural areas. Most compliance problems are expected for PM10, least for SO2. Central estimates of the costs to meet standards range from 21 MECU (SO2), to 79 MECU (NO2) to 87--225 MECU (PM10). The estimated benefits are 83--3783 MECU (SO2), 408--5900 MECU (NO2), and 5007--51247 MECU (PM10). Uncertainties are high, due to errors and incertitude in various steps of the methodology, mainly the estimation of the human health effects, in particular effects on mortality, and in the valuation of a statistical life. In the case of PM10, additional uncertainty results from the small size of the air quality database. Notwithstanding the uncertainties, the indications are that the benefits exceed the costs.

Phage-lift for game theory

Abstract: The prisoner's dilemma is a classic of game theory in which acting for individual advantage is pitted against acting for collective benefit. An example has been identified among clones of a virus that infects bacteria.

Negotiations in Electronic Commerce: Methodological Misconceptions and a Resolution

Abstract: We contrast the software agent and decision support based approaches to negotiation in the context of electronic commerce, and explore their respective limitations. The software agent literature on negotiations shows several misconceptions about the nature of negotiations, interdependencies between goals and issues, the significance of different types of processes and representation schemes, etc. Particularly important among these misconceptions are those involving the distinction between distributive (‘win-lose’) and integrative (‘win-win’) negotiations, and we observe that almost all negotiating software agent approaches support only the former type. We resolve these inconsistencies and suggest how decision support based approaches may be used to shift agent negotiation processes into integrative modes. The discussion of the characteristics of negotiations leads us to suggest an resolution in which both integrative and distributive activities can be used, and to propose an e-commerce infrastructure in which negotiators interact with decision support systems which in turn interact with negotiating software agents. 1 We wish to acknowledge the contribution of Gordon Lo to this paper. Ideas presented by Prof. Mel Shakun in his numerous publications and discussions with Prof. Jeff Teich helped us clarify our views. This work has been partially supported by the Social Science and Humanities Research Council of Canada, the Natural Sciences and Engineering Research Council of Canada, and the International Institute for Applied System Analysis.

Rational inefficient compromises in negotiation

Abstract: It has often been assumed that rational negotiators who achieve inefficient compromises should accept Pareto improvements suggested by some external party, such as an expert mediator, or a computer system. Following this assumption an argument is made to give legitimacy to efficient compromises generated by a negotiation support system or to entice a partymove to a Pareto improvement. The simplificatons made in model construction on the one hand and the very narrow and limited considerations of rationality in present negotiation support systems on the other, suggest a different approach to support. This approach is based on engaging users to a sound process confronting them with their inconsisencies rather than providing solutions or promoting improvements.

Model-based decision support in energy planning

Abstract: Models have become standard tools in energy planning. Fast computers and ever improving optimisation packages now allow us to solve problems within a few minutes that were out of range 20 years ago and that 10 years ago could only be solved in several CPU–hours. Fully interactive data bank systems with standardised user interfaces and on–line data access support easy modifications and adaptations of energy models, retrieval and display of results, as well as coupling decision support tools to all kinds of data available in the system. This article gives a brief overview of the objectives in energy planning, especially with respect to different planning horizons. It reviews the types of models applied to different applications and the requirements such tools have to satisfy. The second part surveys some applications of energy optimisation models. These examples have been chosen to illustrate different application areas of energy models from short–term optimal power supply up to very long–term (100 years) resource allocation and technology choice, and from optimising a municipal district heat system up to an energy model for the whole world.

The Russian Forest Sector and Legislation in Transition

Abstract: This paper is about legislation and the forest sector in Russia. The author examines several fields of law identifying what are the most serious shortcomings in legislation hindering a sustainable recovery of the Russian forest sector. The study begins by discussing problems of legislative power and federalism. The division of power in Russia is unclear in many respects and federalism is still looking for its most suitable form. These uncertainties affect the use of law in every sector of the society. Ownership of forest land, on the other hand, appears to be more settled for the time being. The federal state owns all the forests. There are, however, still some obscurities concerning property rights, especially in the regulation of leasing forestland. Business transactions in Russian forest enterprises are a combination of old and new, mainly old, but there is a possibility that the trend will slowly turn towards a modern way of doing business and settling disputes between enterprises. The use of Arbitration Courts, for example, is increasing. When it comes to forest and nature protection legislation, there are, as well as in other legislations, inconsistencies that might be an obstacle for nature protection and sustainable forestry in Russia. Generally speaking, the poor level of implementing laws, the enforcement of court decisions, and the lack of trust in official institutions, are the biggest hurdles on the way towards positive changes in the Russian forest sector.

A Subjective Measure Of Complexity

Abstract: This article presents a quantitative measure of complexity, subjectively understood as a property of the relationship between a system and its observer instead of as a property of the system itself Within this framework, complexity is quantified by assuming to know the mental categories and the mental model by which a system is represented in the mind of its observer It is argued that this subjectivist concept of complexity is not in contrast with objective measures of complexity introduced in particular domains, but generalizes complexity to domains where no objective measure is feasible An extensive numerical example is presented and thoroughly discussed

The long-term effect of the timing of fertility decline on population size

Abstract: Existing long-range population projections imply that the timing of the fertility transition has a relatively unimportant effect on long-term population size when compared with the impact of the level at which fertility is assumed eventually to stabilize However, this note shows that the effect of the timing of fertility decline is a function of the eventual fertility rate: the lower the eventual fertility rate, the greater the effect of the timing of the transition becomes This finding has important implications for projection methodology, as well as for policies related to the consequences of long-term levels of population size

Evolving structure and function of neurocontrollers

Abstract: The presented evolutionary algorithm is especially designed to generate recurrent neural networks with non-trivial internal dynamics. It is not based on genetic algorithms, and sets no constraints on the number of neurons and the architecture of a network. Network topology and parameters like synaptic weights and bias terms are developed simultaneously. It is well suited for generating neuromodules acting in sensorimotor loops, and therefore it can be used for evolution of neurocontrollers solving also nonlinear control problems. We demonstrate this capability by applying the algorithm successfully to the following task: a rotating pendulum is mounted on a cart; stabilize the rotator in an upright position, and center the cart in a given finite interval.

Towards Applied Disequilibrium Growth Theory: VI. Substitution, Money-Holdings, Wealth-Effects and Further Extensions

Abstract: In this paper we present a theoretical disequilibrium growth model of an open economy with a full set of markets and sectors and with heterogeneous agents in the household sector. This model allows, on the one hand, for basic consistency checks, such as fully specified bedget identities and a well-defined steady state refernce path and is therefore carefully specified from the theoretical point of view. On the other hand, the model is already fairly close to applied modern structural model building and thus is rich in descriptive detail. The model exhibits five real and five financial markets. Consumption behavior is formulated by way of the life cycle hypothesis and savings of worker households are allocated to money and short-term bonds, while savings of pure asset holders concern all financial assets considered (equities and long-term bonds, domestic and foreign ones). Firms use three inputs (labor, capital and imports) to produce two outputs (domestic goods and export commodities) by way of a nested CES/CET technology and they produce in a cost-minimizing way subject to a domestic demand constraint, also formulating medium run targets that guide their investment and pricing decision. The government sector is described in a very detailed way, including a variety of taxation schemes in particular and also a debt target according to which taxes are adjusted. We consider sluggishly adjusting wages and prices, coupled with heterogeneous expectations formation, and have on this basis fluctuating rates of capacity utilization on the labor market as well as on the market for goods. Financial markets, finally, are described by delayed adjustment processes towards interest rate parity conditions. The paper itself presents only the extensive form of the model with all of its details and compares it to the Murphy model for the Australian economy and also with the Multimod model, Mark III of the IMF. In subsequent papers we derive the intensive form of the model, its interior steady state solution and a 22 dimensional core dynamics which is then investigated from the theoretical and the numerical point of view, concerning the major feedback loops it contains and the stabilizing or destabilizing implications they give rise to. The main perspective of our work is to contribute to a better theoretical underpinning and understanding of modern applied macrodynamic models which nowadays also attempt to be complete with respect to budget identities and steady state reference paths, but which have not yet fully grasped the stability implications of their model buildings and basically have not yet included heterogeneity with respect to households and expectations formation.

Land Use Change in China: A Scenario Analysis Based on Input- Output Modeling

Abstract: Land availability is of crucial importance for china's food security and economic development in the next century. Economic growth, urbanization, diet structure changes, and population growth will influence both the demand of and the supply for land. A recursive input-output model enlarged by land is used to develop various scenarios of changes in the economy and society and to evaluate their effects on land-use change in China. Due to inefficiency and structural problems, China's land productivity has ample room to increase significantly above current levels even by further exploiting the potential of the existing technology. Results of some scenarios show that China would not be able to support the increasing demand for land intensive products with its land base without significant improvement in land productivity and/or by increasing import.

Spatio-Temporal Processes in Ecological Communities

Abstract: Ecological systems evolve in space and time. Until recently, however, research in ecology separately has focused either on the spatial domain (patterns) or on the temporal domain (processes). In this paper we describe novel approaches for progressing towards an integration of pattern and process, a goal long called for in ecology. First, we present a sequence of alternative stochastic models of spatially extended processes. Second, we advance two new methods for the estimation, or calibration, of model parameters from spatio-temporal processes observed in the field. Third, we provide tools for reducing the complexity of spatially extended ecological processes to manageable dynamical systems. Steps and techniques are illustrated in the context of data from a montane grassland community from the Czech Republic. The authors thank the Wissenschaftskolleg zu Berlin, Institute for Advanced Study, Germany, for generous support of the research reported in this paper.

Endogenous growth of population and income depending on resource and knowledge

Abstract: We consider a three sector demoeconomic model and its interdependence with the accumulation of human capital and resources. The primary sector harvests a renewable resource which constitutes the input into industrial production, the secondary sector of our economy. Both sectors are always affected by the stock of knowledge. The tertiary sector is responsible for the accumulation of this stock that represents a public good for all three sectors. Labour is divided up between the three sectors under the assumption of competitive labour markets. The economy exhibits two externalities – free access to renewable resource harvesting and the existence of a public stock of knowledge – that are not properly reflected in competitive markets. We internalize these externalities by taxing the output of the primary sector and use these taxes together with taxes on labour income to finance the inputs of the tertiary sector. The central focus of this study is whether and what kind of interactions between the economy, the population and the environment foster sustainability and if possible, continuous growth.