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  • 1
    ISSN: 1573-8477
    Keywords: Evolutionarily stable strategy ; risk-spreading ; dispersal behavior ; flight muscle histolysis ; waterstrider
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Evolutionary stable dispersal and wing muscle histolysis strategies are studied in the waterstriderGerris thoracicus. These strategies relate to spreading reproductive risk. Overwintering individuals have the choice of dispersing to either a brackish sea bay or a rock pool habitat. The former is reproductively more favorable than the latter during warm dry years and less favorable during cool wet years. After spring migration, individuals may histolyse their flight muscles and lay all their eggs in one pool or they may retain their flight ability and lay fewer eggs in total but spread them in several pools. We use a simple two-habitat model to examine the question of habitat dispersal. Our results indicate that, although the value of the evolutionary stable dispersal depends on the degree of variability in the environment and on the probability of local extinctions in either habitat, the population always disperses to both habitats as a consequence of density dependent growth. We use a more detailed multiple-rockpool habitat model to examine the question of wing muscle histolysis as a response to density dependence. Our results indicate that a wing muscle histolysis response to population density is an evolutionarily stable strategy when compared with the two alternatives of females always histolysing or never histolysing their flight muscles. The application of evolutionarily stable theory to stochastic problems presents a number of difficulties. We discuss these difficulties in the context of computing evolutionarily stable strategies for the problems at hand.
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  • 2
    ISSN: 1573-8477
    Keywords: genetic models ; inbreeding depression ; mating cost ; Hymenoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Existing genetic models of the evolution of sibmating behaviour in diploids incorporate inbreeding depression in terms of reduced fecundity of consanguineous mating pairs rather than reduced survival or fecundity of the progeny of such matings. Here we derive a model to correct this deficiency and extend the model to haplodiploids where differential effects of inbreeding in males and females is a crucial consideration. Our analyses indicate that sibmating can readily evolve in both diploids and haplodiploids in which male mating costs and inbreeding depression are reasonably low, provided there is some mechanism to permit sibmating such as siblings being reared in nests or other forms of aggregation. Our analyses also indicate that once sibmating invades, it typically will go to fixation, although sib-/randommating polymorphisms can persist in both diploids and haplodiploids if male mating costs are close to zero and inbreeding depression reduces survival by around one-third. The conditions favouring sibmating are slightly more restrictive in haplodiploids than in diploids. In light of this we may ask why we see intense sibmating in many haplodiploids such as parasitic wasps, fig wasps, ants, bark beetles and mites, and only rarely in diploid animals. The common factor could be certain kinds of aggregation behaviour that are a prerequisite for sibmating in the absence of kin recognition. Another possibility is that inbreeding depression is likely to be more severe in diploids than in haplodiploids because deleterious recessives are purged from haplodiploid populations when expressed by haploid males. Thus, lower levels of inbreeding depression might be one important reason why sibmating appears to arise more frequently in haplodiploids than diploids. Phylogenetic analysis of groups, such as bark beetles and mites, exhibiting both diploid and haplodiploid populations may be useful in elucidating the relative importance of gregarious behaviour and haplodiploidy in facilitating sibmating systems.
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  • 3
    ISSN: 1573-8477
    Keywords: delayed reproduction ; evolutionarily stable strategy ; life history polymorphism ; population dynamics ; chaos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Behavioural and life history polymorphisms are often observed in animal populations. We analyse the timing of maturation and reproduction in risky and resource-limited environments. Field and laboratory evidence suggests that female voles and mice, for example, can adjust their breeding according to the level of risk to their own survival and to survival probabilities and recruitment of young produced under different environmental conditions. Under risky or harsh conditions breeding can be postponed until later in the current breeding season or even to the next breeding season. We develop a population dynamics and life history model for polymorphism in reproduction (co-existence of breeding and non-breeding behaviours) of females in an age-structured population, with two temporally distinct mating events within the breeding season. We assume that, after overwintering, the females can breed in spring and again in summer or they can delay breeding in spring and breed in summer only. Young females born in spring can either mature and breed in summer or stay immature and postpone breeding over the winter to the next breeding season. We show that an evolutionarily stable breeding strategy is either an age-structured combination of pure breeding behaviours (old females breed and young delay maturity) or a mixed breeding behaviour within age-classes (a fraction of females breed and the rest of the age class postpones breeding). Co-occurrence of mixed reproductive behaviour in spring and summer within a single breeding season is observed in fluctuating populations only. The reproductive patterns depend on intraspecific, possibly interspecific, and ecological factors. The density dependence (e.g. social suppression) and predation risk are shown to be possible evolutionary mechanisms in adjusting the relative proportions of the different but co-existing reproductive behaviours.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Dynamics and control 1 (1991), S. 239-252 
    ISSN: 1573-8450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Aircraft take-off control under conditions of windshear has recently received considerable attention in the control-theory literature. Severe windshear may cause difficulties during aircraft take-off, it has been a major cause of at least 30 aircraft accidents during the two last decades. We study the controlled take-off of an aircraft flying through an unavoidable windshear. The purpose of the guidance is to guarantee aircraft take-off without crash; no other performance criteria are applied. The proposed aircraft take-off control scheme consists of a memoryless state feedback control strategy for a class of continuous-time aircraft models including unpredictable but bounded windshear. The design of the take-off control scheme is carried out by applying a theory of deterministic control of uncertain systems. The time or the place of encountering a windshear is not known but, according to the basic assumption, the upper bound of the uncertainty—here the maximum rate of the change of the wind velocity—is assumed to be known. Such knowledge allows one to design a deterministic controller to stabilize the relative path inclination of the aircraft.
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  • 5
    ISSN: 1432-5217
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract In this paper we analyse a fishery resource exploitation model in which a single firm or a cartel has leased the rights to manage the resources independently. Two variables, resource level and the capital level, determine the dynamics of the resource system. The leasing contract includes an incentive for the agent to maintain the resource level high. The main result is that sole-agent resource management and efficiency of the resource use do not necessarily imply that the fishery is stabilized at a unique steady state level. Instead, the optimal resource exploitation may lead to periodic capital investments in fishing vessels and gear which in turn causes cycles in the resource economy. We show analytically that nonzero discount rate and low capital depreciation rate both favor the conditions under which periodic optimal solutions may occur. Simulation results related to a Baltic herring fishery are used to illustrate the results.
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  • 6
    ISSN: 1573-1502
    Keywords: Pollution contron ; acidification ; acid rain game ; transboundary air pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract Transboundary air pollution is analysed as a dynamic game between Finland and the nearby areas of the Soviet Union. Sulphur emissions are used as the environmental control variables and the acidities of the soils as the state variables. Acidification is consequently considered to be a stock pollutant having long-lasting harmful effects on the environment. The state dynamics consist of two relationships: first, of a sulphur transportation model between the regions and, second, of a model describing how the quality of the soil is affected by sulphur deposition. The countries are assumed to be interested in maximizing the net benefits from pollution control as measured by the impacts on the values of forest growth net of the abatement costs. Cooperative and noncooperative solutions of the game are compared to assess the benefits of bilateral cooperation. Using empirical estimates of abatement costs, acidification dynamics and impacts on forest growth it is shown that cooperation is beneficial to Finland but not to the Soviet Union. Consequently, Finland has to offer monetary compensation to induce her neighbor to invest in environmental protection.
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  • 7
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In the first part of the paper we analyse dynamics of the genetic mechanisms responsible for maintaining biased sex ratios in host-parasitoid interactions. We begin by reviewing recent results relating to the maintenance of sibmating in haplo-diploid populations. We then investigate the evolutionary stable sex ratio in populations in which all or some of the females mate with their brothers. In particular, we derive a diallelic one-locus model for studying evolutionary stable sex ratios in partially sibmating haplo-diploid populations. In the second part of the paper we review the impact of sex ratio on host-parasitoid populations. We then analyse how the sex ratio strategy of one parasitoid species may affect its interaction with another parasitoid species competing for the same host. In particular we show that, although a female biased sex ratio may enhance the inherent competitiveness of one species, it may also destabilize the ecological interaction of the three species so that all become extinct.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We explore evolutionarily stable co-evolution of host-macroparasite interactions in a discrete-time two-species population dynamics model, in which the dynamics may be stable, cyclic or chaotic. The macroparasites are assumed to harm host individuals through decreased reproductive output. Hosts may develop costly immune responses to defend themselves against parasites. Parasites compete with conspecifics by adjusting their fecundities. Overall, the presence of both parasites and the immune response in hosts produces more stable dynamics and lower host population sizes than that observed in the absence of the parasites. In our evolutionary analyses, we show that maximum parasite fecundity is always an evolutionarily stable strategy (ESS), irrespective of the type of population interaction, and that maximum parasite fecundity generally induces a minimum parasite population size through over-exploitation of the host. Phenotypic polymorphisms with respect to immunity in the host species are common and expected in ESS host strategies: the benefits of immunication depend on the frequency of the immune hosts in the population. In particular, the steady-state proportions of immune hosts depend, in addition to all the parameters of the parasite dynamics only on the cost of immunity and on the virulence of parasites in susceptible hosts. The implicit ecological dynamics of the host-parasite interaction affect the proportion of immune host individuals in the population. Furthermore, when changes in certain population parameters cause the dynamics of the host-parasite interaction to move from stability to cyclicity and then to chaos, the proportion of immune hosts tends to decrease; however, we also detected counter-examples to this result. As a whole, incorporating immunological and genetic aspects, as well as life-history trade-offs, into host-macroparasite dynamics produces a rich extension to the patterns observed in the models of ecological interactions and epidemics, and deserves more attention than is currently the case.
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  • 9
    ISSN: 1572-9338
    Keywords: fisheries management ; game theory ; Norwegian spring‐spawning herring ; straddling and highly migratory stocks ; United Nations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract The intergovernmental United Nations Conference on Highly Migratory and Straddling Stocks, initiated in 1993 and finished in 1995, addressed the conservation and management of fishery resources located both within the coastal state 200 mile Exclusive Economic Zone (EEZ) and the adjacent high seas. These types of marine resources continue to be a source for international conflicts and debates. The original United Nations Law of the Sea of 1982 failed to address transboundary fisheries in a proper way. In particular, the agreement did not recognize the emergence of the complicated “straddling stock” issue. In the new United Nations Law of the Sea agreement of 1995, a consensus was reached that the management of the straddling and highly migratory fish stocks should be carried out through regional fisheries management organizations. We present a review of the straddling stock issues in the international agreement emerging from the negotiations within the United Nations. The review is contrasted with and clarified by game theoretic analyses. We also discuss one international fishery exemplifying the case, the Norwegian spring‐spawning herring. The main conclusion is that the local problems, faced during the stage of setting up regional fisheries organizations for the management of straddling and highly migratory fish stocks, are expected to be much more complicated and difficult to solve as compared to the cases of “shared fish stocks”. In the current paper, we present two reasons for this increased complexity. The first is the larger number of players as compared to the case of “shared fish stocks” and the second is the possibility of new members entering the regional fisheries organizations.
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  • 10
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    Helsinki: The Research Institute of the Finnish Economy (ETLA)
    Publication Date: 2018-12-01
    Keywords: ddc:330
    Repository Name: EconStor: OA server of the German National Library of Economics - Leibniz Information Centre for Economics
    Language: English
    Type: doc-type:workingPaper
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