Showing papers on "Selection (genetic algorithm) published in 1993"

Linear Model Selection by Cross-validation

Abstract: We consider the problem of selecting a model having the best predictive ability among a class of linear models. The popular leave-one-out cross-validation method, which is asymptotically equivalent to many other model selection methods such as the Akaike information criterion (AIC), the C p , and the bootstrap, is asymptotically inconsistent in the sense that the probability of selecting the model with the best predictive ability does not converge to 1 as the total number of observations n → ∞. We show that the inconsistency of the leave-one-out cross-validation can be rectified by using a leave-n v -out cross-validation with n v , the number of observations reserved for validation, satisfying n v /n → 1 as n → ∞. This is a somewhat shocking discovery, because nv/n → 1 is totally opposite to the popular leave-one-out recipe in cross-validation. Motivations, justifications, and discussions of some practical aspects of the use of the leave-n v -out cross-validation method are provided, and results ...

Classification of Hypotheses on the Advantage of Amphimixis

Abstract: A classification of hypotheses on the advantage of amphimixis over apomixis is presented. According to "Immediate Benefit" hypotheses, amphimixis is advantageous regardless of reciprocal gene exchange, because either it directly increases fitness of the progeny, reduces the deleterious mutation rate, or makes selection more efficient. In contrast, "Variation and Selection" hypotheses attribute the advantage of amphimixis to the reciprocal gene exchange that alters genetic variability and response to selection among the progeny. Most such hypotheses assume that amphimixis increases variability and efficiency of selection, but some claim that amphimixis decreases response to selection. Variation and Selection hypotheses require that some factor, either random drift or epistatic selection, makes distributions of different alleles nonindependent, while another factor, either changes of the genotype fitnesses or deleterious mutations, makes overrepresented genotypes non-optimal. Numerous Variation and Selection hypotheses, dealing with either unstructured or spatially structured populations, are reviewed. Two of them seem most plausible: better responsiveness of the amphimictic population to widely fluctuating selection, and lower mutation load in the amphimictic population under synergistic selection against deleterious mutations. In both cases the large advantage of amphimixis requires rather stringent conditions, which could be falsified by careful experiment. Further progress in understanding the evolution of amphimixis will depend mostly on such experimental work.

Reservoir‐System Simulation and Optimization Models

Abstract: A broad array of computer models has been developed for evaluating reservoir operations. Selecting a modeling and analysis approach for a particular application depends upon the characteristics of ...

Frequency-dependent natural selection in the handedness of scale-eating cichlid fish.

Abstract: Frequency-dependent natural selection has been cited as a mechanism for maintaining polymorphisms in biological populations, although the process has not been documented conclusively in field study Here, it is demonstrated that the direction of mouth-opening (either left-handed or right-handed) in scale-eating cichlid fish of Lake Tanganyika is determined on the basis of simple genetics and that the abundance of individuals with left- or right-handedness depends on frequency-dependent natural selection Attacking from behind, right-handed individuals snatched scales from the prey's left flank and left-handed ones from the right flank Within a given population, the frequency of the two phenotypes oscillated around unity This phenomenon was effected through frequency-dependent selection exerted by the prey's alertness Thus, individuals of the rare phenotype had more success as predators than those of the more common phenotype

On the edge

Abstract: The Origins of Order: Self-Organization and Selection in Evolution. By Stuart A. Kauffman. Oxford University Press: 1993. Pp. 709. $75, £55 (hbk); $29.95, £17.95 (pbk).

Phenotypic plasticity and selection in Drosophila life-history evolution. I. Nutrition and the cost of reproduction

Abstract: Earlier experiments have shown that the evolution of postponed senescent populations can be achieved by selection on either demographic or stress resistance characters. Both types of selection have produced results in which survival characters (stress resistance and longevity) have apparently traded-off against early-life fecundity. Here we present the results of a series of experiments in which an environmental variable — the level of live yeast inoculate applied to the substrate — produces a qualitatively similar phenotypic response: longevity and starvation resistance are enhanced by lower yeast levels, at the expense of fecundity. For the starvation resistance versus fecundity experiments we show a negative and linear relationship between the norms of reaction for each character across a gradient of yeast levels. This phenotypic trade-off is stable across the 20 populations and 4 selection treatments reported on here, and its general agreement with earlier selection results suggests that the evolutionary response and the phenotypically plastic response may share a common physiological basis. However, an important discrepancy in the lifetime fecundity data between the selection response and the dietary manipulations preclude strict analogy. The results broadly conform to a simple “Y-model” of allocation, in which a limited resource is divided between survival and reproduction; here the characters are starvation resistance and longevity versus fecundity.

The evolution of virulence

Abstract: Why is there variation in the virulence of infectious diseases? Virulence can have substantial effects on the genetic contribution of both host and pathogen to future generations. Understanding it therefore requires explanation not only in terms of cellular and molecular mechanisms1, 2, but also in evolutionary terms: what is the nature of the selection acting on genes responsible for virulence?

Adaptive Phenotypic Plasticity: Target or By-Product of Selection in a Variable Environment?

Abstract: Predictable changes in the values of ecologically important phenotypic characters that are induced by environmental cues (phenotypic plasticity) can provide a selective advantage in a variable environment. Classic examples of phenotypic plasticity include morphological differences between aerial and aquatic leaves in plants (Bradshaw 1965) and induction of antipredatory morphologies in invertebrates (Gilbert 1966; Harvell 1984, 1990; Dodson 1989). Basic descriptions of the phenomenon of phenotypic plasticity are not controversial, and there is general agreement that adaptive plasticity can evolve under natural selection (Schlichting 1986; Stearns 1989). However, there is disagreement about how to best measure phenotypic plasticity (Via 1987), and it has been even more difficult to reach a consensus on the mechanisms by which adaptive phenotypic plasticity might evolve (Schlichting and Levin 1984, 1986; Via and Lande 1985, 1987; Schlichting 1986, 1989; Via 1987; Scheiner and Lyman 1989, 1991; Stearns 1989). A major area of controversy that has emerged in recent studies of the evolution of phenotypic plasticity centers around the assertion that phenotypic plasticity is a character that is independent of trait means and the attendant implication that plasticity itself is the target of selection. This viewpoint has led to the twin suggestions that phenotypic plasticity evolves independently of character means and that \"genes for plasticity\" exist that are separate from genes that affect he mean values of quantitative characters (Schlichting and Levin 1984, 1986; Schlichting 1986; Jinks and Pooni 1988; Scheiner and Lyman 1989, 1991). This view may have its origins in Bradshaw's (1965) classic review, in which he presented a very detailed compilation of the known cases of phenotypic plasticity in plants. One of Bradshaw's major points is that plasticity isnot a property of the genome as a whole but \"is a property specific to individual characters in relation to specific environmental influences\" (p. 122). His review also revealed that many closely related species differ considerably in their degree of phenotypic sensitivity to the environment. From this observation, Bradshaw (1965, p. 119) concluded that \"such differences are difficult toexplain unless it is assumed that the plasticity of a character is an independent property of that character and is under its own specific genetic control.\" Given the absence of detailed models describing the evolutionary genetics of quantitative traits at the time, Bradshaw's interpretation fthe mechanisms of species differences in plasticity was reasonable. However, current models illustrate how phenotypic plasticity can evolve due to selection toward different phe-

Broadening the Definition of Decision Making: The Role of Prechoice Screening of Options

Abstract: Decision theory and research have focused almost exclusively on choice—the selection of the best option from a choice set containing two or more options. Largely overlooked is the question of how those particular options got there in the first place—why them and not others? This article describes a theory, called image theory, about how prechoice screening of options governs the contents of the set from which a choice is made and summarizes empirical tests of the theory. The research results suggest that screening plays a far more important role in decision making than is generally appreciated and that our view of decision making must be broadened accordingly.

The science of breeding and its application to the breeder genetic algorithm (bga)

Abstract: The breeder genetic algorithm (BGA) models artificial selection as performed by human breeders. The science of breeding is based on advanced statistical methods. In this paper a connection between genetic algorithm theory and the science of breeding is made. We show how the response to selection equation and the concept of heritability can be applied to predict the behavior of the BGA. Selection, recombination, and mutation are analyzed within this framework. It is shown that recombination and mutation are complementary search operators. The theoretical results are obtained under the assumption of additive gene effects. For general fitness landscapes, regression techniques for estimating the heritability are used to analyze and control the BGA. The method of decomposing the genetic variance into an additive and a nonadditive part connects the case of additive fitness functions with the general case.

Species selection on variability.

Abstract: Most analyses of species selection require emergent, as opposed to aggregate, characters at the species level. This "emergent character" approach tends to focus on the search for adaptations at the species level. Such an approach seems to banish the most potent evolutionary property of populations--variability itself--from arguments about species selection (for variation is an aggregate character). We wish, instead, to extend the legitimate domain of species selection to aggregate characters. This extension of selection theory to the species level will concentrate, instead, on the relation between fitness and the species character, whether aggregate or emergent. Examination of the role of genetic variability in the long-term evolution of clades illustrates the cogency of broadening the definition of species selection to include aggregate characters. We reinterpret, in this light, a classic case presented in support of species selection. As originally presented, the species selection explanation of volutid neogastropod evolution was vulnerable to a counterinterpretation at the organism level. Once this case is recast within a definition of species selection that reflects the essential structure and broad applicability of hierarchical selection models, the organism-level reinterpretation of variability loses its force. We conclude that species selection on variability is a major force of macroevolution.

Moth Pheromone Genetics and Evolution

Abstract: Sex pheromone communication in moths is a well investigated case of mate-finding by chemical signals, but the evolutionary causes of the great complexity and diversity of these signals are still not generally agreed on. In the present paper, I argue that there is no reason to dismiss species recognition as a possible cause of evolutionary change in moth sex pheromones. Admittedly, selection for species recognition cannot explain all of the diversity in sex pheromones and the data supporting this contention are weak, but the alternative causes suggested, invoking mate choice between conspecifics as the mechanism of sexual selection, has so far no empirical support. Finding and analysing genes responsible for mate choice is important to corroborate any theory of sexual selection and speciation. In this respect genetic dissection of moth pheromone communication has provided important progress. Mendelian genes controlling differences in mate choice and in the production of mate recognition signals have been found. Polymorphic pheromone systems give the population biologists unique possibilities to study mate choice and selection at the genotype level in nature.

Sensor placement for on-orbit modal identification via a genetic algorithm

Abstract: The selection and reproduction schemes of the genetic algorithm are modified, and a new operator called forced mutation is introduced. These changes are shown to improve the convergence of the algorithm and to lead to near-optimal sensor locations. Two practical examples are investigated: sensor placement for an early version of the space station and an individual space station photovoltaic array

Plant breeding: principles and prospects.

Abstract: Introduction. Genetic systems and population structure. Genetic systems, recombination and variability. Population structure and variability. Sources variation. Plant genetic resources. Induced mutations. Interspecific hybridization by sexual means. Chromosome manipulation and polyploidy. Somatic hybridization. Gene cloning and identification. Gene transfer to plants: approaches and available techniques. The role of gene technology in plant breeding. Assessment of variation. Biometrical genetics in breeding. Biochemical characterization of populations. Manipulation of genetic systems. Self- and cross-incompatibility systems. Male sterility. Apomixis. Micropropagation and somatic embryogenesis. Andro- and parthenogenesis. Selection methods. Selection strategies and choice of breeding methods. Marker-assisted selection. Gametophytic and sporophytic selection. In vitro selection. Adaptation. Genotype x environment interaction and adaptation. Augmenting yield-based selection. Resistance to abiotic stresses. Resistance to parasites. Specific trait breeding. Breeding for improved symbiotic nitrogen fixation. Photosynthetic and respiratory efficiency. Breeding for efficient root systems. On the utilization of renewable plant resources. Epilogue. The need for comprehensive plant breeding strategy.

Selection of exaggerated male traits by female aesthetic senses

Abstract: DARWIN1 suggested that many apparently deleterious secondary sexual characters in males, such as bright colours, elaborate ornaments and conspicuous displays, evolved as a result of female choice Darwin never tried to explain the crucial agent of selection, that females have preferences for exaggerated male traits Rather, he took it for granted that females of many species possess a 'sense of the beautiful', akin to the aesthetic sense in humans The question of why such preferences evolve remains a controversial issue2,3 Here we report that mechanisms concerned with signal recognition possess inevitable biases in response that act as important agents of selection on signal form The existence of such biases may be sufficient to explain the evolution of exaggerated male secondary sexual traits, and elaborate signals in general

Multiobjective genetic algorithms

Abstract: Multiobjective genetic algorithms (MOGAs) are introduced as a modification of the standard genetic algorithm at the selection level. Rank-based fitness assignment and the implementation of sharing in the objective value domain are two of the important aspects of this class of algorithms. The ability of the decision maker (DM) to progressively articulate its preferences while learning about the problem under consideration is one of their most attractive features. Illustrative results of how the DM can interact with the genetic algorithm are presented. They also show the ability of the MOGA to uniformly sample regions of the trade-off surface.

Diet selection : an interdisciplinary approach to foraging behaviour

Abstract: Introduction The Importance Of State Digestive Constraints On Diet Choice The Psychology Of Diet Selection Foraging As A Self-Organizational Learning Process: Accepting Adaptability At The Expense Of Predictability Hunger-Dependent Food Selection In Suspension-Feeding Zooplankton Gourmands Of Mud: Diet Selection In Marine Deposit Feeders Diet Selection In Mammalian Herbivores: Constraints And Tactics Effects Of Ecological Interactions On Forager Diets: Competition, Predation Risk, Parasitism And Prey Behaviour

Non-numeric multi-criteria multi-person decision making

Abstract: We describe a decision making technique, ME-MCDM, for the evaluation and selection of alternatives using a non-numeric scale. Using this procedure each alternative is evaluated by an expert for satisfaction to a multi-criteria selection function. Each criterion can have a different degree of importance. The individual expert evaluations can then be aggregated to obtain an overall evaluation function. We apply this technique to the problem of proposal selection in the funding environment. In this environment the technique is augmented by some textual information which can also be used to help in the decision process.

Directional selection and the evolution of sex and recombination.

Abstract: Models of the evolutionary advantages of sex and genetic recombination due to directional selection on a quantitative trait are analysed. The models assume that the trait is controlled by many additive genes. A nor-optimal selection function is used, in which the optimum either moves steadily in one direction, follows an autocorrelated linear Markov process or a random walk, or varies cyclically. The consequences for population mean fitness of a reduction in genetic variance, due to a shift from sexual to asexual reproduction are examined. It is shown that a large reduction in mean fitness can result from such a shift in the case of a steadily moving optimum, under light conditions. The conditions are much more stringent with a cyclical or randomly varying environment, especially if the autocorrelation for a random environment is small. The conditions for spread of a rare modifier affecting the rate of genetic recombination are also examined, and the strength of selection on such a modifier determined. Again, the case of a steadily moving optimum is most favourable for the evolution of increased recombination. The selection pressure on a recombination modifier when a trait is subject to strong truncation selection is calculated, and shown to be large enough to account for observed increases in recombination associated with artificial selection. Theoretical and empirical evidence relevant to evaluating the importance of this model for the evolution of sex and recombination is discussed.