Showing papers on "Selection (genetic algorithm) published in 1987"
Book•
01 Jan 1987TL;DR: Somatic Selection helps clarify the role of language in the selection process and provides a scaffolding for future generations of researchers to study language-based learning and cognition.
Abstract: Somatic Selection * A Summary and Historical Introduction * Structure, Function, and Perception * Neuronal Group Selection Epigenetic Mechanisms * Developmental Bases of Diversity: The Primary Repertoire * Cellular Dynamics of Neural Maps * Evolution and Function of Distributed Systems * Synapses as Populations: The Bases of the Secondary Repertoire Global Functions * Action and Perception * Categorization and Memory * Selective Networks and Recognition Automata * Selection, Learning, and Behavior Conclusion * Summary, Predictions, and Implications
1,937 citations
TL;DR: It is found that the heritability of morphological traits is significantly lower for ectotherms than it is for endotherms which may in part be a result of the strong correlation between life history and body size for many ectotherm.
Abstract: The hypothesis that traits closely associated with fitness will generally possess lower heritabilities than traits more loosely connected with fitness is tested using 1120 narrow sense heritability estimates for wild, outbred animal populations, collected from the published record. Our results indicate that life history traits generally possess lower heritabilities than morphological traits, and that the means, medians, and cumulative frequency distributions of behavioural and physiological traits are intermediate between life history and morphological traits. These findings are consistent with popular interpretations of Fisher's (1930, 1958) Fundamental Theorem of Natural Selection, and Falconer (1960, 1981), but also indicate that high heritabilities are maintained within natural populations even for traits believed to be under strong selection. It is also found that the heritability of morphological traits is significantly lower for ectotherms than it is for endotherms which may in part be a result of the strong correlation between life history and body size for many ectotherms.
1,483 citations
TL;DR: The data from 27 studies show a common theme: multiclonal populations of intermediate diversity and evenness tend to be the rule, most clones are restricted to one or a few populations, and widespread clones are exceptional.
Abstract: We compile and analyze data on the population genetic structure of broad-sense clonal plant populations where sexual recruitment is rare or absent. The data from 27 studies show a common theme: multiclonal populations of intermediate diversity and evenness tend to be the rule, most clones are restricted to one or a few populations, and widespread clones are exceptional. While a few studies have demonstrated that ecological differences among sympatric clones do occur, more experimental and theoretical studies are necessary to determine the role of selection and other evolutionary forces in maintaining clonal polymorphism.
1,003 citations
TL;DR: While fitness regression permits direct assessment of selection in a form suitable for predicting selection response, it is suggested that the aim of inferring causal relationships about the effects of phenotypic characters on fitness is greatly facilitated by manipulative experiments.
Abstract: Recent theoretical work in quantitative genetics has fueled interest in measuring natural selection in the wild. We discuss statistical and biological issues that may arise in applications of Lande and Arnold's (1983) multiple-regression approach to measuring selection. We review assumptions involved in estimation and hypothesis testing in regression problems, and we note difficulties that frequently arise as a result of violation of these assumptions. In particular, multicollinearity (extreme intercorrelation of characters) and extrinsic, unmeasured factors affecting fitness may seriously complicate inference regarding selection. Further, violation of the assumption that residuals are normally distributed vitiates tests of significance. For this situation, we suggest applications of recently developed jackknife tests of significance. While fitness regression permits direct assessment of selection in a form suitable for predicting selection response, we suggest that the aim of inferring causal relationships about the effects of phenotypic characters on fitness is greatly facilitated by manipulative experiments. Finally, we discuss alternative definitions of stabilizing and disruptive selection.
892 citations
TL;DR: The results suggest that population managers should be concerned with the variation-depleting effects of genetic drift, perhaps almost to the exclusion of consideration of selection and mutation.
Abstract: A computer simulation program was used to examine interacting effects of genetic drift, mutation, immigration from outside populations, directional and balancing selection, and population subdivision on the loss of genetic variability from small, managed populations. Stochastic ewnts were simulated with a pseudo-random number generator, and the genetic variation (expected heterozygosity) witbin and between populations was monitored in 25 populations for 100 generations.
Genetic drift was the overriding factor controling the loss of genetic variation Mutation has no noticeable effect on populations of the size typically managed in zoos and nature preserves Immigration from a large source population can strikingly slow, halt, or even reverse the loss of genetic variation, even with only one or a few migrants per generation. Unless selection is stronger than commonly observed in natural populations, it is inefficient in countering drift when population sizes are on the order of 100 or fewer. Subdivided populations rapidly lose variability from within each sub-population but retain variation across the subpopulations better than does a panmictic population.
These results suggest that population managers should be concerned with the variation-depleting effects of genetic drift, perhaps almost to the exclusion of consideration of selection and mutation Drift can be countered by the introduction of vety occasional immigrants or, less effectively, by division of the managed population into smaller breeding groups that interchange enough migrants to prevent unacceptably deleterious inbreeding within each subpopulation
673 citations
Book•
01 Jan 1987
TL;DR: In this article, the authors present an advanced treatment of the technical issues involved in developing and implementing selection programs within organizations and present the most thorough and up-to-date coverage of HR selection on the market.
Abstract: This leading text offers an advanced treatment of the technical issues involved in developing and implementing selection programs within organizations. The new edition offers the most thorough and up-to-date coverage of HR selection on the market and is appropriate for upper-level undergraduate and graduate courses in management and industrial/organizational psychology departments, as well as for corporate HR departments.
661 citations
TL;DR: The selection of the proper clustering procedure to use in the development of an objective synoptic methodology may have far-reaching implications on the composition of the final homogeneous groupings as mentioned in this paper.
Abstract: The selection of the proper clustering procedure to use in the development of an objective synoptic methodology may have far-reaching implications on the composition of the final “homogeneous” groupings The goal of this study is to evaluate three common clustering techniques (Ward's, average linkage, and centroid) to determine which yields the most meaningful synoptic classification The three clustering procedures were applied to a temporal synoptic index which classified days in Mobile, Alabama into meteorologically homogeneous units The final meteorological groupings differed widely among the three pressures Ward's tended to produce groups with relatively similar numbers of days Thus, many extreme weather days were grouped with less extreme days, and the final meteorological units did not duplicate reality with great precision The centroid procedure produced one very large group and many single-day groups, yielding unsatisfactory results The average linkage procedure, which minimizes wit
510 citations
TL;DR: The authors modify the basic self-selection model for the effects of education, training, unions, and other activities on wages, by including "heterogeneity of rewards" to the activity.
Abstract: The authors modify the basic self-sele ction model for the effects ofeducation, training, unions, and other activities on wages, by including "heterogeneity of rewards" to the activity-i.e., diffe rences across individuals in the rate of return to the activity. The authors sho w that such heterogeneity creates a new form of selectionbias. They provide tes ts for its presence and draw out its implications for the wage and welfare gains to the activity. An empirical application provides strong support for such hete rogeneityin one particular training program. Copyright 1987 by MIT Press.
388 citations
TL;DR: In this paper, the relative performance of sample selection and two-part models for data with a cluster at zero was examined in terms of mean squared error, mean bias and pointwise bias.
381 citations
Book•
01 Feb 1987
TL;DR: A survey of population phenomena can be found in this article, where the authors present an overview of population genetics, including the Hardy-Weinberg Law, genetic drift, and the Neutrality Controversy.
Abstract: 0 Introductory Survey of Population Phenomena I THE BASICS OF POPULATION GENETICS 1 An Overview of Population Genetics 2 The Hardy-Weinberg Law 3 Natural Selection and Mutation at One Locus with Two Alleles 4 The Fundamental Theorem of Natural Selection 5 Genetic Drift 6 The Neutrality Controversy II COMPLEX GENETIC SYSTEMS 7 Natural Selection with Multiple Alleles at One Locus 8 Population Genetics with Multiple Loci 9 Natural Selection and Quantitative Inheritance 10 Nonrandom Mating III SPECIAL TOPICS IN EVOLUTION 11 Evolution of the Genetic System 12 Evolution in Spatially Varying Environments 13 Natural Selection in Temporally Varying Environments 14 The Evolution of Altruism: Kin Selection and Group Selection IV EVOLUTIONARY ECOLOGY OF SINGLE POPULATIONS 15 An Overview of Evolutionary Ecology 16 Exponential and Logistic Population Growth 17 Density-Dependent Natural Selection 18 Population Growth with Age Structure 19 Age-Specific Selection and Life History Strategies 20 Stochastic Environments: Extinction, Resource Tracking, and Patchiness V EVOLUTIONARY ECOLOGY OF INTERACTING POPULATIONS 21 Competition 22 Predation 23 Coevolution in Ecological Systems 24 Niche Theory and Island Biogeography VI APPENDICES A1 The Mean and Variance A2 How to Write a Computer Program in BASIC A3 Matrix Algebra and Stability Theory Index Bibliography
374 citations
TL;DR: In this paper, a framework is proposed to account for strategy selection in question answering, and six experiments support the assumptions of the proposed framework: the first three experiments show that strategy selection is under the strategic control of the subjects, while Experiment 6 suggests variables that influence the evaluation of the question.
TL;DR: A more-specific rapid-gain version of the continuous model suggests that the amount of parental care is influenced primarily by the level of care at which offspring success increases rapidly.
Abstract: A continuous, analytical model of the selection of size-number compromises is presented and applied to the selection of the amount of parental investment in each offspring until its independence. At the evolutionarily stable strategy, the proportional gain in the success of an offspring from an increment in the investment in the offspring equals the proportional loss in offspring numbers. A parallel marginal-value theorem applies to discontinuous variation in the amount of care. When selection acts directly on offspring size rather than on number, the evolutionarily stable level of care depends only on the fitness curve relating the fitness of single offspring to the amount of resources received. General conditions for brood reduction are described. A more-specific rapid-gain version of the continuous model suggests that the amount of parental care is influenced primarily by the level of care at which offspring success increases rapidly. The model can explain various observed differences in amounts of par...
01 Mar 1987
TL;DR: In this article, a review of methods of summarizing the relationships within a set of objects by a set hierarchically-nested classes of similar objects, representable by a rooted tree diagram, is presented.
Abstract: SUMMARY A review is presented of methods of summarizing the relationships within a set of objects by a set of hierarchically-nested classes of similar objects, representable by a rooted tree diagram. Material covered includes algorithms for obtaining tree diagrams, comments on the selection of appropriate methods of analysis and the validation of classifications, distributions of different types of tree, and consensus trees.
TL;DR: This work presents a variety of Approaches to Habitat Selection in Birds and concludes with a call for further investigation into the role of enrichment in the selection process.
Abstract: Introduction. Habitat Selection in Specific Bird Taxa. Habitat Selection in Specific Habitat Types. A Variety of Approaches to Habitat Selection in Birds.
TL;DR: In this article, the authors present a method for analyzing phenotypic selection in hierarchically structured populations, called contextual analysis, which is a generalization to structured populations of the "selection gradient" method developed by Lande and Arnold (1983).
Abstract: Individual fitness depends on the particular ecological, genetic, and social contexts in which organisms are found. Variation in individual context among subunits of a population thus raises interesting questions about selection in nature but also complicates its study. We present a method for analyzing phenotypic selection in hierarchically structured populations. Applying this method, called contextual analysis, to the study of selection allows explicit answers to two frequently controversial questions. First, must group membership be taken into account in explaining differences in individual fitness? Second, what particular group properties are associated with observable group-level effects? Contextual analysis is a generalization to structured populations of the "selection gradient" method developed by Lande and Arnold (1983). The aim of the gradient method is to distinguish characters that have a causal relationship with fitness from others that do not but are still subject to selection as a result o...
TL;DR: A major resurgence of work on sexual selection has occurred over the last two decades as discussed by the authors, and many current discussions of sexual selection by female choice are centered around a lively debate, which can be traced back to the early 20th century following Darwin's work.
Abstract: Darwin's theory of organic evolution identifies two forms of selection that occur in the wild: natural selection, involving the adaptation of a population to its biotic and abiotic environment, and sexual selection, resulting from competition for reproductive access to the other sex (27, 28). Sexual selection arises through a direct struggle between members of the same sex (typically males) and through the mating preferences of one sex for the other (typically females for males). Darwin developed the concept of sexual selection to account for many spectacular phenomena, such as the plumage of male peacocks, that seem incompatible with natural selection. He wrote that "sexual selection has played an important part in the history of the organic world," and devoted most of his largest book to the subject. Despite this early impetus, sexual selection in general, and female choice in particular, were largely neglected by biologists for almost a century following Darwin's work (48, 67, 97, 111). The reasons for this have yet to be fully understood but must in part have been caused by the skepticism of Wallace (133) and Huxley (63), who discounted Darwin's ideas on the subject. Important contributions during this hiatus were made by Poulton (105) and Belt (8), who added their comparative observations to Darwin's, and by Fisher (45), whose verbal theory has been a source of inspiration and controversy ever since. Over the last two decades a major resurgence of work on sexual selection has occurred. Evolutionists have reexamined Darwin's ideas and are now much more impressed by their cogency. Many current discussions of sexual selection by female choice are centered around a lively debate. Given the vacuum of thought on the subject for the first part of the
TL;DR: The Gaussian-based prediction that evolution of the phenotypic mean does not change the genetic variance is shown to be a consequence of the assumption that the allelic distributions are never skewed and the parameter values consistent with this assumption are presented.
Abstract: Summary The maintenance of polygenic variability by a balance between mutation and stabilizing selection has been analysed using two approximations: the 'Gaussian' and the 'house of cards'. These lead to qualitatively different relationships between the equilibrium genetic variance and the parameters describing selection and mutation. Here we generalize these approximations to describe the dynamics of genetic means and variances under arbitrary patterns of selection and mutation. We incorporate genetic drift into the same mathematical framework. The effects of frequency-independent selection and genetic drift can be determined from the gradient of log mean fitness and a covariance matrix that depends on genotype frequencies. These equations describe an 'adaptive landscape', with a natural metric of genetic distance set by the covariance matrix. From this representation we can change coordinates to derive equations describing the dynamics of an additive polygenic character in terms of the moments (means, variances, ...) of allelic effects at individual loci. Only under certain simplifying conditions, such as those derived from the Gaussian and house-of-cards approximations, do these general recursions lead to tractable equations for the first few phenotypic moments. The alternative approximations differ in the constraints they impose on the distributions of allelic effects at individual loci. The Gaussian-based prediction that evolution of the phenotypic mean does not change the genetic variance is shown to be a consequence of the assumption that the allelic distributions are never skewed. We present both analytical and numerical results delimiting the parameter values consistent with our approximations.
TL;DR: The prediction that variation in seed Germination time should be purely environmental is supported by the demonstration of low heritability of germination time in the two available studies, and some models may compete to produce a given selected level of phenotypic variance.
Abstract: A cornerstone of evolutionary theory is that the phenotypic variance of a population may be partitioned into genetic and environmental (nonheritable) components. The traditional motivation for this distinction is that the rate of evolution under natural selection depends on the (relative) magnitudes of certain genetic components of variance. The components of variation are also interesting from another perspective, as illustrated here. Phenotypic variation may be selectively maintained in a population according to its components: selection may favor the maintenance of only the environmental components, only the genetic components, or be indifferent to the composition of the variance. Even when selection is shown to favor phenotypic variation regardless of its components, the possibility exists that environmental variance will evolve to displace the genetic components or vice versa. Environmental and genetic factors may thus compete to produce a given selected level of phenotypic variance. A test of some of these models is provided from the example of seed dormancy: the prediction that variation in seed germination time should be purely environmental is supported by the demonstration of low heritability of germination time in the two available studies.
TL;DR: Two distinct heroin-using populations have been discovered who are distinguished by their life cycle stage and it is suggested that the snowball sampling method may have utility in studying the temporal and social contexts of other populations of clinical interest.
Abstract: Snowball sampling is a method that has been used in the social sciences to study sensitive topics, rare traits, personal networks, and social relationships. The method involves the selection of samples utilizing “insider” knowledge and referral chains among subjects who possess common traits that ar
TL;DR: In this article, the authors present a method that retail managers can use to assess competitive effectiveness and identify opportunities for improvement as consumers move through the choice process, and the basis of t...
Abstract: The authors present a method that retail managers can use to assess competitive effectiveness and identify opportunities for improvement as consumers move through the choice process. The basis of t...
TL;DR: Regression and fitness tests were used to explore the pattern of density-dependent habitat use in two temperate-zone rodents and found habitat selection models appeared to be much less capable of predicting variation in population density.
Abstract: A simple regression analysis can be used to assess the response of animal density to differences in habitat quality. The same test can evaluate general predictions of habitat selection theory as well as search for differences in the shapes of habitat suitability- density functions, something previous tests have been unable to do. Combined with de- mographic or other estimates of fitness, regression tests can provide new insights into the evolution of habitat selection. Regression and fitness tests were used to explore the pattern of density-dependent habitat use in two temperate-zone rodents. The intensity of population regulation appeared to be inversely related to a habitat's carrying capacity. Variation in density-dependent habitat choice suggests new and unexpected dispersal strategies that vary with habitat heterogeneity. The predictions of the theory are complicated when habitat quality varies independently of population density. Sweepstake fitness rewards may be reaped by animals that would previously have been assumed to have made a suboptimal habitat choice. At the level of microhabitat, habitat selection models appeared to be much less capable of predicting variation in population density. Such a relation could be due to complex and inverse relationships between microhabitat quality and carrying capacity, or it could simply reflect scaling patterns in habitat selection.
TL;DR: A number of traditional and popular functional forms are catalogued with respect to intrinsic properties to provide an improved and uniform basis for form selection.
Abstract: Functional form selection is a sometimes neglected aspect of applied research in production analysis. To provide an improved and uniform basis for form selection, a number of traditional and popular functional forms are catalogued with respect to intrinsic properties. Guidelines for the conduct of form selection are also discussed.
01 Jan 1987
TL;DR: Mazer et al. as mentioned in this paper measured the additive genetic variance of seed weight, life history characters, and several fitness components in a wild radish population and evaluated the genetic correlation between seed weight and individual fitness.
Abstract: A main effect of natural selection is to reduce additive genetic variance by culling genotypes of low fitness, thereby increasing mean population fitness. If natural selection has been a strong force in wild species, one would expect to find relatively low levels of additive genetic variance of traits that are strongly correlated with fitness and are undergoing directional selection (Fisher 1930; Endler 1986). Although the absence of detectable additive genetic variance of a character does not necessarily mean that it has experienced strong selection (it could simply mean that phenotype is determined solely by the environment), the magnitude of additive genetic variance of a trait does reflect the rate at which selection can result in its genetic and phenotypic evolution. To establish the potential for natural selection to effect evolutionary change in a phenotypically variable trait correlated with fitness, one must measure the additive genetic component of the phenotypic variation; estimate the additive genetic variance of total fitness, not just its components; and estimate the genetic correlation between the trait and total fitness. The presence of both additive genetic variance of a trait and a genetic correlation between phenotype and total fitness presents a puzzle to evolutionists; surprisingly, it is rare that both elements are measured in natural populations. In order to determine the evolutionary significance of seed-weight variation in an experimental population of wild radish (Raphanus raphanistrum, Brassicaceae), I estimate here the additive genetic variance of seed weight, life history characters, and several fitness components in this population. Although estimates of the genetic correlations exhibited by this population are provided elsewhere (Mazer 1986), this paper evaluates the genetic correlation between seed weight and individual fitness. Natural populations of wild radish harbor 20-fold phenotypic variation in seed weight (Stanton 1984a; Mazer et al. 1986). Two observations suggest that natural selection should operate to diminish seed-weight variation in natural populations
TL;DR: Whatever promotes the behavior of habitat selection also promotes the evolution of extreme morphologies and physiologies.
Abstract: Question: What are the conditions required for natural selection to produce phenotypes specially adapted to the various habitats available in nature?
TL;DR: It is shown that the coevolutionary model of Rummel and Roughgarden (1985) does contain frequency‐dependent selection, and thus, their application of Roughg Garden's criterion for evolutionary stability to a model for which it is not applicable leads to the erroneous conclusion that the ecological and evolutionary processes are in conflict.
Abstract: Coevolution is modeled as a continuous game where the fitness-maximizing strategy of an individual is assumed to be a function of the strategy of other individuals who are also under selection to maximize fitness. An evolutionary stable strategy (ESS) is sought such that no rare alternative strategies can invade the community. The approach can be used to model coevolution because the ESS may be composed of a coalition of more than one strategy. This work, by modeling frequency-dependent selection, extends the approach of Roughgarden (1976) which only considered density-dependent selection. In particular, we show that the coevolutionary model of Rummel and Roughgarden (1985) does contain frequency-dependent selection, and thus, their application of Roughgarden's criterion for evolutionary stability to a model for which it is not applicable leads to the erroneous conclusion that the ecological and evolutionary processes are in conflict. The utility of the game theoretic approach is illustrated by two examples. The first considers an ESS composed of a single strategy, the second an ESS composed of a coalition of two strategies. Evolution occurs on a frequency-dependent adaptive landscape. For this reason, the approach is appropriate for modeling competitive speciation (Rosenzweig, 1978). Also, the game theoretic approach is designed to combine the interplay between the background environment (including the biotic components) and the evolutionary potential of the populations or organisms. The actual application of this theory will require knowledge of both.