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Journal ArticleDOI

Is the gene the unit of selection

01 Aug 1970-Genetics (Genetics)-Vol. 65, Iss: 4, pp 707-734
About: This article is published in Genetics.The article was published on 1970-08-01. It has received 293 citations till now. The article focuses on the topics: Unit of selection & Gene.
Citations
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Journal ArticleDOI
01 Mar 1975-Nature
TL;DR: The Economy of Nature and the Evolution of Sex*.
Abstract: The Economy of Nature and the Evolution of Sex *. By Michael T. Ghiselin. Pp. xii + 346. (University of California: Berkeley, Los Angeles and London, December 1974.) $12.05; £7.10.

2,034 citations

Journal ArticleDOI
TL;DR: The linkage disequilibrium process, the nonrandom association of alleles at different loci, and the population genetic processes that affect it are reviewed.
Abstract: Linkage disequilibrium — the nonrandom association of alleles at different loci — is a sensitive indicator of the population genetic forces that structure a genome. Because of the explosive growth of methods for assessing genetic variation at a fine scale, evolutionary biologists and human geneticists are increasingly exploiting linkage disequilibrium in order to understand past evolutionary and demographic events, to map genes that are associated with quantitative characters and inherited diseases, and to understand the joint evolution of linked sets of genes. This article introduces linkage disequilibrium, reviews the population genetic processes that affect it and describes some of its uses. At present, linkage disequilibrium is used much more extensively in the study of humans than in non-humans, but that is changing as technological advances make extensive genomic studies feasible in other species.

1,194 citations

Journal ArticleDOI
TL;DR: In this paper, an example of how simulated evolution can be applied to a practical optimization problem, and more specifically, how the addition of co-evolving parasites can improve the procedure by preventing the system from sticking at local maxima.

1,049 citations

Journal ArticleDOI
Eviatar Nevo1
TL;DR: Analysis of allozymic variation in natural populations of plants, animals, and humans based on studies published prior to early 1976 and involving 243 species, suggests that the amounts of genetic polymorphism and heterozygosity vary nonrandomly between loci, populations, species, habitats, and life zones, and are correlated with ecological heterogeneity.

964 citations

Journal ArticleDOI
01 Oct 1987-Genetics
TL;DR: Five different measures of gametic disequilibrium in current use and a new one based on R. C. Lewontin's D', are examined and compared, showing large variances for all the measures in samples taken from populations at equilibrium under neutrality, with the measure based on D' having the lowest variance.
Abstract: Five different measures of gametic disequilibrium in current use and a new one based on R. C. Lewontin's D', are examined and compared. All of them, except the measure based on Lewontin's D', are highly dependent upon allelic frequencies, including four measures that are normalized in some manner. In addition, the measures suggested by A. H. D. Brown, M. F. Feldman and E. Nevo, and T. Ohta can have negative values when there is maximum disequilibrium and have rates of decay in infinite populations that are a function of the initial gametic array. The variances were large for all the measures in samples taken from populations at equilibrium under neutrality, with the measure based on D' having the lowest variance. In these samples, three of the measures were highly correlated, D2, D (equal to the correlation coefficient when there are two alleles at each locus) and the measure X(2) of Brown et al. Using frequency-dependent measures may result in mistaken conclusions, a fact illustrated by discussion of studies inferring recombinational hot spots and the effects of population bottlenecks from disequilibrium values.

901 citations

References
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Book
01 Jan 1963

7,870 citations

Journal ArticleDOI
26 Mar 1964-Copeia

5,857 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the variance of a human measurement from its mean follows the Normal Law of Errors, and that the variability may be measured by the standard deviation corresponding to the square root of the mean square error.
Abstract: Several attempts have already been made to interpret the well-established results of biometry in accordance with the Mendelian scheme of inheritance. It is here attempted to ascertain the biometrical properties of a population of a more general type than has hitherto been examined, inheritance in which follows this scheme. It is hoped that in this way it will be possible to make a more exact analysis of the causes of human variability. The great body of available statistics show us that the deviations of a human measurement from its mean follow very closely the Normal Law of Errors, and, therefore, that the variability may be uniformly measured by the standard deviation corresponding to the square root of the mean square error. When there are two independent causes of variability capable of producing in an otherwise uniform population distributions with standard deviations σ1 and σ2, it is found that the distribution, when both causes act together, has a standard deviation . It is therefore desirable in analysing the causes of variability to deal with the square of the standard deviation as the measure of variability. We shall term this quantity the Variance of the normal population to which it refers, and we may now ascribe to the constituent causes fractions or percentages of the total variance which they together produce. It is desirable on the one hand that the elementary ideas at the basis of the calculus of correlations should be clearly understood, and easily expressed in ordinary language, and on the other that loose phrases about the “percentage of causation,” which obscure the essential distinction between the individual and the population, should be carefully avoided.

3,800 citations

Journal ArticleDOI
TL;DR: A theoretical investigation has been made of the influence of population size and recombination fraction on linkage disequilibrium between a pair of loci and it was found that the mean value ofr2 was determined almost entirely byN c and time, measured proportional toN.
Abstract: A theoretical investigation has been made of the influence of population size (N) and recombination fraction (c) on linkage disequilibrium (D) between a pair of loci. Two situations were studied: (i) where both loci had no effect on fitness and (ii) where they showed heterozygote superiority, but no epistacy. If the populations are initially in linkage equilibrium, then the mean value ofD remains zero with inbreeding, but the mean ofD 2 increases to a maximum value and decreases until fixation is reached at both loci. The tighter the linkage and the greater the selection, then the later is the maximum in the mean ofD 2 reached, and the larger its value. The correlation of gene frequencies,r, in the population of gametes within segregating lines was also studied. It was found that, for a range of selection intensities and initial gene frequencies, the mean value ofr 2 was determined almost entirely byN c and time, measured proportional toN. The implication of these results on observations of linkage disequilibrium in natural populations is discussed.

1,914 citations

Journal ArticleDOI
10 Jan 1964-Genetics
TL;DR: The results of these investigations were sufficient to show that even for relatively simple cases (two loci, simple symmetrical selective values) linkage might have profound effects on the course of natural selection and, pari passu, natural selection may have major effect on the distribution of coupling and repulsion linkage in a population.
Abstract: HILE the theory of the genetic changes in a population due to selection is quite well understood for single loci, our theory for multiple-gene characters is in a rudimentary stage. Most of the formulations for multiple-gene characters are simply extensions of single-locus models, extensions which ignore the problem of linkage. There are, however, a few papers in which the role of linkage has been investigated for more or less special cases of selection (KIMURA 1956; LEWONTIN and KOJIMA 1960; BODMER and PARSONS 1962). The results of these investigations were sufficient to show that even for relatively simple cases (two loci, simple symmetrical selective values) linkage might have profound effects on the course of natural selection and, pari passu, natural selection may have major effects on the distribution of coupling and repulsion linkage in a population. The results of the investigations of LEWONTIN and KOJIMA (1960) of the twolocus model can be summarized as follows: (1) If the fitnesses are additive between loci (no epistasis), linkage does not effect the final equilibrium state of the population. (2) If linkage is tighter than the value demanded by the magnitude of the epistasis (the greater the epistasis the greater the value) there may be permanent linkage disequilibrium and alteration of equilibrium gene frequencies. (3) The rate of genetic change with time is affected by the tightness of the linkage. (4) In some cases stable gene frequency equilibria are possible only if linkage is tight enough. Although these conclusions were based only on two-locus model and for selective values of a fairly restricted sort, they point clearly to the importance of taking linkage into account in understanding the changes of gene frequencies in populations. In fact, some experimental results (an example of which will be given below) can be understood only if the interaction of selection and linkage is taken into account, The equations describing the interaction between selection and linkage (see below) do not usually have general literal solutions. It is for this reason that the authors cited above have restricted themselves to relatively simple cases. In view of the interesting findings of those previous papers, however, it is worthwhile to explore the subject more intensively. To do so requires the numerical rather than general literal solutions to the equations, but such numerical solutions apply, obviously, only to the particular parameter values chosen. To make such a nu-

1,913 citations