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THE GOODNESS–OF–FIT TEST FOR DETECTING NATURAL SELECTION IN RANDOM MATING POPULATIONS
Author(s) -
Lewontin R. C.,
Cockerham C. Clark
Publication year - 1959
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1959.tb03043.x
Subject(s) - goodness of fit , biology , mating , selection (genetic algorithm) , natural selection , statistics , test (biology) , genealogy , demography , evolutionary biology , genetics , ecology , mathematics , computer science , artificial intelligence , sociology , history
Suppose, now, that a sample is taken from such a population and that the three genotypes are distinguishable. There will be three observed frequencies, nl, ns and ns, but only two independent observations since there is the linear restriction The issue has recently been raised in the pages of this journal and elsewhere as to the possibility of judging the relative fitnesses of genotypes from the frequencies of these genotypes in populations. Wallace (1958) has provided several numerical examples where severe selection pressures do not result in appreciable deviations of the observed zygotic frequencies from expectation under Hardy-Weinberg equilibrium. Novitski and Dempster (1958) attempted by means of a digital computer to estimate the adaptive values of genotypes in Drosophila melanogaster using only the observed genotypic frequencies. They found that the computer produced an infinite variety of best fit values for the fitnesses. We are indebted to them for first calling our attention to this problem and to Dr. Bruce Wallace for urging us to publish our findings. If the frequency of an allele B in a population is p and that of its alternate allele b ia q = 1 p, then following random mating but before any natural selection has occurred the zygotes will be in the relative frequencies