A correction for allele frequency estimates derived from isofemale lines
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Isofemale lines are commonly used inDrosophila and other genera for the purpose of assaying genetic variation. Isofemale lines can be kept in the laboratory for many generations before genetic work is carried out, and permit the confirmation of newly discovered alleles. A problem not realized by many workers is that the commonly used estimate of allele frequency from these lines is biased. This estimation bias occurs at all times after the first laboratory generation, regardless of whether single individuals or pooled samples are used in each well of an electrophoretic gel. This bias can potentially affect the estimation of population genetic parameters, and in the case of rare allele analysis it can cause gross overestimates of gene flow. This paper provides a correction for allele frequency estimates derived from isofemale lines for any time after the lines are established in the laboratory. When pooled samples are used, this estimator performs better than the standard estimator at all times after the first generation. The estimator is also insensitive to multiple inseminations. After the lines have drifted oneNe generations, multiple inseminations actually make the new estimator perform better than it does in singly inseminated females. Simulations show that estimates made using either estimator after the lines have drifted to fixation have a much greater error associated with their use than do those estimates made earlier in time using the correction. In general it is better to use corrected estimates of gene frequency soon after lines are established than to use uncorrected estimates made after the first laboratory generation.
Key wordsisofemale allele frequency estimation population structure allozyme microsatellites restriction fragment length polymorphisms Drosophila
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- Choudhary, M., and Singh, R. S. (1987). A comprehensive study of genic variation in natural populations ofDrosophila melanogaster. III. Variations in genetic structure and their causes betweenDrosophila melanogaster and its sibling speciesDrosophila simulans.Genetics 117697.Google Scholar
- Crow, J. F., and Kimura, M. (1970).An Introduction to Population Genetics Theory Harper and Row, New York.Google Scholar
- Falconer, D. S. (1981).Introduction to Quantitative Genetics Longman, New York.Google Scholar
- Griffiths, R. C., McKechnie, S. W., and McKenzie, J. A. (1982). Multiple matings and sperm displacement in a natural population ofDrosophila melanogaster.Theoret. Appl. Genet. 6289.Google Scholar
- Manly, B. F. J. (1985).The Statistics of Natural Selection Edited by M. B. Usher and M. L. Rosenzweig. Population and Community Biology. Chapman and Hall, New York.Google Scholar
- Milkman, L., and Zeitler, R. R. (1974). Cocurrent multiple paternity in natural and laboratory populations ofDrosophila melanogaster.Genetics 781191.Google Scholar
- Nevo, E., Beiles, A., and Ben-Shlomo, R. (1984). The evolutionary significance of genetic diversity: Ecological, demographic and life history correlates. In Mani, G. S. (ed.),Evolutionary Dynamics of Genetic Diversity Springer-Verlag, Berlin, pp. 13–213.Google Scholar
- Richmond, R. C. (1976). Frequency of multiple insemination in natural populations of Drosophila.Am. Nat. 117133.Google Scholar
- Singh, R. S., and Rhomberg, L. R. (1987a). A comprehensive study of genic variation in natural populations ofDrosophila melanogaster. I. Estimates of gene flow from rare alleles.Genetics 115313.Google Scholar
- Singh, R. S., and Rhomberg, L. R. (1987b). A comprehensive study of genic variation in natural populations ofDrosophila melanogaster. II. Estimates of heterozygosity and patterns of geographic differentiation.Genetics 117255.Google Scholar
- Slatkin, M. (1985). Rare alleles as indicators of gene flow.Evolution 39323.Google Scholar