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Online Document
J. L. Hubby and
R. C. Lewontin, "A Molecular Approach to the Study of Genic
Heterozygosity in Natural Populations. I. The Number of Alleles at
Different Loci in Drosophila pseudoobscura," Genetics 54
(1966): 546-595.
[Summary]
[PDF 3MB]
In this set of two papers, Hubby
and Lewontin use protein electrophoresis to determine how much genetic
variation there is in Drosophila pseudoobscura. They place this study
firmly within the context of traditional evolutionary theory,
especially the idea that natural selection acts upon pre-existing
genetic and phenotypic differences in nature. The purpose of the first
paper (Hubby and Lewontin) is to describe the method they use to
elucidate isoallelic variation among numerous individuals at a single
locus. Their method relies on the supposition that nucleotide
substitutions at the level of the gene will lead to amino acid
substitutions in the polypeptide, which will, in most cases, lead to a
change in the net charge of the polypeptide. By comparing differences
in the electrophoretic mobility of a given protein in many individuals,
Lewontin and Hubby believe that they can reach certain conclusions
about variation at the genetic level. The fact that all of the
electrophoretic differences they found tended to segregate in a
Mendelian fashion lends credence to their methodology. In this paper,
they report the results of their preliminary investigations, in which
they determined that of 21 proteins sampled in various D. psuedoobscura
strains, nine appear to show a significant amount of
electrophoretic-and therefore genetic-variation. They conclude with a
brief discussion of the biases and limitations of their methodology,
which they explore more fully in the accompanying paper (see below).
(jda)
This page was written by Michael Dietrich and Jay
Aronson. It was last updated on May 15, 2004.
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