FREQUENCY DISTRIBUTION OF ESTERASE-5 ALLELES IN TWO POPULATIONS OF DROSOPHILA PSEUDOOBSCURA

Tim Perri Keith ¹

¹ Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts 02138

Statistical tests comparing allele frequencies in natural populations with those predicted by various theories of genic variation depend critically on the accurate enumeration of alleles. This study used a series of five sequential electrophoretic conditions to characterize the allele frequency distributions of esterase-5 in two large population samples of Drosophila pseudoobscura from California. In Standard chromosome lines 12 electromorphs were discriminated using a single electrophoretic condition. When four additional criteria were used, the number of electromorphs increased to 41, 33 in one population and 22 in the other. Both populations had the same two alleles in high frequency, with other alleles present in frequencies of 6% or less. Although each population had a number of unique alleles, a ² contingency test demonstrated no significant genetic divergence between them. A statistical comparison of allele frequencies in both populations with that predicted by neutral models suggests that the individual and combined distributions deviate from neutrality in the direction of purifying selection.—Sex-Ratio chromosomes differed markedly from Standard chromosomes in both allelic content and diversity. In 32 Sex-Ratio chromosomes from one population only three alleles were found, all of which were detected under the initial "standard" electrophoretic conditions. Moreover, none of these alleles was found in the Standard chromosome lines.

This article has been cited by other articles:

				M. V. Trotter and H. G. Spencer The Generation and Maintenance of Genetic Variation by Frequency-Dependent Selection: Constructing Polymorphisms Under the Pairwise Interaction Model Genetics, November 1, 2008; 180(3): 1547 - 1557. [Abstract] [Full Text] [PDF]

				M. V. Trotter and H. G. Spencer Frequency-Dependent Selection and the Maintenance of Genetic Variation: Exploring the Parameter Space of the Multiallelic Pairwise Interaction Model Genetics, July 1, 2007; 176(3): 1729 - 1740. [Abstract] [Full Text] [PDF]

				M. Kovacevic and S. W. Schaeffer Molecular Population Genetics of X-Linked Genes in Drosophila pseudoobscura Genetics, September 1, 2000; 156(1): 155 - 172. [Abstract] [Full Text]

				The Role of Gene Conversion in Determining Sequence Variation and Divergence in the Est-5 Gene Family in Drosophila pseudoobscura Genetics, January 1, 1998; 148(1): 305 - 316.