THE DISTRIBUTION OF ENZYME AND INVERSION POLYMORPHISM OVER THE GENOME OF DROSOPHILA: EVIDENCE AGAINST BALANCING SELECTION

E. Zouros ¹

¹ Department of Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada

In species of the repleta group of Drosophila about 70% of the electrophoretic variability is absorbed by the same chromosome which absorbs about 70% of the cytological variability of the group. However, this does not imply that inversions are actively involved in the maintenance of protein variation. A comparison of cytological and electrophoretic variation of homologous chromosomes points out that the amount of cytological polymorphism varies greatly over species of Drosophila while electrophoretic variation does not. This suggests that allelozymes do not constitute part of the coadapted complexes of genes characterizing the inversions. Rather, the amount of electrophoretic variation is determined by properties intrinsic to the polypeptide molecule and is largely independent of factors such as background genotype and differences in the environment.

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