Modes of selection maintaining an inversion polymorphism in Drosophila paulistorum

Gromko, M.H. and Richmond, R.C. (1978) Modes of selection maintaining an inversion polymorphism in Drosophila paulistorum. Genetics, 88 (2). pp. 357-366.

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The possibility that fitness relationships associated with an inversion polymorphism in D. paulistorum were frequency-dependent was investigated. Using allozymes of tetrazolium oxidase to mark inversions, the effects of genotype frequency, larval density and culture conditions on fitness were assessed. The proportions of genotypes among egg-laying females were varied, thus changing the expected proportions of progeny produced in the absence of fecundity or viability selection. The genotypes of progeny were determined by electrophoresis, and comparisons of the ratio of the numbers of the different genotypes produced to the expected ratio were used to evaluate fitness relationships. Fitness relationships were dependent on genotype frequency, larval density and culture conditions. Selection was absent, directional frequency dependent (favouring rare types) or heterotic, depending on density and culture conditions. It is implied that the adaptive value of genetic variants need not be apparent in all environments, or may change with changing conditions. There is evidence for different criteria for selection in the 2 sexes. These results add to the evidence supporting the importance of frequency-dependent selection. It is argued that for frequency dependence to be of general importance, selection must act on genes in groups, either as an inversion or as lengths of chromosome with integrity maintained by disequilibrium.

Item Type: Article
Additional Information: SNNigam Collection
Uncontrolled Keywords: Polymorphism, Drosophila paulistorum, chromosome , allozymes.
Author Affiliation: Department of Zoology, Indiana University, Bloomington, Indiana 47401, USA.
Subjects: Crop Improvement > Genetics/Genomics
Crop Improvement > Biotechnology
Divisions: General
Depositing User: Mr Balakrishna Garadasu
Date Deposited: 02 Apr 2013 10:10
Last Modified: 02 Apr 2013 10:10

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