Annual variation of enzyme polymorphism in four natural populations ofDrosophila melanogaster occupying different niches

Abstract

Gene and gametic frequencies of the Adh, Aox, a-Gpdh and Est-6 loci (map position: .0 respectively) have been studied in two wine cellar populations at 40 km distance from each other, and two field populations, one near each of the wine cellars. Only one locus, Aox was polymorphic for more than two electromorphs. The Adh locus seems to follow a different mode of change in genic frequencies in wine cellars, than in the field, while the other loci exhibit a similar pattern of polymorphism in the field and in the wine cellar. Linkage disequilibrium in the gamete Adh/ct-Gpdh is affected by different phenomena in the field than in the wine cellar. A stronger linkage disequilibrium in the Adh/-gametes observed in the field, may be a consequence of a mixture of subpopulations subjected to differential selection at the A dh locus. The A dh locus is the only one in which selection is detected, in one environment. It is neutral in other environments. The c~-Gpdh, Aox and Est-6 polymorphisms, however, behave as though they were neutral both in the wine cellar and in the field.

Latitudinal variation of Adh gene frequencies in Drosophila melanogaster: a Mediterranean instability

“…More precisely, a high frequency of F allele would be favoured in wine cellars, while a much lower equilibrium would be favoured in field populations. A higher frequency of Adh-F in wine cellar populations has been observed by various authors in Spain (Briscoe et a!., 1975;Alonso-Moraga et a!., 1985 and Canada (Hickey and McLean, 1980) but not in Australia (McKenzie and Parsons, 1974;McKenzie and McKecknie, 1978) nor in California (Marks et a!., 1980) nor in France (Charles-Palabost et a!., 1985;. There is no general solution to this ecological problem.…”

“…These were from southern Africa (David ci' a!., 1986), Australia (Oakeshott ci a!., 1982) and the west coast of America (Smith ci a!., 1984 between continents, will be considered in the discussion. Among the Mediterranean populations, numerous samples were collected around Cordoba (southern Spain) over a limited geographic area (Alonso-Moraga et at., 1985;Munoz-Serrano et at., 1985;Alonso-Moraga and Munoz-Serrano, 1986, and unpublished data), confirm the other observations. Adh gene frequencies were calculated after gel electrophoresis and staining for enzyme activity.…”