Evolution. 1999 Feb;53(1):175-186. doi: 10.1111/j.1558-5646.1999.tb05343.x.

COMPETITION AND GENOTYPE-BY-ENVIRONMENT INTERACTION IN NATURAL BREEDING SUBSTRATES OF DROSOPHILA.

Evolution; international journal of organic evolution

Mauro Santos, Karel T Eisses, Antonio Fontdevila

PMID: 28565175 DOI: 10.1111/j.1558-5646.1999.tb05343.x

Abstract

Although empirical studies frequently suggest that genotype-by-environment (G X E) interaction can maintain genetic variation, very few data are available to test for the specific conditions necessary for the existence of a protected polymorphism (i.e., the property of persistence of an allele even when initially rare). Drosophila species live in patchy environments and their local population structure may be characterized to some extent by Levene's migration pattern, namely by a single pool of individuals that presumably mate at random and breed on discrete and ephemeral resources. We present here a field experiment that links Drosophila ecology and population genetics, which used the alcohol dehydrogenase (Adh) and α-glycerophosphate dehydrogenase (αGpdh) polymorphic loci in D. melanogaster flies raised from Opuntia ficus-indica fruits (prickly pears). The results show that there is density-dependent mortality in those fruits with a relatively high number of larvae (i.e., selection is "soft") and suggest that there is differential viability for αGpdh genotypes. Additionally, a pattern of G X E interaction for fitness values, which is fully compatible with the theoretical conditions required for the existence of a protected polymorphism, was found after weighting the fitness estimates by the relative contribution that each fruit makes to the total adult population. The strong association between Adh

© 1999 The Society for the Study of Evolution.

Keywords: Adh; Drosophila melanogaster; Levene's model; density-dependent mortality; genotype-by-environment interaction; inversions; natural population; protected polymorphism; αGpdh

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• Journal Article