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Isolement reproducteur par homogamie entre deux « races d'habitat » sympatriques chez Drosophila melanogaster

1993; Volume: 48; Issue: 2 Linguagem: Inglês

10.3406/revec.1993.2102

0249-7395

Madeleine Paillette, Pierre Capy, Éliane Pla, Jean R. David,

Insect behavior and control techniques

Two races of D. melanogaster, morphologically identical, have been detected in the Brazzaville district (Congo). One (Loua = L), from the countryside, feeds and reproduces on manihot. The other (Kronenbourg = K) is found in the city bars and breweries, breeding on beer residues in empty bottles. These two populations can be distinguished by their genotypes at the Adh locus. The Kronenbourg population harbors 85 % of the F allele, while the frequency of this allele is less than 5 % in Loua. It is therefore easy to recognize them by mere electrophoresis. Under laboratory conditions, fertile FI and F2 hybrids are easily obtained. In natural conditions L and K remain separated. Behaviour plays probably a major role in reducing the gene flow through habitat choice and sexual behaviour. Sexual behaviour of these two races was analysed in laboratory. Sexual activity and mating choices were investigated by performing tests with four individuals (one male and one female of each race). In all tests, virgin adults were used. The L flies of both sexes exhibited a lower sexual activity than the K’s. Moreover, a significant homogamy independent of sexual activity was evidenced. It is the first time that such a phenomenon is found in D. melanogaster. This observation is of particular interest, since it concerns two sympatric races.