The genetic basis of sexual isolation between Drosophila melanogaster and D. simulans

• Published in: Evolution Vol. 46; no. 5; pp. 1385 - 1398
• Main Authors: Welbergen, Philip, van Dijken, Folchert R., Scharloo, Wim, Kohler, Wolfgang
• Format: Journal Article
• Language: English
• Published: Malden, MA Society for the Study of Evolution 01-10-1992; Blackwell; Oxford University Press
• Subjects: Animals; Biological and medical sciences; Biometric genetics; Classical genetics, quantitative genetics, hybrids; Drosophila; Drosophila melanogaster; Drosophila simulans; Evolutionary genetics; Female animals; Fundamental and applied biological sciences. Psychology; genetic variation; genetica; Genetics; Genetics of eukaryotes. Biological and molecular evolution; genetique; Genotypes; Hybridity; Inbred strains; Insect genetics; Insects; intraspecific variability; Invertebrata; Male animals; Mating behavior; Quantitative genetics; Sexual behavior; sexual isolation; variacion genetica; variation genetique; Drosophila simulans; Reproductive isolation; Genetic variability; Arthropoda; Insecta; Sexual behavior; Interspecific hybridization; Diallel analysis; Invertebrata; Drosophila melanogaster; Diptera; Drosophilidae; intraspecific variability; Biometric genetics; Drosophila; sexual isolation
• ISSN: 0014-3820; 1558-5646
• DOI: 10.1111/j.1558-5646.1992.tb01131.x

The genetic analysis of sexual isolation between the closely-related species Drosophila melanogaster and Drosophila simulans involved two experiments with no-choice tests. The efficiency of sexual isolation was measured by the frequency of courtship initiation and interspecific mating. We first surveyed the variation in sexual isolation between D. melanogaster strains and D. simulans strains of different geographic origin. Then, to investigate variation in sexual isolation within strains, we made F1diallel sets of reciprocal crosses within strains of D. melanogaster and D. simulans. The F1diallel progeny of one sex were paired with the opposite sex of the other species. The first experiment showed significant differences in the frequency of interspecific mating between geographic strains. There were more matings between D. simulans females and D. melanogaster males than between D. melanogaster females and D. simulans males. The second experiment uncovered that the male genotypes in the D. melanogaster diallel significantly differed in interspecific mating frequency, but not in courtship initiation frequency. The female genotypes in the D. simulans diallel were not significantly different in courtship initiation and interspecific mating frequency. Genetic analysis reveals that in D. melanogaster males sexual isolation was not affected by either maternal cytoplasmic effects, sex-linked effects, or epistatic interaction. The main genetic components were directional dommance and overdominance. The F1males achieved more matings with D. simulans females than the inbred males. The genetic architecture of sexual isolation in D. melanogaster males argues for a history of weak or no selection for lower interspecific mating propensity. The behavioral causes of variation in sexual isolation between the two species are discussed.