FURTHER CHARACTERIZATION OF THE ODYSSEUS LOCUS OF HYBRID STERILITY INDROSOPHILA - ONE GENE IS NOT ENOUGH

Previously we mapped by genetical and molecular means a gene that cont ributes to hybrid-male sterility between Drosophila mauritiana and D. simulans to the cytological interval of 16D. In this report, we refine the mapping of this gene, Odysseus (Ods) and show that it can be deli neated to a region the size of an average gene. We further demonstrate that, while Ods appears to be a discrete element, it requires other n earby gene (s) to be cointrogressed to confer full hybrid sterility ef fect. This observation is in agreement with the view that reproductive isolation between closely related species of Drosophila is usually ca used by several genes of weak effect from the same species that intera ct strongly among themselves as well as with the foreign genetic backg round.