Genital coupling and copulatory wounding in Drosophila teissieri (Diptera: Drosophilidae)

We report genital coupling of Drosophila teissieri Tsacas, 1971, a member of the Drosophila melanogaster species subgroup. The species subgroup consists of nine described species including the model organism Drosophila melanogaster Meigen, 1830. Despite numerous studies on the biology of this group, our understanding of the evolutionary significance of the diversity in their genital structures is limited. This study provides evidence that (i) during the copulation, which lasts 41.1 min, a paired male genital part (dorsal branches of the basal processes of the aedeagus) open after being inserted into the female reproductive tract, (ii) female D. teissieri have a pair of pockets on the dorsal side of their genitalia that receive bifurcated spines of the male genitalia (ventral branches of the basal processes of the aedeagus), and (iii) male genital parts, especially unique strong spines of the cerci, cause multiple copulatory wounds on membranous areas of the female genitalia. Within the established phylogeny of the D. melanogaster species subgroup, we discuss possible functions of and evolutionary transitions in these genital structures.

Properties of transgenic strains of Drosophila melanogaster containing I transposable elements from Drosophila teissieri

SummaryI factors are transposable elements of Drosophila melanogaster similar to mammalian LINEs, that transpose by reverse transcription of an RNA intermediate and are responsible for the I–R system of hybrid dysgenesis. There are two categories of strains in this species: inducer, that contain about 15 I elements at the various sites on chromosomal arms, and reactive, that lack active I factors. I elements occur in various Drosophila species. Potentially functional I factors from Drosophila teissieri can transpose when introduced by P-element-mediated transformation in a reactive strain of Drosophila melanogaster. We have studied the properties of Drosophila melanogaster strains into which such an I factor from Drosophila teissieri, named Itei, was introduced. Typical hybrid dysgenesis is produced when males carrying Itei are crossed with reactive females. However, more than one copy of the element seems necessary to produce dysgenic traits, whereas only one I factor of Drosophila melanogaster seems to be sufficient. The copy number of Itei in transformed lines maintained by endogamous crosses increases rapidly and stabilizes at values similar to those observed in inducer strains. As Drosophila teissieri contains much fewer copies than the Drosophila melanogaster strains, this suggests that the copy number of I elements is not simply regulated by sequences present in the element itself.