An Evidence of Enhanced Fitness by Male Remounting during the Courtship in three Species of Montium Subgroup of Drosophila

Abstract

Male mating a second female after first mate (male remating) is a common feature in Drosophila, particularly in mass culture. On the other hand, female remating is not as frequent as that of male remating because the sperms introduced along with the semen into the spermatheca are stored there. However, the phenomena of female remating have been reported in few species. During sexual activity, the males and females are involved an elaborate courtship at the end of which the male mounts on to the female followed by mating. During each mating, the mounted male through its ejaculate, transmits the sperms into the females' genital tract where it is stored. The sperms are stored in the spermatheca. Usually, with one mount maximum sperms are transferred to female hence second mounting does not occur. In most Drosophila, when a male mounts a female after an elaborate courtship, the pairs remain in cupola for a fixed period then dismounts. No more courtship or mounting is performed by the male towards the same female. In D.jambulina, D.nagarholensis and D.gangotrii remounting occurs two or three times immediately after the first mount. The reason for remounting has been analyzed in the present study through measuring the width of the female reproductive tract and sperm count after each mount. The female reproductive tract was dissected out and width of uterus was measured. The result showed significant difference in the width after each mount. The sperm count of these species after each mount also showed significant variation. Remounting perhaps enhances the fitness of the mating pairs.