Developmental isolation and subsequent adult behavior of Drosophila paulistorum. II. prior experience.

Preadult seclusion imposed upon members of the Drosophila paulistorum complex of intersterile semispecies significantly decreased sexual isolation between adults of the semispecies. While seclusion at any developmental stage had this effect, there were quantitative variations correlated with the stage at which seclusion had been initiated: the earlier the stage at which seclusion began, the more frequent were the heterogamic matings. All the stages of development seemed to contribute to final adult sexual behavior, with no single stage emerging as the most important experiential phase. Seclusion also significantly affected intrasemispecific matings, in that flies were more likely to mate with partners having similar experiences.