The reproductive isolation of sympatric closely related species is one of the important issues in ecology and evolutionary biology. Closely related species of angiosperms that often grow in sympatry, have similar flower shape and overlapping flowering periods. In such situations, the attraction of different pollinator species is an important mechanism for promoting reproductive isolation. In this presentation, I show that differences in floral scents play an important role in maintaining the reproductive isolation of closely related plant species in highly specialized pollination mutualisms in Phylanthaceae and Saxifragaceae. The highly specific mutualistic interactions with pollinator insects are mediated by a few, system-specific compounds through ‘private channels’ that attract single species of pollinators. Our results suggest that changes in floral scent profiles trigger pollinator shifts and led to the speciation of these plants.