“…With an estimated 350,000 species, the producers of these signals, the angiospenn plants, are the most successful division of land plants, and the vast majority of them rely on animals as pollen vectors (e.g., 80% in central Europe; Gottsberger, 1989). The large variety of signals used to advertise to pollinators has been implicated in facilitating efficient and directed pollen transfer (Heinrich, 1975;Waser and Price, 1983;Menzel and Shmida, 1993), but also as isolating mechanisms, in speciation processes and maintenance of plant species integrity (Grant, 1949;Jones, 1978;Gottsberger, 1989; but see Chittka and Waser, 1997, this issue). Floral color signals have been assumed to influence the evolution of their receivers, i.e., the color vision systems of flower-visiting animals (Chittka and Menzel, 1992).…”