Signals and speciation in plant-feeding insects

Abstract

Communication can play a role in speciation when differences in signaling systems reduce gene flow between diverging lineages. However, the observation that closely related species have different signals leaves open the question of cause and effect, because divergence in signals can also occur after speciation is completed. The relationship of signals and divergence is being investigated in the Enchenopa binotata species complex of treehoppers, a group of plant-feeding insects that communicate using substrate-borne vibrational signals. Speciation in the E. binotata complex is hypothesized to have resulted from repeated shifts to novel host plants. Sources of selection on the signals of these treehoppers can be studied not only in fully differentiated species, but also in experimental populations in the early stages of divergence. Some unique features of vibrational communication through plant stems will be discussed, as well as how shifts to novel host plants may influence signaling systems, and what role(s) communication may have played in the process of evolutionary divergence in this group.