A PHYLOGENETIC ANALYSIS OF THE EVOLUTION OF THE STRIDULATORY APPARATUS IN TRUE CRICKETS (ORTHOPTERA, GRYLLOIDEA)

The stridulatory apparatus (or stridulum) is currently assumed ancestr al in crickets. Models of its subsequent evolution consider only one m odality of evolutionary change: the stridulum would have been progress ively lost in multiple cricket lineages. A phylogenetic test of this h ypothesis is presented here. The morpho-functional types of stridulum have been optimized on the cladistic phylogenies of two monophyletic c ricket clades, and parsimonious evolutionary scenarios of the evolutio n of the stridulum in these clades have been derived. The phylogenetic patterns thus obtained support the hypothesis that the stridulum has been lost several times convergently in crickets. They indicate, howev er, that the loss of the stridulum could be reversible, and that sever al modalities of evolutionary change exist for the stridulum. Phylogen etic analysis thus reveals an unsuspected complexity in the evolution of acoustic communication in crickets. (C) 1997 The Willi Hennig Socie ty.