ABSENCE OF PREY CHEMICAL-DISCRIMINATION BY TONGUE-FLICKING IN AN AMBUSH-FORAGING LIZARD HAVING ACTIVELY FORAGING ANCESTORS

Lingually mediated detection of prey chemicals is widespread in one ma jor clade of lizards, Scleroglossa, but rare in the other, Iguania. It is absent in all ambush-foraging families tested and present in all a ctively foraging families. In Iguania, prey chemical discrimination is known only in the herbivorous Iguanidae; in Scleroglossa, it was here tofore known to be absent only in ambush-foraging gekkonids. Because a mbush foraging precludes lingual sampling of a wide area and tongue-fl icking would disrupt the crypticity ambushers maintain by immobility, we predicted that prey chemical discrimination would be absent in scle roglossans that have secondarily adopted ambush foraging. The Cape gir dled lizard, Cordylus cordylus, is member of Cordylidae, a family of a mbush foragers considered derived from active foragers in the Autarcho glossa, a group of scleroglossan families having highly developed ling ual chemosensory behaviours. As predicted, this species did not discri minate surface chemicals of three prey species from control substances in a series of standardized experiments in which prey chemicals were presented on cotton-tipped applicators. Thus, even in taxa having high ly developed prey chemical discrimination, adoption of ambush foraging may induce loss of prey chemical discrimination, providing further an d stronger evidence that prey chemical discrimination is adaptively ad justed to foraging mode.