FORAGING MODE, PREY CHEMICAL-DISCRIMINATION, AND PHYLOGENY IN LIZARDS

The long-held hypothesis that active foragers should use chemical senses to detect food more than do ambush foragers is verified for lizards. In actively foraging and herbivorous families, tongue-flicking permits sampling of chemicals for detection and identification of prey, but in ambush-foraging families the tongue does not participate even in detection of prey. Because foraging mode and prey chemical discrimination are stable within most families and in some higher taxa, their states are often historically determined. Possible influences of foraging ecology and phylogeny on prey chemical discrimination were analysed by studying correlated changes in the two variables. For several alternative phylogenetic reconstructions, shifts in foraging mode are coincident with shifts in prey chemical discrimination. These results suggest adaptive adjustment of prey chemical discrimination to foraging mode. Other possible interpretations are discussed. Evolution of lingual morphology and behaviour and of the vomeronasal system for enhanced efficiency of active foraging suggest that foraging behaviour may have driven much of the diversification of squamate reptiles. (C) 1995 The Association for the Study of Animal Behaviour