Visual signal syntax in the Jacky dragon (Amphibolurus muricatus)

The syntactical structure of communicative signals inherently elicits social interaction between conspecific species provided that the signals are identified as a function of signal order. Syntax in this case is defined as a temporal order of association pertaining to the way in which signal segments are linked. However, with much attention to syntax burgeoning from early acoustic studies, few have examined changes in the visual system. The Jack dragon (Amphibolurus muricatus) is a native Australian agamid lizard characterized by a highly sterotyped display action pattern (DAP) used for social interactions. Twenty Jacky dragons were used in a series of computer-generated playback experiments designed to engage subjects in either attention alerting (conspicuousness) or recognition mechanisms. Experiment 1 and 2 examined the nature of conspicuousness by segmenting the DAP of a tail-flick (TF) , backward-forward arm wave (BFAW) and push-up body rock (PUBR) matched to population typical displays into various combinations. Experiment 1 manipulated syntactical order between TF and PUBR, while Experiment 2 manipulated the order of the full DAP display (TF x BFAW x PUBR). Experiment 3 examined whether syntactical recognition is truly a function of normal DAP or reversed order, as well as relative texture and morphology. Preliminary results suggest that all movement is inherently conspicuous and that matched movement-based characteristics are the most important feature in signal recognition. This suggests that Jacky dragons can recognize and engage in social interactions strongly based on movement and normal syntactical signal structure, while ignoring unnatural sequences of irrelevant motor patterns.