POPULATION DIFFERENCES IN A LIZARD COMMUNICATIVE DISPLAY - EVIDENCE FOR RAPID CHANGE IN STRUCTURE AND FUNCTION

Population differences in a communicative display can lead to reproduc tive isolation and speciation, and are an indicator of the potential f or rapid change in the display. Herein, we describe differences in-the push-up displays produced by three populations of sagebrush lizards, Sceloporus graciosus, in the field. Lizards from these three populatio ns differ in the use of display body postures, the number of legs exte nded to produce the up-and-down motion of the display, and the number of headbobs produced in each of three segments of the display. In addi tion, there is at least one behaviour that is unique to one of the thr ee populations (the 'nodding run'). These differences among population s suggest that both the structure and the function of the push-up disp lay are undergoing far more rapid change than was previously thought. (C) 1998 The Association for the Study of Animal Behaviour.