Interspecific variation in motion displays

Signaling species occurring in sympatry areoften exposed to similar environmental constraints, so similar adaptations to enhance signal efficacy are expected. However, potentially opposing selective pressures mightbe present to ensure species recognition. Here, we analyzed the movement-based signals of two pairs of sympatric lizard species to consider how reliable communicationis maintained while avoiding misidentification. Our novel approach allows us to quantify signal contrast with plant motion noise at any site we measure, including those uti-lized by other species. Ctenophorus caudicinctus and Gowidon longirostris differed in display complexity and motor pattern use. They also differed in overall morphology, but their signal contrast scores are strikingly similar. These results demonstrate similar adaptations to their shared environment while maintaining species recognition cues. In contrast, Ctenophorus fordi and Ctenophorus pictus are much closer in appearance, but C. pictus produces considerably higher signal contrast scores, which we suggest is attributable to the absence of territoriality in C. fordi. Taken together, our data provide evidence for adaptation to the local environment in movement-based signals, while also meeting species recognition requirements, but the selective pressure to deal with local conditions is mediated by signal function.
Ramos JA,Peters RA (2017) Motion-based signaling in sympatric species of Australian agamid lizards Journal of Comparative Physiology A 203, 661-671
Figure | Habitat, average snout-vent length and known repertoire of core motor patterns for both species pairs. Gowidon longirostris andCtenophorus caudicinctus occur in sympatry at West-MacDonnellNational Park, Northern Territory. Ctenphorus pictus and C. fordioccur in sympatry within Ngarkat Conservation Park, South Australia. The core motor patterns refer to HB head bob, LW limb wave,PU push up, TC tail coil, and TF tail  ick (Ramos and Peters 2016). Ctenophorus caudicinctus has been observed performing limb waves, but this motor pattern is not present during its territorial displays