Active space of a movement-based signal: response to the Jacky dragon(Amphibolurus muricatus) display is sensitive to distance, but independent of orientation

Abstract

SUMMARY The efficacy of any animal signal is constrained by the range over which it remains above the sensory threshold of potential receivers. The spatial area in which reliable detection occurs defines active space; this is influenced by signal structure, the signalling environment and the sensory characteristics of receivers. Identification of the factors influencing active space has provided valuable insights into signal design, particularly in bioacoustics,in which signal distortion and degradation can be easily quantified. In the present study, we consider whether active space can similarly help to explain the design of a movement-based visual signal. The Jacky dragon(Amphibolurus muricatus) threat display is composed of five distinct motor patterns delivered in an obligatory sequence: tail-flicks, backward and forward foreleg waves, a push-up and a `body-rock'. In contrast to other communication systems, the introductory element is characterized by reduced intensity (average speed) but greater duration than subsequent motor patterns. Furthermore, the tail-flick sweeps a three-dimensional (3D) space around the lizard, whereas the motor patterns that follow are largely restricted to a single plane. Structural properties thus suggest that the active space of the tail-flick might be greater than that of the other motor patterns in the display, which would provide a parsimonious explanation for its use as an alerting component. We tested this prediction in a playback experiment incorporating 3D animations of lizard displays, comparing response probabilities to the factorial combination of three motor patterns, three viewing angles and three distances. Results suggest that the tail-flick does not have a greater active space than other display motor patterns, but that each degrades predictably with distance, thereby providing potential ranging cues. In addition, display components are remarkably robust to variation in receiver orientation, so that efficacy should be maximized in most potential signalling situations. These findings are consistent with the hypothesis that duration is the principal determinant of signal efficacy in this system.

Aggressive Signal Design in the Jacky Dragon (Amphibolurus muricatus): Display Duration Affects Efficiency

“…2007). However, our results support Peters et al. (2007)’s findings reporting that Amphibolurus muricatus increased signal length rather than speed when signalling against fast moving vegetation background, suggesting that A. muricatus adopted an alternative strategy to cope with an increase in environmental visual noise.…”

Aggressive Signal Design in the Jacky Dragon (Amphibolurus muricatus): Display Duration Affects Efficiency

“…2007). However, our results support Peters et al. (2007)’s findings reporting that Amphibolurus muricatus increased signal length rather than speed when signalling against fast moving vegetation background, suggesting that A. muricatus adopted an alternative strategy to cope with an increase in environmental visual noise.…”

Tail Tales: How Ecological Context Mediates Signal Effectiveness in a Lizard

“…Tail lashing is only marginally more effective than tail coiling in the absence of noise when viewed from ground level but becomes significantly more effective when environmental noise is present. This vigorous and dynamic movement stands out against noisy backgrounds, aligning with previous research indicating that certain lizard species use tail flicking to attract more attention by sweeping through a three-dimensional space (Peters and Evans 2007;Peters and Ramos 2022). Our simulations also showed that tail lashing is most effective when the lizard faces the viewer directly (front-on) in noisy environments.…”

Receivers Limit the Prevalence of Deception in Humans: Evidence from Diving Behaviour in Soccer Players

“…Furthermore, our results emphasise that receivers can play an important role in the maintenance of honesty under conflict of interest. Therefore our study of deception in humans supports theoretical models of animal signalling [15], [18], [20], [21], [22], [23], [26]. Furthermore, we hope this study has demonstrated the value of applying nonhuman research to human systems, to better understand human behaviour [29].…”

“…Dives were rewarded less often relative to tackles when closest to the referee thereby supporting the prediction that receiver discrimination improves with closer proximity to the signaller [20], [21], [22]. Overall, more falls were rewarded when closer to the referee supporting the idea that signal detection improves with closer proximity to the signaller [21], [22], [26]. Another interpretation is that referees were reluctant to reward signals nearest to the goal, where the outcome for the signaller is highly costly, or beneficial.…”

Aggressive Signal Design in the Jacky Dragon (Amphibolurus muricatus): Display Duration Affects Efficiency

“…2007). However, our results support Peters et al. (2007)’s findings reporting that Amphibolurus muricatus increased signal length rather than speed when signalling against fast moving vegetation background, suggesting that A. muricatus adopted an alternative strategy to cope with an increase in environmental visual noise.…”

Tail Tales: How Ecological Context Mediates Signal Effectiveness in a Lizard

“…Tail lashing is only marginally more effective than tail coiling in the absence of noise when viewed from ground level but becomes significantly more effective when environmental noise is present. This vigorous and dynamic movement stands out against noisy backgrounds, aligning with previous research indicating that certain lizard species use tail flicking to attract more attention by sweeping through a three-dimensional space (Peters and Evans 2007;Peters and Ramos 2022). Our simulations also showed that tail lashing is most effective when the lizard faces the viewer directly (front-on) in noisy environments.…”

Receivers Limit the Prevalence of Deception in Humans: Evidence from Diving Behaviour in Soccer Players

“…Furthermore, our results emphasise that receivers can play an important role in the maintenance of honesty under conflict of interest. Therefore our study of deception in humans supports theoretical models of animal signalling [15], [18], [20], [21], [22], [23], [26]. Furthermore, we hope this study has demonstrated the value of applying nonhuman research to human systems, to better understand human behaviour [29].…”

“…Dives were rewarded less often relative to tackles when closest to the referee thereby supporting the prediction that receiver discrimination improves with closer proximity to the signaller [20], [21], [22]. Overall, more falls were rewarded when closer to the referee supporting the idea that signal detection improves with closer proximity to the signaller [21], [22], [26]. Another interpretation is that referees were reluctant to reward signals nearest to the goal, where the outcome for the signaller is highly costly, or beneficial.…”

Aggressive Signal Design in the Jacky Dragon (Amphibolurus muricatus): Display Duration Affects Efficiency

“…2007). However, our results support Peters et al. (2007)’s findings reporting that Amphibolurus muricatus increased signal length rather than speed when signalling against fast moving vegetation background, suggesting that A. muricatus adopted an alternative strategy to cope with an increase in environmental visual noise.…”

Tail Tales: How Ecological Context Mediates Signal Effectiveness in a Lizard

“…Tail lashing is only marginally more effective than tail coiling in the absence of noise when viewed from ground level but becomes significantly more effective when environmental noise is present. This vigorous and dynamic movement stands out against noisy backgrounds, aligning with previous research indicating that certain lizard species use tail flicking to attract more attention by sweeping through a three-dimensional space (Peters and Evans 2007;Peters and Ramos 2022). Our simulations also showed that tail lashing is most effective when the lizard faces the viewer directly (front-on) in noisy environments.…”

Receivers Limit the Prevalence of Deception in Humans: Evidence from Diving Behaviour in Soccer Players

“…Furthermore, our results emphasise that receivers can play an important role in the maintenance of honesty under conflict of interest. Therefore our study of deception in humans supports theoretical models of animal signalling [15], [18], [20], [21], [22], [23], [26]. Furthermore, we hope this study has demonstrated the value of applying nonhuman research to human systems, to better understand human behaviour [29].…”

“…Dives were rewarded less often relative to tackles when closest to the referee thereby supporting the prediction that receiver discrimination improves with closer proximity to the signaller [20], [21], [22]. Overall, more falls were rewarded when closer to the referee supporting the idea that signal detection improves with closer proximity to the signaller [21], [22], [26]. Another interpretation is that referees were reluctant to reward signals nearest to the goal, where the outcome for the signaller is highly costly, or beneficial.…”