Limits...
Visually guided avoidance in the chameleon (Chamaeleo chameleon): response patterns and lateralization.

Lustig A, Ketter-Katz H, Katzir G - PLoS ONE (2012)

Bottom Line: We found two equal-sized sub-groups, each displaying lateralization of motor responses to a given direction of stimulus approach.Such an anti-symmetrical distribution of lateralization in a population may be indicative of situations in which organisms are regularly exposed to crucial stimuli from all spatial directions.This is because a bimodal distribution of responses to threat in a natural population will reduce the spatial advantage of predators.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology and Ethology, University of Haifa, Haifa, Israel. Lustigavi@gmail.com

ABSTRACT
The common chameleon, Chamaeleo chameleon, is an arboreal lizard with highly independent, large-amplitude eye movements. In response to a moving threat, a chameleon on a perch responds with distinct avoidance movements that are expressed in its continuous positioning on the side of the perch distal to the threat. We analyzed body-exposure patterns during threat avoidance for evidence of lateralization, that is, asymmetry at the functional/behavioral levels. Chameleons were exposed to a threat approaching horizontally from the left or right, as they held onto a vertical pole that was either wider or narrower than the width of their head, providing, respectively, monocular or binocular viewing of the threat. We found two equal-sized sub-groups, each displaying lateralization of motor responses to a given direction of stimulus approach. Such an anti-symmetrical distribution of lateralization in a population may be indicative of situations in which organisms are regularly exposed to crucial stimuli from all spatial directions. This is because a bimodal distribution of responses to threat in a natural population will reduce the spatial advantage of predators.

Show MeSH

Related in: MedlinePlus

Patterns of motor response of a chameleon on a narrow pole.The degree of body exposure is depicted during three consecutive runs (respectively, triangles, circles, and squares) along with their mean (continuous line). The images are of the chameleon as viewed by the observer (the “threat”) at the respective time points.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3369868&req=5

pone-0037875-g006: Patterns of motor response of a chameleon on a narrow pole.The degree of body exposure is depicted during three consecutive runs (respectively, triangles, circles, and squares) along with their mean (continuous line). The images are of the chameleon as viewed by the observer (the “threat”) at the respective time points.

Mentions: Distinct spatio-temporal motor patterns were observed in the exposure of the chameleon’s body. In Phase 1, an initial increase in ventral body exposure was observed and in Phase 2, there was a decrease in exposure (Fig. 6). Phase 1, which covered the duration from the onset to the termination of pole rotation, resulted in the “leading side” of the chameleon being relatively more exposed to the threat. During Phase 1, exposure at any given moment could be viewed as the product of the rotation itself and the actual movement of the chameleon. Keeping motionless (“frozen”) or moving with the trajectory of the pole would result in increased overall exposure, while moving counter to the rotation of the pole would result in decreased overall exposure. Consequently, a chameleon that actively counter-rotated during pole rotation would reach the end of the perturbation with lower surface exposure than that of a “frozen” chameleon. In Phase 2, the “correction phase,” body exposure changed from the very end of the pole rotation to the end of the test (point of final exposure) due only to the motion of the chameleon in relation to the now stationary threat. This is depicted in Fig. 4, with the decrease in exposure being due to the chameleon’s counter-rotation relative to the threat.


Visually guided avoidance in the chameleon (Chamaeleo chameleon): response patterns and lateralization.

Lustig A, Ketter-Katz H, Katzir G - PLoS ONE (2012)

Patterns of motor response of a chameleon on a narrow pole.The degree of body exposure is depicted during three consecutive runs (respectively, triangles, circles, and squares) along with their mean (continuous line). The images are of the chameleon as viewed by the observer (the “threat”) at the respective time points.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369868&req=5

pone-0037875-g006: Patterns of motor response of a chameleon on a narrow pole.The degree of body exposure is depicted during three consecutive runs (respectively, triangles, circles, and squares) along with their mean (continuous line). The images are of the chameleon as viewed by the observer (the “threat”) at the respective time points.
Mentions: Distinct spatio-temporal motor patterns were observed in the exposure of the chameleon’s body. In Phase 1, an initial increase in ventral body exposure was observed and in Phase 2, there was a decrease in exposure (Fig. 6). Phase 1, which covered the duration from the onset to the termination of pole rotation, resulted in the “leading side” of the chameleon being relatively more exposed to the threat. During Phase 1, exposure at any given moment could be viewed as the product of the rotation itself and the actual movement of the chameleon. Keeping motionless (“frozen”) or moving with the trajectory of the pole would result in increased overall exposure, while moving counter to the rotation of the pole would result in decreased overall exposure. Consequently, a chameleon that actively counter-rotated during pole rotation would reach the end of the perturbation with lower surface exposure than that of a “frozen” chameleon. In Phase 2, the “correction phase,” body exposure changed from the very end of the pole rotation to the end of the test (point of final exposure) due only to the motion of the chameleon in relation to the now stationary threat. This is depicted in Fig. 4, with the decrease in exposure being due to the chameleon’s counter-rotation relative to the threat.

Bottom Line: We found two equal-sized sub-groups, each displaying lateralization of motor responses to a given direction of stimulus approach.Such an anti-symmetrical distribution of lateralization in a population may be indicative of situations in which organisms are regularly exposed to crucial stimuli from all spatial directions.This is because a bimodal distribution of responses to threat in a natural population will reduce the spatial advantage of predators.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology and Ethology, University of Haifa, Haifa, Israel. Lustigavi@gmail.com

ABSTRACT
The common chameleon, Chamaeleo chameleon, is an arboreal lizard with highly independent, large-amplitude eye movements. In response to a moving threat, a chameleon on a perch responds with distinct avoidance movements that are expressed in its continuous positioning on the side of the perch distal to the threat. We analyzed body-exposure patterns during threat avoidance for evidence of lateralization, that is, asymmetry at the functional/behavioral levels. Chameleons were exposed to a threat approaching horizontally from the left or right, as they held onto a vertical pole that was either wider or narrower than the width of their head, providing, respectively, monocular or binocular viewing of the threat. We found two equal-sized sub-groups, each displaying lateralization of motor responses to a given direction of stimulus approach. Such an anti-symmetrical distribution of lateralization in a population may be indicative of situations in which organisms are regularly exposed to crucial stimuli from all spatial directions. This is because a bimodal distribution of responses to threat in a natural population will reduce the spatial advantage of predators.

Show MeSH
Related in: MedlinePlus