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
Definitions of body side motion.A chameleon perched on a vertical pole (P) and the threat, as viewed from above. (A) The chameleon is positioned opposite (ca.180°) the threat, in an initial state. (B) The position of the chameleon during, or immediately following, pole rotation. A given side of a chameleon is termed the “leading side” if the threat approaches from that side (i.e., the left side of the chameleon during left-approaching threat, as shown here, or the right side of the chameleon during right-approaching threat). The side opposite the leading side in each test is termed the “following side.”
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3369868&req=5

pone-0037875-g004: Definitions of body side motion.A chameleon perched on a vertical pole (P) and the threat, as viewed from above. (A) The chameleon is positioned opposite (ca.180°) the threat, in an initial state. (B) The position of the chameleon during, or immediately following, pole rotation. A given side of a chameleon is termed the “leading side” if the threat approaches from that side (i.e., the left side of the chameleon during left-approaching threat, as shown here, or the right side of the chameleon during right-approaching threat). The side opposite the leading side in each test is termed the “following side.”

Mentions: The temporal aspect of the response, “latency to final exposure,” was calculated by counting the number of frames from the moment of termination of the pole rotation to the moment (frame) when the chameleon had reached its final exposure and remained still. The data extracted for each sampled frame in each run represented the exposed surface (in pixels) for each chameleon and for each side of the pole, within the above-defined area. In each test, only the side that approached the threat during a given pole rotation, termed the “leading side,” was used for analysis (Fig. 4).


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

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

Definitions of body side motion.A chameleon perched on a vertical pole (P) and the threat, as viewed from above. (A) The chameleon is positioned opposite (ca.180°) the threat, in an initial state. (B) The position of the chameleon during, or immediately following, pole rotation. A given side of a chameleon is termed the “leading side” if the threat approaches from that side (i.e., the left side of the chameleon during left-approaching threat, as shown here, or the right side of the chameleon during right-approaching threat). The side opposite the leading side in each test is termed the “following side.”
© Copyright Policy
Related In: Results  -  Collection

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

pone-0037875-g004: Definitions of body side motion.A chameleon perched on a vertical pole (P) and the threat, as viewed from above. (A) The chameleon is positioned opposite (ca.180°) the threat, in an initial state. (B) The position of the chameleon during, or immediately following, pole rotation. A given side of a chameleon is termed the “leading side” if the threat approaches from that side (i.e., the left side of the chameleon during left-approaching threat, as shown here, or the right side of the chameleon during right-approaching threat). The side opposite the leading side in each test is termed the “following side.”
Mentions: The temporal aspect of the response, “latency to final exposure,” was calculated by counting the number of frames from the moment of termination of the pole rotation to the moment (frame) when the chameleon had reached its final exposure and remained still. The data extracted for each sampled frame in each run represented the exposed surface (in pixels) for each chameleon and for each side of the pole, within the above-defined area. In each test, only the side that approached the threat during a given pole rotation, termed the “leading side,” was used for analysis (Fig. 4).

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