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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.

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Avoidance response patterns of the two side-biased groups on a narrow pole.Ventral surface exposure (mean ± SE) on narrow poles in response to right- or left-approaching threats in chameleons of the right-biased group (10.1, N  = 14) and of the left-biased group (10.2, N  = 10). Exposure readings are at 200-ms intervals, (A) at the onset of pole rotation, (B) at the end of pole rotation, and (C) at the end of the test.
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pone-0037875-g010: Avoidance response patterns of the two side-biased groups on a narrow pole.Ventral surface exposure (mean ± SE) on narrow poles in response to right- or left-approaching threats in chameleons of the right-biased group (10.1, N  = 14) and of the left-biased group (10.2, N  = 10). Exposure readings are at 200-ms intervals, (A) at the onset of pole rotation, (B) at the end of pole rotation, and (C) at the end of the test.

Mentions: In the tests on narrow poles, for the right-biased group, all three spatial parameters were significantly lower for right-approaching threats than for left-approaching threats (Initial exposure: F(1,13)  = 16.721, p  = 0.001; End of rotation exposure: F(1,13)  = 18.049, p  = 0.001; Final exposure: F(1,13)  = 10.853, p  = 0.006) (Figs. 10.1, 11). For the left-biased group, all three spatial parameters were significantly lower in tests on left-approaching threats vs. right-approaching threats (Initial exposure: F(1,10)  = 10.465, p  = 0.009; End of rotation exposure: F(1,10)  = 13.051, p  = 0.005; Final exposure: F(1,10)  = 5.586, p  = 0.04) (Figs. 10.2, 11). The latency to final exposure (Fig. 12) did not differ between right- and left-approaching threats in either the right-biased group (F(1,13)  = 0.513, p  = 0.487) or the left-biased group (F(1,10)  = 0.086, p  = 0.775).


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

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

Avoidance response patterns of the two side-biased groups on a narrow pole.Ventral surface exposure (mean ± SE) on narrow poles in response to right- or left-approaching threats in chameleons of the right-biased group (10.1, N  = 14) and of the left-biased group (10.2, N  = 10). Exposure readings are at 200-ms intervals, (A) at the onset of pole rotation, (B) at the end of pole rotation, and (C) at the end of the test.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0037875-g010: Avoidance response patterns of the two side-biased groups on a narrow pole.Ventral surface exposure (mean ± SE) on narrow poles in response to right- or left-approaching threats in chameleons of the right-biased group (10.1, N  = 14) and of the left-biased group (10.2, N  = 10). Exposure readings are at 200-ms intervals, (A) at the onset of pole rotation, (B) at the end of pole rotation, and (C) at the end of the test.
Mentions: In the tests on narrow poles, for the right-biased group, all three spatial parameters were significantly lower for right-approaching threats than for left-approaching threats (Initial exposure: F(1,13)  = 16.721, p  = 0.001; End of rotation exposure: F(1,13)  = 18.049, p  = 0.001; Final exposure: F(1,13)  = 10.853, p  = 0.006) (Figs. 10.1, 11). For the left-biased group, all three spatial parameters were significantly lower in tests on left-approaching threats vs. right-approaching threats (Initial exposure: F(1,10)  = 10.465, p  = 0.009; End of rotation exposure: F(1,10)  = 13.051, p  = 0.005; Final exposure: F(1,10)  = 5.586, p  = 0.04) (Figs. 10.2, 11). The latency to final exposure (Fig. 12) did not differ between right- and left-approaching threats in either the right-biased group (F(1,13)  = 0.513, p  = 0.487) or the left-biased group (F(1,10)  = 0.086, p  = 0.775).

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