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4 November 2020 The Effects of Limited Visual Acuity and Context on the Appearance of Anolis Lizard Dewlaps
Leo J. Fleishman, Maya G. F. Prebish, Manuel Leal
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Abstract

Male Anolis lizards display their colorful dewlaps in a variety of contexts, ranging from long-distance territorial displays to close-range agonistic and courtship displays. Anoles have eyes of high optical quality and a retina that contains tightly spaced, small-diameter photoreceptors. Highest visual acuity is associated with the center of the retina (=12.5 cycles o-1), whereas acuity is much lower in the periphery. Anoles possess a small eye that creates a small retinal image, which limits their maximum visual spatial acuity to approximately 1/10 that of humans. In animal visual systems spatial resolution falls rapidly with distance from the stimulus. In some species, dewlap color patterns are fairly complex and may transmit various kinds of information. To gain insight into the visual information that conspecifics can potentially extract from dewlap color patterns, we modified high-resolution digital photographs reflecting the limits imposed by the acuity of the Anolis eye. For central retinal vision, from a distance of 0.5 m or less, the finest levels of dewlap pattern spatial detail were visible. At greater distances, and/or for peripheral vision, much less detail could be resolved. When viewed from 1 m away with peripheral vision, only the average color of the large patches could be detected, and all pattern detail was lost. The potential information content of the dewlap patterns changes dramatically with the context in which it is viewed. We show that a clear knowledge of an animal's sensory limitations can lead to greatly improved hypotheses about signal function.

Copyright 2020 Society for the Study of Amphibians and Reptiles
Leo J. Fleishman, Maya G. F. Prebish, and Manuel Leal "The Effects of Limited Visual Acuity and Context on the Appearance of Anolis Lizard Dewlaps," Journal of Herpetology 54(3), 355-360, (4 November 2020). https://doi.org/10.1670/19-108
Accepted: 21 April 2020; Published: 4 November 2020
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