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Color Vision and Signal Color Evolution in Anolis lizards
Author(s) -
Maximov Katherine Joy,
Wadman Catherine
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.lb800
Subject(s) - anolis , lizard , arboreal locomotion , orange (colour) , biology , zoology , habitat , ecology , horticulture
Animals rely on different signaling patterns to communicate both within and between different species. Anolis is a diverse genus of small arboreal lizards that utilize a colorful expandable throat‐fan (or dewlap) for visual communication, in order to attract females and repel males. The environment the lizard lives in has influenced the coloring of these dewlaps in different species. Species that occupy shaded habitats tend to have yellow dewlaps while those that inhabit brighter, less shaded, habitats, tend to have red or orange dewlaps. Natural backgrounds are formed by green vegetation. Modelling these dewlap colors in a perceptual color space predicts that red is more visible against a green background than yellow, yet studies have shown that the majority of anoles have yellow dewlaps. However, quantal fluctuations under low lighting may result in a higher degree of receptor noise for some colors which can affect the discrimination of one color from another by changing the distance between them in perceptual color space. Modelling that takes receptor noise into account predicts that yellow colors, which reflect more photons, will be more visible than red in low light conditions, while red should be more visible in bright light where receptor noise is less. In this experiment, we used a color perception assay to test whether a red or yellow stimulus was more visible to the lizard under different light intensities against a green background, mimicking a dewlap appearing in a forested or open habitat. We flashed red, yellow, and green (control) stimuli against a green background. If the lizard detected a change, indicated by a swift head or eye movement towards the stimulus, a positive response was noted. We found that there was a significantly greater response to red stimuli in high light compared to low light. The visibility of yellow, however, did not change significantly with light intensity. In high light there was a greater response to red than to yellow, while in low light there was a greater response to yellow than to red. Our experiment confirmed the results predicted by the perceptual color space model when accounting for receptor noise. Since light intensity has a greater effect on the discriminability of red against green than yellow against green, this may account for the prevalence of yellow dewlaps in shaded habitats.