Temperature ‐dependent colour change is a function of sex and directionality of temperature shift in the eastern fence lizard (Sceloporus undulatus)

Sexually dimorphic colour traits are widespread across taxa, but relatively little is known about how and why these features change with body temperature. To examine whether sex and directionality (warming vs. cooling) influence temperature‐dependent colour change, we used spectrophotometry to characterize ventral and dorsal coloration in eastern fence lizards (Sceloporus undulatus), a species with temperature‐dependent conspecific signals (ventral patches). In general, we found that skin colour (hue) in both sexes changed with temperature. Only ventral patch colour in males changed visibly to human observers; ventral patch hue decreased (green to blue shift) with an increase in body temperature. Male dorsal colour also changed with temperature, with cooler males exhibiting a longer‐wavelength hue (red shift) than that exhibited by warmer males. Female dorsal hue changed in a manner paralleling that of males, and female ventral hue trended in the same direction: overall, warmer females tended to exhibit shorter‐wavelength hues. However, the magnitude of male ventral patch colour change was highly dependent upon temperature sequence; the colourful badges of males that were progressively warmed changed from green to blue, whereas those of males that were cooled over the same time period did not change hue. Notably, only the coloration of male ventral patches was dependent on the directionality of temperature change; no other measured skin surfaces in either sex exhibite...

Source: Biological Journal of the Linnean Society - August 30, 2016 Category: Research Authors: Barry P. Stephenson, Nikolett Ih ász, David C. Byrd, John Swierk, Lindsey Swierk Tags: Research Article Source Type: research