Environmental control of seasonal variation in the butterfly Colias eurytheme: Effects of photoperiod and temperature on pteridine pigmentation

Abstract

Photoperiod and temperature were examined for their effects on the four major pteridine components of the wings of Colias eurytheme. Orange individuals show reduced pteridine pigmentation in response to short photoperiods, but make no significant adjustment of pigmentation as a result of varying temperatures. ‘Alba’ females, on the other hand, respond to temperature, but levels of the coloured pteridines are apparently insufficient for there to be an observable effect of photoperiod. Low temperature causes an increase in the concentrations of the coloured pteridines in these white females. The action of photoperiod in reducing resources committed to pigmentation in orange animals is consistent with the notion that it is advantageous to free nitrogen for other purposes under thermally stringent conditions. The response of the ‘alba’ females to temperature is more puzzling, but it may reflect the absence of selection for the canalization of this phenotype against the effects of temperature.