GEOGRAPHIC-VARIATION IN SEXUAL DICHROMATISM IN THE COLLARED LIZARD, CROTAPHYTUS-COLLARIS (SAURIA, CROTAPHYTIDAE)

We recorded the color of male and female collared lizards (Crotaphytus collaris collaris) from three populations using reflectance spectroph otometry to examine interpopulation differences in sexual dichromatism . The degree of sexual dichromatism within this species varied signifi cantly among local populations. We also examined brightness of colorat ion and sexual dichromatism in these populations using appraisal by na ive observers. Subjective appraisal also showed significant difference s among these populations. However, the population appraised as most b rightly colored was not appraised as most dichromatic. This study demo nstrates that sexual dichromatism may vary significantly among populat ions of a single species. Although subjective appraisal of sexual dich romatism may yield reliable results when carried out under carefully c ontrolled conditions, assessment of a single pair of individuals or as sessment of only male coloration is not sufficient for a study of sexu al dichromatism.