Individual Facial Coloration in Male Eulemur fulvus rufus: A Condition-dependent Ornament?

Abstract

Researchers studying individual variation in conspicuous skin coloration in primates have suggested that color indicates male quality. Although primate fur color can also be flamboyant, the potential condition dependence and thus signaling function of fur remains poorly studied. We studied sources of variation in sexually dichromatic facial hair coloration in red-fronted lemurs (Eulemur fulvus rufus). We collected data on 13 adult males in Kirindy Forest, Madagascar, during two study periods in 2006 and 2007, to determine whether variation in facial hair coloration correlates with male age, rank, androgen status, and reproductive success. We quantified facial hair coloration via standardized digital photographs of each male, assessed androgen status using fecal hormone measurements, and obtained data on reproductive success through genetic paternity analyses. Male facial hair coloration showed high individual variation, and baseline coloration was related to individual androgen status but not to any other parameter tested. Color did not reflect rapid androgen changes during the mating season. However, pronounced long-term changes in androgen levels between years were accompanied by changes in facial hair coloration. Our data suggest that facial hair coloration in red-fronted lemur males is under proximate control of androgens and may provide some information about male quality, but it does not correlate with dominance rank or male reproductive success.

Fig. 1

( Top) Sexual dichromatism in facial coloration between male (left) and female (right) red-fronted lemurs. ( Bottom) Individual variation in facial coloration of red-fronted lemur males. This study focused on the colored forehead, which ranges in color from pale to rufous.

Fig. 2

Individual red-fronted lemur males differed significantly from each other in facial hair coloration. Social groups all included both pale and rufous males (group A: , B: ,F: , J: ). Data for 2007.

Fig. 3

Individual variation in hair coloration and androgen level between years. Lines link repeated measures of the same individual in different years. a Color scores of color chart standard patches did not differ between years. b Color scores of gray control patches were significantly higher in 2007. c Color scores of red patches increased significantly between years, and effect size explaining the difference between red patches between years was greater than that explaining the difference between gray patches between years. d Androgen levels were significantly increased in 2007 versus 2006.

Fig. 4

Mean individual color scores of red-fronted lemur males correlate positively with mean fecal androgen levels in both years. Both color scores and androgen levels were higher in 2007.