Dominance, Coloration, and Social and Sexual Behavior in Male Drills Mandrillus leucophaeus

Abstract

Sexual selection has driven the evolution and elaboration of a wide variety of displays and ornaments in male nonhuman primates, including capes, cheek flanges, and sexual coloration. Among the most sexually dimorphic of all primates is the drill (Mandrillus leucophaeus), the males of which can be 3 times the mass of females, possess large canines, and exhibit extremely bright sexual skin coloration. However, the function of male coloration in this species has never been examined. Here, we present data on male color (measured objectively using digital photography), dominance rank, measures of male-female association, and key sexual behaviors, of adult male drills (n=17) living in four semi free-ranging enclosures at the Drill Rehabilitation and Breeding Center in Nigeria. We test the hypothesis that male coloration is a badge of status, indicating dominance rank, and the hypothesis that male coloration attracts females. We found that male coloration did indicate rank, and that high ranking, strongly colored males were more likely to associate with adult females, and more specifically with fully tumescent females. These males also engaged in more sexual activity. However, measures of male-female association and sexual behaviors were not related to male color once rank had been taken into consideration; i.e., for males of a given rank, females did not prefer those that were more colorful. We discuss the results in light of what is known about the wild drill social system, in which unfamiliar Int J Primatol (

Color in competition contexts in non-human animals

“…Such combinations can act as redundant (or back-up) signals, reflecting the same quality of the bearer, or multiple messages about different qualities of the bearer (Candolin, 2003). The multiple regions of colour that (mainly) correlate in mandrills (Setchell & Dixson, 2001a), drills (Marty et al, 2009), and rhesus macaques (Higham et al, 2013) may be redundant. Blue in mandrills appears to amplify the potential information content of red (Renoult et al, 2011).…”

“…Male lip and groin coloration correlate positively (Marty et al, 2009), but there are no studies relating these two areas to the (complex) colour of the hindquarters. As in mandrills, higher-ranking males are more colourful in both colour saturation and the extent of colour (Marty et al, 2009). …”

“…However, in contrast to the red and blue faces of mandrills, drills have shiny black faces set off by a white fringe of hair. Males have a horizontal red stripe under the lower lip, a red penis and extensive red above the penis, extending down the legs (which may be more extensive than in mandrills), a lilac scrotum, and blue, violet and pink on the hindquarters (Marty, Higham, Gadsby, & Ross, 2009;Osman Hill, 1970). As in mandrills, red coloration is linked to testosterone: experimental administration of testosterone led to 'flushing' of the lip and groin (Zuckerman & Parkes, 1939).…”

“…As in mandrills, red coloration is linked to testosterone: experimental administration of testosterone led to 'flushing' of the lip and groin (Zuckerman & Parkes, 1939). Male lip and groin coloration correlate positively (Marty et al, 2009), but there are no studies relating these two areas to the (complex) colour of the hindquarters. As in mandrills, higher-ranking males are more colourful in both colour saturation and the extent of colour (Marty et al, 2009).…”

Adaptive evolution of facial colour patterns in Neotropical primates

“…(i) Individual recognition hypothesis: first, it is possible that facial colour patterns evolved to be more complex in species with larger groups, as more complex faces would provide a template in which parts can vary and evolve independently, facilitating individual recognition. Socially relevant variation in the colour of individual facial parts has been reported in Old World primates, such as mandrills and drills [5,26].…”