1Institute for Mind and Biology, University of Chicago, 2The Kinsey Institute, Indiana University, 3Department of Anthropology, New York University, 4Life Sciences, University of Roehampton, 5Department of Mathematics, Washington University
March 26, 2015 11:30, Grand Ballroom E/F/G
Sexual selection explains the evolution of behavioral and morphological traits that influence an individual’s reproductive rate, which can take place both intra- (e.g. male-male competition) and inter-sexually (e.g. female mate choice). These two mechanisms can covary, such as when females are more attracted to males who win physical contest. Recent observational and experimental work has shown that rhesus females are more attracted to dark red males, which does not covary with dominance rank. Here, we examine whether inter-male variation in skin coloration contributes to the variation in mating success of high-ranking males. More specifically, we test the prediction that high-ranking males exhibiting dark red skin color receive more sexual solicitation and mate more frequently than pale pink ones. To do so, we collected behavioral observations and color images during the mating season for the top-ranked males of 9 social groups (N=21) of free-ranging rhesus macaques (Macaca mulatta) on Cayo Santiago, Puerto Rico. We use GLMs in SPSS with a significance level of 0.05 to test variation in male reproductive rates and the potential behavioral and physical traits that may be impacting these rates. We found inter-male variation in time spent consorting (p=0.000, F=10.115) and yearly reproductive rates (p=0.000, F=24.323). However, these rates are not associated with variation in affiliative behaviors (P=0.560, F=0.704) or agonistic interactions (p=0.395, F=1.040). Instead, a combination of both behavioral traits, rank, and skin color impacts male reproductive success. Thus, sexual selection results in a combination of behavioral and morphological traits that influence male sexual strategies.