Abstract # 13330 Event # 215:

Scheduled for Saturday, August 24, 2019 02:00 PM-02:15 PM: (Room 309) Oral Presentation


MALE ANOGENITAL DISTANCE AND COMPETITIVE ABILITY: A TEST IN COLOBUS MONKEYS

J. A. Teichroeb1, S. M. Stead1, P. D. Edwards2, F. Landry1, R. Palme3 and R. Boonstra2
1University of Toronto Scarborough, Dept. of Anthropology, Toronto, ON M1C1A4, Canada, 2Dept. of Biology, University of Toronto Scarborough, 3Dept. of Biomedical Sciences, University of Veterinary Medicine
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     Anogenital distance (AGD) is positively correlated to fetal androgen exposure and developmental masculinization in rodents and humans. Male AGD is typically measured as the distance from the posterior scrotum to the anus. Independent of body size, AGD shows a strong positive correlation with male fertility and, in rodents, it is associated with female choice and indicates resource holding potential. We hypothesized that AGD is also predictive of male competitive ability in the nonhuman primates. To test this, we measured AGD non-invasively with parallel lasers in wild Angolan colobus monkeys (Colobus angolensis ruwenzorii) in Uganda. This species form a multi-level society with both one-male/multi-female units (OMUs) and multi-male/multi-female units (MMUs). We compared AGD measurements to fecal androgen metabolites, dominance rank, body size, and the number of females associated with males in 5 OMUs and 6 MMUs. Overall, we found that AGDs were not longer for males in OMUs relative to MMUs [Mann-Whitney: p=0.64], even though males in OMUs had access to more females. However, AGD was associated with rank nested within core unit in MMUs [Regression: p=0.05], demonstrating that higher-ranked males in these multi-male units had longer AGDs independent of body size [Regression: p=0.31]. This implies that AGD is predictive of male competitive ability and a useful measure of male resource holding potential in nonhuman primates. We recommend that this be tested further in other primates.