Abstract # 144:

Scheduled for Friday, August 18, 2006 05:15 PM-05:30 PM: Session 14 (Regency East #2) Oral Presentation

The development of sexual behavior and first conception in free-ranging adolescent female rhesus monkeys

K. L. Robbins1, M. S. Gerald2, A. Ruiz Lambides2, A. A. Accamando2 and S. J. Suomi1
1NICHD Laboratory of Comparative Ethology, NIH Animal Center, Bldg. 112, P.0.Box 529, Poolesville, MD 20837, USA, 2Caribbean Primate Research Center, University of Puerto Rico
     A cohort of 28 three-year-old female rhesus monkeys (Macaca mulatta) was studied on the island of Cayo Santiago, PR, to examine the development of sexual behavior and influences on the probability of conception. Physiological and morphological measures were collected during the annual trapping of the colony; focal behavioral observations were collected throughout the year. Female rank played a major role in the young females’ interactions with sub-adult and adult males: high-ranking females approached males more than did lower-ranking females (Z=-1.94, p<0.05), but tended to more often be targets of contact aggression from the males. In contrast, low ranking females grimaced and fled more from males than high-ranking females, and received more non-contact aggression. Fifteen of the 28 females conceived for the first time during their third year. The probability of conception and live birth was not related to affiliative or sexual interactions with males, nor to hormonal or immune status; rather, females who conceived were larger (Z=-2.82, p<0.01), had more body fat (Z=-3.21, p<0.01), and showed fewer nervous behaviors such as visual scanning (Z=-2.56, p<0.01) than females who did not conceive. The results suggest that rank is a major determinant of females’ interactions with males at age three, and that growth status is of primary importance in age at first conception. This study was supported in part by the National Institutes of Health (NICHD) intramural program and NIH/NCRR grant CM-5-P40RR003640-13 to the Caribbean Primate Research Center.