DOMINANCE RANK, RESOURCE AVAILABILITY, AND REPRODUCTIVE MATURATION INFEMALE SAVANNA BABOONS

Ten years of data collected from a population of savanna baboons, Papi o cynocephalus anubis, residing near Gilgil, Kenya were analyzed to as certain the extent to which social and ecological factors influence re productive maturation in females. First sexual swelling occurred at an average age of 4.79 years and first birth occurred at an average age of 6.92 years. Age at first menses was significantly correlated with a ge at first sexual swelling, but age at first sexual swelling was not a good predictor of age at first birth. The amount of rainfall in the 6 months preceding first sexual swelling and resource availability wer e significantly correlated with age at first sexual swelling. When eco logical factors were taken into account, dominant females had an earli er age at onset of puberty, but not an earlier age at first birth, tha n did subordinate females. We suggest that nutritional and social stre ss operate at the same physiological level to disrupt GnRH pulsatility and retard reproductive maturation in some females. Given that socioe cological variables modify the timing of life history events related t o fitness in female baboons, the task for the future is to unravel how socioecological factors influence different life history components a nd generate variation in lifetime reproductive success.