Hedging their Bets? Explaining Long-term Investment in Juveniles by Male Baboons.
Friday, September 4, 2009
Lecture Hall 2, 4:00 PM
L. R. Moscovice, M. Heesen, A. Di Fiore, R. M. Seyfarth & D. L. Cheney
Adult male chacma baboons (Papio hamadryas ursinus) form preferential associations, or “friendships”, with particular lactating females. Males exhibit high levels of affiliative contact with their friends’ infants and defend them from potentially infanticidal attacks. Little is known about males’ relationships with juveniles once they have passed the period of infanticidal risk. We conducted an observational, experimental, and genetic study of adult male and juvenile chacma baboons in the Moremi Reserve, Botswana. We identified preferential associations between males and juveniles and used behavioral data and a playback experiment to explore whether those associations have potential fitness benefits for juveniles. We examined whether males preferentially invest in care of their own offspring and how often males invest in care of their former friends’ offspring. The majority of juveniles exhibited preferential associations with one or two male caretakers, who had almost always been their mother’s friend during infancy. However, in only a subset of these relationships was the male the actual father, in part because many fathers died or disappeared before their offspring were weaned. Male caretakers intervened on behalf of their juvenile associates in social conflicts more often than they intervened on behalf of unconnected juveniles, and they did not appear to differentiate between genetic offspring and unrelated associates when providing aid. Playbacks of juveniles’ distress calls elicited a stronger response from their caretakers than from control males. In discussing these results, I will present a theoretical framework to explain how chacma males and females may both benefit by forming friendships that reflect a high relative probability of paternity, and that result in long-term male investment in probable, but not always actual, offspring.
My interests in the causes and consequences of primate social behavior have led to a range of research projects in captive and field settings. As a graduate student in the Psychology Department at the University of Wisconsin-Madison I initially studied social learning in captive groups of cotton-top tamarins. Through this research, I became interested in primate behavioral flexibility in response to social and ecological variables. These interests led to my dissertation research examining the socioecology of a unique chimpanzee population on Rubondo Island, Tanzania. My dissertation examined the behavior of the current population, which descended from founders introduced to the island over forty years ago. From 2006-2009 I was a postdoctoral researcher at the University of Pennsylvania, where I conducted a field study of chacma baboons in the Moremi Reserve, Botswana. My research combined behavioral observations, experimental playbacks of vocalizations and genetic analyses to explore the function of social bonds between adult males and immature baboons and between unrelated females. In the last year of my postdoctoral position I also gained teaching experience as an adjunct faculty member in the Biology Department at Bard College. This year I am looking forward to being a part of the EvoS community through a postdoctoral teaching position at Binghamton University.