Sex does not predict responses to novel foods in captive golden lion tamarins
Tara A. Brown, Haylee K. Knotts, Megan M. O’Brien, Brett M. Frye, Dr. Lisa G. Rapaport
Clemson University Department of Biological Sciences
Introduction
Many studies have documented sex differences in primates, including humans. Human males have generally been found to be more assertive and to have higher self-esteem while females tend to be more extraverted, trusting, and nurturing (4). Human men are on average larger, more robust, and more aggressive than women. This sexual dimorphism may influence the consistent behavioral differences between the sexes. If sexual dimorphism is in-part responsible for behavioral differences, we would predict that sex would not be a significant source of variation in monomorphic primate species. Callitrichines are a group of New World monkeys consisting of the marmosets and tamarins that exhibit few, if any, morphological differences between the sexes.
There is conflicting evidence for sex differences in exploratory behavior in marmosets and tamarins. Box (1997) found that females attempted foraging tasks more frequently and spent more time attempting to obtain food than males. However, Koski and Burkart (2015) found that consistency of exploratory tendencies across contexts was not influenced by sex in common marmosets (Callithrix jacchus). A better understanding of the role of sex in influencing behavioral differences is important because such variation has evolutionary, ecological, and conservation implications. For example, behavioral differences may affect mortality and/or reproductive rates. Additionally, marmosets and tamarins are common biomedical research subjects. A more advanced comprehension of callitrichine behavioral ecology may allow for improved environmental enrichment practices in captivity.
Lion tamarins have not been included in many previous studies of callitrichine sex differences. To further investigate the question of sex effects on exploration, we conducted novel food experiments on zoo-living golden lion tamarins (Leontopithecus rosalia).
Methods
Results
The mean latencies and standard errors of male and female individuals to approach, sniff, and taste novel foods. There were no significant differences between males and females in exploratory behavior (approach p=0.42, sniff p=0.43, taste p=0.95).
Individual mean latencies to approach novel foods at 30 second intervals from when the novel food was placed in the enclosure.
Discussion
Our study did not uncover significant differences in latencies to approach, sniff, or taste novel foods as a function of sex, suggesting that male and female golden lion tamarins are equally quick to investigate novel, potentially energy-rich foods. Though not statistically significant, a larger proportion of males approached and sniffed novel food objects within the first 30 seconds of the experimental trials. Males also showed more variability in their latencies to explore a novel food compared to females. These patterns suggest variation in exploration strategies between the sexes. This is consistent with De Sousa et al.’s (2015) findings that male and female marmosets exhibit different cortisol-level responses to stressful situations.
Golden lion tamarin mothers are the primary caregivers for newborns, but males help in transporting and provisioning food for juveniles. Male participation in cooperative rearing, in addition to the physical monomorphism of the species, suggests male and female golden lion tamarins do not have largely different life strategies. This may account for the similarity we found in the exploratory behaviors between the sexes.
Other factors may overshadow the influence of sex on exploratory behaviors in golden lion tamarins. Kendal et al. (2005) found that adult callitrichines had shorter latencies than juveniles and infants to manipulate novel food tasks, demonstrating an age effect on exploration. Social environment may also play an important role in molding behavioral response to novel foods. Studies have shown that common marmosets exhibit group-level similarity in exploratory behavior(7). Additionally, Goeldi’s monkeys (Callimico goeldii) explore novel foods more when their group members are also presented with novel foods(1). Group size did not have a predictive effect on exploratory behavior in our study but this does not rule out the possibility that individuals within the same group may converge in their reactive behavior, independent of group size.
Future projects should look to examine possible differences between the sexes in exploration of non-food novel objects and in response to potential predators, and should consider the effects of other factors such as group composition and prior experience on exploratory behavior.
References
1. Addessi, E, Chiarotti, F, Visalberghi, E, Azenberger, G. (2007). Response to novel food and the role of social influences in common marmosets (Callithrix jacchus) and Goeldi’s monkeys (Callimico goeldi). American Journal of Primatology 69: 1210-1222.
2. Box, H.O. (1997). Foraging Strategies among Male and Female Marmosets and Tamarines (Callitrichdae): New Perspectives in an underexplored Area. Folia Primatol, 68: 296-306.
3. Box, H.O., Yamamota, M.E., Lopes, F.A. (1999). Gender differences in marmosets and tamarins: responses to food tasks. International Journal of Comparative Psychology, 12(2): 59-70.
4. Feingold, A. (1994). Gender differences in personality: a meta-analysis. Psychological Bulletin, 116(3): 429-456.
5. Kendal, RL., Leland, K. (2005). Age differences in neophilia, exploration, and innovation, in family groups of Callitrichid monkeys. American Journal of Primatology 66:167-188.
6. Kleiman, DG, Rylands, AB, eds. Lion Tamarins Biology and Conservation.Washington and London: Smithsonian Institution Press, 2002. Print.
7. Koski, S.E. & Burkart, J.M. (2015) Common marmosets show social plasticity and group-level similarity in personality. Scientific Reports. 5, 8878; DOI:10.1038/ srep08878
8. Wolf, M. and Weissing, F. J. (2012). Animal personalities: consequences for ecology and evolution. Trends in Ecology and Evolution, 27(8): 452-461.
9. Yamamoto, ME, Domeniconi, C, & Box, H (2004). Sex differences in common marmosets (Callithrix jacchus) in response to an unfamiliar food task. Primates, 45, 249-254.
Acknowledgements
We would like to thank Clemson University, Creative Inquiry, Clemson University’s Graduate Student Senate for providing funding throught the Professional Enrichment Grant, Clemson University’s Biological Sciences Graduate Student Association for providing travel award funding, Clemson University Honors College, Riverbanks Zoo, Zoo Atlanta, Micke Grove Zoo, and Albuquerque Zoo.