The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)

Juvenile growth and socioecological correlates in a wild colobine


1Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, SUNY, 2Department of Anthropology, Stony Brook University, SUNY

March 28, 2015 3:30, Grand Ballroom E/F/G Add to calendar

Primate growth patterns have been shown to respond flexibly to socioecological variation on both ultimate and proximate scales, the latter of which makes growth rate a potential proxy for fitness variation in pre-reproductive individuals. Yet concurrent size and behavioral data of non-adults from wild populations are scarce, therefore, our current understanding of growth patterns is based largely on captive datasets. Here we present limb growth curve estimations for Phayre’s leaf monkeys (Trachypithecus phayrei crepusculus) at the Phu Khieo Wildlife Sanctuary in northeastern Thailand. Between November 2006 and May 2008, we photographed individuals from three habituated groups and collected corresponding laser-measured distances-to-subject. Following photogrammetric methods, we determined knee-to-heel length for 51 individuals (19 males, 32 females), including 35 of known age and four with age estimated from known birth season. We employed cubic spline regression to fit growth and pseudo-velocity curves to the mixed longitudinal and cross-sectional dataset, and calculated size-for-age residuals from separate male and female cubic polynomial regressions. We found that juvenile males grew at slightly faster rates than females to attain larger adult length, though adult length dimorphism was very mild (1.07). Limb length was a significant positive predictor of feeding intake rates among juveniles and sub-adults. Despite the potential disadvantage of small size to feeding efficiency, we found no evidence of longer lactation periods for small-for-age juveniles (p>0.05, n=11), suggesting that, despite a mechanically demanding diet, mothers did not invest longer to supplement small offspring during the transition to nutritional independence.

Data collection supported by the American Society of Primatologists, Leakey Foundation, NSF DDIG (BCS-0647837), NSF (BCS-0542035), and the Wenner-Gren Foundation.