Abstract # 38:

Scheduled for Thursday, June 18, 2015 03:05 PM-03:20 PM: (Cascade H) Oral Presentation


TESTING THE VARIABILITY SELECTION HYPOTHESIS IN MACAQUES.

A. R. Eller, K. G. Morley, H. A. Sullivan III and F. J. White
University of Oregon, Department of Anthropology, Eugene, Oregon 97403, USA
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     The Variability Selection Hypothesis (VSH) proposes that early Homo gained adaptive benefit from being versatile in unpredictable climates. Greater intra-taxon variation in body size of early, then later, Homo populations suggests increased developmental plasticity. Extant Macaca is an ideal taxa in which to examine the VSH because they are known to have broad geographic, niche, and dietary ranges. If ecological flexibility predicts developmental plasticity, then we predict macaques to be as variable as modern humans in developmental markers. We used established developmental osteological markers (dental eruption and long bone epiphyseal fusion); original data was collected on Macaca mulatta specimens (n=292) and compared to published data from human populations (n>25000). Two-way anovas without replication were used to test whether species had similar variation in dental eruption and fusion time. The two species had significantly different eruption variation (males F=33.71, df=15,1, p <0.0001; females F=119.06, df =15,1, p <0.0001) with macaques being more variable than humans. The two species also had different ranges in fusion time (F=7.28, df=13,1, p <0.5) with macaque males being more variable than human males. Variation in the onset and duration of these developmental markers is indicative of phenotypic plasticity, and this preliminary data indicates macaques are as plastic as humans. Additionally, the similarity in ecological profiles between taxa supports the idea that some macaque species may be under variability selection.