Presenter: Julia Arenson
Mentors: Frances White and Stephen Frost, Anthropology
Poster: 1
Major: Anthropology
Bergmann’s rule predicts that body size increases with distance from the equator. This pattern has been noted in wild macaque populations, but relocated captive populations have not been examined for this cline. Captive populations provide an opportunity to analyze whether Bergmann’s rule is influenced more by natural selection or phenotypic plasticity. Forty-five 3D cranial landmarks were collected using a Microscribe-3DX on a sample of 251 adult crania of wild Macaca fascicularis, M. cyclopis, M. fuscata and M. mulatta with known provenience, as well as 18 captive M. mulatta from Beaverton, OR (lat=45.5) and 40 from Cayo Santiago, Puerto Rico (lat=18.2). Cranial centroid size was calculated for each specimen as a proxy measure of body size. The covariation between shape and geography was assessed with a 2-Block Partial Least Squares (2B-PLS) analysis. Regression analyses were used to predict the expected latitudes for the captive samples based on size and shape. For wild macaques, distance from the equator was significantly correlated with both size (males R2=0.370; p=0.00; females R2=0.475; p=0.00) and shape (pooled sex R2=0.51, p=0.00). Predicted latitudes based on cranial sizes (Beaverton=38.0; Cayo Santiago=44.9) were higher than the current captive locations but were lower when based on shape (Cayo Santiago=13.3; Beaverton=8.5). These results suggest the latitudinal pattern of skull shape and size in wild fascicularis group macaques is more influenced by phenotypic plasticity than natural selection.