The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

Lines of least evolutionary resistance and the evolution of the canine honing complex


Department of Anthropology, University of Arkansas

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Previous research has shown that the elements of the canine honing complex are strongly linked pleiotropically in both male and female anthropoids. Additionally, the elements of the complex are characterized by significant among species correlations, indicating that the complex has coevolved in both sexes. This study addresses the hypothesis that lines of least evolutionary resistance (i.e., the vector describing the maximum within-population variance) are shared among species. Additionally, as evolutionary change between populations in directions not aligned with this vector are relatively constrained, then among species differences should be strongly correlated with this vector. These hypotheses were tested for seven dimensions of the canine honing complex (height, mesiodistal, and labiolingual dimension of each canine; the length of the premolar’s honing surface) for 10 female samples (8 catarrhine; 2 platyrrhine) and 4 male samples (3 catarrhine; 1 platyrrhine). Every dimension was recorded for a minimum of 15 individuals for each sample. Using a randomization procedure, the null hypothesis that lines of least of evolutionary resistance are shared was rejected in only 2 of 45 comparisons for the females and only 1 of 6 comparisons for the males. In contrast, the null hypothesis that among divergence accumulated along shared lines of least evolutionary resistance was rejected in 64 out of 90 comparisons for females and 8 out of 12 comparisons for males. Despite sharing similar patterns of covariation within species, the elements of the complex have changed in dimensions not aligned with the vector of maximum variance.

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