Leigh Steven R
Department of Anthropology, University of Illinois, Urbana, Illinois 61801, USA.
Am J Phys Anthropol. 2006 May;130(1):71-84. doi: 10.1002/ajpa.20319.
Cranial form in subspecies of Papio baboons (Papio hamadryas) varies in relation to size, geography, and sex. However, knowledge about this variation is based mainly on adults, precluding direct assessments of the evolutionary factors that are ultimately responsible for adult shape variation. Consequently, this study tests hypotheses about the development of size and shape differences among subspecies of Papio baboons, anticipating limited evolutionary divergences in the ontogenetic pathways leading to adult endpoints. Geometric morphometric and bivariate allometric analyses are used to explore developmental size and shape variation. Allometric scaling in adult Papio baboons occurs because both sexes and all subspecies follow similar developmental pathways to a variety of adult forms. However, complex allometry contributes to form differences, producing potentially important shape differences that emerge during development. Modest shape differences that are statistically independent of size distinguish chacma baboons (P. h. ursinus) from other forms. A small-headed subspecies, the Kinda baboon (P. h. kindae), also presents a distinctive ontogeny, and may provide insights into the evolution of size change in this species. Variation among subspecies that is statistically independent of size involves the rostrum, zygomatic breadths, and cranial flexion. These features may be related to diet, but the precise biomechanical correlates of baboon form variation remain unclear.
东非狒狒（阿拉伯狒狒）亚种的颅骨形态因体型、地理位置和性别而异。然而，关于这种变异的认识主要基于成年个体，这使得无法直接评估最终导致成年形态变异的进化因素。因此，本研究检验了关于东非狒狒亚种间体型和形态差异发育的假设，预计导致成年终点的个体发育途径中的进化分歧有限。采用几何形态测量和双变量异速生长分析来探究发育过程中的体型和形态变异。成年东非狒狒的异速生长缩放现象存在，因为雄性和雌性以及所有亚种都遵循相似的发育途径，形成多种成年形态。然而，复杂的异速生长导致了形态差异，产生了发育过程中出现的潜在重要形状差异。在统计学上与体型无关的适度形状差异将南非草原狒狒（P. h. ursinus）与其他形态区分开来。一种小头亚种，金达狒狒（P. h. kindae），也呈现出独特的个体发育过程，并可能为该物种体型变化的进化提供见解。在统计学上与体型无关的亚种间变异涉及吻部、颧骨宽度和颅骨弯曲度。这些特征可能与饮食有关，但狒狒形态变异的确切生物力学关联仍不清楚。
