Singleton Michelle, Seitelman Brielle C, Krecioch Joseph R, Frost Stephen R
Department of Anatomy, Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, Illinois.
Department of Anatomy, Midwestern University, Downers Grove, Illinois.
Am J Phys Anthropol. 2017 Dec;164(4):665-678. doi: 10.1002/ajpa.23304. Epub 2017 Sep 6.
The smallest extant member of genus Papio, the Kinda baboon exhibits low sexual dimorphism and a distinctive cranial shape. Ontogenetic scaling accounts for most cranial-shape differences within Papio, but studies have shown that the Kinda follows a separate ontogenetic trajectory. If so, its cranial-dimorphism pattern should differ from other subspecies. To evaluate this hypothesis, morphometric analysis was used to investigate cranial dimorphism in Papio.
Three-dimensional landmarks were digitized on 434 adult crania representing six Papio subspecies. Size- and shape-dimorphism magnitudes were quantified using centroid size and Procrustes distances. Patterns of sex- and size-related variation were explored using MAN(C)OVA, multivariate regression, and form-space PCA. Canine dimorphism was investigated using dental metrics.
Kinda size and shape dimorphism are significantly lower than in other Papio subspecies. The relative magnitude of Kinda shape dimorphism is similar to other southern baboons; Kinda canine dimorphism is unremarkable. MAN(C)OVA results support subspecies differences in cranial dimorphism and scaling. Allometric and dimorphism vectors differ significantly in some subspecies, and their vector-angle matrices are strongly correlated. The Kinda's allometric vector angles are divergent. Form-space PC3, summarizing size-independent dimorphism, separates the Kinda from other subspecies.
The Kinda baboon exhibits significantly lower size and shape dimorphism than other baboons, but its relative dimorphism levels are unexceptional. The Kinda differs from other subspecies in patterns of allometry, size-related shape dimorphism, and residual shape dimorphism. Kinda facial shape is "masculinized" relative to size, especially in females, suggesting female sexual selection contributed to the evolution of Kinda dimorphism.
金达狒狒是狒狒属现存最小的成员，表现出较低的两性异形和独特的颅骨形状。个体发育缩放解释了狒狒属内大多数颅骨形状差异，但研究表明金达狒狒遵循不同的个体发育轨迹。如果是这样，其颅骨两性异形模式应与其他亚种不同。为了评估这一假设，采用形态计量分析来研究狒狒属的颅骨两性异形。
在代表六个狒狒亚种的434个成年颅骨上数字化三维地标。使用质心大小和普洛克斯距离对大小和形状两性异形程度进行量化。使用多变量协方差分析（MAN(C)OVA）、多元回归和形态空间主成分分析（PCA）探索性别和大小相关变异模式。使用牙齿测量指标研究犬齿两性异形。
金达狒狒的大小和形状两性异形明显低于其他狒狒亚种。金达狒狒形状两性异形的相对程度与其他南部狒狒相似；金达狒狒的犬齿两性异形不明显。多变量协方差分析结果支持颅骨两性异形和缩放方面的亚种差异。在一些亚种中，异速生长和两性异形向量显著不同，且它们的向量角矩阵高度相关。金达狒狒的异速生长向量角不同。总结与大小无关的两性异形的形态空间主成分3（PC3）将金达狒狒与其他亚种区分开来。
金达狒狒的大小和形状两性异形明显低于其他狒狒，但其二性异形相对水平并无异常。金达狒狒在异速生长模式、与大小相关的形状两性异形和残余形状两性异形方面与其他亚种不同。相对于体型而言，金达狒狒的面部形状“男性化”，尤其是雌性，这表明雌性性选择促成了金达狒狒两性异形的进化。
