title: Exploring phylogenetic and functional signals in complex morphologies: the hamate of extant anthropoids as a test-case study.
abstract: Three-dimensional geometric morphometrics (3DGM) is a powerful tool for capturing and visualizing the "pure" shape of complex structures. However, these shape differences are sometimes difficult to interpret from a functional viewpoint, unless specific approaches (mostly based on biomechanical modeling) are employed. Here, we use 3DGM to explore the complex shape variation of the hamate, the disto-ulnar wrist bone, in anthropoid primates. Major trends of shape variation are explored using principal components analysis along with analyses of shape and size covariation. We also evaluate the phylogenetic patterning of hamate shape by plotting an anthropoid phylogenetic tree onto the shape space (i.e., phylomorphospace) and test against complete absence of phylogenetic signal using posterior permutation. Finally, the covariation of hamate shape and locomotor categories is explored by means of 2-block partial least squares (PLS) using shape coordinates and a matrix of data on arboreal locomotor behavior. Our results show that 3DGM is a valuable and versatile tool for characterizing the shape of complex structures such as wrist bones in anthropoids. For the hamate, a significant phylogenetic pattern is found in both hamate shape and size, indicating that closely related taxa are typically the most similar in hamate form. Our allometric analyses show that major differences in hamate shape among taxa are not a direct consequence of differences in hamate size. Finally, our PLS indicates a significant covariation of hamate shape and different types of arboreal locomotion, highlighting the relevance of this approach in future 3DGM studies seeking to capture a functional signal from complex biological structures.
authors.affiliation: Department of Anatomical Sciences, Stony Brook University School of Medicine, Stony Brook, New York; Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Edifici Z (ICTA-ICP), campus de la UAB, c/ de les Columnes, s/n., 08193 Cerdanyola del Vallès, Barcelona, Spain; NYCEP Morphometrics Group.
authors.forename: Sergio
authors.initials: S
authors.lastname: Almécija
authors.forename: Caley M
authors.initials: CM
authors.lastname: Orr
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Tocheri
authors.forename: Biren A
authors.initials: BA
authors.lastname: Patel
authors.forename: William L
authors.initials: WL
authors.lastname: Jungers
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001696:Biomechanical Phenomena / Q000502:physiology; D002427:Cebidae; D051225:Hamate Bone / Q000033:anatomy & histology* / Q000502:physiology*; D000882:Haplorhini / Q000033:anatomy & histology* / Q000502:physiology*; D015186:Hominidae; D006801:Humans; D006922:Hylobates; D021621:Imaging, Three-Dimensional; D008124:Locomotion / Q000502:physiology; D008433:Mathematics; D010802:Phylogeny; D025341:Principal Component Analysis; D014953:Wrist / Q000033:anatomy & histology / Q000502:physiology
keywords: 3D geometric morphometrics; shape-function complex; wrist morphology