Form, Function, and Geometric Morphometrics

Abstract

Geometric morphometrics (GM) has increasingly become an important tool in assessing and studying shape variation in a wide variety of taxa. While the GM toolkit has unparalleled power to quantify shape, its use in studies of functional morphology have been questioned. Here, we assess the state of the field of GM and provide an overview of the techniques available to assess shape, including aspects of visualization, statistical analysis, phylogenetic control, and more. Additionally, we briefly review the history of functional morphology and summarize the main tools available to the functional morphologist. We explore the intersection of geometric morphometrics and functional morphology and we suggest ways that we may be able to move forward in profitably combining these two research areas. Finally, this paper provides a brief introduction to the papers in this special issue and highlights the ways in which the contributing authors have approached the intersection of GM and functional morphology. Anat Rec, 298:5-28, 2015. V C 2014 Wiley Periodicals, Inc.

Using Geometric Morphometrics to Quantify Variation of Shape and Magnitude of the Pattern of Milk Production of Dairy Cattle

“…Morphometrics is overall defined in the biological-shape literature as the measurement of shape variation and its covariation with other variables [22] [24]. This relatively new method has undergone changes in the way it is applied.…”

“…This relatively new method has undergone changes in the way it is applied. It has been employed in biology, medicine, and engineering [24] [25] to capture the shape of 2-dimen-sional (2D) or 3-dimensional (3D) structures images using specifically defined homologous landmarks [24].…”

“…Shape corresponds an outline with landmarks after differences in location, scale, and orientation has been removed [37]; size refers to the magnitude in an area or volume of a structure, often measured through the centroid size: the square root of the summed squared distances between all landmarks and their centroid [38]; and form includes both the shape and size of an object [24]. GM relies on multivariate analysis such as General Procrustes Analysis, Principal Component Analysis, ANOVA, MANOVA, Regression, and other tests.…”

“…The previous methods (PCA and visualization) are largely exploratory and others statistical analysis are employed for testing hypotheses [24]. GM employs several techniques for this purpose such as Procrustes ANOVA, MANOVA, discriminant function analysis (DFA), canonical variate analysis (CVA).…”

“…However, the geometric morphometric (GM) methods, which provide analyses for quantifying, testing, and visualizing shape variation and its covariation with biotic and abiotic variables [21]- [23], has already proved to contribute to increase the scientific rigor in the description of shape on Biology, Medicine, and Engineering [24] [25]. GM, a relatively new methodological achievement by scientists on Biology, analyzes the relative position of anatomical landmarks and sets of point representing outlines and surfaces to quantify size (magnitude) and shape [25].…”