Geometric morphometrics

One month ago, I participated in a course entitled "Geometric Morphometrics in R" of the company Transmitting Science. My goal was to acquire new skills in this statistical technique, and apply it to know more about past lagomorphs. 

Geometric morphometrics (GM) is a method used to study and analyze the shape of biological structures. Unlike traditional morphometrics, which primarily measures distances, angles, and ratios, GM focuses on the coordinates of specific anatomical landmarks. This technique allows for a more detailed and comprehensive analysis of shape and its variation. The technique uses landmarks, which are specific points on a biological structure that can be consistently identified across all specimens. They are chosen based on their biological relevance and the ability to be located accurately and reliably. Depending on the study, landmarks are recorded in two or three dimensions using various tools such as digitizing tablets, 3D scanners, or specialized software

The next steps involve aligning the landmark configurations of all specimens to remove differences in position, orientation, and scale (Procrustes Superimposition). This alignment process ensures that the comparison of shapes is not influenced by size or orientation. The average shape of all specimens is calculated, providing a reference for subsequent analyses. Finally a shape analysis is carried out (Principal Components Analysis, Thin-Plate Splines, Regression Analysis, etc.).

GM is widely used in various fields such as Evolutionary Biology, Paleontology, Anthropology, Ecology or Medicine. Overall, GM provides a powerful and precise framework for studying the shape and form of biological structures, facilitating a deeper understanding of morphological variation and its underlying causes.

After this course, I am eager to implement all the concepts and analyses of GM that we have learnt to delve into the biology, ecology and evolution of past lagomorphs! 

Figure 1. Example of landmarking and obtaining curves with StereoMorph package. CC BY-NC-ND 4.0 DEED.

Figure 2. Example of coding, wireframes and PCA, using R, of a geometric morphometrics analysis. CC BY-NC-ND 4.0 DEED.