Using geometric morphometric visualizations of directional selection gradients to investigate morphological...

Area of Science:

• Evolutionary biology
• Paleontology
• Biometrics

Background:

• Understanding evolutionary processes requires distinguishing neutral evolution from natural selection.
• Directional selection gradients link morphological differences to within-taxon variation.
• Current methods for selection gradients primarily use linear measurements, not geometric morphometrics (GM).

Purpose of the Study:

• To present a novel GM approach for visualizing and comparing between-taxon selection gradients.
• To address the methodological gap in applying GM to selection gradient analysis.
• To demonstrate the utility of this approach for understanding morphological evolution.

Main Methods:

• Developed a geometric morphometrics (GM) approach for selection gradient analysis.
• Applied the method to 3D landmark data from primate crania (humans, chimpanzees, bonobos, gorillas).
• Compared between-taxon selection gradients with difference vectors and neutral simulations.

Main Results:

• The GM approach effectively visualizes and compares selection gradients between taxa.
• Incorporating geometric information provides significant insights into evolutionary processes.
• Demonstrated utility in analyzing the evolution of the human braincase.

Conclusions:

• The new GM approach bridges a methodological gap in evolutionary studies.
• It offers a powerful tool for investigating the targets and patterns of natural selection.
• This method advances the understanding of morphological evolution across diverse taxa.