Neural crest cell biology shapes lizard skull evolution across evolutionary time scales

Area of Science:

• Developmental biology
• Evolutionary biology
• Comparative anatomy

Background:

• Vertebrate skulls develop from mesoderm and neural crest, providing insights into phenotypic variation and evolutionary diversification.
• Understanding the interplay between developmental origins and evolutionary trajectories is crucial for macroevolutionary studies.

Purpose of the Study:

• To investigate skull shape variation in lacertid lizards using 3D geometric morphometrics.
• To determine the distinct evolutionary roles of mesoderm- and neural crest-derived skull bones at micro- and macroevolutionary scales.
• To explore how developmental biases influence the evolutionary rates and disparity of skull modules.

Main Methods:

• 3D geometric morphometrics applied to lacertid lizard skulls.
• Analysis of skull shape variation across micro- and macroevolutionary scales.
• Comparative analysis of evolutionary rates and morphological disparity between mesoderm- and neural crest-derived bones.

Main Results:

• Mesoderm- and neural crest-derived bones form distinct, conserved modules in skull evolution.
• In *Podarcis muralis*, neural crest bones primarily drive rapid skull evolution under sexual selection.
• Neural crest bones show slower evolutionary rates and lower disparity compared to mesodermal bones at macroevolutionary scales.

Conclusions:

• Developmental biases from neural crest cell biology may explain discrepancies in their role across evolutionary scales.
• Neural crest's role in coupling skull shape, coloration, and behavior facilitates rapid adaptation but may constrain long-term skull evolvability.
• This highlights the complex relationship between developmental mechanisms and evolutionary outcomes in vertebrate skull diversification.