Deciphering mechanical determinants of morphological evolution.

Area of Science:

• Developmental Biology
• Biophysics
• Evolutionary Morphology

Background:

• Understanding the evolution of biological form requires identifying the mechanical underpinnings of morphological diversity.
• While biomechanical forces are known to shape tissues, the specific variations in force-generating systems across species that lead to diverse forms remain largely unknown.
• Cnidarians, with their deep evolutionary divergence, offer a valuable model system to investigate the origins of morphological variation.

Purpose of the Study:

• To identify the mechanical basis of larval shape diversity across six cnidarian species.
• To develop a quantitative framework for comparing morphological variation based on biomechanical principles.
• To understand how variations in tissue-scale mechanical parameters generate diverse organismal forms.

Main Methods:

• Comparative morphogenesis across six cnidarian species.
• Application of active matter theory to analyze tissue mechanics.
• Definition and analysis of species-specific mechanical modules (mechanotypes).
• Interspecies perturbations to assess the role of regulatory differences in morphology.

Main Results:

• Species-specific configurations of mechanical modules, termed mechanotypes, were defined and quantitatively predict larval shapes.
• Shape elongation was identified as a simple trait dependent on one mechanical module, while shape polarity is a complex trait involving multiple modules.
• Simulated interspecies regulatory differences reprogrammed larval morphology, producing forms resembling sister species.

Conclusions:

• A mesoscale mechanical framework was established for cross-species comparison of morphology.
• Variations in a limited set of tissue-scale parameters can generate significant morphological diversity.
• This study provides a mechanistic understanding of how biomechanical processes contribute to evolutionary diversification.