Concerted and mosaic evolution of functional modules in songbird brains

Area of Science:

• Evolutionary biology
• Neuroscience
• Comparative anatomy

Background:

• Vertebrate brain evolution involves complex interplay between size, composition, and function.
• Two prominent models, concerted and mosaic, offer contrasting explanations for brain structure covariation.
• Reconciling these models is crucial for understanding adaptive brain evolution from developmental constraints.

Purpose of the Study:

• To investigate the evolutionary processes shaping vertebrate brain structure variation.
• To test the applicability of concerted and mosaic models in songbird brain evolution.
• To unify existing models for a comprehensive understanding of brain evolution.

Main Methods:

• Comparative analysis of discrete neural system sizes in diverse songbird species.
• Statistical examination of nucleus volume variation and its relationship to functional domains and behavior.
• Investigating allometric relationships and residual variation patterns.

Main Results:

• Songbird brain evolution supports key aspects of both concerted and mosaic models.
• Most nucleus volume variation is shared across functional domains, aligning with the concerted model.
• Residual variation correlates within functional systems and predicts specific behaviors, supporting the mosaic model.

Conclusions:

• Oscine brains evolved predominantly as a coordinated unit, influenced by developmental sequences.
• Independent modifications of dedicated neural systems occurred due to specific selection pressures.
• Covariation patterns suggest underlying developmental mechanisms driving brain evolution.