Anatomical comparison across heads, fore- and hindlimbs in mammals using network models

Area of Science:

• Evolutionary Biology
• Comparative Anatomy
• Developmental Biology

Background:

• Animal body parts exhibit variable integration, forming functional phenotypes.
• Understanding developmental and evolutionary constraints is key to explaining phenotypic integration.
• Anatomical Network Analysis (AnNA) quantifies phenotypic modules based on physical connections.

Purpose of the Study:

• To identify commonalities and differences in modularity across species.
• To determine if anatomical modules possess phylogenetic character.
• To ascertain if modules reflect developmental, functional, or combined aspects of anatomy.

Main Methods:

• Constructed anatomical network models for the head, forelimb, and hindlimb of mouse, opossum, and human.
• Nodes represented anatomical units, and links represented physical connections.
• Analyzed skeletal and musculoskeletal networks to assess modularity and topology.

Main Results:

• Skeletal networks showed greater similarity across species than musculoskeletal networks.
• Musculoskeletal networks of heads and forelimbs exhibited more variation than hindlimbs.
• Human limb modules (digit 1) and opossum ear ossicles showed specialized functional adaptations.

Conclusions:

• Anatomical network topology is largely influenced by functional constraints.
• Developmental and phylogenetic factors may also play a role, particularly in specialized structures.
• Comparative AnNA provides insights into the evolution of anatomical integration and modularity.