Anatomical Network Analysis applied to the posterior locomotor system of aquatic birds

DE MENDOZA RICARDO S.; CARRIL JULIETA; DEGRANGE FEDERICO JAVIER; TAMBUSSI CLAUDIA P.

Durban

Congreso; International Ornithological Congress (IOC 2022); 2022

INTERNATIONAL ORNITHOLOGISTS? UNION COUNCIL

Anatomical network analysis (AnNA) has been developed in the past few years to investigate morphological information at the level of connectivity among anatomical parts, supplying new information that complements classic other analytical tools. This novel approach has been recently applied by our research team to the musculoskeletal system of different birds in order to answer questions about their development, functional morphology and evolution. Herein we modelled the musculoskeletal system of the hind limbs of extant and extinct aquatic birds with different locomotor habits (non-divers, wing-propelled and foot-propelled divers) as anatomical multi-networks (undirected multigraphs where bones and muscles are formalized as nodes and the physical junctions between them as links). We aimed to compare their connectivity patterns and explore if it is conditioned by their evolutionary history or by their locomotor habits. Also, we explored the applicability of AnNA to muscular reconstructions of fossil taxa. From each network, we calculated the number of nodes and links, and connectivity parameters (density, average shortest path length, diameter, average clustering coefficient, parcellation, heterogeneity). With these parameters, we performed a principal component analysis and constructed a phylomorphospace. Our results show that both phylogenetic history and locomotor habits contributed to shaping the hind limb musculoskeletal connectivity pattern of extant aquatic birds. Interestingly, wing-propelled divers (especially penguins) and highly diving foot-propelled divers deviate in opposite ways from the connectivity patterns observed in non-divers and lesser foot-propelled divers. Also, most network parameters are robust in networks built with complete reconstructed muscle attachments in fossils, making them suitable for comparisons with extant taxa. These results encourage the exploration of AnNA in other locomotor modules and in birds with different habits and phylogenetic histories in order to weigh the contribution of ecology and evolution in shaping the musculoskeletal connectivity patterns, and to grasp generalities in highly specialized taxa.