3D analysis of vertebral morphology in Dall?s porpoise (Phocoenoides dalli): an example of habitat driven morphology-functional adaptation

MARCHESI, MARÍA CONSTANZA; ZAFFINO, MARTINA; COSCARELLA, M. A.; GONZÁLEZ JOSÉ, ROLANDO

Montpellier - Virtual

Simposio; 11TH SYMPOSIUM ON MORPHOMETRICS AND EVOLUTION OF SHAPE; 2021

Institute of Evolutionary Science of Montpellier

Particular vertebral morphologies have been reported for coastal and pelagic whales and dolphins. Dall?s porpoise (Phocoenoides dalli) vertebral column has been considered one of the most derived among cetaceans, having vertebrae strongly compressed and with exceptionally long neural and transverse processes. We employed 3D geometric morphometric techniques to analyze vertebral morphologies of Dall?s porpoise, contrasting with other four species of porpoises and an oceanic dolphin known to show vertebral morphologies associated with fast swimming in an oceanic environment. Principal component analyses (PCA) showed significant differentiation of Dall?s porpoise with the other species, except when comparing the mid-torso with the oceanic dolphin. In the small odontocetes, vertebral morphology is distinctive and varies with the differential foraging strategies and habitat of each species. In the oceanic Dall?s porpoise, an extremely high vertebral count in conjunction with vertebrae morphological features (i.e., disk-shaped vertebrae with long strongly bent processes) reveal a vertebral column structure that would be associated with greater stability, particularly adapted for fast swimming. These findings reveal morphological plasticity among porpoise species and possible morphological convergence between Dall?s porpoise and an oceanic dolphins in the mid-column, one of the main areas for force production by swimming muscles. Our results highlight the importance of behavioral traits in the evolutionary development of morphological adaptations.