Vertebral Morphology in Partially Sympatric Dolphins: A 3D Approach

• Published in: Frontiers in Marine Science
• Main Authors: Marchesi, María Constanza, Mora, Matias Sebastian, Dans, Silvana Laura, Coscarella, Mariano Alberto, Gonzalez-Jose, Rolando
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A.
• Subjects: DOLPHIN; FLEXIBILITY; GEOMETRIC MORPHOMETRICS; MANEUVERABILITY; SOUTHERN HEMISPHERE; VERTEBRAL MORPHOLOGY; https://purl.org/becyt/ford/1.6; https://purl.org/becyt/ford/1; Hourglass dolphin; Lagenorhynchus cruciger
• Online Access: http://hdl.handle.net/11336/135375

In cetaceans, increased body flexibility is associated with increased maneuverability, this affects the animal’s swimming speed and foraging behavior. A more stable body form is associated with fast swimming and wide turns. One factor that affects the flexibility of a cetacean’s body is the structure and interaction of its vertebrae. Differences in vertebral morphology confer different muscular insertion sites and affect mechanical properties of swimming muscles. We studied vertebral morphology in four closely related and partially sympatric dolphin species from the Southern Hemisphere: Commerson’s dolphin (Cephalorhynchus commersonii), Peale’s dolphin (Lagenorhynchus australis), the dusky dolphin (Lagenorhynchus obscurus) and the hourglass dolphin (Lagenorhynchus cruciger). The former two species are usually considered coastal, associated with complex habitats where foraging strategies require greater maneuverability; they also show plasticity in their prey preferences. The latter two species are considered fastswimming cooperative feeders, with long distance movements reflecting prey availability in pelagic habitats. We employed three-dimensional (3D) geometric morphometric techniques and multivariate analyses to evaluate differences in vertebral morphology. Our analyses tested whether particular morphologies that limit or enhance flexibility were associated with preferred habitats and feeding strategies. We established links between morphology and behavioral patterns based on the biomechanical significance of specific vertebral morphological features. Principal component analyses (PCA) showed great differentiation between species in all the studied regions along the vertebral column. This was especially evident in the middle area, except in the case of dusky and hourglass dolphins which showed no discernible morphological difference in their mid-column vertebrae. PCA results were supported by statistically significant Mahalanobis distances (MD) between species. Species associated with complex habitats and ...