Head adaptation for sound production and feeding strategy in dolphins (Odontoceti: Delphinida). Issue 5 (14th December 2020)

• Record Type: Journal Article
• Authors: Frainer, Guilherme; Huggenberger, Stefan; Moreno, Ignacio B.; Plön, Stephanie; Galatius, Anders
• Is Part Of: Journal of anatomy. Volume 238:Issue 5(2021)
• Page Start: 1070
• Page End: 1081
• Publication Date: 2020-12-14
• Subjects: 3D morphometrics -- echolocation -- feeding strategy -- macroevolution -- ontogeny -- toothed whales; Anatomy -- Periodicals; 571.3
• DOI: 10.1111/joa.13364
• Languages: English
• ISSNs: 0021-8782

Abstract

Abstract: Head morphology in toothed whales evolved under selective pressures on feeding strategy and sound production. The postnatal development of the skull ( n = 207) and mandible ( n = 219) of six Delphinida species which differ in feeding strategy but exhibit similar sound emission patterns, including two narrow‐band high‐frequency species, were investigated through 3D morphometrics. Morphological changes throughout ontogeny were demonstrated based on the main source of variation (i.e., prediction lines) and the common allometric component. Multivariate trajectory analysis with pairwise comparisons between all species was performed to evaluate specific differences on the postnatal development of skulls and mandibles. Changes in the rostrum formation contributed to the variation (skull: 49%; mandible: 90%) of the entire data set and might not only reflect the feeding strategy adopted by each lineage but also represents an adaptation for sound production and reception. As an important structure for directionality of sound emissions, this may increase directionality in raptorial feeders. Phylogenetic generalized least squares analyses indicated that shape of the anterior portion of the skull is strongly dependent on phylogeny and might not only reflect feeding mode, but also morphological adaptations for sound production, particularly in raptorial species. Thus, postnatal development seems to represent a crucial stage for biosonar maturation in some raptorial species such as Pontoporia blainvillei and Sousa plumbea . The ontogeny of their main tool for navigation and hunting might reflect their natural history peculiarities and thus potentially define their main vulnerabilities to anthropogenic changes in the environment. Abstract : Sound production may be influenced by the rostrum morphology in toothed whales, mainly for raptorial specialists that tend to present higher values of centroid frequency and source level. Thus, postnatal development seems to represent a crucial stage for biosonar maturation in some raptorial species as the rostrum exhibits remarkable transformation compared to what is seen in specialized suction feeders. The ontogeny of the main tool for navigation and hunting in toothed whales might reflect their natural history peculiarities and thus potentially define their main threats.