[MARMAM] Variation in cranial asymmetry among the Delphinoidea

Maíra Laeta mairalaeta at gmail.com
Sun Feb 21 14:01:36 PST 2021

Dear MARMAMers,

We are pleased to share our publication on cranial asymmetry and aspects of
sound production in odontocetes of the superfamily Delphinoidea. Our models
revealed associations of the magnitude of cranial asymmetry with source
level of echolocation clicks, and dive depth of the species.

Laeta, M.; Ruenes, G.F.; Siciliano, S.; Oliveira, J.A.; Galatius, A. 2021.
Variation in cranial asymmetry among the Delphinoidea. Biological Journal
of the Linnean Society 132 (2): 414-430.

The remarkable directional cranial asymmetry of odontocete skulls has been
proposed to be related to sound production. We investigated the variation
in quality and quantity of cranial asymmetry in the superfamily
Delphinoidea using geometric morphometrics and then investigated the
relationship between asymmetry and aspects of sound production. In the
average asymmetric shape, the dorsal aspect of the skull outline and
interparietal suture crest were displaced to the right, while the nasal
septum, nasal bones and right premaxilla were displaced to the left. The
nasal bone, premaxilla and maxilla were all larger on the right side. Three
delphinoid families presented similar expressions of asymmetry; however,
the magnitude of the asymmetry varied. The Monodontidae showed the greatest
magnitude of asymmetry, whereas the Phocoenidae were much less asymmetric.
The most speciose family, the Delphinidae, presented a wide spectrum of
asymmetry, with globicephalines and lissodelphinines among the most and
least asymmetric species, respectively. Generalized linear models
explaining the magnitude of asymmetry with characteristics of echolocation
clicks, habitat use and size revealed associations with source level, dive
depth and centroid size. This supports a relationship between asymmetry and
sound production, with more asymmetric species emitting louder sounds. For
example, louder clicks would be beneficial for prey detection at longer
ranges in deeper waters.

Please let us know of any questions!

The paper can be accessed at
https://doi.org/10.1093/biolinnean/blaa161, or you send me an email to
mairalaeta at gmail.com requesting the pdf.

Best regards, Maíra.
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