Does shape co-variation between the skull and the mandible have functional consequences? A 3D approach for a 3D problem

Authors

  • Raphaël Cornette,

    Corresponding author
    1. UMS CNRS/MNHN 2700, Outils et Méthodes de la Systématique Intégrative, Plate-forme de morphométrie, Paris, France
    • UMR CNRS/MNHN 7205, Origine Structure et Evolution de la Biodiversité, Muséum National d'Histoire Naturelle, Paris, France
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  • Michel Baylac,

    1. UMR CNRS/MNHN 7205, Origine Structure et Evolution de la Biodiversité, Muséum National d'Histoire Naturelle, Paris, France
    2. UMS CNRS/MNHN 2700, Outils et Méthodes de la Systématique Intégrative, Plate-forme de morphométrie, Paris, France
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  • Thibaud Souter,

    1. UMR CNRS/MNHN 7205, Origine Structure et Evolution de la Biodiversité, Muséum National d'Histoire Naturelle, Paris, France
    2. UMS CNRS/MNHN 2700, Outils et Méthodes de la Systématique Intégrative, Plate-forme de morphométrie, Paris, France
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  • Anthony Herrel

    1. UMR CNRS/MNHN 7179, Mécanismes adaptatifs: des organismes aux communautés, Paris, France
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Correspondence

Raphaël Cornette, UMR CNRS/MNHN 7205, Origine, Structure et Evolution de la Biodiversité, Muséum National d'Histoire Naturelle, 45 Rue Buffon, 75005 Paris, France. T: ++ 33-140798015 E: cornette@mnhn.fr

Abstract

Morpho-functional patterns are important drivers of phenotypic diversity given their importance in a fitness-related context. Although modularity of the mandible and skull has been studied extensively in mammals, few studies have explored shape co-variation between these two structures. Despite being developmentally independent, the skull and mandible form a functionally integrated unit. In the present paper we use 3D surface geometric morphometric methods allowing us to explore the form of both skull and mandible in its 3D complexity using the greater white-toothed shrew as a model. This approach allows an accurate 3D description of zones devoid of anatomical landmarks that are functionally important. Two-block partial least-squares approaches were used to describe the co-variation of form between skull and mandible. Moreover, a 3D biomechanical model was used to explore the functional consequences of the observed patterns of co-variation. Our results show the efficiency of the method in investigations of complex morpho-functional patterns. Indeed, the description of shape co-variation between the skull and the mandible highlighted the location and the intensity of their functional relationships through the jaw adductor muscles linking these two structures. Our results also demonstrated that shape co-variation in form between the skull and mandible has direct functional consequences on the recruitment of muscles during biting.

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