Evolutionary Trends of the Pharyngeal Dentition in Cypriniformes (Actinopterygii: Ostariophysi)

Emmanuel Pasco-Viel,Cyril Charles,Marie Semon,Laurent Viriot,Pascale Chevret,Vincent Laudet,Paul Tafforeau

doi:10.1371/journal.pone.0011293

Abstract

BackgroundThe fish order Cypriniformes is one of the most diverse ray-finned fish groups in the world with more than 3000 recognized species. Cypriniformes are characterized by a striking distribution of their dentition: namely the absence of oral teeth and presence of pharyngeal teeth on the last gill arch (fifth ceratobranchial). Despite this limited localisation, the diversity of tooth patterns in Cypriniformes is astonishing. Here we provide a further description of this diversity using X-ray microtomography and we map the resulting dental characters on a phylogenetic tree to explore evolutionary trends.ResultsWe performed a pilot survey of dental formulae and individual tooth shapes in 34 adult species of Cypriniformes by X-ray microtomography (using either conventional X-ray machine, or synchrotron microtomography when necessary) or by dissecting. By mapping morphological results in a phylogenetic tree, it emerges that the two super-families Cobitoidea and Cyprinoidea have followed two distinct evolutionary pathways. Furthermore, our analysis supports the hypothesis of a three-row dentition as ancestral for Cyprinoidea and a general trend in tooth row reduction in most derived lineages. Yet, this general scheme must be considered with caution as several events of tooth row gain and loss have occurred during evolutionary history of Cyprinoidea.SignificanceDentition diversity in Cypriniformes constitutes an excellent model to study the evolution of complex morphological structures. This morphological survey clearly advocates for extending the use of X-ray microtomography to study tooth morphology in Cypriniformes. Yet, our survey also underlines that improved knowledge of Cypriniformes life traits, such as feeding habits, is required as current knowledge is not sufficient to conclude on the link between diet and dental morphology.

Highlights

Many biological structures such as somites, segments or limbs, exhibit repeated patterns and these structures are often variable between related species
This is for example the case of the zebrafish, Danio rerio, a member of the order Cypriniformes (Actinopterygii, Osteichthyes) that comprises an excellent model for developmental biology studies [4,12,13]
In Cyprinoidea with several tooth rows, the tooth shape was determined for teeth on the ventral row as they are the biggest and the most differentiated

Summary

Introduction

Many biological structures such as somites, segments or limbs, exhibit repeated patterns and these structures are often variable between related species. Actinopterygian fish display a great diversity in tooth number and location [4,8]: they display rows of hundreds of teeth which can be located on the lower and upper jaws, the floor of the mouth (basihyal, basibranchials), the roof of the mouth (e.g. vomer, palatine), the upper and lower pharyngeal regions In addition to this diversity, Actinopterygian fish include several wellstudied experimental models that allow for the study of tooth development from a mechanistic perspective [9,10,11]. This is for example the case of the zebrafish, Danio rerio, a member of the order Cypriniformes (Actinopterygii, Osteichthyes) that comprises an excellent model for developmental biology studies [4,12,13]. We provide a further description of this diversity using X-ray microtomography and we map the resulting dental characters on a phylogenetic tree to explore evolutionary trends

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Results

Conclusion