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Molecular Phylogenetic Evidence Refuting the Hypothesis of Batoidea (Rays and Skates) as Derived Sharks
Molecular Phylogenetics and Evolution
  • Christophe J. Douady, Dalhousie University - Canada
  • Mine Dosay, Queen's University - Belfast
  • Mahmood S. Shivji, Nova Southeastern University
  • Michael Stanhope, Queen's University - Belfast
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Early morphological studies regarding the evolutionary history of elasmobranchs suggested sharks and batoids (skates and rays) were respectively monophyletic. More modern morphological cladistic studies, however, have tended to suggest that batoids are derived sharks, closely related to sawsharks and angelsharks, a phylogenetic arrangement known as the Hypnosqualea hypothesis. Very few molecular studies addressing interordinal relationships of elasmobranchs have been published; the few that do exist, are very limited in terms of both taxon representation and/or aligned sequence positions, and are insufficient to answer the question of whether batoids are derived sharks. The purpose of this study was to address this issue with more complete taxon representation, concomitant with a reasonable number of aligned sequence positions. The data set included a 2.4-kb segment of the mitochondrial 12S rRNA—tRNA valine—16S rRNA locus, and in terms of taxa, representatives of two orders of Batoidea, at least one representative of all orders of sharks, and as an outgroup, the widely recognized sister group to elasmobranchs—Holocephali. The results provide the first convincing molecular evidence for shark monophyly and the rejection of the Hypnosqualea hypothesis. Our phylogenetic placement of batoids as a basal elasmobranch lineage means that much of the current thinking regarding the evolution of morphological and life history characteristics in elasmobranchs needs to be re-evaluated.


Copyright © 2002 Elsevier Science (USA). All rights reserved.

Additional Comments
This work was made possible by an infrastructure operating grant to M.J.S., from The Queen’s University of Belfast and via a Florida Sea Grant and Hai Stiftung Foundation grant to M.S.S. M.D. was supported by a studentship award from the Turkish Ministry of Education and Canakkale 18 Mart University. C.J.D. was supported by a Killam Postdoctoral Fellowship.
Citation Information
Christophe J. Douady, Mine Dosay, Mahmood S. Shivji and Michael Stanhope. "Molecular Phylogenetic Evidence Refuting the Hypothesis of Batoidea (Rays and Skates) as Derived Sharks" Molecular Phylogenetics and Evolution Vol. 215 Iss. 2 (2003) p. 215 - 221 ISSN: 1055-7903
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