Parasitology

Research Article

A novel phylogeny for the genus Echinococcus, based on nuclear data, challenges relationships based on mitochondrial evidence

U. SAARMAa1 c1, I. JÕGISALUa1a2, E. MOKSa1, A. VARCASIAa3, A. LAVIKAINENa4, A. OKSANENa5, S. SIMSEKa6, V. ANDRESIUKa7, G. DENEGRIa7, L. M. GONZÁLEZa8, E. FERRERa8a9, T. GÁRATEa8, L. RINALDIa10 and P. MARAVILLAa11

a1 Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, 51014, Tartu, Estonia

a2 Department of Game Monitoring, Centre of Forest Protection and Silviculture, Rõõmu tee 2, 51013, Tartu, Estonia

a3 Dipartimento di Biologia Animale Sezione di Parassitologia e Malattie Parassitarie, Università degli Studi di Sassari, Via Vienna 2, 07100, Sassari

a4 Department of Bacteriology and Immunology (FINPAR), Haartman Institute, P.O. Box 21, FI-00014 University of Helsinki, Finland

a5 Finnish Food Safety Authority Evira, Fish and Wildlife Health Research Unit (FINPAR), P.O. Box 517, FI-90101 Oulu, Finland

a6 Department of Parasitology, Faculty of Veterinary Medicine, University of Firat, 23119, Elazig, Turkey

a7 Laboratory of Parasitic Zoonoses, Department of Biology, FCEyN, Mar del Plata National University, Funes 3350, CP 7600, Mar del Plata, Buenos Aires, Argentina (CONICET)

a8 Instituto de Salud Carlos III, Centro Nacional de Microbiología, Ctra. Majadahonda Pozuelo Km 2,2, 28220 Majadahonda, Madrid, Spain

a9 Departamento de Parasitología and Instituto de Investigaciones Biomédicas (BIOMED), Universidad de Carabobo, Maracay, Venezuela

a10 Department of Pathology and Animal Health, Faculty of Veterinary Medicine, University of Naples Federico II, Naples, Italy

a11 Direccion de Investigacion, Hospital General “Dr. Manuel Gea Gonzalez”, SSA, Mexico DF, Mexico

SUMMARY

The taxonomic status of Echinococcus, an important zoonotic cestode genus, has remained controversial, despite numerous attempts to revise it. Although mitochondrial DNA (mtDNA) has been the source of markers of choice for reconstructing the phylogeny of the genus, results derived from mtDNA have led to significant inconsistencies with earlier species classifications based on phenotypic analysis. Here, we used nuclear DNA markers to test the phylogenic relationships of members of the genus Echinococcus. The analysis of sequence data for 5 nuclear genes revealed a significantly different phylogeny for Echinococcus from that proposed on the basis of mitochondrial DNA sequence data, but was in agreement with earlier species classifications. The most notable results from the nuclear phylogeny were (1) E. multilocularis was placed as basal taxon, (2) all genotypes of Echinococcus granulosus grouped as a monophyletic entity, and (3) genotypes G8 and G10 clustered together. We conclude that the analysis of nuclear DNA data provides a more reliable means of inferring phylogenetic relationships within Echinococcus than mtDNA and suggest that mtDNA should not be used as the sole source of markers in future studies where the goal is to reconstruct a phylogeny that does not only reflect a maternal lineage, but aims to describe the evolutionary history at species level or higher.

(Received October 02 2008)

(Revised November 11 2008)

(Accepted November 12 2008)

(Online publication January 21 2009)

Correspondence:

c1 Corresponding author: Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, 51014, Tartu, Estonia. Tel: +37 27375099. Fax: +37 27375830. E-mail: Urmas.Saarma@ut.ee

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