Parasitology

Research Article

A DNA sequence-based study of the Schistosoma indicum (Trematoda: Digenea) group: population phylogeny, taxonomy and historical biogeography

S. W. ATTWOODa1a2 c1, F. A. FATIHa2, M. M. H. MONDALa3, M. A. ALIMa3, S. FADJARa4, R. P. V. J. RAJAPAKSEa5 and D. ROLLINSONa2

a1 State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu 610041, PR China

a2 Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK

a3 Department of Parasitology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh

a4 Department of Parasitology and Pathology, Faculty of Veterinary Medicine, Bogor Agricultural University (IPB), Jl. Agathis – Kampus IPB Darmaga, Bogor 16680, Indonesia

a5 Faculty of Veterinary Medicine and Animal Science, Department of Veterinary Pathobiology, University of Peradeniya, Peradeniya 20400, Sri Lanka

SUMMARY

Partial (DNA) sequences were collected for 2 mitochondrial loci (Srrna and Lrrna, the rrnS and rrnL rRNA genes respectively) for Schistosoma indicum group species from 4 Southeast Asian countries. The samples included 7 populations, 4 of which were previously unstudied. In 11 cases the combination of locus and population was new. The aim of the study was to provide a phylogeny based on new independent data and multiple populations (earlier studies had mostly used a common set of field samples or laboratory lines) and to examine interrelationships and phylogeography within this species group. Paraphyly of the S. indicum group was confirmed, as was the basal position of Schistosoma incognitum in the Schistosoma phylogeny. Southeast Asian Schistosoma spindale and S. incognitum populations were shown to fall into their respective con-specific cohesive groupings. Estimated divergence times for these taxa were shown to be related to Pleistocene changes in sea level and the radiation of definitive host groups. A revised phylogeographical model is proposed in the light of these findings.

(Received June 09 2007)

(Revised June 29 2007)

(Accepted June 29 2007)

(Online publication September 06 2007)

Correspondence:

c1 Corresponding author: State Key Laboratory of Biotherapy, Gaopeng Street, Keyuan Road 4, Chengdu 610041, China. Tel: +86 28 85164098. Fax: +86 28 85164092. E-mail: swahuaxi@yahoo.com

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