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Open Access Research article

Analyses of mitochondrial amino acid sequence datasets support the proposal that specimens of Hypodontus macropi from three species of macropodid hosts represent distinct species

Abdul Jabbar1*, Ian Beveridge1, Namitha Mohandas1, Neil B Chilton2, D Timothy J Littlewood3, Aaron R Jex1 and Robin B Gasser1*

Author Affiliations

1 Faculty of Veterinary Science, The University of Melbourne, Parkville, Melbourne, Victoria 3010, Australia

2 Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada

3 Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK

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BMC Evolutionary Biology 2013, 13:259  doi:10.1186/1471-2148-13-259

Published: 21 November 2013

Abstract

Background

Hypodontus macropi is a common intestinal nematode of a range of kangaroos and wallabies (macropodid marsupials). Based on previous multilocus enzyme electrophoresis (MEE) and nuclear ribosomal DNA sequence data sets, H. macropi has been proposed to be complex of species. To test this proposal using independent molecular data, we sequenced the whole mitochondrial (mt) genomes of individuals of H. macropi from three different species of hosts (Macropus robustus robustus, Thylogale billardierii and Macropus [Wallabia] bicolor) as well as that of Macropicola ocydromi (a related nematode), and undertook a comparative analysis of the amino acid sequence datasets derived from these genomes.

Results

The mt genomes sequenced by next-generation (454) technology from H. macropi from the three host species varied from 13,634 bp to 13,699 bp in size. Pairwise comparisons of the amino acid sequences predicted from these three mt genomes revealed differences of 5.8% to 18%. Phylogenetic analysis of the amino acid sequence data sets using Bayesian Inference (BI) showed that H. macropi from the three different host species formed distinct, well-supported clades. In addition, sliding window analysis of the mt genomes defined variable regions for future population genetic studies of H. macropi in different macropodid hosts and geographical regions around Australia.

Conclusions

The present analyses of inferred mt protein sequence datasets clearly supported the hypothesis that H. macropi from M. robustus robustus, M. bicolor and T. billardierii represent distinct species.

Keywords:
Hypodontus macropi; Mitochondrial genome; Kangaroo; Wallaby; Sliding window analysis; Next-generation sequencing; Genetics; Systematics