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Title: MOLECULAR VIEW OF THE SUPERFAMILY DIOCTOPHYMATOIDEA (NEMATODA)

Author
item KOEHLER, ANSON V A - U NEW MEXICO
item TORRES-PEREZ, FERNANDO - U NEW MEXICO
item Hoberg, Eric
item COOK, JOSEPH - U NEW MEXICO

Submitted to: Comparative Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2008
Publication Date: 1/1/2009
Citation: Koehler, A., Torres-Perez, F., Hoberg, E.P., Cook, J.A. 2009. Molecular view of the superfamily Dioctophymatoidea (Nematoda). Comparative Parasitology. 76(1):100-104.

Interpretive Summary: Nematodes are among the most ubiquitous of parasites and pathogens in human, domestic and wildlife hosts throughout the world. The origins of associations for parasites and their host, however, continue to remain obscure. In this regard, we explored the phylogenetic (genealogical) relationships of parasitic nematodes considered to be among the most primitive among this diverse organismal group. Monophyly of the superfamily Dioctophymatoidea using 3 constituent genera was tested using analysis of DNA sequence variation. Phylogenetic reconstruction involved different algorithms including maximum parsimony, maximum likelihood and Bayesian inference of 18s nuclear DNA (786 base-pair segment) and mitochondrial cytochrome oxidase I (293 bp) genes. Dioctophymatoids are sister to Trichocephaloidea which includes Trichinella and Trichuris, parasites of considerable economic and medical importance. Dioctophymatoidea includes a group with Dioctophyme renale + Eustrongylides ignotus (Dioctophymatidae) as the sister of Soboliphyme baturini, S. jamesoni and S. abei (Soboliphymatidae). Our studies corroborated the basal position for Dioctophymatoidea within the Nematoda. This relationship is indicative of ancient, historically deep and multiple origins of parasitism for nematodes among vertebrate hosts. Further insights are supported about a role for host-switching (acquisition of new hosts and host-groups) in contrast to deep coevolution in the origins of species in this group of parasites. Findings constitute fundamental information in a broadened understanding of the process that shape diversity for complex host-parasite systems, including those which affect humans and an array of associated domestic and wildlife species.

Technical Abstract: Monophyly of the superfamily Dioctophymatoidea using 3 constituent genera was tested using a multilocus analysis of DNA sequence variation. Phylogenetic reconstruction involved maximum parsimony, maximum likelihood and Bayesian inference of 18s nuclear DNA (786 bp segment) and mitochondrial cytochrome oxidase 1 (293 bp) genes. Dioctophymatoids are sister to Trichocephaloidea. Dioctophymatoidea includes a clade with Dioctophyme renale + Eustrongylides ignotus (Dioctophymatidae) as the sister of Soboliphyme baturini, S. jamesoni and S. abei (Soboliphymatidae). The basal position for Dioctophymatoidea within the Nematoda is corroborated and indicative of historically deep and multiple origins of parasitism among vertebrate hosts. A secondary radiation among soricids following a host colonization from mustelids is suggested.