The evolutionary position of nematodes

Jaime E. Blair, Kazuho Ikeo, Takashi Gojobori, S. Blair Hedges*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

158 Scopus citations

Abstract

Background: The complete genomes of three animals have been sequenced by global research efforts: a nematode worm (Caenorhabditis elegans), an insect (Drosophila melanogaster), and a vertebrate (Homo sapiens). Remarkably, their relationships have yet to be clarified. The confusion concerns the enigmatic position of nematodes. Traditionally, nematodes have occupied a basal position, in part because they lack a true body cavity. However, the leading hypothesis now joins nematodes with arthropods in a molting clade, Ecdysozoa, based on data from several genes. Results: We tested the Ecdysozoa hypothesis with analyses of more than 100 nuclear protein alignments, under conditions that would expose biases, and found that it was not supported. Instead, we found significant support for the traditional hypothesis, Coelomata. Our result is robust to different rates of sequence change among genes and lineages, different numbers of taxa, and different species of nematodes. Conclusion: We conclude that insects (arthropods) are genetically and evolutionarily closer to humans than to nematode worms.

Original languageEnglish (US)
Article number7
JournalBMC Evolutionary Biology
Volume2
DOIs
StatePublished - Apr 8 2002

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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