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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/15177

Title: A Comprehensive Molecular Phylogeny of Dalytyphloplanida (Platyhelminthes: Rhabdocoela) Reveals Multiple Escapes from the Marine Environment and Origins of Symbiotic Relationships
Authors: Van Steenkiste, Niels
Tessens, Bart
Willems, Wim
Backeljau, Thierry
Jondelius, Ulf
Artois, Tom
Issue Date: 2013
Citation: PLOS ONE, 8 (3)
Abstract: In this study we elaborate the phylogeny of Dalytyphloplanida based on complete 18S rDNA (156 sequences) and partial 28S rDNA (125 sequences), using a Maximum Likelihood and a Bayesian Inference approach, in order to investigate the origin of a limnic or limnoterrestrial and of a symbiotic lifestyle in this large group of rhabditophoran flatworms. The results of our phylogenetic analyses and ancestral state reconstructions indicate that dalytyphloplanids have their origin in the marine environment and that there was one highly successful invasion of the freshwater environment, leading to a large radiation of limnic and limnoterrestrial dalytyphloplanids. This monophyletic freshwater clade, Limnotyphloplanida, comprises the taxa Dalyelliidae, Temnocephalida, and most Typhloplanidae. Temnocephalida can be considered ectosymbiotic Dalyelliidae as they are embedded within this group. Secondary returns to brackish water and marine environments occurred relatively frequently in several dalyeliid and typhloplanid taxa. Our phylogenies also show that, apart from the Limnotyphloplanida, there have been only few independent invasions of the limnic environment, and apparently these were not followed by spectacular speciation events. The distinct phylogenetic positions of the symbiotic taxa also suggest multiple origins of commensal and parasitic life strategies within Dalytyphloplanida. The previously established higher-level dalytyphloplanid clades are confirmed in our topologies, but many of the traditional families are not monophyletic. Alternative hypothesis testing constraining the monophyly of these families in the topologies and using the approximately unbiased test, also statistically rejects their monophyly.
Notes: Van Steenkiste, N (reprint author),Fisheries & Oceans Canada, Pacific Biol Stn, Dept Fisheries & Oceans, Nanaimo, BC V9R 5K6, Canada. Hasselt Univ, Ctr Environm Sci, Diepenbeek, Belgium. Univ Antwerp, Dept Biol, B-2020 Antwerp, Belgium. Royal Belgian Inst Nat Sci, Dept Invertebrates, Brussels, Belgium. Royal Belgian Inst Nat Sci, Joint Expt Mol Unit, Brussels, Belgium. Swedish Museum Nat Hist, Dept Invertebrate Zool, S-10405 Stockholm, Sweden. niels_van_steenkiste@hotmail.com
URI: http://hdl.handle.net/1942/15177
DOI: 10.1371/journal.pone.0059917
ISI #: 000317397200042
ISSN: 1932-6203
Category: A1
Type: Journal Contribution
Validation: ecoom, 2014
Appears in Collections: Research publications

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