title: From sea to land and beyond--new insights into the evolution of euthyneuran Gastropoda (Mollusca).
abstract: BACKGROUND
  The Euthyneura are considered to be the most successful and diverse group of Gastropoda. Phylogenetically, they are riven with controversy. Previous morphology-based phylogenetic studies have been greatly hampered by rampant parallelism in morphological characters or by incomplete taxon sampling. Based on sequences of nuclear 18S rRNA and 28S rRNA as well as mitochondrial 16S rRNA and COI DNA from 56 taxa, we reconstructed the phylogeny of Euthyneura utilising Maximum Likelihood and Bayesian inference methods. The evolution of colonization of freshwater and terrestrial habitats by pulmonate Euthyneura, considered crucial in the evolution of this group of Gastropoda, is reconstructed with Bayesian approaches.
  
  
  RESULTS
  We found several well supported clades within Euthyneura, however, we could not confirm the traditional classification, since Pulmonata are paraphyletic and Opistobranchia are either polyphyletic or paraphyletic with several clades clearly distinguishable. Sacoglossa appear separately from the rest of the Opisthobranchia as sister taxon to basal Pulmonata. Within Pulmonata, Basommatophora are paraphyletic and Hygrophila and Eupulmonata form monophyletic clades. Pyramidelloidea are placed within Euthyneura rendering the Euthyneura paraphyletic.
  
  
  CONCLUSIONS
  Based on the current phylogeny, it can be proposed for the first time that invasion of freshwater by Pulmonata is a unique evolutionary event and has taken place directly from the marine environment via an aquatic pathway. The origin of colonisation of terrestrial habitats is seeded in marginal zones and has probably occurred via estuaries or semi-terrestrial habitats such as mangroves.
authors.affiliation: Institute for Ecology, Evolution and Diversity, Biosciences, J.W. Goethe-University, 60054 Frankfurt am Main, Germany. Klussmann-Kolb@bio.uni-frankfurt.de
authors.forename: Annette
authors.initials: A
authors.lastname: Klussmann-Kolb
authors.forename: Angela
authors.initials: A
authors.lastname: Dinapoli
authors.forename: Kerstin
authors.initials: K
authors.lastname: Kuhn
authors.forename: Bruno
authors.initials: B
authors.lastname: Streit
authors.forename: Christian
authors.initials: C
authors.lastname: Albrecht
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D016009:Chi-Square Distribution; D017753:Ecosystem; D019143:Evolution, Molecular; D049851:Gastropoda / Q000145:classification* / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S