title: Phylogenetic analysis of Thecosomata Blainville, 1824 (holoplanktonic opisthobranchia) using morphological and molecular data.
abstract: Thecosomata is a marine zooplankton group, which played an important role in the carbonate cycle in oceans due to their shell composition. So far, there is important discrepancy between the previous morphological-based taxonomies, and subsequently the evolutionary history of Thecosomata. In this study, the remarkable planktonic sampling of TARA Oceans expedition associated with a set of various other missions allowed us to assess the phylogenetic relationships of Thecosomata using morphological and molecular data (28 S and COI genes). The two gene trees showed incongruities (e.g. Hyalocylis, Cavolinia), and high congruence between morphological and 28S trees (e.g. monophyly of Euthecosomata). The monophyly of straight shell species led us to reviving the Orthoconcha, and the split of Limacinidae led us to the revival of Embolus inflata replacing Limacina inflata. The results also jeopardized the Euthecosomata families that are based on plesiomorphic character state as in the case for Creseidae which was not a monophyletic group. Divergence times were also estimated, and suggested that the evolutionary history of Thecosomata was characterized by four major diversifying events. By bringing the knowledge of palaeontology, we propose a new evolutionary scenario for which macro-evolution implying morphological innovations were rhythmed by climatic changes and associated species turn-over that spread from the Eocene to Miocene, and were shaped principally by predation and shell buoyancy.
authors.affiliation: IMBE (UMR CNRS 7263, IRD 237) Evolution Génome Environnement, Aix-Marseille Université, Marseille, France. Emmanuel.corse@gmail.com
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Corse
authors.forename: Jeannine
authors.initials: J
authors.lastname: Rampal
authors.forename: Corinne
authors.initials: C
authors.lastname: Cuoc
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pech
authors.forename: Yvan
authors.initials: Y
authors.lastname: Perez
authors.forename: André
authors.initials: A
authors.lastname: Gilles
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D030541:Databases, Genetic; D003576:Electron Transport Complex IV / Q000235:genetics; D019143:Evolution, Molecular; D049851:Gastropoda / Q000033:anatomy & histology* / Q000145:classification*; D010802:Phylogeny; D012339:RNA, Ribosomal, 28S / Q000235:genetics
chemical_list: D012339:RNA, Ribosomal, 28S; D003576:Electron Transport Complex IV