title: A time-calibrated multi-gene phylogeny of the diatom genus Pinnularia.
abstract: Pinnularia is an ecologically important and species-rich genus of freshwater diatoms (Bacillariophyceae) showing considerable variation in frustule morphology. Interspecific evolutionary relationships were inferred for 36 Pinnularia taxa using a five-locus dataset. A range of fossil taxa, including newly discovered Middle Eocene forms of Pinnularia, was used to calibrate a relaxed molecular clock analysis and investigate temporal aspects of the genus' diversification. The multi-gene approach resulted in a well-resolved phylogeny of three major clades and several subclades that were frequently, but not universally, delimited by valve morphology. The genus Caloneis was not recovered as monophyletic, confirming that, as currently delimited, this genus is not evolutionarily meaningful and should be merged with Pinnularia. The Pinnularia-Caloneis complex is estimated to have diverged between the Upper Cretaceous and the early Eocene, implying a ghost range of at least 10 million year (Ma) in the fossil record.
authors.affiliation: Laboratory of Protistology and Aquatic Ecology, Ghent University, Krijgslaan 281 - S8, 9000 Gent, Belgium.
authors.forename: Caroline
authors.initials: C
authors.lastname: Souffreau
authors.forename: Heroen
authors.initials: H
authors.lastname: Verbruggen
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Wolfe
authors.forename: Pieter
authors.initials: P
authors.lastname: Vanormelingen
authors.forename: Peter A
authors.initials: PA
authors.lastname: Siver
authors.forename: Eileen J
authors.initials: EJ
authors.lastname: Cox
authors.forename: David G
authors.initials: DG
authors.lastname: Mann
authors.forename: Bart
authors.initials: B
authors.lastname: Van de Vijver
authors.forename: Koen
authors.initials: K
authors.lastname: Sabbe
authors.forename: Wim
authors.initials: W
authors.lastname: Vyverman
mesh_terms: D001499:Bayes Theorem; D002138:Calibration; D030561:Databases, Nucleic Acid; D017377:Diatoms / Q000145:classification / Q000235:genetics* / Q000648:ultrastructure; D005580:Fossils; D005796:Genes / Q000235:genetics*; D010802:Phylogeny; D013997:Time Factors