title: A multi-locus time-calibrated phylogeny of the siphonous green algae.
abstract: The siphonous green algae are an assemblage of seaweeds that consist of a single giant cell. They comprise two sister orders, the Bryopsidales and Dasycladales. We infer the phylogenetic relationships among the siphonous green algae based on a five-locus data matrix and analyze temporal aspects of their diversification using relaxed molecular clock methods calibrated with the fossil record. The multi-locus approach resolves much of the previous phylogenetic uncertainty, but the radiation of families belonging to the core Halimedineae remains unresolved. In the Bryopsidales, three main clades were inferred, two of which correspond to previously described suborders (Bryopsidineae and Halimedineae) and a third lineage that contains only the limestone-boring genus Ostreobium. Relaxed molecular clock models indicate a Neoproterozoic origin of the siphonous green algae and a Paleozoic diversification of the orders into their families. The inferred node ages are used to resolve conflicting hypotheses about species ages in the tropical marine alga Halimeda.
authors.affiliation: Phycology Research Group and Center for Molecular Phylogenetics and Evolution, Ghent University, Krijgslaan 281, Building S8, 9000 Ghent, Belgium. heroen.verbruggen@ugent.be
authors.forename: Heroen
authors.initials: H
authors.lastname: Verbruggen
authors.forename: Matt
authors.initials: M
authors.lastname: Ashworth
authors.forename: Steven T
authors.initials: ST
authors.lastname: LoDuca
authors.forename: Caroline
authors.initials: C
authors.lastname: Vlaeminck
authors.forename: Ellen
authors.initials: E
authors.lastname: Cocquyt
authors.forename: Thomas
authors.initials: T
authors.lastname: Sauvage
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Zechman
authors.forename: Diane S
authors.initials: DS
authors.lastname: Littler
authors.forename: Mark M
authors.initials: MM
authors.lastname: Littler
authors.forename: Frederik
authors.initials: F
authors.lastname: Leliaert
authors.forename: Olivier
authors.initials: O
authors.lastname: De Clerck
mesh_terms: D001499:Bayes Theorem; D000460:Chlorophyta / Q000145:classification / Q000235:genetics*; D048028:DNA, Algal / Q000235:genetics; D019143:Evolution, Molecular; D049810:Genetic Speciation; D016013:Likelihood Functions; D008957:Models, Genetic; D010802:Phylogeny; D012624:Seaweed / Q000145:classification / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D048028:DNA, Algal