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Mol Phylogenet Evol. 2010 Aug;56(2):659-74. doi: 10.1016/j.ympev.2010.04.020. Epub 2010 Apr 19.

A multi-locus time-calibrated phylogeny of the brown algae (Heterokonta, Ochrophyta, Phaeophyceae): Investigating the evolutionary nature of the "brown algal crown radiation".

Author information

1
UMR 7138, UPMC, MNHN, CNRS, IRD: Systématique, adaptation, évolution, Département Systématique & évolution, USM 603, Muséum National d'Histoire Naturelle, 75231 Paris cedex 05, France. ilberfeld@mnhn.fr

Abstract

The most conspicuous feature in previous phaeophycean phylogenies is a large polytomy known as the brown algal crown radiation (BACR). The BACR encompasses 10 out of the 17 currently recognized brown algal orders. A recent study has been able to resolve a few nodes of the BACR, suggesting that it may be a soft polytomy caused by a lack of signal in molecular markers. The present work aims to refine relationships within the BACR and investigate the nature and timeframe of the diversification in question using a dual approach. A multi-marker phylogeny of the brown algae was built from 10 mitochondrial, plastid and nuclear loci (>10,000 nt) of 72 phaeophycean taxa, resulting in trees with well-resolved inter-ordinal relationships within the BACR. Using Bayesian relaxed molecular clock analysis, it is shown that the BACR is likely to represent a gradual diversification spanning most of the Lower Cretaceous rather than a sudden radiation. Non-molecular characters classically used in ordinal delimitation were mapped on the molecular topology to study their evolutionary history.

PMID:
20412862
DOI:
10.1016/j.ympev.2010.04.020
[Indexed for MEDLINE]

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