Phylogeny of the Centaurea group (Centaurea, Compositae) - geography is a better predictor than morphology.
The Centaurea group is part of the Circum-Mediterranean Clade (CMC) of genus Centaurea subgenus Centaurea, a mainly Mediterranean plant group with more than 200 described species. The group is traditionally split on morphological basis into three sections: Centaurea, Phalolepis and Willkommia. This division, however, is doubtful, especially in light of molecular approaches. In this study we try to resolve this phylogenetic problem and to consolidate the circumscription and delimitation of the entire group against other closely related groups. We analyzed nuclear (internal transcribed spacer of the ribosomal genes) and chloroplast (rpl32-trnL intergenic spacer) DNA regions for most of the described species of the Centaurea group using phylogenetic and network approaches, and we checked the data for recombination. Phylogeny was used to reconstruct the evolution of the lacerate-membranaceous bract appendages using parsimony. The magnitude of incomplete lineage sorting was tested estimating the effective population sizes. Molecular dating was performed using a Bayesian approach, and the ancestral area reconstruction was conducted using the Dispersal-Extinction-Cladogenesis method. Monophyly of the Centaurea group is confirmed if a few species are removed. Our results do not support the traditional sectional division. There is a high incongruence between the two markers and between genetic data and morphology. However, there is a clear relation between geography and the structure of the molecular data. Diversification in the Centaurea group mainly took place during the Pliocene and Pleistocene. The ancestral area infered for the Circum-Mediterranean Clade of Centaurea is the Eastern Mediterranean, whereas for the Centaurea group it is most likely NW-Africa. The large incongruencies, which hamper phylogenetic reconstruction, are probably the result of introgression, even though the presence of incomplete lineage sorting as an additional factor cannot be ruled out. Convergent evolution of morphological traits may have led to incongruence between morphology-based, traditional systematics and molecular results. Our results also cast major doubts about current species delimitation.
Institut Botànic de Barcelona (IBB-CSIC-ICUB), Pg. del Migdia s/n, ES-08038 Barcelona, Spain. Electronic address: andreas.hilpold@yahoo.de.
Andreas
A
Hilpold
Institut Botànic de Barcelona (IBB-CSIC-ICUB), Pg. del Migdia s/n, ES-08038 Barcelona, Spain.
Roser
R
Vilatersana
Institut Botànic de Barcelona (IBB-CSIC-ICUB), Pg. del Migdia s/n, ES-08038 Barcelona, Spain.
Alfonso
A
Susanna
Real Jardín Botánico de Madrid (RJB-CSIC), Plaza de Murillo, 2, ES-28014 Madrid, Spain.
Andrea S
AS
Meseguer
State Institute for Nature Protection, Trg. Mažuranića 5, HR-10000 Zagreb, Croatia.
Igor
I
Boršić
Department of Ecology & Systematics, Faculty of Biology, National & Kapodistrian University of Athens, Panepistimiopolis, GR-15784 Athens, Greece.
Theophanis
T
Constantinidis
Dipartimento di Scienze Botaniche, Ecologiche e Geologiche, Università degli Studi di Sassari, Via Piandanna 4, I-07100 Sassari, Italy.
Rossella
R
Filigheddu
Institut Botànic de Barcelona (IBB-CSIC-ICUB), Pg. del Migdia s/n, ES-08038 Barcelona, Spain.
Konstantin
K
Romaschenko
Departamento de Botánica, Facultad de Ciencias, Universidad de Granada, Severo Ochoa s/n, ES-18071 Granada, Spain.
Víctor N
VN
Suárez-Santiago
Faculty of Science and Art, Selçuk University, TR-42031 Konya, Turkey.
Osman
O
Tugay
Faculty of Science and Art, Selçuk University, TR-42031 Konya, Turkey.
Tuna
T
Uysal
Department of Biological and Environmental Sciences, University of Göteborg, Box 461, SE-40530 Göteborg, Sweden.
Bernard E
BE
Pfeil
Institut Botànic de Barcelona (IBB-CSIC-ICUB), Pg. del Migdia s/n, ES-08038 Barcelona, Spain.
Núria
N
Garcia-Jacas
D000349:Africa; D001499:Bayes Theorem; D031179:Centaurea / Q000033:anatomy & histology / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D049810:Genetic Speciation; D010802:Phylogeny; D058974:Phylogeography; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA
D018744:DNA, Plant
Centaurea; Hybridization; Incomplete lineage sorting; Mediterranean; Molecular dating; Phylogenetic incongruence