A comprehensive, genus-level time-calibrated phylogeny of the tree flora of Mediterranean Europe and an assessment of its vulnerability

ABSTRACT

We produced the first time-calibrated phylogeny of all 64 native tree genera occurring on the European side of the Mediterranean Basin. This phylogeny is based on 3 plastid DNA sequences (rbcL matK and trnH-psbA), 4 recognized fossil dates and 10 secondary calibrations. Based on the inferred topology, we then tested whether the investigated tree flora exhibits phylogenetic clustering in both life-history traits known to influence reproduction and species’ vulnerability to extinction. Our topology and the estimated dates mostly conform to published partial phylogenies and are highly congruent with the Angiosperm Phylogeny Group classification except for some minor incongruences including the still debated phylogenetic position of Magnoliids. The four strictly endemic genera of the Mediterranean Basin (Chamaerops, Phillyrea, Spartium and Tetraclinis) all showed emergence dates (11–72 Ma) long before the onset of the Mediterranean climate. We did not find any imprints of phylogenetic sorting processes on the life-history traits we studied, except for the mode of seed dispersal, which showed a clustered distribution across our topology. The presence of species at risk of potential extinction within a given genus was randomly distributed along the phylogenetic tree. Species with deficient data were significantly nested within a few of the most recently evolved angiosperm genera. Our analysis closes knowledge gaps and provides a valuable basis for studying the biogeographical and ecological processes that have generated the Mediterranean tree flora. It can also inform conservation planning strategies that aim at broadening traditional taxonomy-focused perspectives with components of evolutionary history and phylogenetic singularity.

KEYWORDS:

• Woody plants
• molecular evolution
• plastid DNA
• conservation
• mating system
• Bayesian
• Maximum likelihood

Acknowledgments

This study was funded by the French Foundation for Research on Biodiversity (FRB) through its Centre for Synthesis and Analysis of Biodiversity data (CESAB) program, as part of the WOODIV research project. And the OT-Med Laboratory of Excellence at Aix-Marseille University (n° ANR-11-LABX-0061). MCA acknowledges funding for his non-permanent employment from Sorbonne Université (Paris) and from the “Programme national d’aide à l’Accueil en Urgence des Scientifiques en Exil (PAUSE)” program of Collège de France.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contribution

MCA conceived the study, performed the analyses (phylogenetic tree and statistic) and wrote the paper, BF conceived the study and wrote the paper, AH wrote the paper, ME and LP performed the phylogenetic tree analyses, AR, IS and FB performed DNA sequencing, ACM, JA, TN, GB, FB, PD, AL, FM and GGV contributed to the writing of the manuscript. All authors revised the text and approved its final version.

Supplementary Material

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Additional information

Funding

This work was supported by the Aix-Marseille University [ANR-11-LABX-0061]; Foundation for Research on Biodiversity (FRB); Sorbonne Université.