Table 1.
Different classification schemes of the genus Fraxinus, including the revisions proposed in this study, and geographic distributions of species.
Table 2.
Sequence variation and parameters of phylogenetic analyses for the various datasets used to estimate the phylogeny of Fraxinus.
Figure 1.
Phylogenetic tree resulting from BIM analysis of the combined dataset (cpDNA, ETS, ITS and phantastica).
Posterior probabilities ≥0.50 are indicated below the branches. Tree nodes that involve floral changes and the relative likelihoods of floral states are indicated by circles: black, complete flower (calyx+corolla); grey, incomplete flower (loss of corolla or calyx); white, naked flower (no calyx or corolla). On the right, schematic floral character states are shown at the tip of the branches. On the right, sections are indicated by vertical bars; the dotted line indicates the occurrence of F. platypoda, previously placed in the section Fraxinus [4], but here shown to be closely related to the incertae sedis species.
Figure 2.
a. Chronogram generated from BEAST analysis and estimations of times of divergence and diversification of sections in Fraxinus (in mya), and showing the results from Lagrange analysis.
Bars at nodes represent the 95% confidence interval; stars indicate the calibration nodes. Map showing the colours used to identify the areas of occurrence of Fraxinus species: red, North America (Am); green, Asia (As); blue, Europe (Eu); yellow, North Africa. The same colours were used on the tree to indicate the reconstructed geographic range across the branches and nodes. For the Lagrange results, a slash indicates the split of areas into two daughter lineages, namely, left/right, where “up” and “down” are the ranges inherited by each descendant branch. The values in brackets represent relative probabilities. When a node has alternative scenarios within 2 log-likelihood units of the optimal reconstruction, the relative probability (fraction of the global likelihood) for the optimal reconstruction is indicated with a smaller font. Circles on nodes indicate migration events or vicariance processes as inferred according to the Lagrange analysis. b. Semilogarithmic Lineage Through Time (LTT) plot (solid line) averaged over 135,000 posterior trees from the BIM analysis: right axis, the solid line represents the cumulative number of lineages and the blue area, the 95% confidence interval; in dark grey, plot of the global deep-sea temperature and its variance, with temperature estimates, geological and biological events reported elsewhere [44]; age in millions of years.
Table 3.
Estimated times for observed divergence and diversification events in the genus Fraxinus.
Figure 3.
Map illustrating major events in the biogeographic history of the genus Fraxinus.
(a) The genus likely appeared in North America (1), the section Dipetalae diverging early (2). (b) Diversifications leading to the sections Melioides and later Pauciflorae (3) in North America were followed by migrations to Asia, leading to the sections Ornus (4) and to the Asian species of the section Melioides (5). (c) The section Sciadanthus expanded in Eurasia and Africa (6), (d) followed by the divergence of the Asian section Fraxinus (7) and the migration of a lineage leading to F. nigra in North America (8). More recently, the differentiation of F. mandshurica in Asia and transcontinental expansion of the lineage towards Europe (9) resulted in the observed geographical diversity of the section Fraxinus throughout Eurasia.