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A review of 27 angiosperm clades (26 genera) of species-rich and species-poor plant groups of the Mediterranean floristic region was performed with phylogenetic and biological trait data., The emergent pattern is that a majority of Mediterranean plant clades split from their sister groups between the Miocene (23-5 Ma) and the Oligocene (34-23 Ma), far earlier than the onset of the Mediterranean climate (ca. 3.2 Ma). In addition, 12 of 14 clades of the species-poor group have stem ages inferred for each clade in the Miocene or older, and six of 13 clades within the species-rich group show divergence of each stem clade within the Oligocene and/or Miocene., High levels of species diversity are related to an ancient (Paleocene-Miocene) origin and also to recent origin (Pliocene-Pleistocene) followed by active speciation and even explosive radiations: some species and lineages diversified over a short period ( Aquilegia, Cistus, Dianthus, Linaria sect. Supinae, Reseda). In the species-rich group, key reproductive characters were found to be significantly more important for species recognition than key vegetative characters in eight clades, but no difference was found in four clades, and vegetative characters were predominant in one clade ( Saxifraga). Geographical differentiation is proposed as predominant over divergence driven by pollination ecology., We hypothesise an evolutionary process in which lineages adapted to pre-Mediterranean (pre-Pliocene) conditions in relatively small, xeric areas became strongly competitive and expanded as the Mediterranean climate became dominant (Pliocene-Quaternary) across the Mediterranean Basin. [ABSTRACT FROM AUTHOR]

Aim We investigated genetic divergence among two widespread eastern Australian orchids ( Dendrobium sect. Dendrocoryne): Dendrobium speciosum and Dendrobium tetragonum. These orchids are endemic to mesic habitats, with distributional ranges that cross major geographical breaks associated with deep divergences in various fauna. We compared the biogeography of these orchids with other taxa and tested for congruence of divergence date estimations. Location Eastern Australia, latitude 14° S to 34° S. Methods Phylogenetic relationships within each species were estimated using maximum parsimony based on sequences of internal transcribed spacer (ITS) regions of nuclear ribosomal DNA and the psbA- trnH spacer region of plastid DNA. Divergence dates were inferred by Bayesian relaxed-clock dating, calibrated on an early Miocene macrofossil, Dendrobium winikaphyllum from New Zealand. Results Deep divergences were revealed within each species. Dendrobium speciosum includes three major geographical clades (deepest 2.6% ITS divergence): a northern Queensland clade, which occurs mainly to the north of the Black Mountain Corridor ( BMC) in the Wet Tropics; a central Queensland clade; and a southern clade related to the central clade and separated from it by a dry corridor, the St Lawrence Gap ( SLG). The central and northern lineages show overlap near the BMC. Divergence in this area is estimated to date from the Pliocene, possibly late Miocene, 4.3 (2.0-6.9) Ma, and at the SLG in the early Pleistocene, possibly late Pliocene, 2.0 (0.6-3.8) Ma. Dendrobium tetragonum also includes two clades, deeply divergent (3%) at the SLG, estimated as Pliocene in age but possibly latest Miocene, 3.7 (1.8-5.9) Ma. Main conclusions Dendrobium orchids reveal significant divergence associated with geographical breaks in eastern Australia, the SLG and BMC, patterns broadly concordant with findings for fauna. We infer that divergences were driven by topographical and climatic conditions, with contraction and fragmentation of mesic biomes during periods of drying in the late Neogene. [ABSTRACT FROM AUTHOR]