Carex sect. Rhynchocystis (Cyperaceae): a Miocene subtropical relict in the Western Palaearctic showing a dispersal-derived Rand Flora pattern

Aim To evaluate how Cenozoic climate changes shaped the evolution and distribution of Carex section Rhynchocystis. Location Western Palaearctic and Afrotropical regions (Rand Flora pattern). Methods DNA regions ITS, ETS (nuclear), matK and rpl32-trnLUAG (plastid) were amplified for 86 samples of species from section Rhynchocystis. Phylogenetic and phylogeographical relationships were inferred using maximum parsimony, Bayesian inference and coalescent-based species tree approaches. Divergence times and ancestral areas were also inferred. Results Carex section Rhynchocystis is a clade that diversified during the middle Miocene in Europe. Most cladogenesis events date to the middle and late Miocene. The Afrotropical group seems to have originated from a colonization event from Europe that occurred in the late Miocene. Main conclusions Species of the section Rhynchocystis in the Western Palaearctic are Miocene relicts. Late Miocene-Pliocene aridification of the Mediterranean rather than the more commonly reported Pleistocene glaciations seems to have shaped the phylogeography of the group. Putative Miocene-Pliocene refugia were probably located in the Mediterranean peninsulas and islands, as well as in the eastern shores of the ancient Paratethys Sea. The colonization of Africa could have been facilitated by Miocene-Pliocene global cooling.