Phylogeny and Historical Biogeography of Geraniaceae in Relation to Climate Changes and Pollination Ecology

Abstract

Chloroplast (trnL–F and rbcL) sequences were used to reconstruct the phylogeny of Geraniaceae and Hypseocharitaceae. According to these data Hypseocharitaceae and Geraniaceae are monophyletic. Pelargonium and Monsonia are sisters to the largest clade of Geraniaceae, formed by Geranium, Erodium and California. According to molecular dating and dispersal-vicariance analysis, the split of the stem branches of Geraniaceae probably occurred during the Oligocene, in southern Africa or in southern Africa plus the Mediterranean area. However, their diversification occurred during the Miocene, coinciding with the beginning of major aridification events in their distribution areas. An ancestor of the largest clade of Geraniaceae (Geranium, Erodium, and California) colonised a number of habitats in the northern hemisphere and in South American mountain ranges. In summary, the evolution of the Geraniaceae is marked by the dispersal of ancestors from Southern Africa to cold, temperate and often disturbed habitats in the rest of world, where only generalist pollination and facultative autogamy could ensure sufficient seed production and survival.