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a b s t r a c tWe reconstruct here the spatial and temporal evolution of the Campanula alliance in order to better understand its evolutionary history. To increase phylogenetic resolution among major groups (Wahlenbergieae-Campanuleae), new sequences from the rbcL region were added to the trnL-F dataset obtained in a previous study. These phylogenies were used to infer ancestral areas and divergence times in Campanula and related genera using a Bayesian approach to molecular dating and dispersal-vicariance analyses that takes into account phylogenetic uncertainty. The new phylogenetic analysis confirms Platycodoneae as the sister group of Wahlenbergieae-Campanuleae, the two last ones inter-graded into a well-supported clade. Biogeographic and dating analyses suggest that Western Asia and the Eastern Mediterranean have played a major role as centers of migration and diversification within the Campanula alliance, probably in relation to the intense orogenic activity that took place in this region during the Late Neogene, and that could have promoted isolation and allopatric speciation within lineages. Diversification rates within several Campanula lineages would have increased at the end of the Miocene, coinciding with the Messinian Stage. Strong selective pressures from climate changes and the expansion of mountainous regions during this period are suggested to explain the adaptation to drought, cold or disturbed environments observed in many Campanula species. Several independent long-distance dispersal events to North America are inferred within the Rapunculus clade, which seem to be related to high ploidy levels.

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.

The genus Hypericum L. ("St. John's wort", Hypericaceae) comprises nearly 500 species of shrubs, trees and herbs distributed mainly in temperate regions of the Northern Hemisphere, but also in high-altitude tropical and subtropical areas. Until now, molecular phylogenetic hypotheses on infra-generic relationships have been based solely on the nuclear marker ITS. Here, we used a full Bayesian approach to simultaneously reconstruct phylogenetic relationships, divergence times, and patterns of morphological and range evolution in Hypericum, using nuclear (ITS) and plastid DNA sequences (psbA-trnH, trnS-trnG, trnL-trnF) of 186 species representing 33 of the 36 described morphological sections. Consistent with other studies, we found that corrections of the branch length prior helped recover more realistic branch lengths in by-gene partitioned Bayesian analyses, but the effect was also seen within single genes if the overall mutation rate differed considerably among sites or regions. Our study confirms that Hypericum is not monophyletic with the genus Triadenum embedded within, and rejects the traditional infrageneric classification, with many sections being para- or polyphyletic. The small Western Palearctic sections Elodes and Adenotrias are the sister-group of a geographic dichotomy between a mainly New World clade and a large Old World clade. Bayesian reconstruction of morphological character states and range evolution show a complex pattern of morphological plasticity and inter-continental movement within the genus. The ancestors of Hypericum were probably tropical shrubs that migrated from Africa to the Palearctic in the Early Tertiary, concurrent with the expansion of tropical climates in northern latitudes. Global climate cooling from the Mid Tertiary onwards might have promoted adaptation to temperate conditions in some lineages, such as the development of the herbaceous habit or unspecialized corollas.

We here explore the use of a Bayesian approach to island biogeography for disentangling the evolutionary origins of a continental-scale floristic pattern, the enigmatic ‘Rand Flora’. The existence of disjunct distributions across many plant lineages between Macaronesia–northwest Africa, Horn of Africa–southern Arabia and east–south Africa has long intrigued botanists, but only now can we start analysing it within a statistical framework. Phylogenetic and distributional data from 13 plant lineages exhibiting this disjunct distribution were analysed to estimate area carrying capacities and historical rates of biotic exchange between areas. The results indicate that there has been little exchange between southern Africa and the northern African region, and that this exchange occurred via east Africa. Northwest Africa–Macaronesia shows the smallest carrying capacity but highest dispersal rate with other regions, suggesting that its flora was built up by immigration of lineages, probably from the Mediterranean region and western Asia. In contrast, southern Africa shows the highest carrying capacity and lowest dispersal rate, suggesting a flora formed by in situ diversification. We discuss further improvements of the method for addressing more complex hypotheses, such as asymmetric dispersal between regions or repeated cyclical events.

Transoceanic distributions have attracted the interest of scientists for centuries. Less attention has been paid to the evolutionary origins of 'continent-wide' disjunctions, in which related taxa are distributed across isolated regions within the same continent. A prime example is the 'Rand Flora' pattern, which shows sister taxa disjunctly distributed in the continental margins of Africa. Here, we explore the evolutionary origins of this pattern using the genus Canarina, with three species: C. canariensis, associated with the Canarian laurisilva, and C. eminii and C. abyssinica, endemic to the Afromontane region in East Africa, as case study. We infer phylogenetic relationships, divergence times and the history of migration events within Canarina using Bayesian inference on a large sample of chloroplast and nuclear sequences. Ecological niche modelling was employed to infer the climatic niche of Canarina through time. Dating was performed with a novel nested approach to solve the problem of using deep time calibration points within a molecular dataset comprising both above-species and population-level sampling. Results show C. abyssinica as sister to a clade formed by disjunct C. eminii and C. canariensis. Miocene divergences were inferred among species, whereas infraspecific divergences fell within the Pleistocene-Holocene periods. Although C. eminii and C. canariensis showed a strong genetic geographic structure, among-population divergences were older in the former than in the latter. Our results suggest that Canarina originated in East Africa and later migrated across North Africa, with vicariance and aridification-driven extinction explaining the 7000 km/7 million year divergence between the Canarian and East African endemics.

Phylogenetic reconstructions in the Mediterranean genus Erodium are for the first time performed using two matrices: one with 96 trnL-trnF sequences from Erodium (90 accessions plus four outgroups) and the other with 72 trnL-trnF sequences plus 23 morphological characters (66 species of a total of 74), using Maximum Parsimony (MP) and Bayesian Inference (BI). An association between reproductive properties (high selfing rates, flower asymmetry, insect-attraction structures), life form, and breeding system distributed in different lineages suggests multiple shifts from allogamy to autogamy in the course of evolution, whereas dioecy has occurred only once. The phylogenetic analyses revealed a remarkable capability for dispersal in Erodium because closely related species occur in different continents. Major lineages containing sublineages of species also from several continents lead us to interpret ancient dispersal activity. Establishment of Mediterranean-like climates in most continents may have been crucial in the evolution of Erodium, as manifested by occurrence of species of the Mediterranean floristic region in the four major lineages. The body of knowledge accumulated from molecular phylogenetics and morphology lead us to conclude that the Mediterranean region harbors the major center of diversity of Erodium, where active radiation in dry, disturbed environments, is still operating.

Geographical isolation by oceanic barriers and climatic stability has been postulated as some of the main factors driving diversification within volcanic archipelagos. However, few studies have focused on the effect that catastrophic volcanic events have had on patterns of within-island differentiation in geological time. This study employed data from the chloroplast (cpDNA haplotypes) and the nuclear (AFLPs) genomes to examine the patterns of genetic variation in Canarina canariensis, an iconic plant species associated with the endemic laurel forest of the Canary Islands. We found a strong geographical population structure, with a first divergence around 0.8 Ma that has Tenerife as its central axis and divides Canarian populations into eastern and western clades. Genetic diversity was greatest in the geologically stable 'palaeo-islands' of Anaga, Teno and Roque del Conde; these areas were also inferred as the ancestral location of migrant alleles towards other disturbed areas within Tenerife or the nearby islands using a Bayesian approach to phylogeographical clustering. Oceanic barriers, in contrast, appear to have played a lesser role in structuring genetic variation, with intra-island levels of genetic diversity larger than those between-islands. We argue that volcanic eruptions and landslides after the merging of the palaeo-islands 3.5 Ma played key roles in generating genetic boundaries within Tenerife, with the palaeo-islands acting as refugia against extinction, and as cradles and sources of genetic diversity to other areas within the archipelago.