Despite most angiosperms being perennial, once-flowering annuals have evolved multiple times independently, making life history traits among the most labile trait syndromes in flowering plants. Much research has focused on discerning the adaptive forces driving the evolution of annual species, and in pinpointing traits that distinguish them from perennials. By contrast, little is known about how ‘annual traits’ evolve, and whether the same traits and genes have evolved in parallel to affect independent origins of the annual syndrome. Here, we review what is known about the distribution of annuals in both phylogenetic and environmental space and assess the evidence for parallel evolution of annuality through similar physiological, developmental, and/or genetic mechanisms. We then use temperate grasses as a case study for modeling the evolution of annuality and suggest future directions for understanding annual-perennial transitions in other groups of plants. Understanding how convergent life history traits evolve can help predict species responses to climate change and allows transfer of knowledge between model and agriculturally important species.

Premise of research. Geothermal areas create living conditions strikingly different from their surroundings, providing opportunities for studying organisms' thermal adaptations and responses to climate warming. However, the origins of geothermal organisms are poorly known, limiting our ability to design and interpret experimental studies. To address this, we tested whether geothermal populations of Agrostis (Poaceae) in Iceland represent a single lineage (clade) and, if so, whether that lineage originated in adjacent, nonthermal areas or elsewhere.Methodology. We studied the phylogeography of A. stolonifera and A. vinealis from geothermally heated and nonheated areas in Iceland, using whole plastome data and Bayesian and likelihood phylogenetic analyses. Having identified an exclusively geothermal clade for A. stolonifera, we performed a common-garden experiment to test for heritable phenotypic differences between geothermal and nonthermal plants.Pivotal results. At least two lineages of A. stolonifera have colonized Iceland independently, one being exclusively geothermal and the other exclusively nonthermal. The geothermal lineage is phylogenetically isolated, and its geographical origin could not be determined. Grown in a common garden, geothermal A. stolonifera produced significantly shorter stolons than nonthermal plants. In contrast, geothermal A. vinealis did not form a clade. Instead, all Icelandic A. vinealis formed a clade with nonthermal A. vinealis from outside of Iceland, plus geothermal A. rossiae and A. scabra.Conclusions. We demonstrate the existence of an exclusively geothermal lineage of A. stolonifera, which also shows heritable phenotypic differences, but not of A. vinealis. These contrasting findings possibly reflect different growth forms and life histories. Our results provide a phylogenetic hypothesis to be tested with nuclear data and a framework for future experimental studies, highlighting the importance of a historical perspective for understanding the peculiar plant communities that thrive in geothermal areas. Finally, our results suggest A. vinealis is in need of taxonomic revision.

PREMISE OF THE STUDY: The Western Indian Ocean Region (WIOR) is a biodiversity hotspot providing an ideal setting for exploring the origins of insular biodiversity and dynamics of island colonization. We aimed to investigate the origins of the WIOR Psychotrieae alliance (Rubiaceae) with typically small, probably mainly bird-dispersed drupes, and the timing and direction or sequence of its colonization events in the region.

METHODS: We used the program BEAST to estimate divergence times and Lagrange for biogeographic reconstruction.

KEY RESULTS: The alliance has reached the WIOR at least 14 times via dispersals from Africa along with Asia and the Pacific mostly during the last 10 My, with at least one back-colonization to Africa. We inferred the earliest dispersal to Madagascar from the Pacific or Asia in the Miocene and numerous out-of-Madagascar dispersals to the nearby archipelagos but no dispersal out of those archipelagos. Gynochthodes with multiple fruits reached Madagascar twice from the Pacific possibly via ocean drifting. Psychotria with dry fruits (schizocarps) colonized Madagascar from the Pacific or Asia before reaching the Comoros from Madagascar possibly via wind dispersal.

CONCLUSIONS: This study reinforces the pivotal role of dispersal in shaping the WIOR biodiversity and as the critical initiating step in the generation of endemic biodiversity on its islands. The WIOR alliance shows strong Asian and Pacific affinities despite the proximity of the region to Africa. Madagascar has served as a stepping-stone for subsequent dispersal to the rest of the region. The Afro-Malagasy-Seychelles genus Craterispermum and the Malagasy Puffia may represent relictual lineages.

Aim The Western Indian Ocean region (WIOR) is home to a very diverse and largely unique flora that has mainly originated via long-distance dispersals. The aim of this study is to gain insight into the origins of the WIOR biodiversity and to understand the dynamics of colonization events between the islands. We investigate spatial and temporal hypotheses of the routes of dispersal, and compare the dispersal patterns of plants of the Coffeeae alliance (Rubiaceae) and their dispersers. Rubiaceae is the second most species-rich plant family in Madagascar, and includes many endemic genera. The neighbouring archipelagos of the Comoros, Mascarenes and Seychelles also harbour several endemic Rubiaceae.

Location The islands of the Western Indian Ocean.

Methods Phylogenetic relationships and divergence times were reconstructed from plastid DNA data of an ingroup sample of 340 species, using Bayesian inference. Ancestral areas and range evolution history were inferred by a maximum likelihood method that takes topological uncertainty into account.

Results At least 15 arrivals to Madagascar were inferred, the majority of which have taken place within the last 10 Myr. Most dispersal events were supported as being from mainland Africa, but Catunaregam may have dispersed from Asia. Although most Coffeeae alliance lineages are zoochorous, the general pattern of dispersals from Africa is incongruent with the biogeographic origins of the extant Malagasy volant frugivores. Several out-of-Madagascar dispersals were inferred to the neighbouring islands, as well as back-colonizations of Africa.

Main conclusions The African flora has been of foremost importance as source of dispersal to the islands of the Western Indian Ocean. Following the colonization of Madagascar, rapid radiations appear to have taken place in some clades, and Madagascar has also been an important source area for subsequent dispersal to the Comoros, Mascarenes and Seychelles.

Divergence time analyses in the coffee family (Rubiaceae) have all relied on the same Gentianales crown group age estimate, reported by an earlier analysis of the asterids, for defining the upper age bound of the root node in their analyses. However, not only did the asterid analysis suffer from several analytical shortcomings, but the estimate itself has been used in highly inconsistent ways in these Rubiaceae analyses. Based on the original data, we here reanalyze the divergence times of the asterids using relaxed-clock models and 14 fossil-based minimum age constraints. We also expand the data set to include an additional 67 taxa from Rubiaceae sampled across all three subfamilies recognized in the family. Three analyses are conducted: a separate analysis of the asterids, which completely mirrors the original asterid analysis in terms of taxon sample and data; a separate analysis of the Gentianales, where the result from the first analysis is used for defining a secondary root calibration point; and a combined analysis where all taxa are analyzed simultaneously. Results are presented in the form of a time-calibrated phylogeny, and age estimates for asterid groups, Gentianales, and major groups of Rubiaceae are compared and discussed in relation to previously published estimates. Our updated age estimates for major groups of Rubiaceae provide a significant step forward towards the long term goal of establishing a robust temporal framework for the divergence of this biologically diverse and fascinating group of plants.

A new species of Chapelieria was discovered during a recent field trip to the Masoala National Park in eastern Madagascar, and is described here as Chapelieria magna Kainul., sp. nov. This species is readily distinguishable from previously described species of the genus by its quadrangular shoots, triangular-calyptrate stipules, sessile leaves, pubescent styles, and ridged fruits. It also differs in the larger number of ovules and the much larger size of leaves and fruits.

In this study we investigate the large and diverse Rubiaceae-Gardenieae and closely related tribes Bertiereae, Coffeeae, Cremasporeae, Octotropideae, and Pavetteae. Some of the tribes or groups have been shown to be monophyletic and strongly supported, but the phylogeny of this large complex is still far from being satisfactorily elucidated particularly for Gardenieae, both in terms of intertribal relationships as well as tribal delimitations. We reconstruct the phylogeny of the complex using an extensive sampling of 108 genera and five plastid DNA regions. Phylogenetic relationships demonstrate that Gardenieae sensu Andreasen & Bremer is polyphyletic, as Burchellia, Didymosalpinx, Monosalpinx, and Mantalania are closer to Octotropideae-Cremasporeae. In addition, Pavetteae and the investigated members of Aulacocalyceae are nested in a supported but partially unresolved Gardenieae-Pavetteae clade. Within this clade, several strongly supported groups are resolved: an Aidia group, an Alibertia group, a Gardenia group, Pavetteae including Pelagodendron, a Porterandia group, a Randia group, a Rothmannia group (including Aulacocalyx and Heinsenia), a Sherbournia group, and the two isolated genera Massularia and Schumanniophyton. The latter genus presented a high rate of genetic substitutions, which resulted in perturbations of the phylogenetic reconstruction. A revised tribal circumscription is given for Gardenieae, the Alibertia group is recognized at tribal level as an emended Cordiereae, and a new tribe, Sherbournieae, is described to accommodate the members of the Sherbournia group.

We performed molecular phylogenetic analyses of the Randia clade of the tribe Gardenieae using both plastid and nuclear DNA data. In the phylogenetic hypotheses presented, the African genera Calochone, Euclinia, Macrosphyra, Oligocodon, Pleiocoryne, and Preussiodora are resolved as a monophyletic group. Support is also found for a clade of the Neotropical genera Casasia, Randia, Rosenbergiodendron, Sphinctanthus, and Tocoyena. This Neotropical clade is resolved as sister group to the African clade in analyses of combined plastid and nuclear data. The genus Euclinia appears polyphyletic. The species described from Madagascar represent an independent lineage, the position of which is moreover found to be incongruent between datasets. Plastid and ribosomal DNA data support a sister-group relationship to the mainland African clade, whereas the low-copy nuclear gene Xdh supports a closer relationship to the Neotropical genera. The phylogenetic reconstructions also indicate that Casasia and Randia are not monophyletic as presently circumscribed. A taxonomic proposal is made for the recognition of the Malagasy taxon at generic level as Melanoxerus.

Subfamily Ixoroideae is one of three major lineages in Rubiaceae, with approximately 4000 species. Previous molecular phylogenetic studies have indicated that many genera and tribes previously placed in other subfamilies are better considered as part of Ixoroideae. However, the internal resolution and clade support have generally been low, and several genera found to be nested in the subfamily do not appear to be associated with any described tribe. In order to resolve the phylogeny and assess the tribal delimitations in the expanded Ixoroideae, phylogenetic reconstructions were performed using Bayesian and parsimony analyses of six plastid DNA regions and a broad sampling of genera from all tribes of the subfamily. In the inferred phylogenetic hypotheses, the tribal relationships were mostly well supported, with Ixoroideae consisting of the Coffeeae and the Vanguerieae alliances as sister groups and a grade comprising Condamineeae, Henriquezieae, Posoquerieae, Retiniphylleae, Sipaneeae and the genus Steenisia. A revised tribal classification, including the description of five new tribes, Airospermeae, Augusteae, Scyphiphoreae, Steenisieae and Trailliaedoxeae, is provided.

Many monotypic genera with unique apomorphic characters have been difficult to place in the morphology-based classifications of the coffee family (Rubiaceae). We rigorously assessed the subfamilial phylogenetic position and generic status of three enigmatic genera, the Seychellois Glionnetia, the Southeast Asian Jackiopsis, and the Chinese Trailliaedoxa within Rubiaceae, using sequence data of four plastid markers (ndhF, rbcL, rps16, trnT-F). The present study provides molecular phylogenetic support for positions of these genera in the subfamily Ixoroideae, and reveals the presence of a basal grade of morphologically distinct, monotypic genera (Crossopteryx,Jackiopsis,Scyphiphora,Trailliaedoxa, and Glionnetia, respectively) in the species-rich Vanguerieae alliance. These five genera may represent sole representatives of their respective lineages and therefore may carry unique genetic information. Their conservation status was assessed, applying the criteria set in IUCN Red List Categories. We consider Glionnetia and Jackiopsis Endangered. Scyphiphora is recognized as Near Threatened despite its extensive range and Crossopteryx as Least Concern. Trailliaedoxa is poorly known (Data Deficient). Finally, the generic status of Glionnetia,Jackiopsis, and Trailliaedoxa and the monogeneric tribe Jackieae as defined by Ridsdale are supported.