Jenny E. E. Smedmark

Phylogenetic Relationships of Geum (Rosaceae) and Relatives Inferred from the nrITS and trnL-trnF Regions

Abstract This is a molecular phylogenetic study of the group formerly known as Dryadeae, based on DNA sequences from the internal transcribed spacers, ITS, of nuclear ribosomal DNA and the trnL intron and the trnL-trnF intergenic spacer of the chloroplast. A total of 1.9 kb, for 26 ingroup species, were analyzed using parsimony and model-based Bayesian inference. Some clades are well supported by both data sets: the ingroup, with Fallugia as the sister to the rest of the clade; Sieversia in a strict sense; a clade consisting of all the herbaceous perennials, and some clades within this last group. Other clades, within the group of herbaceous perennials, differ between the analyses. The data sets in the present study do not support any previous circumscriptions of Geum nor any of the suggested segregate genera, except for the southern hemisphere Oncostylus. Morphological characters, notably fruit characters, mapped onto the combined tree show patterns of widespread parallel evolution and reversals—or possibly the effects of reticulations. Allopolyploidy has been suggested by previous workers and there are some indications of this in our results. Geum andicola appears in different well supported groups in the two separate analyses. This may be caused by inheritance of chloroplast DNA from one parental species and homogenization of ribosomal DNA from the other. Also, the intricate fruit type present in, for example, the type species of Geum, G. urbanum, appears to have evolved twice from progenitors with plumose styles. We propose the name Colurieae for this entire clade and the name Geinae for the group of herbaceous perennials. Communicating Editor: Kathleen A. Kron

Boreotropical migration explains hybridization between geographically distant lineages in the pantropical clade Sideroxyleae (Sapotaceae)

To determine whether the fragmented pantropical distribution of present day Sideroxyleae primarily is the result of long-distance dispersals or represents the remnants of a once continuous distribution in the northern hemisphere, the boreotropical flora, we used phylogenetic analyses of chloroplast and nuclear ribosomal DNA data, Bayesian molecular dating, and Bayesian estimation of ancestral areas. Incongruence between the two data sets was examined with a nuclear low copy gene phylogeny to discover any occurrences of reticulate evolution. The Pacific clade Nesoluma was shown to have two distinct copies of the nuclear low copy gene AAT, one from an African and one from an American ancestral lineage, indicating that it is of allopolyploid origin. We conclude that Sideroxyleae, including the ancestral lineages of Nesoluma, were part of the boreotropical flora and entered the New World via the north Atlantic land bridge. We also suggest that the distribution of extant species resulted from the cooling climate at the end of the Eocene. Sideroxylon oxyacanthum is shown not to belong in the group, but in Chrysophylloideae. A classification reflecting phylogenetic relationships, as well as new combinations for the species in Nesoluma under Sideroxylon, is presented.

Deep divergences in the coffee family and the systematic position of Acranthera

Despite extensive efforts, there are unresolved questions on evolutionary relationships in the angiosperm family Rubiaceae. Here, information from six loci and 149 Rubiaceae taxa provide new insights. Acranthera and Coptosapelta are strongly supported as sisters. Pollen grains of Acranthera possess several features common in Rubiaceae, but amongst potential similarities with the unusual grains of Coptosapelta are the nature of the apertures and the structure of the sexine. Luculia, Acranthera and Coptosapelta are excluded from the three subfamilies Ixoroideae, Cinchonoideae and Rubioideae. Sipaneeae and Condamineeae form a clade, sister to remaining Ixoroideae. Rondeletieae and Guettardeae are sisters to remaining Cinchonoideae. Colletoecema is sister to remaining Rubioideae, followed by the Urophylleae–Ophiorrhizeae clade. Nuclear ITS provided structured information at all phylogenetic levels, but the main gain from adding nrITS was the increased resolution. Average support values also increased but were generally high also without nrITS and the increase was not statistically significant.

A Revised Time Tree of the Asterids : Establishing a Temporal Framework For Evolutionary Studies of the Coffee Family (Rubiaceae)

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.

Patterns of diversification amongst tropical regions compared: a case study in Sapotaceae

Species diversity is unequally distributed across the globe, with the greatest concentration occurring in the tropics. Even within the tropics, there are significant differences in the numbers of taxa found in each continental region. Manilkara is a pantropical genus of trees in the Sapotaceae comprising c. 78 species. Its distribution allows for biogeographic investigation and testing of whether rates of diversification differ amongst tropical regions. The age and geographical origin of Manilkara are inferred to determine whether Gondwanan break-up, boreotropical migration or long distance dispersal have shaped its current disjunct distribution. Diversification rates through time are also analyzed to determine whether the timing and tempo of speciation on each continent coincides with geoclimatic events. Bayesian analyses of nuclear (ITS) and plastid (rpl32-trnL, rps16-trnK, and trnS-trnFM) sequences were used to reconstruct a species level phylogeny of Manilkara and related genera in the tribe Mimusopeae. Analyses of the nuclear data using a fossil-calibrated relaxed molecular clock indicate that Manilkara evolved 32–29 million years ago (Mya) in Africa. Lineages within the genus dispersed to the Neotropics 26–18 Mya and to Asia 28–15 Mya. Higher speciation rates are found in the Neotropical Manilkara clade than in either African or Asian clades. Dating of regional diversification correlates with known palaeoclimatic events. In South America, the divergence between Atlantic coastal forest and Amazonian clades coincides with the formation of drier Cerrado and Caatinga habitats between them. In Africa diversification coincides with Tertiary cycles of aridification and uplift of the east African plateaux. In Southeast Asia dispersal may have been limited by the relatively recent emergence of land in New Guinea and islands further east c. 10 Mya.

Sibbaldia: a molecular phylogenetic study of a remarkably polyphyletic genus in Rosaceae

Using DNA sequence data from nuclear ribosomal ITS in combination with plastid trnLF spacer and trnL intron data, we show that Sibbaldia is a polyphyletic assemblage. It falls into five separate clades of Potentilleae, three within Fragariinae and two within Potentilla (Potentillinae sensu Soják). To a large extent, our results are congruent with Soják’s findings based on morphological characters such as anther structure. Four of the Sibbaldia species included in this study remain in Sibbaldia, while S. adpressa is classified in Sibbaldianthe, S. perpusilloides is considered to represent a new genus in Fragariinae, Chamaecallis Smedmark, S. micropetala is nested within the Potentilla anserina clade, and four species belong to a basal clade of Potentilla. The phylogenetic affinity of Sibbaldiopsis is still unsettled, but one of the three species that have been classified in the genus is found to belong inside Sibbaldia, and it should be named Sibbaldia retusa (O.F. Müller) T. Erikss. Further study will show whether the remaining two species, Potentillacuneifolia and P. miyabei, are more closely related to Sibbaldia, Sibbaldianthe, or if they make up a distinct lineage separate from either of these.

A new species, genus and tribe of Sapotaceae, endemic to Madagascar

Phylogenetic relationships of the two Malagasy Sapotaceae endemic genera Capurodendron and Tsebona have been unclear until now. Recent collections from Madagascar, as well as a better representation of the tribe Isonandreae, altogether 95 terminals, were used to estimate a phylogeny of subfamily Sapotoideae. We analysed sequences of nrDNA (ITS) and cpDNA (trnH-psbA) with Bayesian inference and parsimony jackknifing. As in previous analyses, Sapoteae and Sideroxyleae are recovered monophyletic. In addition, Isonandreae, distributed in the Indo-Pacific, is for the first time resolved as monophy- letic and sister to Sapoteae. All Malagasy accessions of Capurodendron, Tsebona, and a new species are grouped in another well-supported clade. This clade is accommodated in a new tribe Tseboneae characterized by caducous stipules, 5-merous flowers with quincuncial sepals, contorted aestivation of corolla lobes, absence of corolla appendages, one or three stamens opposite each corolla lobe, villous staminodes, seeds with an adaxial scar and plano-convex cotyledons, lacking endosperm. The new species is described in the new genus Bemangidia (B. lowryi) because it has a unique leaf venation for the tribe and combines different morphological features from Capurodendron and Tsebona. All three genera are well-supported monophy- letic groups. Bemangidia lowryi is threatened with extinction due to extensive ongoing forest destruction and is assigned a preliminary conservation status of Critically Endangered.

Corrigendum: Patterns of diversification amongst tropical regions compared: a case study in Sapotaceae.

[This corrects the article on p. 362 in vol. 5, PMID: 25520736.].