Prospecting for rare earth element (hyper)accumulators in the Paris Herbarium using X-ray fluorescence spectroscopy reveals new distributional and taxon discoveries

BACKGROUND

Rare earth elements (REEs) are increasingly crucial for modern technologies. Plants could be used as a biogeochemical pathfinder and a tool to extract REEs from deposits. However, a paucity of information on suitable plants for these tasks exists.

METHODS

We aimed to discover new REE-(hyper)accumulating plant species by performing an X-ray fluorescence (XRF) survey at the Herbarium of the Muséum national d'Histoire naturelle (MNHN, Paris, France). We selected specific families based on the likelihood of containing REE-hyperaccumulating species, using known taxa that accumulate REEs. A total of 4425 specimens, taken in the two main evolutionary lineages of extant vascular plants, were analysed, including the two fern families Blechnaceae (n = 561) and Gleicheniaceae (n = 1310), and the two flowering plant families Phytolaccaceae (n = 1137) and Juglandaceae (n = 1417).

KEY RESULTS

Yttrium (Y) was used as a proxy for REEs for methodological reasons, and a total of 268 specimens belonging to the genera Blechnopsis (n = 149), Dicranopteris (n = 75), Gleichenella (n = 32), Phytolacca (n = 6), Carya (n = 4), Juglans (n = 1) and Sticherus (n = 1) were identified with Y concentrations ranging from the limit of detection (LOD) >49 µg g-1 up to 1424 µg g-1. Subsequently, analysis of fragments of selected specimens by inductively coupled plasma atomic emission spectroscopy (ICP-AES) revealed that this translated to up to 6423 µg total REEs g-1 in Dicranopteris linearis and up to 4278 µg total REEs g-1 in Blechnopsis orientalis which are among the highest values ever recorded for REE hyperaccumulation in plants. It also proved the validity of Y as an indicator for REEs in XRF analysis of herbarium specimens. The presence of manganese (Mn) and zinc (Zn) was also studied by XRF in the selected specimens. Mn was detected in 1440 specimens ranging from the detection limit at 116 µg g-1 up to 3807 µg g-1 whilst Zn was detected in 345 specimens ranging from the detection limit at 77 µg g-1 up to 938 µg g-1.

CONCLUSIONS AND IMPLICATIONS

This study led to the discovery of REE accumulation in a range of plant species, substantially higher concentrations in species known to be REE hyperaccumulators, and records of REE hyperaccumulators outside of the well-studied populations in China.

Systematics and biogeography of the Old World fern genus Antrophyum

Antrophyum is one of the largest genera of vittarioid ferns (Pteridaceae) and is most diverse in tropical Asia and the Pacific Islands, but also occurs in temperate Asia, Australia, tropical Africa and the Malagasy region. The only monographic study of Antrophyum was published more than a century ago and a modern assessment of its diversity is lacking. Here, we reconstructed a comprehensively sampled and robustly supported phylogeny for the genus based on four chloroplast markers using Bayesian inference, maximum likelihood and maximum parsimony analyses. We then explored the evolution of the genus from the perspectives of morphology, systematics and historical biogeography. We investigated nine critical morphological characters using a morphometric approach and reconstructed their evolution on the phylogeny. We describe four new species and provide new insight into species delimitation. We currently recognize 34 species for the genus and provide a key to identify them. The results of biogeographical analysis suggest that the distribution of extant species is largely shaped by both ancient and recent dispersal events.

Phylogenomic evolutionary insights in the fern family Gleicheniaceae

The pantropical fern family Gleicheniaceae comprises approximately 157 species. Seven genera are currently recognized in the family, although their monophyly is still uncertain due to low sampling in phylogenetic studies. We examined the monophyly of the genera through extended sampling, using the first phylogenomic inference of the family including data from both nuclear and plastid genomes. Seventy-six samples were sequenced (70 Gleicheniaceae species and six outgroups) using high throughput sequencing, including all seven currently recognized genera. Plastid and nuclear data were recovered and assembled; the nuclear data was phased to reduce paralogy as well as hybrid noise in the final recovered topology. Maximum likelihood trees were built for each locus, and a concatenated dataset was built for both datasets. A species tree based on a multispecies coalescent model was generated, and divergence time analyses performed. We here present the first genomic phylogenetic inferences concerning Gleicheniaceae, confirming the monophyly of most genera except Sticherus, which we recovered as paraphyletic. Although most of the extant genera of Gleicheniaceae originated during the Mesozoic, several genera show Neogene and even Quaternary diversifications, and our results suggest that reticulation and polyploidy may have played significant roles during this diversification. However, some genera, such as Rouxopteris and Stromatopteris, appear to represent evolutionary relicts.

Morphological and molecular evidence reject conspecificity of Malagasy and Mascarene Parablechnum (Polypodiopsida, Blechnaceae)

Under the current treatment of the Blechnaceae, only one species of the fern genus Parablechnum is recognised in the western Indian Ocean, often referred to as P.marginatum. Two varieties are currently recognised within it: a type variety present in the Mascarene Islands of Réunion and Mauritius and P.marginatumvar.humbertii in Madagascar. Recent molecular evidence suggested that these two varieties are not closely related, questioning their conspecific status. To collect further evidence to support a taxonomic decision, we performed a morphological study based on 57 herbarium specimens comparing traits from general morphology, cross section of the fertile pinnae, sporangia and spores. As a result, Malagasy specimens can be distinguished morphologically from the Mascarene ones by pinna apex and pinna section, the presence of sporangiasters and spore ornamentation. Additionally, spore size analyses resulted in statistically significant differences between both varieties. Our results, aligned with the available phylogenetic data, support that these two taxa should be recognised as separate species and, hence, we propose the necessary new combination and provide full descriptions.

Systematics and Plastome Evolution in Schizaeaceae

While the family Schizaeaceae (Schizaeales) represents only about 0.4% of the extant fern species diversity, it differs from other ferns greatly in gross morphologies, niche preferences, and life histories. One of the most notable features in this family is its mycoheterotrophic life style in the gametophytic stage, which appears to be associated with extensive losses of plastid genes. However, the limited number of sequenced plastomes, and the lack of a well-resolved phylogenetic framework of Schizaeaceae, makes it difficult to gain any further insight. Here, with a comprehensive sampling of ~77% of the species diversity of this family, we first inferred a plastid phylogeny of Schizaeaceae using three DNA regions. To resolve the deep relationships within this family, we then reconstructed a plastome-based phylogeny focusing on a selection of representatives that covered all the major clades. From this phylogenomic backbone, we traced the evolutionary histories of plastid genes and examined whether gene losses were associated with the evolution of gametophytic mycoheterotrophy. Our results reveal that extant Schizaeaceae is comprised of four major clades-Microschizaea, Actinostachys, Schizaea, and Schizaea pusilla. The loss of all plastid NADH-like dehydrogenase (ndh) genes was confirmed to have occurred in the ancestor of extant Schizaeaceae, which coincides with the evolution of mycoheterotrophy in this family. For chlorophyll biosynthesis genes (chl), the losses were interpreted as convergent in Schizaeaceae, and found not only in Actinostachys, a clade producing achlorophyllous gametophytes, but also in S. pusilla with chlorophyllous gametophytes. In addition, we discovered a previously undescribed but phylogenetically distinct species hidden in the Schizaea dichotoma complex and provided a taxonomic treatment and morphological diagnostics for this new species-Schizaea medusa. Finally, our phylogenetic results suggest that the current PPG I circumscription of Schizaea is non-monophyletic, and we therefore proposed a three-genus classification moving a subset of Schizaea species sensu PPG I to a third genus-Microschizaea.

Two new species in the fern genus Lomariopsis (Lomariopsidaceae) from East Asia

Two East Asian Lomariopsis (Lomariopsidaceae, Polypodiales) species, Lomariopsismoorei and Lomariopsislongini, which were previously misidentified as L.spectabilis, are here described as new species based on evidence from morphological characters and a molecular phylogeny. The two species differ from the three other described species in East Asia by their venation, pinna shapes, and perine morphology. A phylogeny based on a combined dataset of three chloroplast regions (rbcL+ rps4-trnS + trnL-L-F) showed that L.moorei and L.longini each formed a well-supported monophyletic group which was distantly related to both L.spectabilis and the other morphologically similar East Asian species, L.boninensis.

Three new records of fern species (Polypodiopsida) in Senegal, from Dindefelo Falls, Kedougou region

Blotiella currorii (Hook.) R.M.Tryon. (Dennstaedtiaceae), Dicranopteris linearis (Burm.F.) Underw. (Gleicheniaceae), and Aleuritopteris farinosa (Forssk.) Fée (Pteridaceae) are reported for the first time in the flora of Senegal. They represent not only three more species but also two new families, Dennstaedtiaceae and Gleicheniaceae, for Senegal. Data on species, morphology, taxonomy, ecology, and geographic distribution are included. These three species were found in the interstices of the cliff of the 100-m Dindefelo Falls, which is in Kedougou region.

Synoptic revision of the fern genus Elaphoglossum Schott ex J.Sm. (Dryopteridaceae) in Madagascar, with the description of 23 new taxa, all but one endemic

After 15 years of field studies in Madagascar, especially focused on the overlooked fern genus Elaphoglossum (Dryopteridaceae), a synoptic revision of the genus is here presented. Based on more than 2,600 herbarium specimens including collections over 200 years, Elaphoglossum is the second most diversified fern genus in Madagascar, with 52 species and three subspecies (with 76% of endemism). It is to be compared to the 34 species treated by Tardieu-Blot in 1960 for the "Flore de Madagascar et des Comores" or the 38 species listed by Roux in 2009 in the seminal "Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and neighboring islands". The 55 taxa represent five out of seven existing generic sections (sect. Amygdalifolia and sect. Wrightiana being monotypic and Neotropical): sect. Lepidoglossa (29 spp. and three subspp.), sect. Elaphoglossum (17 spp.), sect. Setosa (3 spp.), sect. Squamipedia (2 spp.), and sect. Polytrichia (1 sp.). Distribution is given for each species and subspecies, and detailed for each island or archipelago in the Western Indian Ocean (La Réunion, Mauritius, Seychelles, and Comoros). Twenty species and three subspecies are newly described, all but one endemic to Madagascar: Elaphoglossum ambrense Rouhan, Elaphoglossum andohahelense Rouhan, Elaphoglossum anjanaharibense Rouhan, Elaphoglossum approximatum Rouhan, Elaphoglossum brachymischum Rouhan, Elaphoglossum cerussatum Tardieu subsp. brunneum Rouhan, Elaphoglossum coracinolepis Rouhan, Elaphoglossum desireanum Rouhan, Elaphoglossum glabricaule Rouhan, Elaphoglossum gladiifolium Rouhan, Elaphoglossum leucolepis (Baker) Krajina ex Tardieu subsp. nanolepis Rouhan, Elaphoglossum leucolepis (Baker) Krajina ex Tardieu subsp. nigricans Rouhan, Elaphoglossum longiacuminatum Rouhan, Elaphoglossum patriceanum Rouhan, Elaphoglossum perangustum Rouhan, Elaphoglossum prominentinervulum Rouhan, Elaphoglossum rakotondrainibeae Rouhan, Elaphoglossum repandum Rouhan, Elaphoglossum sabineanum Rouhan, Elaphoglossum sinensiumbrarum Rouhan, Elaphoglossum subglabricaule Rouhan, Elaphoglossum tsaratananense Rouhan, and Elaphoglossum viridicaule Rouhan. Morphological description, distribution map, and original illustrations are provided for each new taxon. Novel identification keys to the sections and all species from Madagascar are also presented.

Plant Taxonomy: A Historical Perspective, Current Challenges, and Perspectives

Taxonomy is the science that explores, describes, names, and classifies all organisms. In this introductory chapter, we highlight the major historical steps in the elaboration of this science, which provides baseline data for all fields of biology and plays a vital role for society but is also an independent, complex, and sound hypothesis-driven scientific discipline.In a first part, we underline that plant taxonomy is one of the earliest scientific disciplines that emerged thousands of years ago, even before the important contributions of the Greeks and Romans (e.g., Theophrastus, Pliny the Elder, and Dioscorides). In the fifteenth-sixteenth centuries, plant taxonomy benefited from the Great Navigations, the invention of the printing press, the creation of botanic gardens, and the use of the drying technique to preserve plant specimens. In parallel with the growing body of morpho-anatomical data, subsequent major steps in the history of plant taxonomy include the emergence of the concept of natural classification , the adoption of the binomial naming system (with the major role of Linnaeus) and other universal rules for the naming of plants, the formulation of the principle of subordination of characters, and the advent of the evolutionary thought. More recently, the cladistic theory (initiated by Hennig) and the rapid advances in DNA technologies allowed to infer phylogenies and to propose true natural, genealogy-based classifications.In a second part, we put the emphasis on the challenges that plant taxonomy faces nowadays. The still very incomplete taxonomic knowledge of the worldwide flora (the so-called taxonomic impediment) is seriously hampering conservation efforts that are especially crucial as biodiversity has entered its sixth extinction crisis. It appears mainly due to insufficient funding, lack of taxonomic expertise, and lack of communication and coordination. We then review recent initiatives to overcome these limitations and to anticipate how taxonomy should and could evolve. In particular, the use of molecular data has been era-splitting for taxonomy and may allow an accelerated pace of species discovery. We examine both strengths and limitations of such techniques in comparison to morphology-based investigations, we give broad recommendations on the use of molecular tools for plant taxonomy, and we highlight the need for an integrative taxonomy based on evidence from multiple sources.

A global phylogeny of Stegnogramma ferns (Thelypteridaceae): generic and sectional revision, historical biogeography and evolution of leaf architecture

The thelypteroid fern genus Stegnogramma s.l. contains around 18-35 species and has a global, cross-continental distribution ranging from tropical to temperate regions. Several genera and infrageneric sections have been recognized previously in Stegnogramma s.l., but their phylogenetic relationships are still unclear. In this study, we present a global phylogeny of Stegnogramma s.l. with the most comprehensive sampling to date and aim to pinpoint the phylogenetic positions of biogeographically and taxonomically important taxa. Based on the reconstructed historical biogeography and character evolution, we propose a new (infra)generic classification and discuss the diversification of Stegnogramma s.l. in a biogeographical context. New names or combinations are made for 12 (infra)species, including transferring the monotypic species of Craspedosorus to Leptogramma. Finally, we discuss a possible link between leaf architecture and ecological adaptation, and hypothesize that the increase in leaf dissection and free-vein proportion is an adaptive feature to cool climates in Stegnogramma s.l.

Genomics of sorghum local adaptation to a parasitic plant

Host-parasite coevolution can maintain high levels of genetic diversity in traits involved in species interactions. In many systems, host traits exploited by parasites are constrained by use in other functions, leading to complex selective pressures across space and time. Here, we study genome-wide variation in the staple crop Sorghum bicolor (L.) Moench and its association with the parasitic weed Striga hermonthica (Delile) Benth., a major constraint to food security in Africa. We hypothesize that geographic selection mosaics across gradients of parasite occurrence maintain genetic diversity in sorghum landrace resistance. Suggesting a role in local adaptation to parasite pressure, multiple independent loss-of-function alleles at sorghum LOW GERMINATION STIMULANT 1 (LGS1) are broadly distributed among African landraces and geographically associated with S. hermonthica occurrence. However, low frequency of these alleles within S. hermonthica-prone regions and their absence elsewhere implicate potential trade-offs restricting their fixation. LGS1 is thought to cause resistance by changing stereochemistry of strigolactones, hormones that control plant architecture and below-ground signaling to mycorrhizae and are required to stimulate parasite germination. Consistent with trade-offs, we find signatures of balancing selection surrounding LGS1 and other candidates from analysis of genome-wide associations with parasite distribution. Experiments with CRISPR-Cas9-edited sorghum further indicate that the benefit of LGS1-mediated resistance strongly depends on parasite genotype and abiotic environment and comes at the cost of reduced photosystem gene expression. Our study demonstrates long-term maintenance of diversity in host resistance genes across smallholder agroecosystems, providing a valuable comparison to both industrial farming systems and natural communities.

A first checklist of the Pteridophytes of Togo (West Africa)

BACKGROUND

The present work proposes, for the first time, a study exclusively focused on the diversity of Pteridophytes in Togo.The study was based on fieldwork that resulted in 869 new collections gathered between 2013 and 2017 in the country and on yet existing herbarium specimens kept at the Herbaria of Lomé and Paris. Thus, a total number of 1092 specimens collected throughout the country served as a basis for this work, to which were added the known, published occurrences of Pteridophytes for the country.

NEW INFORMATION

At the end of this study, a total diversity of 134 species belonging to 53 genera and 25 families and 12 orders were recorded and documented for the country. It results in 73 newly cited species for Togolese flora, including 61 spontaneous species. Lycopodiopsida (18 species) and Polypodiopsida (116 species) classes are both represented. The Polypodiales order is the most represented with 97 species. The Pteridaceae and Aspleniaceae families are the most diverse with 24 and 22 species respectively. Finally, notes were provided on species distribution at national level.

The French Muséum national d'histoire naturelle vascular plant herbarium collection dataset

We provide a quantitative description of the French national herbarium vascular plants collection dataset. Held at the Muséum national d’histoire naturelle, Paris, it currently comprises records for 5,400,000 specimens, representing 90% of the estimated total of specimens. Ninety nine percent of the specimen entries are linked to one or more images and 16% have field-collecting information available. This major botanical collection represents the results of over three centuries of exploration and study. The sources of the collection are global, with a strong representation for France, including overseas territories, and former French colonies. The compilation of this dataset was made possible through numerous national and international projects, the most important of which was linked to the renovation of the herbarium building. The vascular plant collection is actively expanding today, hence the continuous growth exhibited by the dataset, which can be fully accessed through the GBIF portal or the MNHN database portal (available at: https://science.mnhn.fr/institution/mnhn/collection/p/item/search/form). This dataset is a major source of data for systematics, global plants macroecological studies or conservation assessments.

250 years of hybridization between two biennial herb species without speciation

Hybridization between plant species can generate novel morphological diversity and lead to speciation at homoploid or polyploid levels. Hybrids between biennial herbs Tragopogon pratensis and T. porrifolius have been studied in experimental and natural populations for over 250 years. Here we examine their current status in natural populations in southeast England. All hybrids found were diploid; they tended to grow taller and with more buds than their parental species; many showed partial fertility; a few showed evidence of backcrossing. However, we found no evidence to suggest that the hybrids are establishing as a new species, nor can we find literature documenting speciation of these hybrids elsewhere. This lack of speciation despite at least 250 years of hybridization contrasts with the fact that both parental species have formed new allopolyploid species through hybridization with another diploid, T. dubius. Understanding why hybrids often do not speciate, despite repeated opportunities, would enhance our understanding of both the evolutionary process and risk assessments of invasive species.

The Pteridaceae family diversity in Togo

BACKGROUND

The Pteridaceae family is the largest fern family in Togo by its specific and generic diversity. Like all other families of ferns in the country, Pteridaceae are poorly studied and has no identification key. The objective of this study is to perform a taxonomic revision and list establishment of this family of leptosporangiate ferns in the light of current available knowledge about the family. Pteridaceae was also assessed in terms of its diversity and conservation status, this was conducted through the recent field data and the existing herbaria specimens. The current study permits to confirm the presence of Pteris similis Kuhn. which brought the number of Pteridaceae to 17 in Togo.

NEW INFORMATION

This study provides first local scientific information about the fern flora of Togo. It confirmed the presence of Pterissimilis Kuhn. in Togo and brought the Pteridaceae family diversity to 17 species. A species identification key is provided for the easy identification of the Pteridaceae of Togo.

Phylogeny and historical biogeography of the lastreopsid ferns (Dryopteridaceae)

• Premise of the study: As currently circumscribed, Lastreopsis has about 45 species and occurs in Australia, southern Asia, Africa, Madagascar, and the neotropics. Previous molecular phylogenetic studies suggested that Lastreopsis is paraphyletic. Our study focuses on resolving relationships among the lastreopsid ferns (Lastreopsis, Megalastrum, and Rumohra), the evolution of morphological characters, and an understanding of the temporal and spatial patterns that have led to the current diversity and geographical distribution of its extant species.• Methods: Phylogenetic relationships were recovered under Bayesian, maximum likelihood, and maximum parsimony methods, using a data set of four plastid markers. Divergence time estimates were made using BEAST, and the biogeographic hypotheses were tested under the DEC model and the RASP/S-DIVA methods.• Key results: Lastreopsis was recovered as paraphyletic, and at least one of its clades should be recognized as a distinct genus, Parapolystichum. Coveniella poecilophlebia and Oenotrichia tripinnata were nested within Lastreopsis s.s., Megalastrum and Rumohra as sister to the Lastreopsis s.s., and the Lastreopsis amplissima clades. The initial diversification of the lastreopsids took place at about 56.55 Ma, from a neotropical ancestor.• Conclusions: Taxonomic recognition of Parapolystichum is warranted to preserve the monophyly of Lastreopsis. Diversification among the main clades of the lastreopsid ferns was influenced by climatic and geological changes in the southern hemisphere. The biogeographic history of the group is intimately related to the trans-Antarctic corridor between Australia and South America, with evidence for multiple lineage interchanges between Australia and South America during the Oligocene and the Eocene epochs.

Molecular phylogeny and biogeography of the fern genus Pteris (Pteridaceae)

BACKGROUND AND AIMS

Pteris (Pteridaceae), comprising over 250 species, had been thought to be a monophyletic genus until the three monotypic genera Neurocallis, Ochropteris and Platyzoma were included. However, the relationships between the type species of the genus Pteris, P. longifolia, and other species are still unknown. Furthermore, several infrageneric morphological classifications have been proposed, but are debated. To date, no worldwide phylogenetic hypothesis has been proposed for the genus, and no comprehensive biogeographical history of Pteris, crucial to understanding its cosmopolitan distribution, has been presented.

METHODS

A molecular phylogeny of Pteris is presented for 135 species, based on cpDNA rbcL and matK and using maximum parsimony, maximum likelihood and Bayesian inference approaches. The inferred phylogeny was used to assess the biogeographical history of Pteris and to reconstruct the evolution of one ecological and four morphological characters commonly used for infrageneric classifications.

KEY RESULTS

The monophyly of Pteris remains uncertain, especially regarding the relationship of Pteris with Actiniopteris + Onychium and Platyzoma. Pteris comprises 11 clades supported by combinations of ecological and morphological character states, but none of the characters used in previous classifications were found to be exclusive synapomorphies. The results indicate that Pteris diversified around 47 million years ago, and when species colonized new geographical areas they generated new lineages, which are associated with morphological character transitions.

CONCLUSIONS

This first phylogeny of Pteris on a global scale and including more than half of the diversity of the genus should contribute to a new, more reliable infrageneric classification of Pteris, based not only on a few morphological characters but also on ecological traits and geographical distribution. The inferred biogeographical history highlights long-distance dispersal as a major process shaping the worldwide distribution of the species. Colonization of different niches was followed by subsequent morphological diversification. Dispersal events followed by allopatric and parapatric speciation contribute to the species diversity of Pteris.

A plea for modern botanical collections to include DNA-friendly material

Botanists have long collected herbarium specimens during their expeditions, and the importance of such collections is broadly acknowledged nowadays. It is largely recognized that material for molecular studies must be accompanied by herbarium material to be deposited in a recognized herbarium (vouchers). By contrast, the collection of herbarium specimens with no material for genetic analyses is unfortunately still common. The evolution of science and the need to face new environmental challenges require some changes in the way science is planned and performed. Here, we highlight some key scientific areas which could greatly benefit from such DNA-friendly collections, and we make a plea - and a call to all botanists - for the routine collection of DNA-friendly material together with herbarium specimens.

AFLP markers provide insights into the evolutionary relationships and diversification of New Caledonian Araucaria species (Araucariaceae)

PREMISE OF THE STUDY

Despite its small size, New Caledonia is characterized by a very diverse flora and striking environmental gradients, which make it an ideal setting to study species diversification. Thirteen of the 19 Araucaria species are endemic to the territory and form a monophyletic group, but patterns and processes that lead to such a high species richness are largely unexplored.

METHODS

We used 142 polymorphic AFLP markers and performed analyses based on Bayesian clustering algorithms, genetic distances, and cladistics on 71 samples representing all New Caledonian Araucaria species. We examined correlations between the inferred evolutionary relationships and shared morphological, ecological, or geographic parameters among species, to investigate evolutionary processes that may have driven speciation.

KEY RESULTS

We showed that genetic divergence among the present New Caledonian Araucaria species is low, suggesting recent diversification rather than pre-existence on Gondwana. We identified three genetic groups that included small-leaved, large-leaved, and coastal species, but detected no association with soil preference, ecological habitat, or rainfall. The observed patterns suggested that speciation events resulted from both differential adaptation and vicariance. Last, we hypothesize that speciation is ongoing and/or there are cryptic species in some genetically (sometimes also morphologically) divergent populations.

CONCLUSIONS

Further data are required to provide better resolution and understanding of the diversification of New Caledonian Araucaria species. Nevertheless, our study allowed insights into their evolutionary relationships and provides a framework for future investigations on the evolution of this emblematic group of plants in one of the world's biodiversity hotspots.

New insights into the phylogeny and historical biogeography of the Lellingeria myosuroides clade (Polypodiaceae)

Grammitid ferns are a well-supported clade of ~900 primarily tropical epiphytic species. Recent phylogenetic studies have found support for a distinctive, geographically diverse group of 24 species referred to as the Lellingeria myosuroides clade and have provided evidence for a variety of phylogenetic relationships within the group, as well as hypotheses of historical processes that have produced current biogeographical patterns. We present new data and analyses that support the following primary conclusions: 1) the L. myosuroides clade is monophyletic and pantropical; 2) that clade is sister to a more species rich clade of entirely Neotropical species (Lellingeria s.s.); 3) we infer two independent dispersal events from the Neotropics to Pacific islands, five independent dispersal events from the Neotropics to the Paleotropics, and two separate dispersal events from mainland tropical America to the West Indies.

Molecular phylogeny, character evolution, and biogeography of the grammitid fern genus Lellingeria (Polypodiaceae)

PREMISE OF THE STUDY

The recognition of monophyletic genera for groups that have high levels of homoplastic morphological characters and/or conflicting results obtained by different studies can be difficult. Such is the case in the grammitid ferns, a clade within the Polypodiaceae. In this study, we aim to resolve relationships among four clades of grammitid ferns, which have been previously recovered either as a polytomy or with conflicting topologies, with the goal of circumscribing monophyletic genera. •

METHODS

The sampling included 89 specimens representing 61 species, and sequences were obtained for two genes (atpB and rbcL) and four intergenic spacers (atpB-rbcL, rps4-trnS, trnG-trnR, and trnL-trnF), resulting in a matrix of 5091 characters. The combined data set was analyzed using parsimony, likelihood, and Bayesian methods. Ninety-six morphological characters were optimized onto the generated trees, using the parsimony method. •

KEY RESULTS

Lellingeria is composed of two main clades, the L. myosuroides and the Lellingeria s.s. clades, which together are sister to Melpomene. Sister to all three of these is a clade with two species of the polyphyletic genus Terpsichore. In the L. myosuroides clade, several dispersal events occurred between the neotropics, Africa, and the Pacific Islands, whereas Lellingeria s.s. is restricted to the neotropics, with about 60% of its diversity in the Andes. •

CONCLUSIONS

Overall, our results suggest that Lellingeria is monophyletic, with two clades that are easily characterized morphologically and biogeographically. Morphological characters describing the indument are the most important to define the clades within the ingroup. A small clade, previously considered in Terpsichore, should be recognized as a new genus.

Human-mediated emergence as a weed and invasive radiation in the wild of the CD genome allotetraploid rice species (Oryza, Poaceae) in the Neotropics

BACKGROUND

The genus Oryza is being used as a model in plant genomic studies although there are several issues still to be resolved regarding the spatio-temporal evolution of this ancient genus. Particularly contentious is whether undated transoceanic natural dispersal or recent human interference has been the principal agent determining its present distribution and differentiation. In this context, we studied the origin and distribution history of the allotetraploid CD rice genome. It is endemic to the Neotropics but the genus is thought to have originated in the Paleotropics, and there is relatively little genetic divergence between some orthologous sequences of the C genome component and their Old World counterparts.

METHODOLOGY/PRINCIPAL FINDINGS

Because of its allotetraploidy, there are several potential pitfalls in trying to date the formation of the CD genome using molecular data and this could lead to erroneous estimates. Therefore, we rather chose to rely on historical evidence to determine whether or not the CD genome was present in the Neotropics before the arrival of Columbus. We searched early collections of herbarium specimens and studied the reports of explorers of the tropical Americas for references to rice. In spite of numerous collectors traveling inland and collecting Oryza, plants determined as CD genome species were not observed away from cultivated rice fields until 1869. Various arguments suggest that they only consisted of weedy forms until that time.

CONCLUSIONS/SIGNIFICANCE

The spatio-temporal distribution of herbarium collections fits a simple biogeographical scenario for the emergence in cultivated rice fields followed by radiation in the wild of the CD genome in the Neotropics during the last four centuries. This probably occurred from species introduced to the Americas by humans and we found no evidence that the CD genome pre-existed in the Old World. We therefore propose a new evolutionary hypothesis for such a recent origin of the CD genome. Moreover, we exemplify how an historical approach can provide potentially important information and help to disentangle the timing of evolutionary events in the history of the Oryza genomes.

Molecular phylogeny of the fern genus Elaphoglossum (Elaphoglossaceae) based on chloroplast non-coding DNA sequences: contributions of species from the Indian Ocean area

We performed a phylogenetic analysis of the fern genus Elaphoglossum using two non-coding chloroplast spacers: trnL-trnF and rps4-trnS. The sampling includes 123 species, of which 80 have not been previously sequenced, and for the first time includes species from Africa and the Indian Ocean area. The results of this expanded study largely agree with an earlier molecular study based on a smaller group of neotropical species and with the morphology-based classification of Mickel and Atehortua. We found, however, that some infrageneric groups such as section Elaphoglossum are not monophyletic. Besides section Elaphoglossum pro parte, we recognize six sections: two new monospecific, unnamed sections, and the previously established sections Lepidoglossa, Squamipedia, Amygdalifolia, and "Subulate-scaled clade." We divide the subulate-scaled clade into subsection Setosa (hydathodes present) and Polytrichia (hydathodes absent), and section Elaphoglossum is divided into subsections Platyglossa and Pachyglossa, two groups that do not appear to be supported by any single morphological character. In general, however, the main clades are supported by morphology. Finally, we discuss the species of the Indian Ocean region and their affinities with the neotropical ones. Out of the 11 species pairs postulated by Moran and Smith on the basis of morphology, two are well supported (E. eximium-E. aubertii; E. piloselloides-E. spatulatum) and three are not supported (E. ciliatum-E. humbertii; E. muscosum-E. poolii; E. paleaceum-E. deckenii), and two remain unresolved (E. erinaceum-E. hybridum; E. glabellum-E. acrostichoides) because our molecular markers were not variable enough. Four species pairs could not be tested because specimens were lacking. Unsupported species pairs are best interpreted as morphological convergences. Two additional species pairs are proposed: E. cuspidatum-E. succisaefolium; E. doanense-E. hornei. Placement of the species from the Indian Ocean suggests that at least 13 long-distance dispersal events occurred between the Neotropics and the Indian Ocean-Africa.