Biogeography, evolution and systematics of Casearia Jacq. (Salicaceae) in the Neotropics

Casearia is a pantropical genus of circa 240 species of the Salicaceae family, and the most species rich genus of the tribe Samydeae. The Neotropics harbours half of all Casearia species, which are present in every biome of the New World. Despite its abundance in tropical biomes, Casearia has been poorly studied, mostly because of the complexity of identification at the species level. This thesis presents the first well-resolved phylogenetic study of the genus Casearia. The objectives were to test its monophyly and to elucidate its relationships to other taxa of the Samydeae tribe, as well as to study the biogeography of the genus. Furthermore, species boundaries of some Neotropical taxa were investigated, using an integrative taxonomy approach. Finally, the last objective was to elaborate a reliable World checklist of every currently accepted Casearia species, a tool most needed for taxonomy, conservation and biodiversity management. A molecular dataset of 103 accessions from four plastid regions (petD, rpl16, rps4/trnLF and trnK/matK) and on nuclear region (ITS) was generated, corresponding to 54 species, of which 42 belong to Casearia. The study focuses on Neotropical species and the dataset included five Samydeae genera: Euceraea, Lunania, Neoptychocarpus, Ryania and Tetrathylacium, to understand the relationship between Casearia and the Samydeae tribe. Phylogenetic relationships were inferred using Bayesian inference, maximum likelihood and parsimony analysis. The origin of Casearia in the Caribbean and its biogeographical relationships to species from the South American mainland was investigated. Therefore, divergence time and ancestral area were estimated. Seven key morphological characters were studied, in order to retrieve synapomorphies for the genus, using BayesTraits. The results of the phylogenetic reconstruction showed a well-supported Samydeae clade and a well-supported Casearia clade, as sister to the other Samydeae. The genus Casearia was identified as not monophyletic, because the included species of the two Neotropical genera Euceraea and Neoptychocarpus were found nested with good support within the Casearia clade. Several major clades were retrieved, mostly constituted of entirely Neotropical species, one of which being consisted of only species from the Caribbean. A clade of all Paleotropical species was found nested in the clade with the New World Casearia taxa. Two morphological characters that work well to delimitate a monophyletic genus concept were identified. First, a branched inflorescence (fasciculate, glomerulous or cymous) and second a single row of stamen. In addition, some traits previously used as diagnostic for the genus, have been identified as homoplastic.For example, the presence of pellucid dots or lines on the leaves, that appeared earlier within Samydeae and were lost in Ryania and Tetrathylacium, a dioeceous reproduction system, used to diagnose Neoptychocarpius, or a higher number of stamen, used to diagnose Laetia and Zuelania. The time estimation analysis of the present study showed that the Samydeae clade originated in South America during the Cretaceous, 102 Ma, which corresponds to the rapid radiation of the Malpighiales. The Casearia clade is of South American origin and begins to diversify in the Eocene, 90 Ma. The Paleotropical clade of Casearia was found to have originated later than the Neotropical one, therefore from New World ancestors, in the Oligocene/Miocene boundary, 40 Ma and that it was divided into two clades, an African and an Asian one. More sampling from Old World taxa would be needed, in order to identify the origin of this Paleotropical clade. The results show that Casearia migrated multiple times to the Caribbean, and gave rise to a clade of Caribbean endemics in the late Miocene, 9 Ma, most likely of South American origin. In addition, the species limits of five Neotropical taxa were investigated. Those taxa were retrieved as nested singletons, which are taxa with a single or few accessions of an accepted species, nested within a clade of another accepted species. Here, an integrative taxonomy approach was applied as a successful way to study the taxonomical status of those taxa, to evaluate whether the singletons may be considered as a synonym, or if they constitute an emerging species, using both morphological and ecological analysis. To that aim, morphological and ecological differentiations were calculated, or on the contrary the absence of differentiation, between those nested singleton and the taxa in which it it nested. Phenotypic differentiation was analysed using morphometry based on the characters that are used as diagnostic characters of the taxa. For the ecological analysis, the niche space differentiation was evaluated and ecological niche equivalency and similarity tests were performed. Furthermore, the distribution range of those species was mapped. One species, C. grandiflora, is recovered nested within a C. arborea clade. However, the analyses showed that it presents some degree of differentiation, both morphological and ecological. Therefore, the results suggest that they are indeed two species and C. grandiflora is most likely a recent emerging lineage. Two other cases of nested singleton were found, C. selloana and C. zizyphoides, retrieved within the C. sylvestris clade. The results show that they present little to no morphological and ecological differentiation and a narrower distribution range as the widely distributed C. sylvestris. Therefore, it suggests that they most likely represent a subspecies of C. sylvestris. Another nested singleton of C. mariquitensis is retrieved within a C. mollis clade and they are most likely synonyms, given the absence of morphological or ecological differentiation. Finally, an up-to-date checklist of all currently accepted Casearia species is presented, which includes both Neotropical and Paleotropical taxa. The database was created using information from floristic treatments, monographs, regional checklists and taxonomic treatments at species level. For each taxon, the complete information on protologue, types and synonyms has been provided. Our aim was to give the genus a taxonomic backbone that can serve as a basis for further research in taxonomy, ecology and species conservation. The EDIT platform for Cybertaxonomy was used; it is an open-source platform that presents all the tools necessary to establish a taxonomic checklist. It provides the user with a taxonomic editor where every relevant taxonomic information can be entered and an online data portal Here, the most complete checklist of Casearia species to date at a global scale is presented. 708 names, 222 accepted species, 464 synonyms and 22 unresolved names were included, combining information from taxonomical revision, floristic treatments and regional checklists

A new species of Casearia Jacq. (Salicaceae) from Central Panama and insights into its phylogenetic position within the genus

We describe here a new species of Casearia from Panama based on both morphological and molecular data. Casearia isthmica sp. nov. is restricted to the mid-elevation cloud forests of Central Panama and presents morphological similarities with two more widespread species, C. sanchezii from high elevation areas of El Salvador and Mexico and C. tremula from the Caribbean, Central America, and Northern South America. Casearia isthmica differs in presenting pedunculated and congested inflorescences with up to 20 flowers, as well as flowers with 12 stamens and a pubescent style. Phylogenetic analysis based on selected plastid (petD, trnK-matK, rpl16 and rps4-trnLF) and nuclear (GBSSI and ITS) markers shows that the new species belongs to subclade B3 of Casearia, a lineage that encompasses species from Central America, Mexico and the Caribbean. Results of the morphological and molecular analysis were congruent and allowed a broader understanding of this new taxon, especially regarding its relationships to other Casearia

Nested singletons in molecular trees: Utility of adding morphological and geographical data from digitized herbarium specimens to test taxon concepts at species level in the case of Casearia (Salicaceae)

Using the genus Casearia, we assessed the status of nested singletons: individual specimens corresponding to accepted species but in molecular trees appearing nested within clades of closely related species. Normally, such cases would be left undecided, while on the other hand, timely taxonomic decisions are required. We argue that morphological, chorological, and ecological data can be informative to illuminate patterns of speciation. Their use can provide a first step in testing taxon concepts at species level. We focused on five cases of nested singletons in trees of the genus Casearia. We employed PCA and cluster analysis to assess phenotypic differentiation. Using geocoordinates, we calculated niche space differentiation based on 19 bioclim variables, by means of PCA and niche equivalency and similarity tests and generated dot maps. We found that the singletons were morphologically distinctive in two of the five cases (Casearia selloana and C. manausensis), relatively distinctive in two other cases (C. zizyphoides and C. mariquitensis), and partially overlapping in the last case (C. grandiflora). For two cases (C. mariquitensis and C. selloana), ecological niche space was broadly overlapping, in two cases it was found broadly nested (C. grandiflora and C. zizyphoides), and in one case narrowly nested (C. manausensis), but in no case niche differentiation was observed. Niche overlap, similarity and equivalency showed corresponding patterns. Given these data, one would interpret C. selloana and C. manausensis as presumably well-distinguished taxa, their narrow distribution ranges suggesting recently emerging lineages. The other three cases are not clearcut. Morphological data would suggest particularly C. grandiflora conspecific with C. arborea, but differences in the distribution are intriguing. Our approach would reject the notion of potential synonymy based on nested phylogenetic placement for at least two of the five cases. The other case also shows no complete lack of differentiation which would support synonymy

Character evolution and biogeography of Casearia (Salicaceae): Evidence for the South American origin of a pantropical genus and for multiple migrations to the Caribbean islands

Casearia (Salicaceae) is a pantropical genus of circa 200 species, around half of which dwell in the Neotropics. Despite the availability of phylogenetic studies that suggest that Casearia sensu Sleumer is not monophyletic, a strong phylogenetic framework was still lacking for this genus. We tested the monophyly of Casearia and examined the relationships of its species to other taxa of the tribe Samydeae, including Laetia, Samyda and Zuelania, which recently have been sunk into Casearia, as well as Euceraea, Lunania, Neoptychocarpus, Ryania and Tetrathylacium. We further put a focus on the Neotropical taxa since Casearia and allies are speciose both on the Caribbean islands and adjacent mainlands, thus providing an interesting group to address the origin of the Caribbean and Cuban flora. Our phylogenetic analyses based on four combined rapidly evolving plastid regions (petD, rpl16, rps4-trnT-L-F, trnK-matK-psbA) as well as nuclear ITS revealed Casearia as monophyletic with high support, including not only the former members of Laetia, Samyda and Zuelania but also Euceraea and Neoptychocarpus. Casearia is constituted by several major clades, mostly being entirely Neotropical, one of which exclusively comprises species endemic to the Caribbean islands. Another clade, which includes all Palaeotropical species, is nested among Neotropical lineages. Our divergence date estimates using the plastid dataset and fossil calibration points in Salicaceae indicate that the Casearia crown group started to diversify during the late Eocene, approximately 39 Ma. The stem of the Old World clade diverged from Neotropical ancestors around 27 Ma, in the Oligocene. We used BayesTraits to reconstruct the evolution of seven characters commonly used to define Casearia and allied genera. We found morphological characters, such as branched inflorescences (fasciculate, glomerulous, cymose) or uniseriate stamen series, that work well to circumscribe the genus, whereas dioecy, which was used to diagnose Neoptychocarpus, or higher stamen numbers (>12), found in Laetia and Zuelania, are homoplastic in Salicaceae, the latter character derived within Casearia from ancestors with 7–12 stamens. Pellucid dots appear to have evolved earlier than the divergence of the Casearia clade in Samydeae, and were lost in Ryania and Tetrathylacium, and thus are no synapomorphy for Casearia. In order to establish a monophyletic genus concept for Casearia, we propose to also merge Euceraea and Neoptychocarpus. Our reconstruction of ancestral areas using BioGeoBears indicate that South America is the ancestral area of Casearia. From there, multiple migrations occurred to Mesoamerica and the Caribbean islands. The Caribbean that comprises nearly all Caribbean endemics started to diversify around 9.5 Ma. Our trees depict C. corymbosa, which exhibits significant infraspecific phylogenetic structure for the sampled Mexican and Colombian individuals, as the sister to the Caribbean clade. The other clade, with Cuban endemics (C. ternstroemioides) but also Mesoamerican and South American taxa, is not sufficiently resolved internally, to allow biogeographic conclusions. The Old World clade of Casearia provides another example for a late Laurasian migration starting in the Neotropics

A new species of Casearia Jacq. (Salicaceae) from Central Panama and insights into its phylogenetic position within the genus

We describe here a new species of Casearia from Panama based on both morphological and molecular data. Casearia isthmica sp. nov. is restricted to the mid-elevation cloud forests of Central Panama and presents morphological similarities with two more widespread species, C. sanchezii from high elevation areas of El Salvador and Mexico and C. tremula from the Caribbean, Central America, and Northern South America. Casearia isthmica differs in presenting pedunculated and congested inflorescences with up to 20 flowers, as well as flowers with 12 stamens and a pubescent style. Phylogenetic analysis based on selected plastid (petD, trnK-matK, rpl16 and rps4-trnLF) and nuclear (GBSSI and ITS) markers shows that the new species belongs to subclade B3 of Casearia, a lineage that encompasses species from Central America, Mexico and the Caribbean. Results of the morphological and molecular analysis were congruent and allowed a broader understanding of this new taxon, especially regarding its relationships to other Casearia

Characteristics and treatment options of glucagonomas: a national study from the French Group of Endocrine Tumors and ENDOCAN-RENATEN network

International audienceOBJECTIVE: Glucagonoma is a very rare functional pancreatic neuroendocrine tumor (PanNET). We aimed to provide data on the diagnosis, prognosis, and management of patients with glucagonoma. DESIGN AND METHODS: In this retrospective national cohort, we included all patients with glucagonoma, defined by at least one major criterion (necrolytic migratory erythema (NME) and/or recent-onset diabetes and/or weight loss ≥ 5 kg) associated with either glucagonemia >2xULN or positive glucagon immunostaining. Antisecretory efficacy was defined as partial/complete resolution of glucagonoma symptoms. Antitumor efficacy was assessed according to the time to next treatment (TTNT). RESULTS: Thirty-eight patients were included with median age 58.7 yo, primary PanNET located in the tail (68.4%), synchronous metastases (63.2%). Median Ki-67 index was 3%. Most frequent glucagonomas symptoms at diagnosis were NME (86.8%), weight loss (68.4%) and diabetes (50%). Surgery of the primary PanNET was performed in 76.3% of cases, mainly with curative intent (61.5%). After surgery, complete resolution of NME was seen in 93.8% (n = 15/16). The secretory response rates were 85.7%, 85.7%, 75% and 60% with surgery of metastases (n = 6/7), chemotherapy (n = 6/7), liver-directed therapy (n = 6/8) and somatostatin analogues (n = 6/10), respectively. All lines combined, longer TTNT was reported with chemotherapy (20.2 months). Median overall survival was 17.3 years. The Ki-67 index >3% was associated with shorter OS (HR 5.27, 95%CI [1.11-24.96], p = 0.036). CONCLUSION: Patients with glucagonoma had prolonged survival, even in the presence of metastases at diagnosis. Curative-intent surgery should always be considered. Chemotherapy, PRRT or liver-directed therapy seem to provide both substantial antitumor and antisecretory efficacy

Chemotherapy in advanced pancreatic adenosquamous carcinoma: A retrospective multicenter AGEO study

International audiencePancreatic adenosquamous carcinoma (PASC) account for < 5% of pancreatic malignancies. The efficacy of modern chemotherapy regimens in patients with advanced PASC is unknown. Patients with advanced PASC from 2008 to 2021 were consecutively included in this retrospective multicenter study. Overall survival (OS) and progression-free survival (PFS) were evaluated by Kaplan-Meier method. Ninety-four PASC from 16 French centers were included (median age, 67.3 years; males, 56.4%; metastatic disease, 85.1%). The first-line treatment was chemotherapy for 79 patients (84.0%) (37 FOLFIRINOX (FX), 7 Gemcitabine-nab paclitaxel (GN) and 35 for all other regimen) or best supportive care (BSC) alone for 15 patients (16.0%). No significant difference was observed between FX and GN in terms of PFS (P = .67) or OS (P = .5). Modern regimens pooled together (FX and GN) as compared to all others chemotherapy regimens showed an improvement of overall response rate (39.5% and 9.7%, P = .002), PFS (median, 7.8 vs 4.7 months, P = .02) and OS (median, 12.7 vs 9.2 months, P = .35). This large study evaluating first-line treatment regimens in advanced PASC suggests that modern regimens as FX or GN may be preferable to all other chemotherapy regimens. These results deserve confirmation in prospective studies

Survival of patients managed in France for duodenal neuroendocrine tumors (D-NET): a 20-year multicenter cohort study from the GTE group: a cohort study

International audienceIntroduction: Duodenal neuroendocrine tumours (D-NETs) have a low incidence; however, their diagnosis has been increasing. Features such as tumour location, size, type, histological grade, and stage were used to adapt the treatment to either endoscopic (ER) or surgical (SR) resections. There is no consensus regarding the definitive treatment. The authors' study aimed to describe the management of non-metastatic, well-differentiated D-NETs in France and its impact on patient survival.Methods: A registry-based multicenter study using prospectively collected data between 2000 and 2019, including all patients managed for non-metastatic G1 and G2 D-NETs, was conducted in the GTE group.Results: A total of 153 patients were included. Fifty-eight benefited from an ER, and 95 had an SR. No difference in recurrence-free survival (RFS) was observed regardless of treatment type. There was no significant difference between the two groups (ER vs. SR) in terms of location, size, grade, or lymphadenopathy, regardless of the type of incomplete resection performed or regarding the pre-therapeutic assessment of lymph node invasion in imaging. The surgery allowed for significantly more complete resection (patients with R1 resection in the SR group: 9 vs. 14 in the ER group, P<0.001). Among the 51 patients with positive lymph node dissection after SR, tumour size was less than or equal to 1 cm in 25 cases. Surgical complications were more numerous (P=0.001). In the sub-group analysis of G1-G2 D-NETs between 11 and 19 mm, there was no significant difference in grade (P=0.977) and location (P=0.617) between the two groups (ER vs. SR). No significant difference was found in both morphological and functional imaging, focusing on the pre-therapeutic assessment of lymph node invasion (P=0.387).Conclusion: Regardless of the resection type (ER or SR) of G1-G2 non-metastatic D-NETs, as well as the type of management of incomplete resection, which was greater in the ER group, long-term survival results were similar between ER and SR. Organ preservation seems to be the best choice owing to the slow evolution of these tumours

Policies Handbook on Using Molecular Collections

The access to molecular collections worldwide greatly improves the quality of scientific research by making a growing number of data available for investigation. The efforts on digitization also aim at facilitating the exchange of material between institutions and researchers that must follow regulations in place and respect best practice. The handbook presented here proposes a workflow to follow to safely exchange materials, in accordance with international laws and legislations. We make numerous recommendations here to help the institutions and researchers to navigate the legal and administrative procedures, to manage molecular collections in the best way possible.

Policies Handbook on Using Molecular Collections

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