Evolution of Plant Architecture, Functional Diversification and Divergent Evolution in the Genus Atractocarpus (Rubiaceae) for New Caledonia

The diversification of ecological roles and related adaptations in closely related species within a lineage is one of the most important processes linking plant evolution and ecology. Plant architecture offers a robust framework to study these processes as it can highlight how plant structure influences plant diversification and ecological strategies. We investigated a case of gradual evolution of branching architecture in Atractocarpus spp. (Rubiaceae), forming a monophyletic group in New Caledonia that has diversified rapidly, predominantly in rainforest understory habitats. We used a transdisciplinary approach to depict architectural variations and revealed multiple evolutionary transitions from a branched (Stone's architectural model) to a monocaulous habit (Corner's architectural model), which involved the functional reduction of branches into inflorescences. We propose an integrative functional index that assesses branching incidence on functional traits influencing both assimilation and exploration functions. We showed that architectural transitions correlate with ecologically important functional traits. Variation in ecologically important traits among closely relatives, as supported by the architectural analysis, is suggestive of intense competition that favored divergence among locally coexisting species. We propose that Pleistocene climatic fluctuations causing expansion and contraction of rainforest could also have offered ecological opportunities for colonizers in addition to the process of divergent evolution

Imidazole propionate is increased in diabetes and associated with dietary patterns and altered microbial ecology

Microbiota-host-diet interactions contribute to the development of metabolic diseases. Imidazole propionate is a novel microbially produced metabolite from histidine, which impairs glucose metabolism. Here, we show that subjects with prediabetes and diabetes in the MetaCardis cohort from three European countries have elevated serum imidazole propionate levels. Furthermore, imidazole propionate levels were increased in subjects with low bacterial gene richness and Bacteroides 2 enterotype, which have previously been associated with obesity. The Bacteroides 2 enterotype was also associated with increased abundance of the genes involved in imidazole propionate biosynthesis from dietary histidine. Since patients and controls did not differ in their histidine dietary intake, the elevated levels of imidazole propionate in type 2 diabetes likely reflects altered microbial metabolism of histidine, rather than histidine intake per se. Thus the microbiota may contribute to type 2 diabetes by generating imidazole propionate that can modulate host inflammation and metabolism

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

What Makes New Caledonia’s Flora So Outstanding?

International audienceThis chapter explores the main characteristics of New Caledonian plant biodiversity, and provides a condensed picture of the major unique elements of its flora. We present the results of recent research conducted in a territory that has much to contribute to science and society. We explore the original and unique representation of some plant lineages and functional groups, as well as the rich and diversified vegetation

Ecology of lianas

The evolution of lianas has punctuated the history of land plants, with the angiosperm lineages representing the most recent stage of liana exploration. The model of lianas as fast-growing, disturbance-loving plants emerges largely from the function of eudicot and magnoliid angiosperms. This chapter looks at some specific properties of ecology and function, derived from functional aspects of stem hydraulics, which appear to be restricted to lianas. It charts the broad picture of xylem structure and function of angiosperm lianescence framed by what is known about the comparative ecophysiologies of eudicot/magnoliid and monocot lianas from temperate/ tropical zones. The chapter reviews the liana hydraulic paradigm illustrated by these angiosperm climbers. Finally, it explores how other climber lineages differ from generally accepted views about how lianas function hydraulically

The climbing flora of New Caledonia: a comprehensive checklist

International audienceNew Caledonia, an archipelago located in the southwest Pacific Ocean, hosts a rich and highly original vascular flora, distributed within a remarkable mosaic of habitats. Despite intensive research on the flora, the diversity and ecology of the climbing flora within the archipelago remain virtually unknown. More globally, while most liana studies have been carried out in continental forests, data from island ecosystems remain scarce. This study aims to document the taxonomic diversity, and to analyze the ecology and functional traits of angiosperms climbers in New Caledonia. Using herbarium data, exhaustive bibliographic review and field studies, we provide a checklist of 274 autochthonous climbing taxa, distributed in 45 families. The majority of climbing plant species in New Caledonia are woody, herbaceous vine being infrequent. Climbing plants account for?~?8% of the native flora (angiosperms), a rather small contribution compared with continental tropical floras. There is, however, a great heterogeneity in the distribution of climbing plants within the different vegetation, as they represent up to 19% of species in the sclerophyll forests, and only?~?8 and 6.5% in respectively shrublands (maquis) and rain forests, which are the most original ecosystems in New Caledonia. The endemicity is relatively low (64%) compared to the global flora (75% of endemism). Three endemic genera are exclusively climbers (Artia, Balgoya and Clematepistephium). The diversity of climbing plants is concentrated within few families: ~29% belonging to Apocynaceae and more than half of the species are included in just four families

Climbing habit and ecophysiology of Schisandra glabra (Schisandraceae): implications for the early evolution of angiosperm lianescence

Evolutionary radiations in growth forms represented key events in the rise of early angiosperm success. However, understanding the directions of early angiosperm growth lability and the traits determining growth form innovations remain unclear. Lianescence appears to represent an early evolved direction of early angiosperm growth form experimentation, owing to occurrence of lianas in the extant, early diverging clade Austrobaileyales. Here we examine biomechanical and hydraulic ecophysiology of Schisandra glabra (Schisandraceae) in the context of its habitat and xylem form-function to test hypotheses about the functional performance of basal angiosperm lianescence. We found that S. glabra evolved much higher twist-bend flexibility, greater hydraulic efficiency, and capacity as compared to a nonclimbing relative from similar habitats, Illicium floridanum. However, lianescence was not associated with increased leaf photosynthetic capacity, drought tolerance, or a more cheaply constructed body plan. We found that a small number of stem structural shifts, involving primarily increases in cell sizes of vessels, tracheids, and the proportions of living tissues, were involved in exploration of the liana habit in the Austrobaileyales. Our results suggest that evolution of early angiosperm lianescence was potentially a relatively facile transition involving relatively small changes in xylem structure to achieve large change in stem biomechanical performance