Phylogénie, datation moléculaire et évolution florale des Magnoliidae (Angiospermes)

Les relations de parentés profondes au sein des Angiospermes ont été longtemps incertaines. A la fin des années 90, les études phylogénétiques à grande échelle ont contribué à l obtention de l arbre actuel des Plantes à fleurs, dans lequel Eudicotylédones, Monocotylédones et Magnoliidae forment les trois plus grands clades. Contrairement aux Monocotylédones et aux Eudicotylédones, la monophylie des Magnoliidae (Canellales, Laurales, Magnoliales et Piperales) n a été soutenue que plus récemment. Les Magnoliidae contiennent actuellement 20 familles et environ 10 000 espèces majoritairement présentes sous les tropiques. Avant cette thèse, de nombreuses parties de ce groupe avaient été étudiées en détail mais l histoire évolutive du groupe dans son ensemble était encore mal connue. Le premier chapitre est une étude phylogénétique des relations entre les familles et les ordres de Magnoliidae. Pour réaliser cette étude, j ai échantillonné 199 espèces du groupe et 12 marqueurs moléculaires issus des trois génomes. J ai ensuite mené des analyses phylogénétiques avec les méthodes de parcimonie, d inférence bayésienne et de maximum de vraisemblance. Les résultats confirment avec un plus fort soutien la présence de deux clades dans ce groupe : Canellales + Piperales et Laurales + Magnoliales. De plus, les relations entre les 20 familles sont généralement bien soutenues, les Lactoridaceae et les Hydnoraceae étant incluses dans les Aristolochiaceae (Piperales). Dans le second chapitre, j ai révisé l âge et la position de 10 fossiles identifiés comme appartenant aux Magnoliidae. Le but de cette étude était de fournir de nouveaux points de calibration fiables afin de conduire de nouvelles analyses de datation moléculaire. Parmi les nombreux fossiles du groupe, nous avons choisi ces espèces car elles avaient été placées phylogénétiquement par des études antérieures. Le schéma de calibration résultant de ce travail inclut six contraintes fiables d âges minimum. Le troisième chapitre est une étude de datation moléculaire utilisant ce schéma de calibration et le même jeu de données moléculaires que le chapitre 1. Les résultats tendent à repousser l âge des Magnoliidae (127.1-198.9 Ma), et des quatre ordres Canellales (126.3-141.0 Ma), Piperales (88.2-157.7 Ma), Laurales (111.8-165.6 Ma) et Magnoliales (115.0-164.2 Ma). Dans ce même chapitre, j ai également étudié le mode de diversification du groupe. Les variations importantes du nombre d espèces entre les différentes parties de l arbre s expliquent le mieux par des modèles de diversification incluant 6 à 14 transition du taux net de diversification. Enfin, dans le dernier chapitre de la thèse, j ai retracé l histoire évolutive de 26 caractères floraux pour reconstruire les fleurs ancestrales de nœuds-clés des Magnoliidae. Pour ce faire, j ai tiré parti de la phylogénie du premier chapitre et utilisé les mêmes espèces dans ma matrice morphologique. Les résultats montrent que l ancêtre commun le plus récent des Magnoliidae présentait des fleurs bisexuées et actinomorphes avec un périanthe différencié de deux cycles trimères à tépales libres et probablement trois étamines libres. Ce travail de thèse apporte des résultats importants sur l évolution des Magnoliidae et soulève de nombreuses questions telles que l impact des crises géologiques sur la diversification du groupe ou l influence des pollinisateurs et de l environnement sur l évolution de la morphologie florale.Deep phylogenetic relationships in the angiosperms had long been uncertain. However, by the end of the 1990s, large-scale studies contributed to the current well resolved picture of the tree of flowering plants, in which eudicots, monocots, and magnoliids are the three largest clades. Whereas monocots and eudicots have been recognized since the very first phylogenetic analyses, the monophyly of magnoliids (Canellales, Laurales, Magnoliales, and Piperales) is a more recent result. Magnoliidae, as now circumscribed, consist of 20 families and ca. 10,000 species mostly distributed in the tropics. Before the present thesis, several parts of the magnoliid tree had been well studied, but little was known about the evolutionary history of Magnoliidae as a whole. The first chapter of this thesis is a phylogenetic study conducted to clarify the relationships among families and orders of Magnoliidae. To do so, I sampled 199 species of Magnoliidae and 12 molecular markers from the three genomes and conducted phylogenetic analyses using parsimony, maximum likelihood, and Bayesian methods. The results confirm, with a greater level of support, two clades in Magnoliidae: Canellale + Piperales, and Laurales + Magnoliales. In addition, the relationships among the 20 families are generally well supported, and Lactoridaceae and Hydnoraceae are nested within Aristolochiaceae (Piperales). In the second chapter, the ages and phylogenetic positions of 10 fossils attributed to Magnoliidae were reviewed in detail. The goal of this study was to provide new reliable calibration points in order to conduct molecular dating analyses. These fossils were selected from the rich fossil record of the group because of their previous inclusion in phylogenetic analyses with extant taxa. The resulting calibration scheme provides six solid, internal minimum age constraints. The third chapter includes molecular dating analyses using the present calibration scheme and the same molecular dataset of Chapter 1. This study tends to push back in time the ages of the crown nodes of Magnoliidae (127.1-198.9 Ma), and of the four orders, Canellales (126.3-141.0 Ma), Piperales (88.2-157.7 Ma), Laurales (111.8-165.6 Ma), and Magnoliales (115.0-164.2 Ma). In the same chapter, I investigated the mode of diversification in the group. The strongly imbalanced distribution of species appears to be best explained by models of diversification with 6 to 14 diversification rate shifts. Finally, in the last chapter, I traced the evolution of 26 floral characters to reconstruct the ancestral flowers in key nodes of Magnoliidae. I used the phylogeny of Chapter 1 and an exemplar approach. Our results show that the most recent common ancestor of all Magnoliidae was a tree bearing actinomorphic, bisexual flowers with a differentiated perianth of two alternate, trimerous whorls of free perianth parts (outer and inner tepals) and probably three free stamens. This work provides key results on the evolution of Magnoliidae and raises several new questions such as the impact of geological crises on diversification of the group or the influence of pollinators and the environment on the evolution of floral morphology.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

A global experiment on motivating social distancing during the COVID-19 pandemic

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges

Phylogénie, datation moléculaire et évolution florale des Magnoliidae (Angiospermes)

Deep phylogenetic relationships in the angiosperms had long been uncertain. However, by the end of the 1990s, large-scale studies contributed to the current well resolved picture of the tree of flowering plants, in which eudicots, monocots, and magnoliids are the three largest clades. Whereas monocots and eudicots have been recognized since the very first phylogenetic analyses, the monophyly of magnoliids (Canellales, Laurales, Magnoliales, and Piperales) is a more recent result. Magnoliidae, as now circumscribed, consist of 20 families and ca. 10,000 species mostly distributed in the tropics. Before the present thesis, several parts of the magnoliid tree had been well studied, but little was known about the evolutionary history of Magnoliidae as a whole. The first chapter of this thesis is a phylogenetic study conducted to clarify the relationships among families and orders of Magnoliidae. To do so, I sampled 199 species of Magnoliidae and 12 molecular markers from the three genomes and conducted phylogenetic analyses using parsimony, maximum likelihood, and Bayesian methods. The results confirm, with a greater level of support, two clades in Magnoliidae: Canellale + Piperales, and Laurales + Magnoliales. In addition, the relationships among the 20 families are generally well supported, and Lactoridaceae and Hydnoraceae are nested within Aristolochiaceae (Piperales). In the second chapter, the ages and phylogenetic positions of 10 fossils attributed to Magnoliidae were reviewed in detail. The goal of this study was to provide new reliable calibration points in order to conduct molecular dating analyses. These fossils were selected from the rich fossil record of the group because of their previous inclusion in phylogenetic analyses with extant taxa. The resulting calibration scheme provides six solid, internal minimum age constraints. The third chapter includes molecular dating analyses using the present calibration scheme and the same molecular dataset of Chapter 1. This study tends to push back in time the ages of the crown nodes of Magnoliidae (127.1-198.9 Ma), and of the four orders, Canellales (126.3-141.0 Ma), Piperales (88.2-157.7 Ma), Laurales (111.8-165.6 Ma), and Magnoliales (115.0-164.2 Ma). In the same chapter, I investigated the mode of diversification in the group. The strongly imbalanced distribution of species appears to be best explained by models of diversification with 6 to 14 diversification rate shifts. Finally, in the last chapter, I traced the evolution of 26 floral characters to reconstruct the ancestral flowers in key nodes of Magnoliidae. I used the phylogeny of Chapter 1 and an exemplar approach. Our results show that the most recent common ancestor of all Magnoliidae was a tree bearing actinomorphic, bisexual flowers with a differentiated perianth of two alternate, trimerous whorls of free perianth parts (outer and inner tepals) and probably three free stamens. This work provides key results on the evolution of Magnoliidae and raises several new questions such as the impact of geological crises on diversification of the group or the influence of pollinators and the environment on the evolution of floral morphology.Les relations de parentés profondes au sein des Angiospermes ont été longtemps incertaines. A la fin des années 90, les études phylogénétiques à grande échelle ont contribué à l’obtention de l’arbre actuel des Plantes à fleurs, dans lequel Eudicotylédones, Monocotylédones et Magnoliidae forment les trois plus grands clades. Contrairement aux Monocotylédones et aux Eudicotylédones, la monophylie des Magnoliidae (Canellales, Laurales, Magnoliales et Piperales) n’a été soutenue que plus récemment. Les Magnoliidae contiennent actuellement 20 familles et environ 10 000 espèces majoritairement présentes sous les tropiques. Avant cette thèse, de nombreuses parties de ce groupe avaient été étudiées en détail mais l’histoire évolutive du groupe dans son ensemble était encore mal connue. Le premier chapitre est une étude phylogénétique des relations entre les familles et les ordres de Magnoliidae. Pour réaliser cette étude, j’ai échantillonné 199 espèces du groupe et 12 marqueurs moléculaires issus des trois génomes. J’ai ensuite mené des analyses phylogénétiques avec les méthodes de parcimonie, d’inférence bayésienne et de maximum de vraisemblance. Les résultats confirment avec un plus fort soutien la présence de deux clades dans ce groupe : Canellales + Piperales et Laurales + Magnoliales. De plus, les relations entre les 20 familles sont généralement bien soutenues, les Lactoridaceae et les Hydnoraceae étant incluses dans les Aristolochiaceae (Piperales). Dans le second chapitre, j’ai révisé l’âge et la position de 10 fossiles identifiés comme appartenant aux Magnoliidae. Le but de cette étude était de fournir de nouveaux points de calibration fiables afin de conduire de nouvelles analyses de datation moléculaire. Parmi les nombreux fossiles du groupe, nous avons choisi ces espèces car elles avaient été placées phylogénétiquement par des études antérieures. Le schéma de calibration résultant de ce travail inclut six contraintes fiables d’âges minimum. Le troisième chapitre est une étude de datation moléculaire utilisant ce schéma de calibration et le même jeu de données moléculaires que le chapitre 1. Les résultats tendent à repousser l’âge des Magnoliidae (127.1-198.9 Ma), et des quatre ordres Canellales (126.3-141.0 Ma), Piperales (88.2-157.7 Ma), Laurales (111.8-165.6 Ma) et Magnoliales (115.0-164.2 Ma). Dans ce même chapitre, j’ai également étudié le mode de diversification du groupe. Les variations importantes du nombre d’espèces entre les différentes parties de l’arbre s’expliquent le mieux par des modèles de diversification incluant 6 à 14 transition du taux net de diversification. Enfin, dans le dernier chapitre de la thèse, j’ai retracé l’histoire évolutive de 26 caractères floraux pour reconstruire les fleurs ancestrales de nœuds-clés des Magnoliidae. Pour ce faire, j’ai tiré parti de la phylogénie du premier chapitre et utilisé les mêmes espèces dans ma matrice morphologique. Les résultats montrent que l’ancêtre commun le plus récent des Magnoliidae présentait des fleurs bisexuées et actinomorphes avec un périanthe différencié de deux cycles trimères à tépales libres et probablement trois étamines libres. Ce travail de thèse apporte des résultats importants sur l’évolution des Magnoliidae et soulève de nombreuses questions telles que l’impact des crises géologiques sur la diversification du groupe ou l’influence des pollinisateurs et de l’environnement sur l’évolution de la morphologie florale

Modélisation multiphasique d'écoulements et de phénomènes de dispersion issus d'explosion

Ce travail porte sur la modélisation de la formation et la dispersion d'un nuage de gouttes, par déconfinement d'un liquide: agression extérieure ou situation accidentelle. Le but est la construction d'un modèle apte à reproduire simultanément les conditions génératrices de la formation du nuage et l'évolution de ce nuage dans le temps (dispersion). La principale difficulté réside en la différence des modèles adaptés à la description d'écoulements caractérisant chaque étape du phénomène global: modèle d'écoulement multiphasique à phases compressibles (milieux continus) initialement, puis fragmentation et formation du nuage de gouttes dispersées dans une phase porteuse (modèle d'écoulements dilués). En l'absence de modèle analytique unique apte à décrire l'ensemble de ces processus, on propose une approche originale pour réaliser un couplage effectif entre ces deux modèles. La problématique de formation et de dispersion de liquide implique la prise en compte de plusieurs phénomènes physiques: fragmentation, transferts de chaleur et de masse ainsi que la traînée entre les phases. Ces différents phénomènes sont introduits dans le modèle global via des termes d'interactions présents dans les systèmes d'équations. La construction de ce modèle complet à permis la réalisation de calculs décrivant la formation et la dispersion d'un nuage de gouttes pouvant intervenir lors de situations accidentelles sur des sites industriels par exemple.This work focuses on modeling the formation and the dispersion of a cloud of droplets, induced by ejection of a liquid, resulting from an external aggression or an accidental situation. The goal is to build a model able to reproduce simultaneously the conditions which generate the cloud formation and the cloud evolution in time (dispersion). The main difficulty lies in the differences between the already existing models adapted to the description of flows which are able to characterize each stage of the global phenomenon: initially a multiphase flow model with compressible phases (Continuum), then the atomization and the formation of a cloud of droplets dispersed in a carrier phase (dilute flow model). We propose a new approach to achieve an effective coupling between these two models. The problem of the formation and the dispersion of the liquid requires to take into account several physical phenomena: atomization, heat and mass transfers and drag between phases. These phenomena are included in the global model through interaction terms involved in the systems of equations. The construction of this model has permited the realization of calculations describing the formation and dispersion of a cloud of droplets which may occur during, for axample, in accidental situations at industrial sites.AIX-MARSEILLE1-Bib.electronique (130559902) / SudocSudocFranceF

Data from: Five major shifts of diversification through the long evolutionary history of Magnoliidae (angiosperms)

With 10,000 species, Magnoliidae are the largest clade of flowering plants outside monocots and eudicots. Despite an ancient and rich fossil history, the tempo and mode of diversification of Magnoliidae remain poorly known. Using a molecular data set of 12 markers and 220 species (representing >75% of genera in Magnoliidae) and six robust, internal fossil age constraints, we estimate divergence times and significant shifts of diversification across the clade. In addition, we test the sensitivity of magnoliid divergence times to the choice of relaxed clock model and various maximum age constraints for the angiosperms. Compared with previous work, our study tends to push back in time the age of the crown node of Magnoliidae (178.78-126.82 million years, Myr), and of the four orders, Canellales (143.18-125.90 Myr), Piperales (158.11-88.15 Myr), Laurales (165.62-112.05 Myr), and Magnoliales (164.09-114.75 Myr). Although families vary in crown ages, Magnoliidae appear to have diversified into most extant families by the end of the Cretaceous. The strongly imbalanced distribution of extant diversity within Magnoliidae appears to be best explained by models of diversification with 6 to 13 shifts in net diversification rates. Significant increases are inferred within Piperaceae and Annonaceae, while the low species richness of Calycanthaceae, Degeneriaceae, and Himantandraceae appears to be the result of decreases in both speciation and extinction rates. This study provides a new time scale for the evolutionary history of an important, but underexplored, part of the tree of angiosperms. The ages of the main clades of Magnoliidae (above the family level) are older than previously thought, and in several lineages, there were significant increases and decreases in net diversification rates. This study is a new robust framework for future investigations of trait evolution and of factors influencing diversification in this group as well as angiosperms as a whole

r8s angio-170

PL tree (with 95% credibility intervals for age estimates) of the angio-170 analysis with r8s

r8s angio-150

PL tree (with 95% credibility intervals for age estimates) of the angio-150 analysis with r8s

Capacity of soil bacteria to reach the phyllosphere and convergence of floral communities despite soil microbiota variation

Leaves and flowers are colonized by diverse bacteria that impact plant fitness and evolution. Although the structure of these microbial communities is becoming well-characterized, various aspects of their environmental origin and selection by plants remain uncertain, such as the relative proportion of soilborne bacteria in phyllosphere communities. Here, to address this issue and to provide experimental support for bacteria being filtered by flowers, we conducted common-garden experiments outside and under gnotobiotic conditions. We grew Arabidopsis thaliana in a soil substitute and added two microbial communities from natural soils. We estimated that at least 25% of the phyllosphere bacteria collected from the plants grown in the open environment were also detected in the controlled conditions, in which bacteria could reach leaves and flowers only from the soil. These taxa represented more than 40% of the communities based on amplicon sequencing. Unsupervised hierarchical clustering approaches supported the convergence of all floral microbiota, and 24 of the 28 bacteria responsible for this pattern belonged to the Burkholderiaceae family, which includes known plant pathogens and plant growth-promoting members. We anticipate that our study will foster future investigations regarding the routes used by soil microbes to reach leaves and flowers, the ubiquity of the environmental filtering of Burkholderiaceae across plant species and environments, and the potential functional effects of the accumulation of these bacteria in the reproductive organs of flowering plants.ISSN:0027-8424ISSN:1091-649

Development of Graphidium strigosum (Nematoda, Haemonchidae) in its natural host, the rabbit (Oryctolagus cuniculus) and comparison with several Haemonchidae parasites of ruminants

International audienceThe morphogenesis (studied for the first time) and the chronology of the life cycle of Graphidium strigosum (Dujardin, 1845) were studied in detail in its natural host, Oryctolagus cuniculus. Naive rabbits were each infected per os with G. strigosum infective larvae (L3). Animals were euthanized each day for the first 10 days after infection (DAI), then every 2 days from 12 to 40 DAI. The free living period lasted 5-8 days at 24°C. By 1 DAI, all the larvae were exsheathed in the stomach. The third molt occurred between 9 and 17 DAI. The last molt occurred between 24 and 32 DAI. The prepatent period lasted 42-44 DAI, while the patent period lasted at least 13 months. For each experiment, the morphology of the different stages of the life cycle was described. The chronology of the G. strigosum life cycle and its morpho-genesis were compared to those of different Haemonchidae parasites of ruminants (Ostertagia ostertagi, Teladorsagia circumcincta, Haemonchus contortus, and Haemonchus placei) in their natural hosts