Analysis of sexual phenotype and prezygotic fertility in natural populations of Fucus spiralis, F. vesiculosus (Fucaceae, Phaeophyceae) and their putative hybrids

In the genus Fucus, the character dioecy/hermaphroditism has undergone multiple state changes and hybridization is possible between taxa with contrasting mating systems, e.g. between the dioecious Fucus vesiculosus and the hermaphrodite F. spiralis. In the context of mating system evolution, we evaluated the potential consequences of hybridization by studying the variation in sexual phenotype and prezygotic fertility. Firstly, as a result of hybridization between the two sexual systems, gender variation may arise depending on the relative importance of genes with large versus small phenotypic effects. We thus qualitatively examined the extent of gender variation within and among individual hybrids in comparison with both parental species. Secondly, if hybridization breaks up co-adapted gene complexes, hybrid fertility may be reduced in comparison with both parental species. Therefore, we also quantified male and female prezygotic fertility in parental species and their hybrids in order to test for reduction in hybrid fitness. A total of 89 sexually mature individuals (20 F. spiralis, 40 F. vesiculosus, 10 hermaphrodite hybrids and 19 dioecious hybrids) were sampled in two geographically distant regions (France and Portugal) and six conceptacles per individual were observed. Within-individual variation was very restricted qualitatively – only one hybrid carried a conceptacle with a different sexual phenotype from the five others – as well as quantitatively. This suggests a simple genetic system for sex determination involving a few genes with major effects. In addition, analyses showed no significant decrease in hybrid fertility compared with parental species. Moreover, hybrids exhibited all sexual phenotypes, suggesting several generations of hybridization and backcrossing and, therefore, that hybrids are reproductively successful. Finally, the occurrence of sterile paraphyses in female and hermaphrodite individuals was interpreted as a relic of male function and suggests that, as in higher plants, evolution from hermaphroditism to dioecy may be the most parsimonious pathway

Virtual Partner Interaction (VPI): Exploring Novel Behaviors via Coordination Dynamics

Inspired by the dynamic clamp of cellular neuroscience, this paper introduces VPI—Virtual Partner Interaction—a coupled dynamical system for studying real time interaction between a human and a machine. In this proof of concept study, human subjects coordinate hand movements with a virtual partner, an avatar of a hand whose movements are driven by a computerized version of the Haken-Kelso-Bunz (HKB) equations that have been shown to govern basic forms of human coordination. As a surrogate system for human social coordination, VPI allows one to examine regions of the parameter space not typically explored during live interactions. A number of novel behaviors never previously observed are uncovered and accounted for. Having its basis in an empirically derived theory of human coordination, VPI offers a principled approach to human-machine interaction and opens up new ways to understand how humans interact with human-like machines including identification of underlying neural mechanisms

Evolution des systèmes de reproduction et leur implication dans les processus de spéciation et hybridation chez les algues brunes du genre Fucus

In the genus Fucus, the character dioecy/hermaphroditism has evolved several times and hybridization is possible between taxa with constrasting mating systems, making it an excellent model to study evolution of mating systems at both macro and micro-evolutionary scales.A phylogenetic approach based on intergenic chloroplast sequences showed that, like in higher plants, dioecy evolved from ancestral hermaphroditism in algae. However, relationships between taxa F. vesiculosus, F. spiralis and F. ceranoides are still unresolved, questioning their species status. Using markers of gene flow we confirmed that the three species were reproductively isolated although not totally. In order to study the importance of barriers to gene flow, we focused our analysis at the shore scale which is the transition scale between F. vesiculosus and F. spiralis. Different approaches, including population genetics and population biology have been used. As expected according to ecological models of reproductive systems evolution, the hermaphroditic species shows a very low sperm/egg ratio while resource allocation towards male function is observed in the dioecious species. Our results show that hybridization events are spatially limited by low dispersal capabilities and a high selfing rate in F. spiralis. They are mainly due to F. vesiculosus' sperm fertilizing F. spiralis'eggs.These results provide new evidences for the importance of mating system in the process of speciation.Chez les algues brunes du genre Fucus, le caractère dioécie/hermaphrodisme a évolué plusieurs fois et l'hybridation est possible entre taxa possédant des systèmes de reproduction constrastés. Ces singularités en font un excellent modèle pour étudier l'évolution des systèmes de reproduction aussi bien à l'échelle macro que micro-évolutive. Une approche phylogénétique basée sur l'analyse de séquences chloroplastiques démontre que, comme chez les plantes supérieures, l'hermaphrodisme est ancestral chez ces algues. Cependant, les taxa F. vesiculosus, F. spiralis et F. ceranoides sont compris dans un râteau irrésolu, mettant en question leur statut d'espèce.Par l'utilisation de marqueurs du flux génique nous avons démontré que les trois espèces étaient bien isolées reproductivement quoique incomplètement. Afin d'étudier l'importance de la barrière aux flux géniques, nous avons concentré notre analyse à l'échelle d'un estran, zone de transition entre F. vesiculosus et F. spiralis. Différentes approches, alliant génétique et biologie des populations ont été utilisées. Comme attentu selon les modèles écologiques de l'évolution des systèmes de reproduction, l'espèce hermaphrodite montre un très faible ratio sperme/ovule tandis qu'une réallocation des ressources vers la fonction mâle est constatée chez l'espèce dioïque. Nos résultats démontrent que l'hybridation est fortement limitée spatialement par de faibles capacités de dispersion et un fort taux d'autofécondation chez F. spiralis. Elle est due au sperme F. vesiculosus fécondant les ovules de F. spiralis. Ces résultats apportent de nouvelles preuves de l'importance des régimes de reproduction lors du processus de spéciation.No género Fucus, o carácter dioicismo/hermafroditismo evoluiu várias vezes e a hibridação é possível entre taxa com sistemas de reprodução contrastantes, fazendo com que seja um modelo excelente para estudar a evolução de sistemas tanto em escalas macro como micro-evolutivas. Uma abordagem de filogenia baseada em sequências intergénicas do cloroplasto mostrou que, em algas como em plantas superiores, a dioicia evoluiu a partir de hermafroditismo ancestral. Contudo, as relações entre as espécies F. vesiculosus, F. spiralis e F. ceranoides ainda não estão resolvidas, o que coloca questões relativamente à sua posição como espécies. Utilizando marcadores do fluxo genético, confirmámos que as três espécies estão reprodutivamente isoladas embora não totalmente.Para estudar a importância de barreiras ao fluxo genético, focámos a nossa análise na escalada da região intertidal, que é a escalada de transição entre F. vesiculosus e F. spiralis. Várias técnicas foram utilizadas, incluindo genética de populações e biologia de populações. Como esperado segundo os modelos ecológicos da evolução de sistemas reprodutivos, a espécie hermafrodita mostra uma proporção de espermatozóides/óvulos muito baixa enquanto que maior alocação de recursos na função masculina é observada nas espécies dioicas. Os nossos resultados mostram que os eventos de hibridação são limitados pelo espaço devido a capacidades de dispersão baixas e uma elevada autofecundação em F. spiralis. Estes eventos são principalmente devidos a uma fertilizacao dos óvulos de F. spiralis pelos espermatozóides de F. vesiculosus. Estes resultados forcecem novas evidências sobre a importância dos sistemas de reprodução no processo de especiação

Urban change and neighbourhood politics in San Diego: a comparative perspective

International audienc

Urban change and neighbourhood politics in San Diego: a comparative perspective

International audienc

Evolution des systèmes de reproduction et leur implication dans les processus de spéciation et hybridation chez les algues brunes du genre Fucus

L évolution des systèmes de reproduction (dioécie/hermaphrodisme) à l échelle macro et micro-évolutive a été abordée par trois approches complémentaires dans le genre Fucus, qui montre des possibilités d hybridation entre taxa possédant des systèmes de reproduction contrastés. Une approche phylogénétique démontre que l hermaphrodisme est ancestral chez ces algues même si les relations phylogénétiques entre espèces ne sont pas résolues. L utilisation de marqueurs du flux génique montre qu elles sont néanmoins isolées reproductivement, mais incomplètement. Afin d étudier l importance de la barrière aux flux géniques, notre analyse, alliant génétique et biologie des populations, a été concentrée à l échelle d un estran, zone de transition entre F. vesiculosus (dioïque) et F. spiralis (hermaphrodite). L espèce dioïque montre une réallocation de ressources vers la fonction mâle, orientant le sens de l hybridation. Celle-ci est néanmoins limitée par une faible dispersion et une forte autofécondation chez F. spiralis. Nos résultats apportent de nouvelles preuves de l importance des régimes de reproduction lors du processus de spéciation.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

When is it worth being a self-compatible hermaphrodite? Context-dependent effects of self-pollination on female advantage in gynodioecious Silene nutans

International audienceIn gynodioecious plant species with nuclear-cytoplasmic sex determination, females and hermaphrodites plants can coexist whenever female have higher seed fitness than hermaphrodites. Although the effect of self fertilization on seed fitness in hermaphrodites has been considered theoretically, this effect is far from intuitive, because it can either increase the relative seed fitness of the females (if it leads hermaphrodites to produce inbred, low quality offspring) or decrease it (if it provides reproductive assurance to hermaphrodites). Hence, empirical investigation is needed to document whether relative seed fitness varies with whether pollen is or is not limiting to seed production. In the current study, we measured fruit set and seed production in both females and hermaphrodites and the selfing rate in hermaphrodites in two experimental patches that differed in sex ratios in the gynodioecious plant Silene nutans. We found an impact of plant gender, patch, and their interaction, with females suffering from stronger pollen limitation when locally frequent. In the most pollen-limited situation, the selfing rate of hermaphrodites increased and provided hermaphrodites with a type of reproductive assurance that is not available to females. By integrating both the beneficial (reproductive assurance) and costly effects (through inbreeding depression) of self-pollination, we showed that whether females did or did not exhibit higher seed fitness depended on the degree of pollen limitation on seed production

Data from: The size advantage model of sex allocation in the protandrous sex-changer Crepidula fornicata: role of the mating system, sperm storage, and male mobility

Sequential hermaphroditism is adaptive when the reproductive value of an individual varies with size or age, and this relationship differs between males and females. In this case, theory shows that the lifetime reproductive output of an individual is increased by changing sex (a hypothesis referred to as the size-advantage model). Sex-linked differences in size-fitness curves can stem from differential costs of reproduction, the mating system, and differences in growth and mortality between sexes. Detailed empirical data is required to disentangle the relative roles of each of these factors within the theory. Quantitative data are also needed to explore the role of sperm storage, which has not yet been considered with sequential hermaphrodites. Using experimental rearing and paternity assignment, we report relationships between size and reproductive success of Crepidula fornicata, a protandrous (male-first) gastropod. Male reproductive success increased with size due to the polygamous system and stacking behavior of the species, but females nonetheless had greater reproductive success than males of the same size, in agreement with the size-advantage theory. Sperm storage appeared to be a critical determinant of success for both sexes, and modeling the effect of sperm storage showed that it could potentially accelerate sex change in protandrous species

The Size Advantage Model of Sex Allocation in the Protandrous Sex-Changer Crepidula fornicata: Role of the Mating System, Sperm Storage, and Male Mobility

Sequential hermaphroditism is adaptive when the reproductive value of an individual varies with size or age, and this relationship differs between males and females. In this case, theory shows that the lifetime reproductive output of an individual is increased by changing sex (a hypothesis referred to as the size-advantage model). Sex-linked differences in size-fitness curves can stem from differential costs of reproduction, the mating system, and differences in growth and mortality between sexes. Detailed empirical data is required to disentangle the relative roles of each of these factors within the theory. Quantitative data are also needed to explore the role of sperm storage, which has not yet been considered with sequential hermaphrodites. Using experimental rearing and paternity assignment, we report relationships between size and reproductive success of Crepidula fornicata, a protandrous (male-first) gastropod. Male reproductive success increased with size due to the polygamous system and stacking behavior of the species, but females nonetheless had greater reproductive success than males of the same size, in agreement with the size-advantage theory. Sperm storage appeared to be a critical determinant of success for both sexes, and modeling the effect of sperm storage showed that it could potentially accelerate sex change in protandrous species

Hyperactivité et psychose de l'enfant : l'intérêt de la méthodologie projective dans l'affinement des diagnostics

Hyperactivity and psychosis in the child : the usefulness of projective methods in the clarification of diagnoses. This article proposes to compare the projectif protocols of two children presenting similar symptoms and oriented to a hospital ward for attention deficit with hyperactivity disorder (ADHD).One of the children was given the clinical diagnosis of psychosis, thus excluding him from a psycho-stimulant treatment. The other maintained his clinical diagnosis of ADHD. How were these diagnoses affected when they were reviewed in the light of projective methods ?Hiperactividad y psicosis infantil : el interés de la metodología proyectiva en el afinamiento de los diagnósticos. El propósito de nuestro artículo es de poner en perspectiva las evaluaciones proyectivas de dos niños que presentan una sintomatología cercana, derivados por un “ Trastorno Deficitario de la Atención con Hiperactividad ” a un servicio hospitalario. Sólo uno de estos niños será diagnosticado clínicamente como “psicótico”, lo que excluye para él todo tratamiento psico-estimulante. El otro conserva su diagnóstico clínico de TDAH. Que sucede con los diagnósticos cuando el apoyo se establece sobre la metodología proyectiva?Cet article se propose de mettre en perspective les bilans projectifs de deux enfants présentant une symptomatologie proche, adressés pour un “ Trouble Déficitaire de l'Attention avec Hyperactivité ” (TDAH) dans un service hospitalier. Un seul de ces enfants sera diagnostiqué cliniquement “ psychotique ”, ce qui exclut pour lui tout traitement par un psychostimulant. L’autre conservera son diagnostic clinique de TDAH. Qu’en est-il des diagnostics lorsque l'on s'appuie sur la méthodologie projective