Nicole Mideo

University of Toronto, Canada.

vendredi 7 février 2020 - 11h30 Grand salle réunion du CEFE

Evolutionary ecology has a long and rich history of developing mathematical models to understand the processes that drive population dynamics. Applying these same tools to parasite populations and exposing the processes that govern infection dynamics at multiple biological scales is important for understanding parasite biology, explaining observed experimental or natural disease patterns, and evaluating approaches for disease control. Using a combination of mathematical modeling and experimental data, my research focuses on the ecological and evolutionary process regulating the dynamics and outcomes of vector-borne infections. This seminar will describe two projects. First, I will discuss how processes acting at different biological scales shapes the evolution of a key life history trait of malaria parasites, what this means for clinical and epidemiological outcomes, and the extent to which subtle shifts in this trait may help parasites evade the effects of drugs. Second, I will show how nuances of ecological interactions between parasites, hosts, and vectors can give rise to unexpected, and potentially counterproductive, consequences of efforts to control disease.

Recent publications:

Kamiya, et al. (in press) Temperature-dependent variation in the extrinsic incubation period elevates the risk of vector-borne disease emergence. Epidemics, doi: 10.1016/j.epidem.2019.100382

Greischar, Beck-Johnson & Mideo (2019) Partitioning the influence of ecology across scales on parasite evolution. Evolution 73: 2175–2188.

Hall & Mideo (2018) Linking sex differences to the evolution of infectious disease life-histories. Philosophical Transactions of the Royal Society B 373: 20170431.

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Ville Friman

Department of Biology, University of York, UK

vendredi 24 janvier 2020 - 11h30 Grand salle réunion du CEFE

Bacteriophages have been proposed as an alternative to pesticides to kill bacterial pathogens of crops. However, the efficacy of phage biocontrol is variable and this this is mainly because the underlying ecology and evolution phage-bacteria interactions are poorly understood in natural rhizosphere microbiomes1,2. We used a combination of field sampling studies, experimental evolution and greenhouse experiments to study ecological and evolutionary dynamics between Ralstonia solanacearum plant pathogenic bacterium and its phage parasites. Our results suggest that phages could be used as a precision tool to engineer the composition of rhizosphere microbiomes by selectively targeting pathogens. Furthermore, phage resistance evolution might not be a problem for the long-term efficiency if we use phages that impose strong evolutionary trade-offs to the pathogen.

Recent publications:

Wang, X., Wei, Z., Li, M., Wang, X., Shan, A., Mei, X., Jousset, A., Shen, Q., Xu, Y. and Friman, V.P., 2017. Parasites and competitors suppress bacterial pathogen synergistically due to evolutionary trade‐offs. Evolution, 71(3), pp.733-746.

Wang, X., Wei, Z., Yang, K., Wang, J., Jousset, A., Xu, Y., Shen, Q. & Friman, V-P. (2019). Phage combination therapies for bacterial wilt disease in tomato. Nature Biotechnology 37: 1513-1520.

Wei, Z., Gu, Y., Friman, V.P., Kowalchuk, G.A., Xu, Y., Shen, Q. and Jousset, A., 2019. Initial soil microbiome composition and functioning predetermine future plant health. Science Advances, 5(9), p.eaaw0759.

Contact : Emanuel Fronhofer

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Soutiendra publiquement ses travaux de thèse intitulés :

Origins and functions of iridescence colours in hummingbirds

mercredi 18 décembre 2019 à 14h  

Amphithéâtre de la délégation

DEFENSE IN ENGLISH

Abstract:

The study of colour can offer valuable insights into the fine details of evolutive mechanisms. It is indeed a complex trait, which can evolve along several dimensions, and which is controlled by multiple selective pressures with often opposed effects. Yet, there is one class of colours that has received few attention from evolutionary biologists: iridescent colours. This is due to the inherent complexity of these colours and the fact that even their quantitative measurement is a challenge in itself. During my PhD, I worked with physicists and biologists and I used optical theory to propose a new measurement method for iridescent colours. I then validated this method empirically by showing that it produced reliable and repeatable estimates for both hummingbirds and Morpho butterflies. My work during these three years has also focused on the development of other methodological tools and software for the study of colours. I also focused more precisely on iridescent colours in hummingbirds. I mainly investigated two sides of this topic and tried to find out (i) the proximate causes of iridescence in hummingbirds: how do they produce the striking colours they are renowned for? (ii) the ultimate causes of iridescence: what are the evolutionary mechanisms which control the evolution of iridescence at the community level? I found out that the structures producing iridescence in hummingbirds are way more diverse than what we previously thought. They even display an usual type of structure which has not been described in any other group yet. I also showed that at the interspecific level, iridescent colours on the back of hummingbirds tend to be similar among species occupying the same communities, which suggests a possible role of the environment in the evolution of these colours, possibly for camouflage against predators.

Keywords:

Iridescence, structural colouration, hummingbirds, evolutionary biology, colour science

Membres du jury

Daniel Osorio                                   University of Sussex                                 Rapporteur

Andrew Parnell                                 University of Sheffield                              Rapporteur

Mathieu Joron                                  CEFE, CNRS                                            Examinateur

Nicola Nadeau                                 University of Sheffield                               Examinatrice

Christine Andraud                            CRC, MNHN                                             Invitée

Marianne Elias                                 ISYEB, CNRS                                           Invitée

Claire Doutrelant                              CEFE, CNRS                                            Directrice de thèse

Doris Gomez                                    CEFE, CNRS                                            Directrice de thèse

Josefa Gonzalez 

Institute of Evolutionary Biology, Barcelona.

vendredi 31 janvier 2020 - 11h30 Grand salle réunion du CEFE

Transposable elements are ubiquitous, abundant, and active components of genomes. Although most of the mutations caused by transposable elements are likely deleterious or neutral, adaptive mutations have also been repeatedly identified across species. Drosophila melanogaster is an excellent species to quantify the role of transposable elements in environmental adaptation as it has recently colonized very distinct habitats. We have generated 32 D. melanogaster reference genomes using long-read sequencing of flies collected in arid, cold, and temperate environments. The in depth annotation of these genomes has allowed us to discover three new transposable element families in this well-studied species. We have also generated RNA-seq data for 25 of these genomes to investigate the role of transposable elements in expression quantitative trait loci variation and more specifically in desiccation, oxidative, and heavy-metal stress resistance. Our results will allow us to quantify the role of transposable elements in environmental adaptation and to generate testable hypothesis for follow-up functional validation studies.

Recent publications:

1 Rech, G.E. et al Stress response, behavior, and development are shaped by transposable element-induced mutations in Drosophila. PLoS Genetics, 15(2): e1007900, 2019.

2 Villanueva-Cañas et al. Diverse families of transposable elements affect the transcriptional regulation of stress-response genes in D. melanogaster. Nuc Acids Res, 47 (13): 6842–6857 2019

3 Bogaerts-Márquez, M. T-lex3: an accurate tool to genotype and estimate population frequencies of transposable elements using the latest short-read whole genome sequencing data. Bioinformatics, https://doi.org/10.1093/bioinformatics/btz727. 2019

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 Soutiendra publiquement ses travaux de thèse intitulés :

Potentiels anti-oxydants et anti-inflammatoires de sporophores de
Lentinula edodes (Shiitake) sous différentes conditions de culture

jeudi 19 décembre 2019 à 14 h

Salle des Actes de la Faculté de Pharmacie

Résumé : Lentinula edodes est un champignon comestible cultivé et commercialisé depuis des siècles en raison de ses propriétés nutritionnelles et médicinales. Riche en protéines, en fibres, en minéraux et pauvre en calories, le Shiitake présente de multiples propriétés pharmacolo-giques. Peu d'études ont évalué l'influence des conditions de culture sur les possibles effets « santé » de ce champignon. Nos travaux ont porté sur la comparaison des propriétés antioxy-dantes et anti-inflammatoires de sporophores (souche identique de Shiitake) issus de trois pro-ducteurs de la région Occitanie Française : deux cultivant en non biologique et un cultivant en biologique. Une extraction séquentielle sous sonication (cyclohexane, chloroforme, éthanol et eau) a été réalisée sur ces champignons suivie d’une caractérisation qui a permis d’identifier des molécules dont l’ergostérol dans les extraits apolaires, l’acide ascorbique et des acides ami-nés dans les extraits polaires. La capacité antioxydante de chaque extrait a été évaluée en utili-sant le DPPH et l’ORAC. L’activité anti-inflammatoire des extraits éthanoliques et aqueux de tous les producteurs a été évaluée in vitro sur un modèle de macrophages inflammatoires. A 1 mg/ml, tous les extraits présentent une activité antioxydante modérée avec un potentiel an-tioxydant plus prononcé dans les extraits aqueux, alors que la teneur en polyphénols dosée par le réactif de Folin Ciocalteu est plus importante dans les extraits cyclohexaniques. A 50 µg/ml, les extraits éthanoliques inhibent fortement la production du NO de manière dose dépendante pour les trois producteurs sans affecter la viabilité cellulaire (prétraitement pendant 4 heures ; temps de stimulation par le LPS/IFNγ de 24 heures). Par contre, l’inhibition observée pour les extraits aqueux est très faible. Cette activité constatée ne serait pas due à une activité du NO Scavenging des extraits. Le TNFα sécrété dans les surnageants cellulaires des macrophages pré-traités par les extraits éthanoliques de Shiitake est inhibé de manière concentration dépendante, contrairement aux extraits aqueux qui n’ont pas un effet inhibiteur sur la molécule. Même si les conditions de culture du Shiitake sur lesquelles nous avons travaillé influencent la teneur en er-gostérol et en acides aminés, elles n’affectent pas de façon significative son potentiel antioxy-dant et anti-inflammatoire in vitro.
 
Mots clefs : Shiitake, activité antioxydante, activité anti-inflammatoire, culture biologique, culture non biologique.
 

Membres du jury

Mme Veronica Rodriguez-Nava, Professeur, Université de Lyon 1                                                    Rapporteur

Mme Anne LANDREAU, Maître de Conférences, Université Angers                                                 Rapporteur

M. Finn KJELLBERG, Directeur de Recherche, CEFE                                                                       Examinateur

Mme Françoise FONS, Professeur, Centre d’Ecologie Fonctionnelle et Evolutive                             Examinateur

M. Frédéric BOUDARD, Maître de Conférences, Université de Montpellier                                       Examinateur

M. Lonceny TRAORE, Maître de Conférences, Université Gamal Abdel Nasser de   Conakry          Examinateur

M. Patrick POUCHERET, Maître de Conférences, HDR, Université de Montpellier                            Membre invité

M. Alain MICHEL, Professeur, Université de Montpellier                                                                     Membre invité

Damien Farine

Max Planck Institute of Animal Behaviour and University of Kontstanz, Germany

vendredi 17 janvier 2020 - 11h30 Grand salle réunion du CEFE

Sociality is widespread in the animal kingdom. However, to reap the benefits of social life, animal groups must overcome the challenges of maintaining cohesion, coordinating ac- tion, and making decisions about where to go and when. A major contribution of the study of large animal collectives has been to demonstrate that these challenges can be solved via simple local interaction rules, and thus do not require any global control. But are such insights universal? My research demonstrates that even in highly complex societies, such as those of baboons, groups move and behave in ways that are consistent with the sim- plest models of collective animal behaviour. It has also been suggested that living in such a complex society, where animals are familiar with conspecifics from both their own as well as other groups, requires advanced cognitive capacity. Using data from a recently- established population-level study of vulturine guineafowl, a mostly terrestrial and partic- ularly small-brained gamebird, I show that groups can form part of a complex social struc- ture that have previously been thought to only exist in large-brained mammals. However, while my work has provided extensive evidence that simple rules can underlie apparent complex social outcomes in nature, this does not mean that the consequences of social life are also simple. By combining large-scale studies of populations in the wild with con- trolled captive experiments, I also demonstrate that the consequences of social life can be profound and highly complex. Social structure can modulate how individuals interact with their environment, and thus how selection operates.

Recent publications :

1 Papageorgiou, D., Christensen, C., Gall, G. E., Klarevas-Irby, J. A., Nyaguthii, B., Couzin, I. D., & Farine, D. R. (2019). The multi- level society of a small-brained bird. Current Biology, 29(21), R1120-R1121.

2 Maldonado-Chaparro, A. A., Alarcón-Nieto, G., Klarevas-Irby, J. A., & Farine, D. R. (2018). Experimental disturbances reveal group-level costs of social instability. Proceedings of the Royal Society B, 285(1891), 20181577.

3 Farine, D. R., Strandburg-Peshkin, A., Couzin, I. D., Berger-Wolf, T. Y., & Crofoot, M. C. (2017). Individual variation in local inter- action rules can explain emergent patterns of spatial organization in wild baboons. Proceedings of the Royal Society B: Biological Sciences, 284(1853), 20162243.

Contact :