SEEM EVOLUTION / Adrien Rieux / vendredi 11 avril à 11h30

1054Adrien Rieux (University College of London)

Vendredi 11 avril à 11h30
Salle Louis Thaler, ISEM , bat 22, 2e étage

LABEx CeMEB
Séminaire d’Ecologie et Evolution

Dispersal is a key process for both the dynamics and evolution of natural populations. In addition to being crucial for colonization, dispersal also influences the processes occurring during adaptation. For pathogens in general, a better understanding of dispersal processes may improve our capacity to better predict and control the diseases that they cause. But despite its importance, dispersal in self-dispersing pathogen still remains challenging to characterize accurately. We studied dispersal and gene flow in the fungus Mycosphaerella fijiensis, a wind-dispersed plant pathogen causing black leaf streak disease (BLSD) of banana, one of the most important crop diseases in the world. In this talk, I will (try to) explain how combining several approaches differing in the spatio-temporal scale to which they refer helped us to gain insights on dispersal processes in this pathogen species. First, performing an extensive landscape genetics study allowed us to detect a sharp break in neutral allelic frequencies in South-West Cameroon, probably resulting from the secondary contact between two expanding populations. Second, to benefit from this interesting situation, we introduced a method using rates of change in neutral markers cline shapes to estimate contemporary dispersal in absence of information about initial contact time. Finally, I will illustrate how taking specific precautions in the design of a large-scale mark and recapture experiment, allow a thorough estimation of the valuable dispersal kernel under natural conditions in a wind-dispersed plant pathogen.

contact : Samuel Alizon

SEEM EVOLUTION | Allan Debelle | vendredi 4 avril, 11h30

Vendredi 4 avril 2014, 11:30
Salle Louis Thaler, ISEM , bat 22, 2e étage

LABEx CeMEB
Séminaire d’Ecologie et Evolution

Sexual selection has the ability to solely drive the divergent coevolution of mating signals and mating preferences between populations, potentially leading to sexual isolation. However, direct conclusive evidence of its importance in the speciation process remains scarce, because of the difficulties to demonstrate that both mating traits diverged as a response to sexual selection. Here, I use experimentally evolved populations of Drosophila pseudoobscura in which sexual selection intensity has been manipulated (by enforcing monogamy or elevating promiscuity) to study the role of sexual selection in speciation. After more than 100 generations of experimental sexual selection, I found that both male courtship song and female preference for courtship song have consistently diverged between the sexual selection treatments, providing direct support for the ability of sexual selection to singularly drive the divergent coevolution of mating traits. Using a female choice design to test for assortative mating between the sexual selection treatments, I found that promiscuous males have a higher probability of winning than monogamous males, regardless of female sexual selection treatment. Thus despite mating traits divergence, other sexual traits can have major effects on mating patterns and restrict population divergence and speciation. I discuss the implications of my results for the study of population differentiation, sexual selection and speciation.

contact : Ophélie Ronce

SEEM ECOLOGIE | Jacques Roy | VENDREDI 4 avril 2014 à 10h

L’INEE vient de lancer un appel à projets pour l’utilisation des Ecotrons sur la période 2014-2017 avec une description des Ecotrons et une soumission de projets en ligne sur le site http://www.ir-ecotrons.cnrs.fr/

(La même conférence sera aussi présentée le 11 avril 2014 à l’Ecotron, campus de Baillarguet, Montferrier, 10h. Ce deuxième séminaire sera suivi d’une visite de l’Ecotron à 11h30).

Objectif de l’exposé :

– présenter les caractéristiques particulières de l’Ecotron de Montpellier en ce qui concerne le conditionnement d’écosystèmes, de populations ou d’organismes et la mesure de processus en ligne;

– illustrer ces caractéristiques à partir des résultats des expérimentations déjà réalisées (impacts de changements climatiques sur une prairie, rôle fonctionnel de la biodiversité, rythme circadien de la molécule à l’écosystème, contrôles biotiques et abiotiques de la respiration du sol) ;

– préciser certains aspects de l’appel à projets (financement, étapes, consortium)

– échanger et discuter sur les éventuels projets envisagés,

Les trois plateformes expérimentales disponibles sont conçues pour des expérimentations dans des contextes d’écologie ou d’agronomie, à différentes échelles et abordant, suivant les plateformes, des questions plutôt centrées sur les cycles biogéochimiques ou alors relatives à la dynamique de populations et communautés et à l’évolution.

Contact : Jacques Roy, Ecotron Européen de Montpellier, UPS 3248 CNRS

Grande Salle de Réunion du CEFE
LABEx CeMEB

Séminaire d’Ecologie et Evolution

Séminaire du Lundi

florian schneiderFlorian Schneider, en postdoctorat avec Sonia Kéfi, nous parlera de ses travaux sur:

« Livestock grazing and catastrophic shifts in drylands »

Venez nombreux l’écouter à 11h, Salle Louis Thaler, bat 22, 2e étage, ISEM, UM2.

SEEM INVITE / Fernando Maestre / vendredi 28 mars à 11h

Vendredi 28 mars 2014 à 11:00
Amphi de la délégation CNRS

Substantial research efforts are being devoted to predict how attributes of biotic communities such as species richness, composition and diversity will respond to global environmental change (GEC) drivers like climate change, land use change and increases in [CO2] and nutrient availability. However, their impact on the relationships between biotic attributes and ecosystem processes is virtually unknown. Therefore, much remains unknown on the potential effects of GEC on the pro-cesses and ecosystem services that depend on biotic communities. This is particularly true for ecosystems such as drylands (arid, semi-arid and dry-subhumid areas), which cover over 41% of the total land surface and host ~38% of the global popu-lation.
In this lecture, I will summarize the results of recent and ongoing studies evaluating how biotic attributes (species richness, evenness and composition, cover and spatial pattern) modulate ecosystem responses (nutrient cycling and carbon storage) to GEC drivers (climate change, land use change and changes in the abundance of nutrients like nitrogen) in drylands These studies use multiple experimental approaches (manipulative and natural experiments), biotic communities (vascular plants and biocrusts dominated by mosses, lichens and cyanobacteria) and spatial scales (from local to global).
We found that the relative importance of biotic attributes such as plant cover or species richness as modulators of ecosys-tem responses to GEC drivers varies with the spatial scale considered, being more important at local and regional (~400 km) scales. At these scales, the effects of species richness on ecosystem functions were largely modulated by other biotic at-tributes, such as the total cover and spatial pattern of the plant/biocrust individuals. At the global scale, abiotic variables such as annual temperature or aridity largely determined the variation in functions related to carbon, nitrogen and phos-phorus cycling, but attributes such as species richness and composition explained significant fractions of this variation. Overall, our results indicate that biotic attributes such as cover and species richness may partially buffer negative effects of GEC on ecosystem functioning in drylands.

Recent publications:
Maestre FT et al. (2012) Plant species richness and ecosystem multifunctionality in global drylands. Science 335: 214-218.
Delgado-Baquerizo M et al. (2013) Decoupling of soil nutrient cycles as a function of aridity in global drylands. Nature 502: 672-676.
Maestre FT et al. (2013) Changes in biocrust cover drive carbon cycle responses to climate change in drylands. Global Change Biology 19: 3835-3847.

Contact: Stephan Hättenschwiler
LABEx CeMEB
Séminaire d’Ecologie et Evolution

Séminaire du Lundi 24 mars

 ©Embryon de petite roussetteMélanie Debiais-Thibaud nous parlera de ses travaux en
cours sur les dents de la mer:
« Un os dans mon steack de requin ??? »

N’aillez pas peur de venir nombreux l’écouter à 11h, Salle Louis Thaler, bat 22, 2e étage, ISEM, UM2.

SEEM EVOLUTION | Thibaut Jombart | vendredi 21 mars à 11h30 – Louis Thaler ISEM

thibaut jombartThibaut Jombart  (Imperial College of London)

Who infects whom? Using pathogen genome data for reconstructing disease outbreaks

The increasing availability of pathogen genome sequences opens up exciting perspectives for the analysis of disease outbreaks. Despite recent methodological developments exploiting this information, a general statistical tool for reconstructing transmission trees (‘who acquired infection from whom’) using genetic data is still lacking. In this presentation, we introduce ‘outbreaker’, a new tool for the R software aiming to fill this gap. ‘outbreaker’ implements a Bayesian approach which exploits both pathogen sequences and timing of symptoms to unravel the dynamics of densely sampled outbreaks. Our method identifies likely transmission events and infers dates of infections, mutation rates, unobserved cases and separate introductions of the disease. The analysis of simulated data suggest our approach will be a powerful tool for reconstructing densely sampled outbreaks. Moreover, it also proves useful for inferring numbers of secondary infections and identifying heterogeneous infectivity and super-spreaders. After presenting simulation results, we illustrate ‘outbreaker’ through the analysis of the early stage of the 2003 Singaporean outbreak of Severe Acute Respiratory Syndrome (SARS). We outline the advantages and limitations of the method, and discuss possible and ongoing improvements aiming to exploit spatial information as well as a contact network data. We conclude by emphasizing that ‘outbreaker’ is integrated alongside a broader set of tools for disease outbreak analysis within the R software.

LABEx CeMEB
Séminaire d’Ecologie et Evolution
11h30 salle Louis Thaler – ISEM, bat 22, 2e étage

(contact : Emmanuel Paradis)

SEEM ECOLOGIE | Jamie C. Winternitz | vendredi 21 mars | Salle des colloques, délégation CNRS

LABEx CeMEB
Séminaire d’Ecologie et Evolution

Vendredi 21 mars 2014, 10:00
Salle des Colloques, Délégation CNRS, 1919 route de Mende

Mechanisms of selection and MHC diversity in the montane vole and other wild mammals

The loss of genetic diversity due to reduced gene flow, inbreeding and genetic drift can result in reduced fitness for individuals and extinction risks for populations and species.  One locus for which genetic diversity is vitally important is the Major Histocompatibility Complex (MHC).  The MHC is renowned for its unparalleled allelic diversity which facilities recognition of diverse parasites by vertebrate immune systems, and this genetic diversity has been maintained even in the face of repeated population bottlenecks in some species.  Two selective processes could maintain this diversity: mate choice and parasitism.  This research investigates the relative roles of sexual selection and parasite-mediated selection in maintaining MHC diversity both within populations and across species. Employing both field work and molecular genetics using Next Generation (454) Sequencing technology, I investigated host-parasite interactions and neutral and adaptive genetic diversity in a cyclic montane vole population.  For interspecies analysis, I employed comparative phylogenetic tests to ask whether parasites drive MHC diversity across species, and for the first time, determine if sexual selection is broadly important in explaining MHC diversity across a range of vertebrate species.

Jamie Winternitz is a Postdoctoral Research Associate at the Institute of Botany and the Institute of Vertebrate Biology, Academy of Science, Czech Republic. Her research interests include the genetics of disease resistance in natural populations, sexual selection and parasite-mediated natural selection, the interaction between animal behavior, life history traits and infectious disease risk, and the demographic impact on selection dynamics. She is currently a visiting researcher at the CBGP working on Next Generation Sequencing methods in wild African rodents.

Contact : Jessica Abbate (CEFE)

Gombessa, à la rencontre du cœlacanthe

GOMBESSA 41nJrBmXUAL._SX385_Ça y est, le film Le cOElacanthe, plongée vers nos origines sera programmé samedi 3 mai sur ARTE à 20h50, 1 an presque jour pour jour après l’expédition. CP-DiffusionFilmCoelacanthe-ARTE-11032014

Le livre retraçant cette expédition exceptionnelle est sorti le mois dernier. On peut le trouver à la boutique Andromède à Carnon.

Florian Holon, doctorant ISEM dans l’équipe EEC est l’un des 4 plongeurs.