AgriPop Friday Talks

Friday's Agripop Talk

28 June 2013 - 11:30 - 12:30 Salle Ragondin
2 Master student project presentations

1. Bees and their landscape: 
Mapping the distribution of floral resources in agricultural landscapes and their use by wild bees

Lindy Mary Corredores Hurtado

Centre d’Etudes Biologiques de Chizé & Universidad Javeriana (Colombia)

 &

2. Rôle des adventices dans l’écologie de l’abeille domestique en plaine agricole

Yoanna Marescot

Centre d’Etudes Biologiques de Chizé

 You know, on average one in every three bites of food eaten by humans worldwide depends on bees and other pollinators for a succesful harvest (see here) and our markets and grocery stores would look quite empty without their services:

Source: http://io9.com/if-bees-go-extinct-this-is-what-your-supermarket-will-513604512

and see also this very interesting post on the story of hand pollination in China by Bug_Girl, a researcher in entomology and famous blogger about insects.

Bus so, why are bees declining worldwide? This is actually a tricky question, as there appear to be multiple causes at work (e.g. see here and here) and multiple stressors may be at work, such as parasites or pesticides. In intensive agricultural landscapes, however, one important problem appears also to be the supply of sufficient floral resources over the season. For example, where should bees go to once these massive blooms of rapeseed fields have disappeared after only few weeks and it will take several more weeks before the sunflowers start to open up? 

This is the problem tackeld by the projects of today's speakers, Lindy and Yoanna. 

Lindy will present us her results of an intensive mapping effort wild flower resources in our study area and the use of these resources by domestic bees. Yoanna has investigated the feeding ecology of the domestic bee in our study area, investigating how the bees can manage to cover the period without massive supply of flowers from the crops (rapeseed and sunflower). 

As this will be the first time you see Yoanna's project, here a short abstract, too:

Depuis la modernisation de l’agriculture, les paysages agricoles sont modifiés, s’appauvrissent en diversité écologique alors même qu’ils ont longtemps abrité une grande richesse spécifique, notamment au niveau de la flore herbacée des champs cultivés. Il s’agit plus précisément des adventices, qui voient, comme tant d’autres groupes végétaux ses populations régressées. Pourtant les adventices joueraient un rôle important comme apport alimentaire aux pollinisateurs et plus particulièrement à l’abeille domestique. Nous étudions ici le rôle des adventices  au sein d’une plaine agricole de Poitou-Charentes, caractérisée par deux périodes où les ressources pour l’abeille se trouvent en excès, floraison du colza puis celle du tournesol, et entre les deux: une période d’insuffisance alimentaire.

So, please come, listen, and discuss!

Agripop Friday talks

Friday's Agripop Talk

14 June 2013 - 11:00 - 12:00 Salle Seminaire

Relations plantes-criquets en milieu agricole: 
étude du lien entre l’abondance des criquets et les traits fonctionnels des plantes

Gaëtane Le Provost

Centre d’Etudes Biologiques de Chizé & Université Paris Sud XI

 

Photo by Richard Seaman. Downloaded from http://richard-seaman.com/Arthropods/Russia/

Exciting times - Gaetanne, our master student (M2) has submitted her thesis this week! But now the viva is looming -- it'll be next Monday! You better get prepared ... hence Gaetanne will do a mock talk tomorrow to receive feedback. Please all of you, do come along!

 Here a summary of her thesis:

Agricultural intensification has caused a dramatic loss of perennial lands, which has resulted in strong declines of plant diversity and invertebrate populations, leading to cascade effects at many trophic levels. Understanding the mechanisms involved in the structuring of communities is crucial to understand ecosystem responses to global change. 

In this context, applying the “Holy Grail” hypothesis and the “Response-effect” framework to the study of multitrophic systems will improve our ability to understand the underlying processes implicated in the relationship between functional diversity and ecosystem functioning. By studying the link between plants and grasshoppers in agroecosystems, we want to quantify the relative effects of land use on the functional composition of grasslands and on invertebrate herbivore communities. 

Through analyses of several plant traits and their impact on grasshopper abundance, we have identified the effect of different land use components and plant functional diversity on the relationship between plants and herbivores in grasslands. This work proposes that response traits of plants to land use change the abundance of different grasshopper species. Our results confirm the existence of a functional structure in plant communities in response to land use, affecting grasshopper communities.

 Ah, no, not THIS quest for the holy grail ...:

It refers to a work by Sandra Lavorel and collegues (e.g. see here) ...

Hence, please come all - if you ask nicely you might even get some precious tips about secret spots to do nice "sorties naturalistes" in the surrounding areas ... ;-)

Agripop Friday Talks

Friday's Agripop Talk

07 June 2013 - 11:00 - 12:00 Salle Seminaire

Coupled dynamics of traits and populations in response to environmental change

Prof. Arpat Ozgul

Institute of Evolutionary Biology and Environmental Studies, University of Zurich (Switzerland)

If the environment changes you better change, too -- in behaviour, appearance, size, etc. But how? And what are the time scales of these responses? Our invited speaker this week, Arpat Ozgul from the University of Zurich, will present us results form his recent and ongoing research on this topic.

Here, an abstract of the talk:

A major goal in population ecology is to predict how populations will respond to environmental change. Recent studies have highlighted rapid phenotypic changes accompanying and often preceding demographic regime shifts, indicating that a trait-based demographic approach can improve our ability to predict a population’s response to environmental change. 

Furthermore, these studies show that some species can adapt to environmental change more easily than others through a range of evolutionary and ecological mechanisms; understanding these differences is crucial for identifying species that are more susceptible. 

In this talk, I will present the links between the abiotic environment, population density, individual traits (such as body size) and demography using long-term data from two mammalian systems: Soay sheep and yellow-bellied marmots, and address the following questions: “How do populations respond demographically, ecologically and evolutionarily to environmental perturbations?”

And for the really keen and diligent ones, here a few papers relevant to the talk:

Ozgul A, Coulson T, Reynolds A, Cameron T, Benton T (2012) Population responses to perturbations: the importance of trait-based analysis illustrated through a microcosm experiment. American Naturalist

Ozgul A, Childs DZ, Oli MK, Armitage KB, Blumstein DT, Olson LE, Tuljapurkar S, Coulson S (2010) Coupled dynamics of body mass and population growth in response to environmental change. Nature

Ozgul A, Tuljapurkar S, Benton TG, Pemberton JM, Clutton-Brock TH, Coulson T (2009) The dynamics of phenotypic change and the shrinking sheep of St. Kilda. Science

Photo by Arpat Ozgul

Perhaps most importantly, Arpat will be around on Friday so there will be plenty of opportunities to interact with him - including during a:

  apero et soirée barbecue chez la riviere starting at around 18:00 in Chize. 

 Tous sont le bienvenus!

Apero et barbecue will be held here!

Finally, in case you wonder why the marmot is wearing a mask -- there is a long tradition of scientists engaging beyond the laboratory to try helping their communities (e.g. see here) and Arpat is a recent example. Whilst doing this, he even discovered a new species, the Chapulcu (G. chapullini): A gremlin species native to Anatolia. Spawns when wet, goes nuts when sprayed with pesticide ;-)

Agripop Talks

Agripop Talk

10 June 2013 - 11:30 - 12:00 Salle Ragondin

Dynamique d’occupation des habitats par un Coléoptère carabique dominant des paysages agricoles d’ouest de la France : Poecilus cupreus

Ronan Marrec

Centre d’Etudes Biologiques de Chizé (France)

Downloaded from: http://www.hlasek.com/poecilus_cupreus_bc4959.html

Ronan Marrec, PhD student in our lab, will soon present exciting results from his PhD at the forthcoming french conference on landscape ecology ("6èmes journées françaises de l’Ecologie du Paysage") in Rennes (11-14 June 2013). Ronan will present  his work in the session on 'AgroEcologie et Paysage' and would like to receive some feedback on his presentation. So, please do all come along and help out! Here a description of what you will hear about:


Dans les agroécosystèmes, les facteurs contraignant la distribution et l’abondance des espèces sont instables dans l’espace et dans le temps, les habitats étant dynamiques et subissant de fortes pressions anthropiques. De ce fait, persister dans les paysages agricoles est un défi pour les espèces. Certaines espèces, dites rudérales, savent pourtant tirer profit de cette instabilité spatio-temporelle, notamment via leur capacité à se disperser d’un habitat à l’autre. 

Poecilus cupreus (L.) (Coleoptera, Carabidae) fait partie des espèces très abondantes dans les paysages agricoles de l’ouest de l’Europe. Ce carabique présente l’intérêt de pouvoir agir comme auxiliaire de culture car c’est un prédateur opportuniste de ravageurs et d’adventices. Notre étude a pour objectif d’identifier les habitats de l’agroécosystème qui lui sont favorables à différentes échelles spatiales, de la parcelle au paysage. Elle se fonde sur l’échantillonnage pluriannuel des populations de P. cupreus au sein de la Zone Atelier Plaine et Val de Sèvre, plaine agricole de 450 km² située dans l’Ouest de la France. Les échantillonnages ont eu lieu de 2010 à 2012 au moyen de pots-pièges placés aléatoirement dans les cultures dominantes : céréales d’hiver, colzas, tournesols, prairies et luzernes. 

Notre étude montre que P. cupreus se distribue dans tous les types d’habitats, mais que son activité-densité est plus élevée dans le colza. L’analyse à l’échelle paysagère est basée sur la composition du paysage environnant dans un rayon de 200 m à 1000 m  autour des points d’échantillonnage. Elle montre une influence positive des surfaces en colzas  l’année d’échantillonnage dans les 500m autour du piège sur l’activité-densité de l’espèce. 

L’ensemble de nos résultats suggère que le colza occupe une place privilégiée dans la dynamique des populations de cette espèce. Plusieurs hypothèses sur les mécanismes sont discutées.

A stag stands in a neck high field of canola north of Cremona, Alta., July 31, 2011. THE CANADIAN PRESS/Jeff McIntosh

Yes, the image of a colza (= 'rapeseed' or 'canola') field is highly relevent for Ronan's results but, no, the deer has nothing to do here -- that's just my personal bias towards deer ;-)