Julien Cote

As for stress response, I used to work on carotenoid-based coloration and oxidative stress. Carotenoid-based coloration is a common signal of individual quality that is partly environmentally determined. Indeed, carotenoids are also used for immune function and for antioxidant activity, leading to a trade-off between ornamentation and health for limited carotenoids. I am interested in the physiological aspects of this trade-off and of the maintenance of exaggerated coloration on the common lizard and on the zebra finch (Taeniopygia guttata). I investigated physiological modulations of carotenoid-based colorations (i.e. corticosterone and immune activation) and the consequences on health and condition (i.e. oxidative stress and body condition).

Past collaborators: P. Fitze, G. Sorci, B. Faivre, E. Arnoux, Y. Voituron

Current research projects

Evolutionary ecology of dispersal and spatially structured populations

Phenotypic heterogeneity and biological invasions

Ecological invasions are a major threat to biodiversity and an important element of global change with major economic and ecological costs. Invasions occur when a species introduced to areas beyond its native range spreads from the point of introduction, becomes abundant and have large negative impacts on native species. The management of invasive species is one of the major challenges in modern ecology. One classical approach is to identify characteristics that predispose a species to become a successful invader. This approach has however had only limited success in the predictability of invasion success. We have been studying a new solution to this problem coming through the recognition of within-species variation in phenotypic traits and its influence in eco-evolutionary processes. Indeed, intraspecific variations has been shown to influence invasion dynamics and success. The general hypothesis is various phenotypes are better at different stages of invasion, e.g. some individuals being better invaders than others (asocial individuals, high dispersal rates) and some other individuals better at building high density (social individuals, high reproductive rates). We study the consequences of phenotypic heterogeneity on population, invasion rates and on the functioning of native communities and ecosystems using empircal approaches with different species and modeling approaches.

 

Collaborators: A. Sih, T. Brodin, S. Fogarty, S. Blanchet, J. Cucherousset

Adaptation to climate change: experimental approach

Current scenarios predict an accelerated biodiversity erosion with climate change. However, uncertainties in predictions remain large because the multitude of climate change effects from genes to ecosystems and their interdependencies are still overlooked. This incomplete vision hampers the development of effective mitigation strategies to sustain biodiversity.

 

Climate change can directly modify the phenotype and performance of individuals through phenotypic plasticity and evolution on contemporary time scales. The microevolution of keystone species can spread throughout the whole ecological network due to changes in species interactions and further translate into an altered ecosystem functioning. Conversely, direct impacts on communities and ecosystems can have ripple effects on the phenotypic distribution and evolution of all species of ecological networks.

 

Climate-driven changes at individual and population levels can shape community composition and ecosystem functioning, and vice versa, altering eco-evolutionary feedbacks, namely the reciprocal interactions between ecological and evolutionary processes. Climate-driven ecological and evolutionary dynamics are yet often investigated separately. The role of eco-evolutionary feedbacks in climate change impacts on biological systems therefore hinges on little concrete empirical evidence contrasting with a profuse theoretical development.

 

We will investigate climate-dependent eco-evolutionary feedbacks using a realistic warming experiment reproducing natural conditions and thus allowing for both evolutionary and ecological dynamics to occur under a predicted climate change scenario. Complementary laboratory experiments will quantify reciprocal impacts of climate-dependent evolutionary and ecological changes on each other.

 

Funding: ECOFEED (Altered eco-evolutionary feedbacks in a future climate), ERC consolidator grant (2019-2024)

 

Collaborators: S. Blanchet, E. Bestion, M. Richard, D. Legrand, J. White, R. Aguilée, F. Pellerin, L. Di Gesu, J. Salmona,  S. Jacob , L. Zinger

 

Predation risk, phenotypic plasticity and life history traits

We developed a suite of experiments to test how predator cues (i.e. snake) change lizards phenotypic traits across several generations with subsequent repercussions on their population and community. We show that predation risk change female choice for male partners and modifies offspring  phenotype (i.e. tail length, activity, thermal preference, dispersal behaviour) through maternal and grand-maternal effects.  This transgenerational information is then balanced with personal information (i.e. information acquired during a lifetime) and social information (i.e. others’ personal information available to conspecifics) to improve individuals’ survival in a landscape of fear. We are now studying genetic mechanisms of antipredator responses and chemical processes involved in social information.

 

Collaborators: L. Winandy, L. Di Gesu, F. Pellerin, E. Bestion

Phenotypic heterogeneity, community and ecosystem functioning

I collaborate with three colleagues on several experiments aiming at studying the consequences of predator phenotype on prey community structure and ecosystem functioning. Using mesocosm and experimental lakes, we can link individual physiological, morphological and behavioral state to individual diet and study the consequences of personality bias on prey abundance, diversity and nutrient fluxes. I am for example involved in developing frameworks linking phenotypic traits and ecosystem functioning in invaded species (Juette et al. 2014, Raffard et al. 2017). Model species include largemouth bass , mosquitofish and crayfish.

Collaborators: A. Sih, T. Brodin, J. Cucherousset, S. Blanchet, A. Lecerf, A. Raffard

Ecophysiology of the stress response

I used to work on stress response and I hope to integrate stress response in our work on climate change and predation risk. In response to stressful conditions, animals modify their behavior and physiology to avoid or balance negative effects of stress. In many cases, responses to environmental perturbations involve the production of glucocorticoids that often mediate changes in physiological pathways and behavioural expression that minimize energy expenditure. These stress responses constitute a set of adaptive changes that should promote immediate survival. In common lizards, chronic elevation of glucocorticoids as a response to a long-lasting stressor may be an adaptive mechanism inducing behavioural and physiological changes similar to those involved in the acute stress response. However, as a sustained elevation of glucocorticoid production requires more energy than a temporary one and may have negative consequences (e.g. reduced immunocompetence or neural degeneration), the behavioural and physiological modifications may not be activated in conditions in which resource availability/energetic reserves does not compensate for the energetic requirements of the stress response (e.g. low food availability context).

Past collaborators: S. Meylan, P. Fitze, J. Clobert

Coloration, oxidative stress and immune response

Eco-evolutionary dynamics in a changing climate

© S. Fogarty

© E. Bestion

© E. Bestion

Another major project focuses on ultimate causes and  internal and external proximate triggers of dispersal. We are particularly interested in the resulting dispersal syndrome (i.e. phenotypic specialization in dispersers), its dependency on environmental context (i.e. conditional dispersal syndrome), and the consequences for meta-population and meta-community in a context of global change.

 

We couple experimental approaches on single species (e.g. common lizards) or on multiple species (e.g. Dispnet, https://dispnet.github.io/) with a modelling approach and examine syndromes using both physiological, morphological, behavioural and genomic approaches (in independent studies or all together when we have a chance). Our ultimate purposes is to highlight syndromes in an integrative way, from their multiple causes to their multiple eco-evolutionary consequences.

 

Funding: Most of the time, none.

 

Collaborators: E. Bestion, F. Pellerin, R. Aguilée, J. Salmona, D. Legrand, S. Jacob, L. Winandy, E. Fronhofer, the dispnet team

© E. Bestion

Funding

Current funding:

ECOFEED (Altered eco-evolutionary feedbacks in a future climate), ERC consolidator grant (2019-2024)

FRAIB Molecular basis of responses to climate change: an experimental evolution approach (2018-2019)

 

Past funding:

Young researcher ANR research grant (2013-2017, PI)

European project Biodiversa (2014-2017, Co-PI with S. Blanchet),

TRAM-MIDPYR (2015-2017, Projet Region, PI: Michel Baguette, Role: Participant)

Fyssen foundation research grant (2011-2012 Role: PI, 2012-2013 Role: Participant PI: J. Cucherousset)

IDEX University of Toulouse: Emergence 2013 (PI: J. Cucherousset, Role: Participant)

Still going on research projects

Not so much going on research projects

© L. Therry