Julien Cote

2015-2017   TRAM-MIDPYR (TRAMes vertes et bleues en MIDi-PYRénées) (PI: Michel Baguette, Participant)

2014-2017 European project Biodiversa (Co-PI with S. Blanchet) - http://biodiversa-probis.weebly.com/

2013-2017   Young researcher ANR research grant (PI)

Past funding: Fyssen foundation research grant (2011-2012 PI and 2012-2013 Participant PI: J. Cucherousset), IDEX University of Toulouse: Emergence 2013 (PI: J. Cucherousset, Participant)

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

Research Interests

Dispersal syndromes, metapopulation dynamic and colonization success

Animal personality 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. I have been studying a new solution to this problem coming through the recent recognition of within-species variation in behaviour and animal personality. Indeed, a new exciting approach looks at how such variations might influence invasion dynamics and success. The general hypothesis is individuals’ personality types may affect their colonization success, meaning that some individuals might be better invaders than others (aggressive individual, asocial individuals). We empirically tested this hypothesis using western mosquitofish and modelled the consequences on invasion dynamic. Thanks to J. Cucherousset and S. Blanchet, I am now focusing my research on the consequences of animal personality bias in invaders on the functioning of native communities and ecosystems using several other species.

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

Adaptation to climate change: experimental approach

Thanks to the metatron (http://themetatron.weebly.com/), we created habitat patches connected by corridors and manipulated for their climatic conditions. Through this manipulation, we create thermal differences of 2°C which match predictions of climate change in 50 years. Our main goal is to study 1) the impacts of climate change on the common lizard Zootoca vivipara, both at the individual level (phenotypic changes), at the population level (impact on lizard population and metapopulation dynamics and persistence) and at the lizard community level (impact on lizard gut microbial community) and 2) how common lizards and their community can adapt to global warming. To do so, we measure phenotypic variation (behaviour, melanism and thermal preferences) and life history traits (dispersal, survival, growth) through successive generations of populations maintained in different climatic conditions. Using this approach allows us to tease apart the influence of dispersal, selection and phenotypic plasticity into the adaptation to climate change.

Collaborators: F. Pellerin, E. Bestion, J. White, R. Aguilée, J. Salmona

Predation risk, phenotypic plasticity and life history traits

We recently developed a suites of experiments to test how predator cues (i.e. snake) change lizards behaviour with subsequent repercussions on their population and community. We first measured how predation risk change female choice for male partners and showed that females choose males with the personality type allowing offspring to succeed better in a risky or a safe environment. In a second step, we showed that predation risk during gestation modifies offspring  phenotype (i.e. tail length, activity, thermal preference) and dispersal behaviour in order to improve offspring survival in a landscape of fear. We are now studying how predation risk during offspring development builds up juvenile behavioural types. Overall, we study how a risky situation at different stages of offspring production can be important in the development of behavioural types.

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

Personality traits, community and ecosystem functioning

I collaborate with three colleagues on several experiments aiming at studying the consequences of predator personality traits on prey community structure and ecosystem functioning. Using mesocosm and experimental lakes, we can link individual personality type to individual diet and study the consequences of personality bias on prey abundance, diversity and nutrient fluxes. We also develop a framework linking personality traits and ecosystem functioning in invaded ecosystems (Juette et al. 2014). Our model species include the largemouth bass and crayfish.

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

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

Ecological impacts of climate change

Because species adaptation should be studied in the light of their community, the project above has been coupled with a monitoring of invertebrate, plant and bacterial communities. Then, we can study different pathways for climate change to act on lizard population (e.g. diet change, vegetal cover and thermal niche, gut microbiota and digestion) and the consequences of changes in lizard population on community functioning.

Collaborators: E. Bestion, F. Pellerin, L. Di Gesu, L. Zinger, J. White, S. Jacob

© S. Fogarty

© E. Bestion

© S. Blanchet

© A. Teyssier

© E. Bestion

© E. Bestion

© Q. Bernard

© Q. Bernard

© J. Cote

A major goal of my research is to understand how dispersal syndromes explain metapopulation dynamics using the common lizards as a model (Zootoca vivipara). Recent studies show that individuals leaving their natal population to settle in a novel habitat (dispersers) and individuals staying in their natal population (residents) display different suites of phenotypic traits. Those individuals might differ from residents for physiological, morphological and behavioral traits and these traits might drive their dispersal decisions from the departure to their settlement in specific habitats. Furthermore, even among dispersers, several types of individuals (with different suites of phenotypic traits) can be observed, explaining why some dispersers prefer settling in empty habitats while others settle in already occupied habitats. These different types of dispersers would depart from their population in response to different ecological factors (population density, kin competition). A large part of my research is dedicated to the study of factors inducing dispersal decisions Finally, I aim at integrating previous ideas of the dynamics of fragmented populations (i.e. metapopulation) to show that the diversity of dispersal syndromes can be an important factor explaining meta-population dynamics.

Collaborators: E. Bestion, F. Pellerin, R. Aguilée, J. Salmona

© E. Bestion

© E. Bestion

Funding