Abstract: Stress exposure and stress response are likely to vary according to life history strategies and environmental contexts. Although the acute release of glucocorticoids in response to unpredictable environmental conditions may lead to adaptative behavioral and physiological responses, exposure to high glucocorticoid levels on the long-term usually leads to deleterious cascading effects on animal’s physiology, behavior and fitness. Yet, some species may be more adapted to cope with challenging events than others and might naturally possess protective mechanisms limiting the adverse consequences of prolonged exposure to high glucocorticoid levels. King penguin chicks being naturally exposed to harsh weather, prolonged fasting and constant predation pressure, we investigated the life-history, behavioral and physiological consequences of an experimental increase in corticosterone levels on the medium and long-term (after removing implants), predicting to find relatively few costs associated with such treatment. Although non-significant, CORT-treated chicks were slightly larger, fledged slightly earlier and had slightly higher survival chances than placebo chicks. CORT-treated chicks were significantly more aggressive and displayed lower corticosterone response to acute stress on the medium term, while their physical activity and whole-body energetics were not significantly affected. While mitochondrial density was not significantly affected by the CORT treatment, CORT-treated chicks had lower oxidative stress levels on the long-term than placebo ones, and no significant impact was observed on telomere shortening. Finally, the expression of several genes (i.e. CORT receptor, HSP90, mTOR, NRF2 and TERF2) was up regulated in treated chicks, which could potentially mediate the apparent ‘stress’ resistance we observed at the phenotypic level.

Abstract: Small populations establishing on colonization fronts have to adapt to novel environments with limited genetic variation. The pace at which they can adapt, and the influence of genetic variation on their success, are key questions for understanding intraspecific diversity. To investigate these topics, we performed a reciprocal transplant experiment between two recently founded populations of brown trout in the sub-Antarctic Kerguelen Islands. Using individual tagging and genetic assignment methods, we tracked the fitness of local and foreign individuals, as well as the fitness of their offspring over two generations. In both populations, although not to the same extent, gene flow occurred between local and foreign gene pools. In both cases, however, we failed to detect obvious footprints of local adaptation (which should limit gene flow) and only weak support for genetic rescue (which should enhance gene flow). In the population where gene flow from foreign individuals was low, no clear differences were observed between the fitness of local, foreign, and F1 hybrid individuals. In the population where gene flow was high, foreign individuals were successful due to high mating success rather than high survival, and F1 hybrids had the same fitness as pure local offspring. These results suggest the importance of considering sexual selection, rather than just local adaptation and genetic rescue, when evaluating the determinants of success in small and recently founded populations.

Abstract: Since The Signature Of The Minamata Convention On Mercury In 2017, National Regulation Coordinated At An International Level Will Come Into Force In Order To Limit Anthropogenic Emissions And Therefore Protect The Human Health And Ecosystem From This Highly Toxic Pollutant. One Need To Evaluate The Efficiency Of National Measures, And Long-term Monitoring Of Atmospheric Mercury (Hg) Is An Important Tool To Address The Changes Over Time Of Emission Sources, Transport, And Deposition Patterns.the Global Mercury Observation System (Gmos) Project Was Funded By The European Commission (Http://www.gmos.eu) And Started In November 2010 With The Overall Goal To Develop A Coordinated Global Observing System To Monitor Hg On A Global Scale, Including A Large Network Of Ground-based Monitoring Stations. To Date, More Than 40 Ground-based Monitoring Sites Constitute The Global Network Covering Many Regions Where Little To No Observational Data Were Available Before Gmos (Sprovieri Et Al., 2016). All Gmos Work Is Now Continued In The Framework Of The International Frame Work Of Gos4m (Global Observation System For Mercury – Http://www.gos4m.org)although Essential To Fully Understand The Cycling Of Mercury At The Global Scale, Mercury Species Records In The Southern Hemisphere Were Really Scarce Before Gmos. In This Context, An Atmospheric Mercury Monitoring Station Has Been Set Up On Amsterdam Island (37?48 S, 77?34 E) In The Remote Southern Indian Ocean In 2012. Since 2012, We Continuously Measured Gaseous Mercury Species With A 15 Min Frequency. Angot Et Al. (2014) Discussed The First Two Years Of This Record, Using Principally Wind Sector Analysis And Air Mass Back Trajectories. They Also Include In Their Analysis The Unique Continuous Record Of Radon 222 And 220 (Thoron) (Polian Et Al., 1986; Kritz Et Al., 1990). Radon 222 And 220 (Thoron) Activities Can Be Used To Distinguish Local Soil Outgassing From Remote Continental Source. Combined With Meteorological Data, The Change Of Activities Are Then Powerful Tool To Classify Air Mass Origin For The Atmospheric Gaseous Mercury Record. Rapid And Sharp Variations Of Radon 222 Activity, Referred To As &Ldquo;radonic Storms” (Lambert Et Al., 1970) And Ascribed To Strong Continental Air Mass Advection, Are Then Observed At Amsterdam Island. The Occurrence Of Radonic Storms Was Estimated To Be About 4 % In 2012 And 7 % In 2013. Considering The Works Realized In 2014, The Goal Of This Internship Is To Deeper Explore The Relationships Between The Collected Gaseous Elemental Mercury And Observed Radon (222rn / 220rn) Activities In The Entire Data Set. In Particular, We Will Study The Specific And Coupled Trend Of These Compounds, The Frequency And Intensity Of Radonic Storm Occurrence And Their Potential Link With The Gaseous Elemental Mercury Cycle. Local Meteorology Data As Well As Backtrajectories Simulation (Hysplit And/or Flexpart Model) Will Be Also Used.