Abstract: Life-history theory predicts that, to optimize their fitness, individuals should increase their reproductive effort as their residual reproductive value decreases. Accordingly, several studies have shown that individuals downregulate their glucocorticoid stress response (a proxy of reproductive investment in vertebrates) as they age, and as the subsequent reproductive value decreases. However, and surprisingly, results appear inconsistent, suggesting that the environmental context or the individual state may affect the relationship between age and reproductive effort. Here, we tested for the first time this hypothesis, and more specifically, whether this attenuation of the corticosterone stress response with advancing age depends on the energetic status of individuals. We compared the influence of age on the corticosterone stress response between fasting and non-fasting breeding snow petrels (Pagodroma nivea), an extremely long-lived bird. As expected, we found that the corticosterone stress response was attenuated in old petrels, but only when they were not fasting. Interestingly, this pattern was not apparent in fasting petrels, suggesting that old birds downregulate their corticosterone stress response and increase their parental investment only when they are in good body condition. At the ultimate level, old individuals may maintain a strong corticosterone stress response when fasting because the survival costs of increased stress resistance and parental effort might then outweigh their reproductive benefits.

Abstract: This Paper Reports On Consolidated Ground-based Validation Results Of The Atmospheric No2 Data Produced Operationally Since April 2018 By The Tropomi Instrument On Board Of The Esa/eu Copernicus Sentinel-5 Precursor (S5p) Satellite. Tropospheric, Stratospheric, And Total No2 Column Data From S5p Are Compared To Correlative Measurements Collected From, Respectively, 19 Multi-axis Doas (Max-doas), 26 Ndacc Zenith-scattered-light Doas (Zsl-doas), And 25 Pgn/pandora Instruments Distributed Globally. The Validation Methodology Gives Special Care To Minimizing Mismatch Errors Due To Imperfect Spatio-temporal Co-location Of The Satellite And Correlative Data, E.g., By Using Tailored Observation Operators To Account For Differences In Smoothing And In Sampling Of Atmospheric Structures And Variability, And Photochemical Modelling To Reduce Diurnal Cycle Effects. Compared To The Ground-based Measurements, S5p Data Show, On An Average: (I) A Negative Bias For The Tropospheric Column Data, Of Typically ?23 To ?37?% In Clean To Slightly Polluted Conditions, But Reaching Values As High As ?51?% Over Highly Polluted Areas; (Ii) A Slight Negative Bias For The Stratospheric Column Data, Of About ?0.2?Pmolec/cm2, I.e. Approx. ?2?% In Summer To ?15?% In Winter; And (Iii) A Bias Ranging From Zero To ?50?% For The Total Column Data, Found To Depend On The Amplitude Of The Total No2 Column, With Small To Slightly Positive Bias Values For Columns Below 6?Pmolec/cm2 And Negative Values Above. The Dispersion Between S5p And Correlative Measurements Contains Mostly Random Components, Which Remain Within Mission Requirements For The Stratospheric Column Data (0.5?Pmolec/cm2), But Exceed Those For The Tropospheric Column Data (0.7?Pmolec/cm2). While A Part Of The Biases And Dispersion May Be Due To Representativeness Differences, It Is Known That Errors In The S5p Tropospheric Columns Exist Due To Shortcomings In The (Horizontally Coarse) A-priori Profile Representation In The Tm5-mp Chemistry Transport Model Used In The S5p Retrieval, And To A Lesser Extent, To The Treatment Of Cloud Effects. Although Considerable Differences (Up To 2?Pmolec/cm2 And More) Are Observed At Single Ground-pixel Level, The Near-real-time (Nrti) And Off-line (Offl) Versions Of The S5p No2 Operational Data Processor Provide Similar No2 Column Values And Validation Results When Globally Averaged, With The Nrti Values Being On Average 0.79?% Larger Than The Offl Values.