Wild flies hedge their thermal preference bets in response to seasonal fluctuations

Fluctuating environmental pressures can challenge organisms by repeatedly shifting the optimum phenotype. Two contrasting evolutionary strategies to cope with these fluctuations are 1) evolution of the mean phenotype to follow the optimum (adaptive tracking) or 2) diversifying phenotypes so that at least some individuals have high fitness in the current fluctuation (bet-hedging). Bet-hedging could underlie stable differences in the behavior of individuals that are present even when genotype and environment are held constant. Instead of being simply ‘noise,’ behavioral variation across individuals may reflect an evolutionary strategy of phenotype diversification. Using geographically diverse wild-derived fly strains and high-throughput assays of individual preference, we tested whether thermal preference variation in Drosophila melanogaster could reflect a bet-hedging strategy. We also looked for evidence that populations from different regions differentially adopt bet-hedging or adaptive-tracking strategies. Computational modeling predicted regional differences in the relative advantage of bet-hedging, and we found patterns consistent with that in regional variation in thermal preference heritability. In addition, we found that temporal patterns in mean preference support bet-hedging predictions and that there is a genetic basis for thermal preference variability. Our empirical results point to bet-hedging in thermal preference as a potentially important evolutionary strategy in wild populations

Wild flies hedge their thermal preference bets in response to seasonal fluctuations

Fluctuating environmental pressures can challenge organisms by repeatedly shifting the optimum phenotype. Two contrasting evolutionary strategies to cope with these fluctuations are 1) evolution of the mean phenotype to follow the optimum (adaptive tracking) or 2) diversifying phenotypes so that at least some individuals have high fitness in the current fluctuation (bet-hedging). Bet-hedging could underlie stable differences in the behavior of individuals that are present even when genotype and environment are held constant. Instead of being simply ‘noise,’ behavioral variation across individuals may reflect an evolutionary strategy of phenotype diversification. Using geographically diverse wild-derived fly strains and high-throughput assays of individual preference, we tested whether thermal preference variation in Drosophila melanogaster could reflect a bet-hedging strategy. We also looked for evidence that populations from different regions differentially adopt bet-hedging or adaptive-tracking strategies. Computational modeling predicted regional differences in the relative advantage of bet-hedging, and we found patterns consistent with that in regional variation in thermal preference heritability. In addition, we found that temporal patterns in mean preference support bet-hedging predictions and that there is a genetic basis for thermal preference variability. Our empirical results point to bet-hedging in thermal preference as a potentially important evolutionary strategy in wild populations

Robespierre et la fonction ministérielle

Cette communication n'a pas pour objet l'étude des rapports entre Robespierre et les différents ministres entre 1789 et l'an II. Elle se propose de tenter de définir comment il conçoit la fonction ministérielle, c'est-à-dire le rôle et la place des ministres dans l'organisation des pouvoirs publics. Cette question se justifie pour plusieurs raisons : D'abord, parce que la fonction ministérielle à la fin du XVIIIe siècle est différente de celle que nous connaissons aujourd'hui. En ana..

Robespierre. De la Nation artésienne à la République et aux Nations

Ce volume est l'aboutissement du colloque organisé à Arras en avril 1993 et auquel ont participé près de cinquante historiens de plusieurs pays. Il rassemble 35 contributions, les synthèses de trois jours de débats, le compte rendu d'une table ronde sur "la politique, la morale et le sacré". L'ouvrage concerne le lecteur soucieux de comprendre un personnage qui porte en lui la complexité de la Révolution française ; il sollicite aussi le citoyen qui s'interroge sur l'évolution de la démocratie et de la République

2023 EELS field tests at Athabasca Glacier as an icy moon analogue environment

JPL is developing a versatile and highly intelligent Exobiology Extant Life Surveyor (EELS) robot that would enable access to subsurface oceans and near-surface liquid reservoirs through existing conduits, such as the vents at the south pole of Enceladus or the putative geysers on Europa. A key mobility requirement for future vent exploration missions will be the ability to carefully descend and hold position in the vent to collect and analyze samples while withstanding plume forces without human intervention. Furthermore, this must be accomplished in a highly uncertain environment, requiring versatile hardware and intelligent autonomy. To work towards that goal, we have prototyped the EELS 1.0 and EELS 1.5 robots for horizontal and vertical mobility, respectively, in icy terrain. Autonomous surface mobility of EELS 1.0 was previously validated in a variety of terrain, including snowy mountains, ice rinks, and desert sand. Vertical mobility of EELS 1.5 was developed on laboratory ice walls. This paper presents the first mobility trials for both robots on large-scale, natural icy terrain: the Athabasca Glacier located in Alberta, Canada, a terrestrial analogue to the surfaces and subsurfaces of icy moons. This paper provides a preliminary written record of the test campaign’s four major trials: 1) surface mobility with EELS 1.0, 2) vertical mobility with EELS 1.5, 3) science instrument validation, and 4) terramechanics experiments. During this campaign, EELS 1.5 successfully held position and descended ~1.5 m vertically in an icy conduit and EELS 1.0 demonstrated surface mobility on icy surfaces with undulations and slopes. A miniaturized capillary electrophoresis (CE) instrument built to the form factor of an EELS module was tested in flowing water on the glacier and successfully demonstrated automated sampling and in-situ analysis. Terramechanics experiments designed to better understand the interaction between different ice properties and the screws that propel the robot forwards were performed on horizontal and vertical surfaces. In this paper we report the outcomes of the four tests and discuss their implications for potential future icy missions. The field test also demonstrated EELS’s ability to support Earth science missions. Another potential near-term follow-on could be a technology demonstration on the Moon. This paper is a high level report on the execution of the field test. Data and results will be detailed in subsequent publications