15 research outputs found

    Le soi et le non-soi

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    L'enseignement considĂšre la distinction soi/non-soi comme stable et antĂ©rieure au fonctionnement du systĂšme immunitaire, et fait du soi une entitĂ© bien dĂ©limitĂ©e, se protĂ©geant du monde extĂ©rieur. L'existence des phĂ©nomĂšnes de tolĂ©rance oblige Ă  un premier renversement en faisant du soi un secteur construit par apprentissage, dans un champ oĂč la rĂ©ponse immunitaire est la rĂ©action normalement programmĂ©e. Pourtant, la thĂ©orie du rĂ©seau impose un nouveau renversement : c'est le non-soi qui n'est qu'une fraction du " rĂ©pertoire " des molĂ©cules du soi. En sorte que la sĂ©paration soi/non-soi ne semble ni simple, ni peut-ĂȘtre pertinent

    Investigating trophic ecology and dietary niche overlap among morphs of Lake Trout in Lake Superior

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    Four morphs of Lake Trout (Salvelinus namaycush, Walbaum 1792) have been identified in Lake Superior: leans, siscowets, humpers, and redfins. In this comprehensive study, the trophic ecology of Lake Trout morphs were characterized using stomach content, fatty acid, and stable isotope data. Stomach content results indicated a predominately piscivorous diet for leans, siscowets, and redfins, whereas humper diets were comprised of 50% fish and 50% Mysis by mass. Humper and siscowets were most similar in their dietary fatty acid profiles, whereas redfins had the most distinct dietary fatty acid profile. Results from stable isotope analysis revealed some among-morph differences along a pelagic-profundal consumption gradient (34S), but there were no significant differences in trophic position (15N) or basal carbon sources among morphs (13C). Using the recently developed nicheROVER software package, 4-dimensional trophic niches for each morph were quantified using stable isotope ratios (ÎŽ13C, ÎŽ15N, and ÎŽ34S) and fatty acid profiles (30 dietary fatty acids, condensed to one axis). Humpers had the largest 4-dimensional niche regions of all four morphs, and redfins had the smallest. Pairwise probability of overlap among morphs in these four-dimensional niche regions was determined to be < 50% in most cases. Overall, stomach content results indicate that humpers diets were more planktivorous than the other morphs, consistent with previous research. Results of the niche overlap analysis suggests some degree of generalist feeding for all morphs. Better characterization of seasonal variation in diet using tracers that reflect more recent feeding (e.g., fatty acids, stomach contents, and/or stable isotope analyses performed on tissues that turnover more quickly than muscle) are needed to further elucidate among-morph differences and similarities in diet and trophic ecology

    Relation expérimentation modÚle

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    Volcanic Geotourism in France.

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