Nouveau manuel complet de géologie, ou Traité élémentaire de cette science... (Nouvelle édition revue, corrigée et augmentée) / par M. J.-J.-N. Huot,...

Collection : Manuels Roret

Strength and cost of an induced immune response are associated with a heritable melanin-based colour trait in female tawny owls.

1. Melanin pigments provide the most widespread source of coloration in vertebrates, but the adaptive function of such traits remains poorly known. 2. In a wild population of tawny owls (Strix aluco), we investigated the relationships between plumage coloration, which varies continuously from dark to pale reddish, and the strength and cost of an induced immune response. 3. The degree of reddishness in tawny owl feather colour was positively correlated with the concentration of phaeomelanin and eumelanin pigments, and plumage coloration was highly heritable (h(2) = 0.93). No carotenoids were detected in the feathers. 4. In mothers, the degree of melanin-based coloration was associated with antibody production against a vaccine, with dark reddish females maintaining a stronger level of antibody for a longer period of time compared to pale reddish females, but at a cost in terms of greater loss of body mass. 5. A cross-fostering experiment showed that, independent of maternal coloration, foster chicks reared by vaccinated mothers were lighter than those reared by nonvaccinated mothers. Hence, even though dark reddish mothers suffered a stronger immune cost than pale reddish mothers, this asymmetric cost was not translated to offspring growth. 6. Our study suggests that different heritable melanin-based colorations are associated with alternative strategies to resist parasite attacks, with dark reddish individuals investing more resources towards the humoral immune response than lightly reddish conspecifics.

2/6/19, remise du traité de paix aux Autrichiens, sortie de M. Sonnino [préliminaires au traité de Saint-Germain-en-Laye du 10 septembre, au château] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54215

Irak y el club europeo: ¿cuál de ellos?

El pasado 27 de enero, el Consejo de Asuntos Generales y de Relaciones Exteriores de la Unión tomó una decisión altamente significativa para el desarrollo del papel exterior de la Unión: su primera operación militar. Las páginas de la prensa dedicaban, sí lo hacían, unas pocas líneas a la operación de mantenimiento de la paz que la UE llevará a cabo en Macedonia a partir de la próxima primavera. La una de la prensa estaba ocupada por el hecho de que los Quince estaban más desunidos que nunca, a causa de la actual crisis internacional. De ahí que en la misma reunión tan sólo hubieran sido capaces de producir una declaración relativa a la situación en Irak de “minimísimo común denominador”, cuyo eje central son dos temas indiscutibles: la obligación de Irak de cooperar con los inspectores y el papel del Consejo de Seguridad como responsable del matenimiento de la paz y de la seguridad...