Montargis – Le Château, mur nord des jardins Renaissances

La ville de Montargis est probablement née avec l’implantation d’un centre de pouvoir seigneurial vers la fin du xe s. Le château existait dès le début du xiie s., construit par Renault de Courtenay (dates incertaines mais entre 1105-1194). Il passe dans la mouvance royale en 1188. Philippe Auguste fait ériger une grosse tour maîtresse et on peut supposer que la ville s’est fortifiée à la fin du xiie s. ou au début du xiiie s. avec une éventuelle amélioration des défenses lors des travaux ent..

Social interactions modulate the virulence of avian malaria infection

There is an increasing understanding of the context-dependent nature of parasite virulence. Variation in parasite virulence can occur when infected individuals compete with conspecifics that vary in infection status; virulence may be higher when competing with uninfected competitors. In vertebrates with social hierarchies, we propose that these competition-mediated costs of infection may also vary with social status. Dominant individuals have greater competitive ability than competing subordinates, and consequently may pay a lower prevalence-mediated cost of infection. In this study we investigated whether costs of malarial infection were affected by the occurrence of the parasite in competitors and social status in domestic canaries (Serinus canaria). We predicted that infected subordinates competing with non-infected dominants would pay higher costs than infected subordinates competing with infected dominants. We also predicted that these occurrence-mediated costs of infection would be ameliorated in infected dominant birds. We found that social status and the occurrence of parasites in competitors significantly interacted to change haematocrit in infected birds. Namely, subordinate and dominant infected birds differed in haematocrit depending on the infection status of their competitors. However, in contrast to our prediction, dominants fared better with infected subordinates, whereas subordinates fared better with uninfected dominants. Moreover, we found additional effects of parasite occurrence on mortality in canaries. Ultimately, we provide evidence for costs of parasitism mediated by social rank and the occurrence of parasites in competitors in a vertebrate species. This has important implications for our understanding of the evolutionary processes that shape parasite virulence and group living

Montrichard – Le château

Le château de Montrichard est une forteresse seigneuriale du début du xiie s. constituée de deux enceintes abritant une cour haute et une cour basse, dominées par une tour maîtresse carrée à contreforts, elle-même protégée par sa chemise (fig. 1 et 2). Cette forteresse a été bâtie sur un éperon rocheux naturel qui domine la ville et la rivière du Cher ; les murailles suivent la déclivité du terrain. Fig. 1 – Relevé topographique du château Dessin : C. Leon-Holzem. Fig. 2 – Plan du château D..