Originality and biogeographical specificities of intertropical zones.

The author gives a synthesis of original and specific characteristics of in ter-tropical zones, abiotic (climate, soils) and especially biotic data: bi odiversity originality: adaptations, ecosystems. He concludes his review by considering the richness of biological interactions (with two or three par tners) as well as the biotic systems with parasites and hosts and the strug gle against parasites of ecological (via bioindication) or biological natur e.