The South American transition zone

This chapter characterizes the South American transition zone briefly, explains its endemic and characteristic taxa and discusses its biotic relationships. Within the transition zone, it recognizes seven provinces: Paramo, Desert, Puna, Atacama, Cuyan High Andean, Monte and Comechingones. Urtubey et al. conducted a track analysis and a cladistic biogeographical analysis of the provinces of the South American transition zone and the subregions of the Neotropical and Andean regions based on Asteraceae. Roig-Junent et al. distinguished four cenocrons based on insect taxa. The Pangeic cenocron consisted of old taxa present before the break-up of Pangaea, including two varieties: taxa found in eremic environments and taxa from more humid habitats. Vuilleumier suggested a close relationship of the Paramo province with the Puna province based on bird taxa. Studies postulated that the biota of the Paramo province derived from different biotic sources.