By comparison, speciation within curassows ("Crax", "Nothocrax", "Pauxi" and "Mitu") and the piping/wattled guans is supported by better evidence. It was usually caused by changes in topography which divided populations (vicariant speciation), mainly due to the uplift of the Andes which led to the establishment of the modern river basins. The distribution of curassow and piping-guan species for the most part follows the layout of these river systems, and in the latter case, apparently many extinctions of populations in lowland areas (Grau "et al.", 2005). Another result was that the wattled guan belongs to the same genus as the piping-guans, which thus use the older name "Aburria" (Grau "et al.", 2005).