Fig. 4.

Principal dispersal events through time among the bioregions that acted most prominently as species sources and geological events that influenced the connections among drainage systems, triggering principal dispersal events across South America. We depicted, here, only dispersal events since 160 Ma, but older events were included in the total calculation of events. The hydrogeographic events considered follow those represented in Fig. 1. The relative number of dispersal events is the total number of dispersals divided by the log-number of lineages within each time bin (1 My). (A) Dispersal events between Western Amazonia and La Plata bioregions, (B) between Western and Eastern Amazonia, (C) Guianas and Eastern Amazonia, and (D) La Plata and Atlantic Coast. The timescale on the X-axis is logarithmic.