Timing the origin and past connections between Andean and Atlantic Seasonally Dry Tropical Forests in South America: Insights from the biogeographical history of Amorimia (Malpighiaceae)

We investigated the timing of origin and past connections between Andean and Atlantic Seasonally Dry Tropical Forests in South America based on the biogeographical history of Amorimia , a genus of Malpighiaceae restricted to South America. We used a time–calibrated phylogenetic tree based on three cpDNA ( ndhF, rpl16, trnQ–rps16 ) and two nrDNA (ETS, ITS) regions including all currently accepted species in Amorimia for ancestral area reconstructions. Our results show that: (1) the ancestor of Amorimia originated in Atlantic dry forests around 22 Ma; (2) ancestors of both Amorimia subgenera arose in southern Brazilian dry forests from 18 to 14 Ma; (3) the remaining lineages in the genera diversified from mid–Miocene to the late–Pliocene; and (4) a history of two expansion events during early and middle Miocene, besides several colonization events in different nuclei of dry forests in South America is suggested.