Unlocking the secret diversity of Anadenanthera: insights from molecular genetics of four evolving species

Abstract The understanding of genetic diversity and evolutionary relationships within the genus Anadenanthera Speg. (Fabaceae) is limited. Brenan’s classification recognized four species, but Altschul’s classification currently recognizes only two species, each with two varieties. Both classifications were based solely on morphology. We analysed molecular data from 283 specimens using 12 SSRs and 186 specimens using ITS sequence data. The results showed that neither SSR-based genotyping nor ITS-based phylogeny supported Altschul’s classification. Instead, they provided evidence of four reproductively isolated taxa and a single clade corresponding to one of Altschul’s varieties. Additionally, ecological niche modelling (ENM) investigated the influence of past climate on the geographic distribution of Anadenanthera. The ENM results suggest that the ‘varieties’ may have occupied different regions of South America with distinct paleoclimates. On the basis of these findings, the authors suggest recognizing four species, as per Brenan’s original classification.