A preliminary study of genetic diversity in populations of Montrichardia Crueg. (Araceae) estimated with molecular markers.

The two species of (Araceae) are perennial herbs of great ecological, economic, and ethnobotanical importance that form populations by clonal growth and sexual reproduction. Here, genetic diversity was studied within a drainage system distant from Amazonia. Five populations were sampled from the Rio Parnaíba Delta (northeast Brazil) and two outside it. The eight ISSR primers selected generated 342 marker bands. The non‐Delta populations ( ) were grouped together by cluster analysis and Bayesian simulation but the Delta populations ( ) were only grouped weakly. Ordination and Bayesian simulation grouped populations into three pairs along an east–west axis. All population pairs were significantly different (pairwise , ≤ 0.001). Between‐population variance (AMOVA, 39.9% variance, < 0.001) was much greater than between‐species (12.2%, < 0.034), but within‐population variance was greatest (48.0%). Within the Delta, geographical distance between populations did not predict genetic similarity, but relative within‐population diversity appears to be influenced by habitat differences. There is genetic evidence, but relatively weak, for recognizing the Delta populations as and the non‐Delta ones as ; Paulino Neves (Maranhão) appears to be the easternmost record for this species. The strong between‐population differences previously reported for are corroborated