Population genetics shed light on species delimitation and life history of the Dyckia pernambucana complex (Bromeliaceae)

摘要

In the Atlantic Rainforest located north of the SAo Francisco River (northeast Brazil), the humid enclaves called brejos de altitude play a significant role in the diversity dynamics of local flora and fauna. The related species Dyckia pernambucana and D. limae (Bromeliaceae) are characterized by their narrow endemic occurrence in such brejos, and their species status remains unclear. In order to understand the species delimitation in those assigned taxonomic entities, patterns of gene flow and genetic variability were calculated using nuclear and plastid microsatellites and AFLP markers. In this regard, we collected populations of the Pernambuco complex (D. limae and D. pernambucana, from the Borborema Plateau) and the closest relative D. dissitiflora (from the northern Espinhaco Range). Genetic diversity was moderate, despite the possible influence of genetic drift and selfing rates. Dyckia limae could not be undoubtedly discriminated from the remaining populations of Pernambuco, and we propose the synonymization of these species. Thus, the conservation of D. limae as a formerly single species would not reflect the conservation of the minimal gene pool of the studied lineage (D. pernambucana). We also propose the revalidation of the conservation status of this species, endemic to anthropomorphic island-like mountains environments. Finally, the associations found here were consistent with the historical patterns of colonization and fragmentation of the Atlantic Rainforest.