Desvendando relações e inferindo a história biogeográfica de um grupo de bambus herbáceos da Mata Atlântica Nordestina (Piresia: Olyreae: Bambusoideae)

Abstract

Phylogenies with incongruent topologies commonly reflect different evolutionary processes that genes and species may undergo, especially groups with low internal resolution, such as Piresia, a South American herbaceous bamboo genus. Diversification in Piresia is likely recent and associated with hybridization, polyploidization, sympatric speciation and tropical forest dynamics, creating intricate phylogenetic relationships with paraphyletic/cryptic species. This study explored phylogenetic reconstructions, using gene and species trees from different molecular markers to better estimate relationships within the genus in the Atlantic Forest (AF), the most problematic lineage, particularly P. leptophylla, a paraphyletic species. We also applied a biogeographic approach to understand the processes influencing the evolutionary history of the genus. We recovered the disjunction between species from Amazonia (AM) and the AF, and low phylogenetic resolution within the latter. However, our analyses indicated that divergence between datasets may be associated with plastid DNA homoplasy. Therefore, we suggest the exclusion of certain markers in future studies. Moreover, incongruence between gene and species trees confirms the paraphyly of a welldefined species, P. leptophylla, probably by incomplete lineage sorting or differential selective pressures associated with climatic adaptation, suggesting this species needs recircumscription. The biogeographic analyses indicate that Piresia originated during the Pliocene and diversified in the Pleistocene, probably influenced by climatic fluctuations.