Molecular phylogenetics of the palm tribe Geonomeae, and differentiation of Geonoma macrostachys western Amazonian varieties

Phylogenetic analyses were performed on six genera and 46 species of the Neotropical palm tribe Geonomeae. The analyses were based on two low copy nuclear DNA sequences from the genes encoding phosphoribulokinase and RNA polymerase II. The basal node of the tribe was polytomous. Pholidostachys formed a monophyletic group. The currently accepted genera Calyptronoma and Calyptrogyne formed a well-supported clade with Calyptronoma resolved as paraphyletic to Calyptrogyne. Geonoma formed a strongly supported monophyletic group consisting of two main clades. ^ An evaluation of the genetic distinctness between Geonoma macrostachys varieties at a local and regional scale using inter-simple sequence repeat (ISSR) markers was performed. Clustering, ordination, and AMOVA suggested a lack of genetic distinctness between varieties at the regional level. A hierarchical AMOVA revealed that the genetic diversity mainly lies among the four localities sampled. A significant genetic differentiation between sympatric varieties occurred in one locality only. The current taxonomy of G. macrostachys, which recognizes only one species, was therefore supported. ^ The preferred habitat of sympatric G. macrostachys varieties with respect to edaphic, topographic, and light factors in three Peruvian lowland forests was studied. The two varieties were mostly encountered in different physiographically defined habitats, with variety acaulis occurring more often in floodplain forest and variety macrostachys in the tierra firme. Comparison of means tests revealed that nine to eleven of the 16 environmental variables were significantly different between varieties. Edaphic factors, mainly soil texture and K content, were better contributors than light conditions to distinguish the habitats occupied by the two varieties in all three study sites. It is concluded that habitat differentiation plays a role in the coexistence of these closely related species taxa. ^

Molecular Evidence for Taxonomic Relationships of the Endangered Species Jacquemontia Reclinata (Convolvulaceae)

Jacquemontia reclinata House (Convolvulaceae) is a federally-listed endangered species endemic to coastal strand habitat of southeastern Florida, from Palm Beach to Miami-Dade counties. Although J. reclinata is currently defined as a species, its taxonomic distinctness has never been analyzed using phylogenetic evidence. In order to assess the evolutionary distinctness of J. reclinata and identify its closest relatives, internal transcribed spacer (ITS) regions within nuclear ribosomal DNA were sequenced, and the sequence data was used to reconstruct a phylogeny of Jacquemontia. The study included the three putative relatives of J. reclinata and all other species within Jacquemontia known to occur in the Greater Antilles and Bahamas, except for three species. Results concur with previous morphological studies, which suggest that J. reclinata is closely related to J. cayensis Britton, J. curtisii Peter, and J. havanensis Urban. These three species and J. reclinata form an unresolved clade. Therefore, it is not certain which of these Caribbean species is sister to J. reclinata. The lack of resolution within the clade that includes J. reclinata implies that the taxa within the clade are evolutionarily similar. Future taxonomic studies of J. reclinata should focus in resolving relationships within the Jacquemontia reclinata clade.