Ripe for reassessment: A synthesis of available molecular data for the speciose diatom family Bacillariaceae.

The Bacillariaceae is a very species-rich family of raphid diatoms and includes the large and taxonomically difficult genus Nitzschia, whose species are often small-celled and finely structured and have few discrete morphological characters visible in the light microscope. The classification of Nitzschia is still mostly based on one developed in the second half of the 19th century by Grunow, who separated the genus into a series of sections largely on cell shape and symmetry, the position of the raphe, transverse extension of the fibulae, and folding of the valve. We assembled and analysed single-gene and concatenated alignments of nSSU, nLSU, rbcL, psbC and cox1 to test Grunow's and subsequent classifications and to examine selected morphological characters for their potential to help define monophyletic groups.

Dispersal assembly of rain forest tree communities across the Amazon basin.

We investigate patterns of historical assembly of tree communities across Amazonia using a newly developed phylogeny for the species-rich neotropical tree genus We compare our results with those for three other ecologically important, diverse, and abundant Amazonian tree lineages, , Protieae, and Our analyses using phylogenetic diversity metrics demonstrate a clear lack of geographic phylogenetic structure, and show that local communities of and regional communities of all four lineages are assembled by dispersal across Amazonia. The importance of dispersal in the biogeography of and other tree genera in Amazonian and Guianan rain forests suggests that speciation is not driven by vicariance, and that allopatric isolation following dispersal may be involved in the speciation process. A clear implication of these results is that over evolutionary timescales, the metacommunity for any local or regional tree community in the Amazon is the entire Amazon basin.