an expanded phylogeny of social amoebas (dictyostelia) shows increasing diversity and new morphological patterns扩大社会变形虫的发展史(dictyostelia)显示增加多样性和新形态模式.pdf

Romeralo et al. BMC Evolutionary Biology 2011, 11:84 /1471-2148/11/84 RESEARCH ARTICLE Open Access An expanded phylogeny of social amoebas (Dictyostelia) shows increasing diversity and new morphological patterns 1* 2 3 4 1 Maria Romeralo , James C Cavender , John C Landolt , Steven L Stephenson and Sandra L Baldauf Abstract Background: Social Amoebae or Dictyostelia are eukaryotic microbes with a unique life cycle consisting of both uni- and multicellular stages. They have long fascinated molecular, developmental and evolutionary biologists, and Dictyostelium discoideum is now one of the most widely studied eukaryotic microbial models. The first molecular phylogeny of Dictyostelia included most of the species known at the time and suggested an extremely deep taxon with a molecular depth roughly equivalent to Metazoa. The group was also shown to consist of four major clades, none of which correspond to traditional genera. Potential morphological justification was identified for three of the four major groups, on the basis of which tentative names were assigned. Results: Over the past four years, the Mycetozoan Global Biodiversity Survey has identified many new isolates that appear to be new species of Dictyostelia, along with numerous isolates of previously described species. We have determined 18S ribosomal RNA gene sequences for all of these new isolates. Phylogenetic analyses of these data show at least 50 new species, and these arise from throughout the dictyostelid tree breaking up many previously isolated long branches. The resulting tree now shows eight well-supported major groups instead of the original four. The new species also expand the known morphological diversity of