XENORHABDUS AND PHOTORHABDUS - ARE THEY SISTER GENERA OR ARE THEIR MEMBERS PHYLOGENETICALLY INTERTWINED

The evolution of an organism can be considered as the sum or mean of t he evolution of its genes. Thus, the restriction of the phylogenetic a nalysis to a single molecule, such as the most widely used 16S rDNA, h ighlights the evolution of the molecule but not necessarily the evolut ion of the organisms from which the molecule was isolated for analysis . For a few groups of bacteria more than only a single conservative mo lecule has been analysed; most of these data sets agree with each othe r and even provide more insight into the evolution and phylogeny of th e organisms. For the majority of bacterial taxa, however, genealogical patterns are exclusively based on a single molecule and support for t he order of lineages must be derived from phenotypic properties of its members. As additional factors have been identified that influence th e topology of the branching pattern, the stability of a phylogenetic b ranching pattern need to be assessed carefully before taxonomic conclu sions are made.