ИСТИНА

Combined 18 and 28S rRNA gene sequences were used for resolution of the deep Nematoda phylogeny since analysis of the 18S rRNA gene sequences alone does not clear relationships of major groups (Dorylaimia, Enoplia, Triplonchida) at the base of the Nematoda phylogenetic tree. Phylogenetic content of 18 and 28S rRNA gene sequences taken separately as well as combined was evaluated by several criteria: 1) by congruency of tree topologies derived by different methods (maximum parsimony, MP; maximum likelihood, ML; neighbor-joining, NJ; Bayesian analysis, BA); 2) by number of unresolved quartets in likelihood mapping using Tree-puzzle; 3) by statistical support of major tree nodes using nonparametric bootstrapping. By all criteria used, phylogenetic content of combined 18 and 28S rRNA gene sequences exceeded phylogenetic content of 18 and 28S rRNA gene sequences taken separately. Providing the absence of data for the Triplonchida, phylogenetic analysis of concatenated 18 and 28S rRNA gene sequences places Dorylaimia (Trichinella sp. and Xiphinema rivesi) at the base of the Nematoda tree with Enoplia (Enoplis brevis и Tripyla sp.) branching after them and before Chromadoria. This analysis support also the branching order of major groups of Chromadoria that was inferred earlier from the 18S rRNA gene sequences.