Fig. 1

Phylogenetic analysis of methanogen partial 16S rRNA sequences from clone libraries. The phylogenetic tree was constructed using the diatance and neighbor-joining method with the Kimura two-parameter model for nucleotide change. In which, sequences from Methanomassiliicoccales are presented in (a), and sequences from Methanobacteriales are presented in (b). The scale bar represents 5% estimated sequence divergence. Bootstrap values above 50 (based on 1000 bootstrap resamplings) were indicated. The 16S rRNA gene sequences obtained in this study are shown in bold, and numbers of clones in each OTU are labeled in the brackets. The prefix TM and GM represent methanogen 16S rRNA gene sequences from Tibetan sheep and Gansu Alpine Finewool sheep rumen clone libraries, respectively