Fig. 3

The phylogenetic tree inferred from a comparison of the deduced CENH3 proteins using the ML method, the JTT matrix-based model (Jones et al. 1992) and bootstrapping (1000 replicates). Initial tree(s) for the heuristic search were obtained automatically by applying Neighbor-Join and BioNJ programs to a matrix of pairwise distances estimated using a JTT model, and then selecting the topology with superior log likelihood value. The tree with the highest log likelihood (− 4953.06) is shown. A discrete Gamma distribution was used to model evolutionary rate differences among sites (5 categories (+G, parameter = 1.0416)). The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. This analysis involved 45 amino acid sequences. There were a total of 200 positions in the final dataset. Evolutionary analyses were conducted in MEGA X [43]. Bootstrap values were calculated from at least 1000 replications. Amino acid sequences were aligned using MUSCLE with default settings. On the branches: bootstrap values. The αCENH3-only clade is in a gray-filled shape, the βCENH3-only clade is in a light-blue-filled shape; the βCENH3 clade comprised of Stipa spp. and Brachypodium sylvaticum is in a dark-blue-filled shape