Proposed model for GHF5 endoglucanase gene structure evolution in plant-parasitic nematodes. The model was constructed by phylogenetic mapping of gene structure changes applying the parsimony principle (reducing the number of intron gains/losses during evolution), onto a Bayesian tree obtained from those PPN GHF5 genes for which gene structure information was available (Posterior probabilities are indicated in red for each node). Introns are numbered as specified in Figure 4. Assumed gene structures are schematically drawn for certain interesting nodes: the catalytic domain is represented by a white box, the linker is shown as a grey box and the CBM2 is shown as a green box; Intron presence is shown by dotted lines. RT: Reverse Transcription. See text for a more detailed explanation.