Figure 2.

A. N2 carries a derived insertion of 8 bp (red) relative to the ancestral allele. The insertion duplicates an 8-bp sequence present in the ancestor (underlined). B. col-182 gene tree and model for C. elegans CB4856 and other Caenorhabditis species. The x-axis shows distance from the start codon for each genome. C. Protein alignment, including predicted sequences for C. elegans wild isolates CB4856, AB1 and ED3040 assembled from young adult RNAseq data, and the frame-shifted N2 translation (marked with a blue dot). Gray-scale shading represents site conservation (% identity), and labels are colored by predicted collagen triplet stability (melting temperature) for runs of >1 G-X-Y repeats conserved across all sequences other than N2. The positions of conserved triplets are indicated above the alignment by gray boxes, and the positions of conserved cysteine residues potentially involved in inter-strand disulphide bridges are shown as red boxes.