Maximum likelihood tree of aligned vertebrate vitellogenin codons. Novel sequences, including genomic variants are annotated with a "*". Arrows represent the duplication of genes outlined in Fig. 5. Numbers in brackets represent Bayesian posterior probabilities of codon and amino acid alignments, respectively. Unlabelled nodes had 100% posterior probabilities and 100% bootsrap values for Bayesian and parsimony analyses, respectively. Branch lengths represent estimates of the number of nucleotide substitutions per site.