Phylogenomics and Class Occurrence. The trees illustrate the phylogenetic relationship between the arthropod species. The phylogenomic trees are based on a total of 682 concatenated protein sequences. Methods are indicated. The class occurrence tree was constructed using Bayesian inference based on the presence or absence of protein classes/variants as indicated in the inventory (Figures 1, 3, 5, and 6). The average standard deviation of split frequencies was 0.0087.