Fig. 7

Gene trees support the common duplication of genes in Arachnopulmonata. Analysis of gene trees inferred from six arthropod genomes was conducted, with the gene trees binned by topology. Trees corresponding to a shared duplication event were binned as Hypothesis 1, and trees corresponding to lineage-specific duplication events as Hypothesis 2. Gene trees with spider paralogs forming a clade with respect to a single scorpion paralog were treated as partially consistent with Hypothesis 1. Top row of panels shows hypothetical tree topologies; bottom row of panels shows empirical examples. Right panel shows distribution of gene trees as a function of bin frequency