Figure 1.

Phylogenetic tree of the chelicerate hemocyanin subunits. The numbers at the nodes represent Bayesian posterior probabilities estimated with the WAG model of amino acid substitution. The species abbreviations are: Aau, Androctonus australis; Ago, Acanthoscurria gomesiana; Cro, Carcinoscorpius rotundicauda; Csa, Cupiennius salei; Eba, Euphrynichus bacillifer; Eca, Eurypelma californicum; Esp, Endeis spinosa; Lpo, Limulus polyphemus; Mgi, Mastigoproctus giganteus; Nin, Nephila inaurata; Pim, Pandinus imperator; Ttr, Tachypleus tridentatus. The bar represents 0.1 expected substitutions per site. See Additional file 1 for abbreviations of the proteins