calcin_data

Scorpions have evolved venoms with diverse variety of toxins with a plethora of biological targets, but characterizing the evolution of this molecular diversity has been limited by the lack of a comprehensive phylogenetic hypothesis of scorpion relationships. Here, we elucidate the origin of calcins and lambda potassium channel toxins (LKTx), a type of inhibitor cystine knot (ICK) toxins. In this study, we compiled the most comprehensive sampling of ICK peptide homologs across the breath of scorpion diversity. Using a de novo phylogenomic tree, and morphometric analysis of 3D molecular models of these peptides, we traced the evolutionary change in the shape of these peptides. The discovery of phylogenetic signal in 3D molecular models of calcins and LKTx, provides the first synapomorphies for the two extant scorpion parvorders, which are otherwise morphologically diverse and undefined. Our morphometric analyses further reveal that calcins and LKTx evolved different shapes with minimal overlap in morphospace, supporting their characterization as stable (non-convergent) synapomorphies.