For decades, the study of venomous animals has focused on the isolation and biochemical characterization of specific venom components that have medical or biotechnological importance. Indeed, scorpions have been extensively studied under this optics, which has led to the identification of hundreds of different transcripts encoding toxic peptides. However, scorpions are interesting organisms not only because of their toxin diversity but also because they represent the most ancient terrestrial animals that fossil records have identified. About 2,000 species have been described around the world, which also implies that scorpions are extremely well-adapted arthropods that have managed to survive in different environmental conditions. Even though the divergence timing of scorpions places them as interesting model organisms for evolutionary inferences, little is known about the genomic organization, speciation events, and population dynamics of these arthropods.
Different “omic” approaches have become a very powerful strategy for understanding the complexity of venomous animals. Transcriptomics, in particular, has been widely used to explore the transcriptional diversity of venom glands of several scorpion species. Recently, high-throughput sequencing platforms have substantially improved our capacity to describe biological features of scorpions but, most importantly, have outlined new directions toward a more complete understanding of the evolution of these arthropods.
In this chapter, those transcriptomic strategies followed in the last two decades that went from cDNA cloning to next-generation sequencing methods will be described. Some biological and evolutionary questions about scorpion speciation and venom diversification will also be addressed. Finally, an attempt to raise some future directions in the field will be made.