77-9 Sat Jan 2 Co-diversification of scorpion mammalian predators and mammal-specific sodium channel toxins in scorpion venom Santibanez-Lopez, CE*; Ballesteros, JA; Baker, CM; Gavish-Regev, E; Sharma, PP; Department of Biology, Eastern Connecticut State University, 83 Windham Street, Willimantic, CT 06226; Department of Integrative Biology, University of Wisconsin–Madison, Madison, WI 53706; Department of Integrative Biology, University of Wisconsin–Madison, Madison, WI 53706; National Natural History Collections, The Hebrew University of Jerusalem, Jerusalem, Israel; Department of Integrative Biology, University of Wisconsin–Madison, Madison, WI 53706 santibanezlopezc@easternct.edu http://arachnomics.org
Scorpions constitute an ancient lineage of arachnids with more than 2,500 described species distributed worldwide. While all scorpions are venomous, nearly 60 species are medically significant to humans, with all but one included in the family Buthidae. In recent years, the study of scorpion venom components has benefited from next-generation sequencing and high throughput proteomic analyses, but the evolutionary history of the most toxic scorpion genera remains unclear. Here, we assembled a large-scale phylogenomic dataset of 100 scorpion venom transcriptomes and/or genomes, including exemplars of highly toxic buthid genera. We inferred divergence times of venom gene families, including those affecting mammal-specific tissues, using a phylogenomic node dating approach and phylostratigraphic bracketing for inferring gene ages. Our results showed that mammal-specific sodium channel toxins have independently evolved in five lineages within Buthidae, with these gains temporally coincident with the diversification of major scorpion mammal predators.
