title: Multiple genes elucidate the evolution of venomous snail-hunting Conus species.
abstract: The species-rich Cone snails (Conus sp.) are predatory, marine gastropods known for small venom peptides that are valuable for pharmacological research applications. Phylogenetic analyses with mitochondrial rRNA sequences have facilitated peptide discovery. However, these relatively conserved genes leave unresolved the closer relationships among many species. We sequenced 26 internal transcribed spacer 2 (ITS2) sequences from genomic ribosomal DNA to elucidate the evolutionary relationships among molluscivorous species and to piscivorous and vermivorous species. We show that ITS2 sequences are well conserved within species but are sufficiently variable among species to resolve recent divergences. Using Bayesian, maximum likelihood and log-determinant methods, we use the ITS sequences to resolve portions of the tree that could not be resolved using the more conventional mt rRNA sequences. When the ITS2 sequences are added to existing COI and to the more conserved rRNA sequences and then properly modeled, support throughout the tree is increased. This enables us to show finer relationships among the molluscivorous species that reveal three well-supported clades (Conus, Cylinder, and Darioconus) and renders the ITS2 sequences an essential component in advancing the discovery and pharmacological characterization of novel peptides from the venoms of these molluscs.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Hannah H
authors.initials: HH
authors.lastname: Nam
authors.forename: Patrice Showers
authors.initials: PS
authors.lastname: Corneli
authors.forename: Maren
authors.initials: M
authors.lastname: Watkins
authors.forename: Baldomero
authors.initials: B
authors.lastname: Olivera
authors.forename: Pradip
authors.initials: P
authors.lastname: Bandyopadhyay
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D052078:Conus Snail / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D019143:Evolution, Molecular; D016013:Likelihood Functions; D008978:Mollusk Venoms / Q000235:genetics*; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial; D021903:DNA, Ribosomal Spacer; D008978:Mollusk Venoms; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; C075526:RNA, ribosomal, 12S