Geographic variation in venom allelic composition and diets of the widespread predatory marine gastropod Conus ebraeus

• Published in: PloS one 2009-07, Vol.4 (7), p.e6245-6245
• Main Authors: Duda, Jr, Thomas F, Chang, Dan, Lewis, Brittany D, Lee, Taehwan
• Format: Article
• Language: English
• Subjects: Alleles; Amino Acid Sequence; Analysis; Animals; Base Sequence; Chloroplasts; Coevolution; Conotoxins; Conus; Conus ebraeus; Conus Snail - genetics; Conus Snail - physiology; Cytochrome; Cytochrome oxidase I; Deoxyribonucleic acid; Diet; Differentiation; DNA; DNA Primers; Ecology/Marine and Freshwater Ecology; Electron Transport Complex IV - chemistry; Electron Transport Complex IV - genetics; Eunicidae; Evolution; Evolutionary Biology; Evolutionary Biology/Evolutionary Ecology; Gastropoda; Gene Frequency; Gene sequencing; Genes; Genetic diversity; Genetic research; Genetic Variation; Geography; Haplotypes; Leaves; Loci; Marine; Marine and Aquatic Sciences/Ecology; Marine and Aquatic Sciences/Evolutionary Biology; Marine and Aquatic Sciences/Genetics, Genomics, and Barcoding; Marine ecology; Marine toxins; Mitochondrial DNA; Molecular Sequence Data; Mollusk Venoms - genetics; Mollusks; Morphology; Museums; Nereid; Neurotoxins; Oxidases; Palola; Population; Positive selection; Predator-prey interactions; Predators; Predatory Behavior; Prey; Sequence Homology, Amino Acid; Snakes; Specialization; Studies; Toxins; Venom; Venoms; Zoology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0006245

Members of the predatory gastropod genus Conus use a venom comprised of a cocktail of peptide neurotoxins, termed conotoxins or conopeptides, to paralyze prey and conotoxin gene family members diversify via strong positive selection. Because Conus venoms are used primarily to subdue prey, the evolution of venoms is likely affected by predator-prey interactions. To identify the selective forces that drive the differentiation of venoms within species of Conus, we examined the distribution of alleles of a polymorphic O-superfamily conotoxin locus of Conus ebraeus at Okinawa, Guam and Hawaii. Previous analyses of mitochondrial cytochrome oxidase I gene sequences suggest that populations of C. ebraeus, a worm-eating Conus, are not structured genetically in the western and central Pacific. Nonetheless, because the sample size from Guam was relatively low, we obtained additional data from this location and reexamined patterns of genetic variation at the mitochondrial gene at Okinawa, Guam and Hawaii. We also utilized a DNA-based approach to identify prey items of individuals of C. ebraeus from Guam and compared this information to published data on diets at Okinawa and Hawaii. Our results show that conotoxin allelic frequencies differ significantly among all three locations, with strongest differentiation at Hawaii. We also confirm previous inferences that C. ebraeus exhibits no genetic differentiation between Okinawa, Guam and Hawaii at the mitochondrial locus. Finally, DNA-based analyses show that eunicid polychaetes comprise the majority of the prey items of C. ebraeus at Guam; while this results compares well with observed diet of this species at Okinawa, C. ebraeus preys predominantly on nereid polychaetes at Hawaii. These results imply that strong selection pressures affect conotoxin allelic frequencies. Based on the dietary information, the selection may derive from geographic variation in dietary specialization and local coevolutionary arms races between Conus and their prey.