![]() In this study, we built and analysed the first near-chromosome level genome assembly of L. The silver-cheeked toadfish (Lagocephalus sceleratus) is a well-known "invasive sprinter" that has invaded and spread, in less than a decade, throughout the Eastern and part of the Western Mediterranean Sea from the Red Sea through the Suez Canal. The Tetraodontidae family encompasses several species which attract scientific interest in terms of their ecology and evolution. Thus, historical contingencies may lead different species of Thamnophis down alternative routes to local adaptation. couchii cannot be explained by the same relationship between genotype and phenotype seen in other taxa. ![]() couchii shows no functional variation in Nav loci among populations or difference in candidate gene expression. As in other Thamnophis, resistance at both levels is highly correlated, suggesting convergence across the biological levels linking organism to organ. couchii possess extensive geographic variation in resistance at the whole‐animal and skeletal muscle levels. We characterize variation in this predatory adaptation across populations at several biological scales: whole‐animal TTX resistance skeletal muscle resistance, functional genetic variation in three Nav encoding loci and levels of gene expression for one of these loci. Here, we investigate the extent of mechanistic convergence in garter snakes (Thamnophis) that prey on TTX‐bearing newts (Taricha) by examining the physiological and genetic basis of TTX resistance in the Sierra garter snake (Th. This stereotyped genetic response suggests molecular and phenotypic evolution may be constrained and predictable. Resistance in taxa bearing this neurotoxin and a few predators appears to come from convergent replacements in specific Nav residues that interact with TTX. This poison is broadly employed as a potent antipredator defense, blocking voltage‐gated sodium channels (Nav) in muscles and nerves, paralyzing and sometimes killing predators. The repeated evolution of tetrodotoxin (TTX) resistance provides a model for testing hypotheses about the mechanisms of convergent evolution. These substitutions are associated with organismal TTX-resistance in other TTX-bearing taxa and are convergent with substitutions that have evolved in fish, salamanders, and some TTX-resistant invertebrates. We identified three amino-acid substitutions in the TTX-binding site of HlNaV1 that likely confer TTX-resistance to both the channel and the organism. ![]() Here we report data demonstrating that the Greater Blue-ringed Octopus (Hapalochlaena lunulata) expresses a VGSC (HlNaV1) gene with mutations that reduce the channel's TTX-binding affinity and likely render the organism TTX resistant. To date there have been no studies of these proteins in tetrodotoxic Blue-Ringed Octopuses. Investigations in puffer fishes and salamanders have provided insights into the acquisition of auto-resistance to TTX through the evolution of voltage-gated sodium ion channels (VGSCs) that have reduced binding affinity for TTX. Despite decades of work, the origin and biosynthetic pathways of TTX remain unresolved. Within Eukaryotes, TTX has only been identified in animals but is known to be present in over five-dozen species of phylogenetically distant Metazoans. ![]() This toxin has a remarkable distribution that spans two domains of life (Bacteria and Eukarya). ![]() The natural history and pharmacology of tetrodotoxin (TTX) has long intrigued biologists. ![]()
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