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Robinson KE, Moniz HA, Stokes AN, Feldman CR. Where Does All the Poison Go? Investigating Toxicokinetics of Newt (Taricha) Tetrodotoxin (TTX) in Garter Snakes (Thamnophis). J Chem Ecol 2024:10.1007/s10886-024-01517-7. [PMID: 38842636 DOI: 10.1007/s10886-024-01517-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 05/14/2024] [Accepted: 05/22/2024] [Indexed: 06/07/2024]
Abstract
Animals that consume toxic diets provide models for understanding the molecular and physiological adaptations to ecological challenges. Garter snakes (Thamnophis) in western North America prey on Pacific newts (Taricha), which employ tetrodotoxin (TTX) as an antipredator defense. These snakes possess mutations in voltage-gated sodium channels (Nav), the molecular targets of TTX, that decrease the binding ability of TTX to sodium channels (target-site resistance). However, genetic variation at these loci that cannot explain all the phenotypic variation in TTX resistance in Thamnophis. We explored a separate means of resistance, toxin metabolism, to determine if TTX-resistant snakes either rapidly remove TTX or sequester TTX. We examined the metabolism and distribution of TTX in the body (toxicokinetics), to determine differences between TTX-resistant and TTX-sensitive snakes in the rates at which TTX is eliminated from organs and the whole body (using TTX half-life as our metric). We assayed TTX half-life in snakes from TTX-resistant and TTX-sensitive populations of three garter snake species with a coevolutionary history with newts (T. atratus, T. couchii, T. sirtalis), as well as two non-resistant "outgroup" species (T. elegans, Pituophis catenifer) that seldom (if ever) engage newts. We found TTX half-life varied across species, populations, and tissues. Interestingly, TTX half-life was shortest in T. elegans and P. catenifer compared to all other snakes. Furthermore, TTX-resistant populations of T. couchii and T. sirtalis eliminated TTX faster (shorter TTX half-life) than their TTX-sensitive counterparts, while populations of TTX-resistant and TTX-sensitive T. atratus showed no difference rates of TTX removal (same TTX half-life). The ability to rapidly eliminate TTX may have permitted increased prey consumption, which may have promoted the evolution of additional resistance mechanisms. Finally, snakes still retain substantial amounts of TTX, and we projected that snakes could be dangerous to their own predators days to weeks following the ingestion of a single newt. Thus, aspects of toxin metabolism may have been key in driving predator-prey relationships, and important in determining other ecological interactions.
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Affiliation(s)
- Kelly E Robinson
- Department of Biology and Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, Reno, NV, USA.
- Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, NV, USA.
| | - Haley A Moniz
- Department of Biology and Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, Reno, NV, USA
- Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, NV, USA
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA, USA
| | - Amber N Stokes
- Department of Biology, California State University Bakersfield, Bakersfield, CA, USA
| | - Chris R Feldman
- Department of Biology and Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, Reno, NV, USA
- Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, NV, USA
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2
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Caudill V, Ralph PL. Genetic architecture, spatial heterogeneity, and the coevolutionary arms race between newts and snakes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.07.570693. [PMID: 38106105 PMCID: PMC10723474 DOI: 10.1101/2023.12.07.570693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Coevolution between two species can lead to exaggerated phenotypes that vary in a correlated manner across space. However, the conditions under which we expect such spatially varying coevolutionary patterns in polygenic traits are not well-understood. We investigate the coevolutionary dynamics between two species undergoing reciprocal adaptation across space and time, using simulations inspired by the Taricha newt - Thamnophis garter snake system. One striking observation from this system is that newts in some areas carry much more tetrodotoxin than in other areas, and garter snakes that live near more toxic newts tend to be more resistant to this toxin, a correlation seen across several broad geographic areas. Furthermore, snakes seem to be "winning" the coevolutionary arms race, i.e., having a high level of resistance compared to local newt toxicity, despite substantial variation in both toxicity and resistance across the range. We explore how possible genetic architectures of the toxin and resistance traits would affect the coevolutionary dynamics by manipulating both mutation rate and effect size of mutations across many simulations. We find that coevolutionary dynamics alone were not sufficient in our simulations to produce the striking mosaic of levels of toxicity and resistance observed in nature, but simulations with ecological heterogeneity (in trait costliness or interaction rate) did produce such patterns. We also find that in simulations, newts tend to "win" across most combinations of genetic architectures, although the species with higher mutational genetic variance tends to have an advantage.
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3
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del Carlo RE, Reimche JS, Moniz HA, Hague MT, Agarwal SR, Brodie ED, Brodie ED, Leblanc N, Feldman CR. Coevolution with toxic prey produces functional trade-offs in sodium channels of predatory snakes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.08.570760. [PMID: 38106015 PMCID: PMC10723449 DOI: 10.1101/2023.12.08.570760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Seemingly unrelated traits often share the same underlying molecular mechanisms, potentially generating a pleiotropic relationship whereby selection shaping one trait can simultaneously compromise another. While such functional trade-offs are expected to influence evolutionary outcomes, their actual relevance in nature is masked by obscure links between genotype, phenotype, and fitness. Here, we describe functional trade-offs that likely govern a key adaptation and coevolutionary dynamics in a predator-prey system. Several garter snake (Thamnophis spp.) populations have evolved resistance to tetrodotoxin (TTX), a potent chemical defense in their prey, toxic newts (Taricha spp.). Snakes achieve TTX resistance through mutations occurring at toxin-binding sites in the pore of snake skeletal muscle voltage-gated sodium channels (NaV1.4). We hypothesized that these mutations impair basic NaV functions, producing molecular trade-offs that should ultimately scale up to compromised organismal performance. We investigate biophysical costs in two snake species with unique and independently evolved mutations that confer TTX resistance. We show electrophysiological evidence that skeletal muscle sodium channels encoded by toxin-resistant alleles are functionally compromised. Furthermore, skeletal muscles from snakes with resistance genotypes exhibit reduced mechanical performance. Lastly, modeling the molecular stability of these sodium channel variants partially explains the electrophysiological and muscle impairments. Ultimately, adaptive genetic changes favoring toxin resistance appear to negatively impact sodium channel function, skeletal muscle strength, and organismal performance. These functional trade-offs at the cellular and organ levels appear to underpin locomotor deficits observed in resistant snakes and may explain variation in the population-level success of toxin-resistant alleles across the landscape, ultimately shaping the trajectory of snake-newt coevolution.
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Affiliation(s)
- Robert E. del Carlo
- University of Nevada, Reno School of Medicine, Department of Pharmacology, Reno, Nevada, USA, 89557
- University of Nevada, Reno Program in Cell & Molecular Pharmacology & Physiology
| | - Jessica S. Reimche
- University of Nevada, Reno, Department of Biology, Reno, Nevada, USA, 89557
- University of Nevada, Reno Program in Ecology, Evolution & Conservation Biology
| | - Haley A. Moniz
- University of Nevada, Reno, Department of Biology, Reno, Nevada, USA, 89557
- University of Nevada, Reno Program in Ecology, Evolution & Conservation Biology
| | - Michael T.J. Hague
- University of Virginia, Department of Biology, Charlottesville, Virginia, USA, 22904
| | - Shailesh R. Agarwal
- University of Nevada, Reno School of Medicine, Department of Pharmacology, Reno, Nevada, USA, 89557
| | - Edmund D. Brodie
- University of Virginia, Department of Biology, Charlottesville, Virginia, USA, 22904
| | - Edmund D. Brodie
- Utah State University, Department of Biology, Logan, Utah, USA, 84322
| | - Normand Leblanc
- University of Nevada, Reno School of Medicine, Department of Pharmacology, Reno, Nevada, USA, 89557
| | - Chris R. Feldman
- University of Nevada, Reno, Department of Biology, Reno, Nevada, USA, 89557
- University of Nevada, Reno Program in Ecology, Evolution & Conservation Biology
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4
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Thompson JN. The ripple effects of clines from coevolutionary hotspots to coldspots. Mol Ecol 2023; 32:4461-4463. [PMID: 37296535 DOI: 10.1111/mec.17042] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/22/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023]
Abstract
Coevolution has the potential to alter not only the ecological interactions of coevolving partners, but also their interactions with yet other species. The effects of coevolution may ripple throughout networks of interacting species, cascading across trophic levels, swamping competitors, or facilitating survival or reproduction of yet other species linked only indirectly to the coevolving partners. These ripple effects of coevolution may differ among communities, amplifying how the coevolutionary process produces geographic mosaics of traits and outcomes in interactions among species. In a From the Cover article in this issue of Molecular Ecology, Hague et al. (2022) provide a clear example, using the well-studied interactions between Pacific newts (Taricha spp.) and their common garter snake (Thamnophis sirtalis) predators in western North America. Pacific newts harbour tetrodotoxin (TTX), which is highly toxic to vertebrate predators. In coevolutionary hotspots, extreme escalation of toxicity in the newts and resistance to toxicity in the snakes have resulted in snake populations that retain high levels of TTX. In two geographic regions, snakes in these hotspot populations have evolved bright, aposematic colours that may act as warning signals to their own vertebrate predators. The warning signals and toxin-resistance alleles in the snake populations decrease clinally away from the coevolutionary hotpots, shaped by a geographically variable mix of selection imposed by the snakes' prey and by their own predators.
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Affiliation(s)
- John N Thompson
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, California, USA
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5
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Hague MTJ, Miller LE, Stokes AN, Feldman CR, Brodie ED, Brodie ED. Conspicuous coloration of toxin-resistant predators implicates additional trophic interactions in a predator-prey arms race. Mol Ecol 2023; 32:4482-4496. [PMID: 36336815 DOI: 10.1111/mec.16772] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/21/2022] [Accepted: 11/03/2022] [Indexed: 08/08/2023]
Abstract
Antagonistic coevolution between natural enemies can produce highly exaggerated traits, such as prey toxins and predator resistance. This reciprocal process of adaptation and counter-adaptation may also open doors to other evolutionary novelties not directly involved in the phenotypic interface of coevolution. We tested the hypothesis that predator-prey coevolution coincided with the evolution of conspicuous coloration on resistant predators that retain prey toxins. In western North America, common garter snakes (Thamnophis sirtalis) have evolved extreme resistance to tetrodotoxin (TTX) in the coevolutionary arms race with their deadly prey, Pacific newts (Taricha spp.). TTX-resistant snakes can retain large amounts of ingested TTX, which could serve as a deterrent against the snakes' own predators if TTX toxicity and resistance are coupled with a conspicuous warning signal. We evaluated whether arms race escalation covaries with bright red coloration in snake populations across the geographic mosaic of coevolution. Snake colour variation departs from the neutral expectations of population genetic structure and covaries with escalating clines of newt TTX and snake resistance at two coevolutionary hotspots. In the Pacific Northwest, bright red coloration fits an expected pattern of an aposematic warning to avian predators: TTX-resistant snakes that consume highly toxic newts also have relatively large, reddish-orange dorsal blotches. Snake coloration also seems to have evolved with the arms race in California, but overall patterns are less intuitively consistent with aposematism. These results suggest that interactions with additional trophic levels can generate novel traits as a cascading consequence of arms race coevolution across the geographic mosaic.
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Affiliation(s)
- Michael T J Hague
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Lauren E Miller
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Amber N Stokes
- Department of Biology, California State University, Bakersfield, California, USA
| | - Chris R Feldman
- Department of Biology, University of Nevada, Reno, Nevada, USA
| | - Edmund D Brodie
- Department of Biology, Utah State University, Logan, Utah, USA
| | - Edmund D Brodie
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
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6
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Agrawal AA, Hastings AP. Tissue-specific plant toxins and adaptation in a specialist root herbivore. Proc Natl Acad Sci U S A 2023; 120:e2302251120. [PMID: 37216531 PMCID: PMC10235950 DOI: 10.1073/pnas.2302251120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 04/17/2023] [Indexed: 05/24/2023] Open
Abstract
In coevolution between plants and insects, reciprocal selection often leads to phenotype matching between chemical defense and herbivore offense. Nonetheless, it is not well understood whether distinct plant parts are differentially defended and how herbivores adapted to those parts cope with tissue-specific defense. Milkweed plants produce a diversity of cardenolide toxins and specialist herbivores have substitutions in their target enzyme (Na+/K+-ATPase), each playing a central role in milkweed-insect coevolution. The four-eyed milkweed beetle (Tetraopes tetrophthalmus) is an abundant toxin-sequestering herbivore that feeds exclusively on milkweed roots as larvae and less so on milkweed leaves as adults. Accordingly, we tested the tolerance of this beetle's Na+/K+-ATPase to cardenolide extracts from roots versus leaves of its main host (Asclepias syriaca), along with sequestered cardenolides from beetle tissues. We additionally purified and tested the inhibitory activity of dominant cardenolides from roots (syrioside) and leaves (glycosylated aspecioside). Tetraopes' enzyme was threefold more tolerant of root extracts and syrioside than leaf cardenolides. Nonetheless, beetle-sequestered cardenolides were more potent than those in roots, suggesting selective uptake or dependence on compartmentalization of toxins away from the beetle's enzymatic target. Because Tetraopes has two functionally validated amino acid substitutions in its Na+/K+-ATPase compared to the ancestral form in other insects, we compared its cardenolide tolerance to that of wild-type Drosophila and CRISPR-edited Drosophila with Tetraopes' Na+/K+-ATPase genotype. Those two amino acid substitutions accounted for >50% of Tetraopes' enhanced enzymatic tolerance of cardenolides. Thus, milkweed's tissue-specific expression of root toxins is matched by physiological adaptations in its specialist root herbivore.
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Affiliation(s)
- Anurag A. Agrawal
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY14853
- Department of Entomology, Cornell University, Ithaca, NY14853
| | - Amy P. Hastings
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY14853
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7
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Medina-Ortiz K, Navia F, Mosquera-Gil C, Sánchez A, Sterling G, Fierro L, Castaño S. Identification of the NA +/K +-ATPase α-Isoforms in Six Species of Poison Dart Frogs and their Sensitivity to Cardiotonic Steroids. J Chem Ecol 2023; 49:116-132. [PMID: 36877397 PMCID: PMC10102066 DOI: 10.1007/s10886-023-01404-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 03/07/2023]
Abstract
Cardiotonic steroids (CTS) are a group of compounds known to be toxic due to their ability to inhibit the Na+/K+-ATPase (NKA), which is essential to maintain the balance of ions in animal cells. An evolutionary strategy of molecular adaptation to avoid self-intoxication acquired by CTS defended organisms and their predators is the structural modification of their NKA where specific amino acid substitutions confer resistant phenotypes. Several lineages of poison dart frogs (Dendrobatidae) are well known to sequester a wide variety of lipophilic alkaloids from their arthropod diet, however there is no evidence of CTS-sequestration or dietary exposure. Interestingly this study identified the presence of α-NKA isoforms (α1 and α2) with amino acid substitutions indicative of CTS-resistant phenotypes in skeletal muscle transcriptomes obtained from six species of dendrobatids: Phyllobates aurotaenia, Oophaga anchicayensis, Epipedobates boulengeri, Andinobates bombetes, Andinobates minutus, and Leucostethus brachistriatus, collected in the Valle del Cauca (Colombia). P. aurotaenia, A. minutus, and E. boulengeri presented two variants for α1-NKA, with one of them having these substitutions. In contrast, O. anchicayensis and A. bombetes have only one α1-NKA isoform with an amino acid sequence indicative of CTS susceptibility and an α2-NKA with one substitution that could confer a reduced affinity for CTS. The α1 and α2 isoforms of L. brachistriatus do not contain substitutions imparting CTS resistance. Our findings indicate that poison dart frogs express α-NKA isoforms with different affinities for CTS and the pattern of this expression might be influenced by factors related to evolutionary, physiological, ecological, and geographical burdens.
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Affiliation(s)
- Katherine Medina-Ortiz
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia.
| | - Felipe Navia
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Claudia Mosquera-Gil
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Adalberto Sánchez
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Gonzalo Sterling
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Leonardo Fierro
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Santiago Castaño
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia.
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8
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Reimche JS, Del Carlo RE, Brodie ED, McGlothlin JW, Schlauch K, Pfrender ME, Brodie ED, Leblanc N, Feldman CR. The road not taken: Evolution of tetrodotoxin resistance in the Sierra garter snake (Thamnophis couchii) by a path less traveled. Mol Ecol 2022; 31:3827-3843. [PMID: 35596742 DOI: 10.1111/mec.16538] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 04/28/2022] [Accepted: 05/12/2022] [Indexed: 11/27/2022]
Abstract
The repeated evolution of tetrodotoxin (TTX) resistance provides a model for testing hypotheses about the mechanisms of convergent evolution. 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. 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 stereotyped genetic response suggests molecular and phenotypic evolution may be constrained and predictable. 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. couchii). 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. We found Th. couchii possess extensive geographic variation in resistance at the whole-animal and skeletal muscle levels. As in other Thamnophis, resistance at both levels is highly correlated, suggesting convergence across the biological levels linking organism to organ. However, Th. couchii shows no functional variation in Nav loci among populations or difference in candidate gene expression. Local variation in TTX resistance in Th. couchii cannot be explained by the same relationship between genotype and phenotype seen in other taxa. Thus, historical contingencies may lead different species of Thamnophis down alternative routes to local adaptation.
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Affiliation(s)
- Jessica S Reimche
- Department of Biology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
| | - Robert E Del Carlo
- Department of Pharmacology and 4Program in Cellular and Molecular Pharmacology and Physiology, University of Nevada, Reno, NV, USA
| | - Edmund D Brodie
- Department of Biology, Utah State University, Logan, UT, USA
| | - Joel W McGlothlin
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
| | | | - Michael E Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Edmund D Brodie
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Normand Leblanc
- Department of Pharmacology and 4Program in Cellular and Molecular Pharmacology and Physiology, University of Nevada, Reno, NV, USA
| | - Chris R Feldman
- Department of Biology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
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9
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Moniz HA, Richard MA, Gienger CM, Feldman CR. Every breath you take: assessing metabolic costs of toxin resistance in garter snakes (Thamnophis). Integr Zool 2021; 17:567-580. [PMID: 34254727 DOI: 10.1111/1749-4877.12574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Trait specialization often comes at the expense of original trait function, potentially causing evolutionary tradeoffs that may render specialist populations vulnerable to extinction. However, many specialized adaptations evolve repeatedly, suggesting selection favors specialization in specific environments. Some garter snake (Thamnophis) populations possess specialized mutations in voltage-gated sodium channels that allow them to consume Pacific newts (Taricha) defended by a highly potent neurotoxin (tetrodotoxin). These mutations, however, also decrease protein and muscle function, suggesting garter snakes may suffer evolutionary tradeoffs. We measured a key physiological process, standard metabolic rate (SMR), to investigate whether specialized adaptations in toxin-resistant garter snakes affect baseline energy expenditure. In snakes, skeletal muscles influence metabolism and power ventilation, so inefficiencies of sodium channels in these muscles might impact whole-animal energy expenditure. Further, because sodium channels are membrane-bound proteins, inefficiencies of channel kinetics and performance might be exacerbated at suboptimal temperatures. We measured SMR in 2 species, Thamnophis atratus and Thamnophis sirtalis, that independently evolved tetrodotoxin resistance through unique mutations, providing replicate experiments with distinct underlying genetics and potential physiological costs. Despite our expectations, neither resistance phenotype nor sodium channel genotype affected metabolism and resistant snakes did not perform worse under suboptimal body temperature. Instead, T. atratus and T. sirtalis show nearly identical rates of mass-adjusted energy expenditure at both temperatures, despite differing eco-morphologies, life histories, and distant phylogenetic positions. These findings suggest SMR may be a conserved feature of Thamnophis, and that any organismal tradeoffs may be compensated to retain whole-animal function.
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Affiliation(s)
- Haley A Moniz
- Department of Biology, University of Nevada, Reno, Nevada, USA.,Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, Nevada, USA
| | - Molly A Richard
- Department of Biology and Center of Excellence for Field Biology, Austin Peay State University, Clarksville, Tennessee, USA
| | - C M Gienger
- Department of Biology and Center of Excellence for Field Biology, Austin Peay State University, Clarksville, Tennessee, USA
| | - Chris R Feldman
- Department of Biology, University of Nevada, Reno, Nevada, USA.,Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, Nevada, USA
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10
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Berlinck RGS, Bernardi DI, Fill T, Fernandes AAG, Jurberg ID. The chemistry and biology of guanidine secondary metabolites. Nat Prod Rep 2020; 38:586-667. [PMID: 33021301 DOI: 10.1039/d0np00051e] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Covering: 2017-2019Guanidine natural products isolated from microorganisms, marine invertebrates and terrestrial plants, amphibians and spiders, represented by non-ribosomal peptides, guanidine-bearing polyketides, alkaloids, terpenoids and shikimic acid derived, are the subject of this review. The topics include the discovery of new metabolites, total synthesis of natural guanidine compounds, biological activity and mechanism-of-action, biosynthesis and ecological functions.
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Affiliation(s)
- Roberto G S Berlinck
- Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, CEP 13560-970, São Carlos, SP, Brazil.
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11
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Hague MTJ, Stokes AN, Feldman CR, Brodie ED, Brodie ED. The geographic mosaic of arms race coevolution is closely matched to prey population structure. Evol Lett 2020; 4:317-332. [PMID: 32774881 PMCID: PMC7403720 DOI: 10.1002/evl3.184] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 05/11/2020] [Accepted: 05/22/2020] [Indexed: 01/09/2023] Open
Abstract
Reciprocal adaptation is the hallmark of arms race coevolution. Local coadaptation between natural enemies should generate a geographic mosaic pattern where both species have roughly matched abilities across their shared range. However, mosaic variation in ecologically relevant traits can also arise from processes unrelated to reciprocal selection, such as population structure or local environmental conditions. We tested whether these alternative processes can account for trait variation in the geographic mosaic of arms race coevolution between resistant garter snakes (Thamnophis sirtalis) and toxic newts (Taricha granulosa). We found that predator resistance and prey toxin levels are functionally matched in co-occurring populations, suggesting that mosaic variation in the armaments of both species results from the local pressures of reciprocal selection. By the same token, phenotypic and genetic variation in snake resistance deviates from neutral expectations of population genetic differentiation, showing a clear signature of adaptation to local toxin levels in newts. Contrastingly, newt toxin levels are best predicted by genetic differentiation among newt populations, and to a lesser extent, by the local environment and snake resistance. Exaggerated armaments suggest that coevolution occurs in certain hotspots, but prey population structure seems to be of particular influence on local phenotypic variation in both species throughout the geographic mosaic. Our results imply that processes other than reciprocal selection, like historical biogeography and environmental pressures, represent an important source of variation in the geographic mosaic of coevolution. Such a pattern supports the role of "trait remixing" in the geographic mosaic theory, the process by which non-adaptive forces dictate spatial variation in the interactions among species.
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Affiliation(s)
- Michael T J Hague
- Division of Biological Sciences University of Montana Missoula Montana 59812.,Department of Biology University of Virginia Charlottesville Virginia 22904
| | - Amber N Stokes
- Department of Biology California State University Bakersfield California 93311
| | - Chris R Feldman
- Department of Biology University of Nevada Reno Nevada 89557
| | - Edmund D Brodie
- Department of Biology Utah State University Logan Utah 84322
| | - Edmund D Brodie
- Department of Biology University of Virginia Charlottesville Virginia 22904
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12
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Reimche JS, Brodie ED, Stokes AN, Ely EJ, Moniz HA, Thill VL, Hallas JM, Pfrender ME, Brodie ED, Feldman CR. The geographic mosaic in parallel: Matching patterns of newt tetrodotoxin levels and snake resistance in multiple predator-prey pairs. J Anim Ecol 2020; 89:1645-1657. [PMID: 32198924 DOI: 10.1111/1365-2656.13212] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 02/10/2020] [Indexed: 01/12/2023]
Abstract
The Geographic Mosaic Theory of Coevolution predicts that coevolutionary arms races will vary over time and space because of the diverse ecological settings and population histories of interacting species across the landscape. Thus, understanding coevolution may require investigating broad sets of populations sampled across the range of the interaction. In addition, comparing coevolutionary dynamics between similar systems may reveal the importance of specific factors that structure coevolution. Here, we examine geographic patterns of prey traits and predator traits in the relatively unstudied interaction between the Sierra garter snake (Thamnophis couchii) and sympatric prey, the rough-skinned newt (Taricha granulosa), Sierra newt (Ta. sierrae) and California newt (Ta. torosa). This system parallels, in space and phenotypes, a classic example of coevolution between predatory common garter snakes (Th. sirtalis) and their toxic newt prey exhibiting hotspots of newt tetrodotoxin (TTX) levels and matching snake TTX resistance. We quantified prey and predator traits from hundreds of individuals across their distributions, and functional trait matching at sympatric sites. We show strong regional patterns of trait covariation across the shared ranges of Th. couchii and newt prey. Traits differ significantly among localities, with lower newt TTX levels and snake TTX resistance at the northern latitudes, and higher TTX levels and snake resistance at southern latitudes. Newts and snakes in northern populations show the highest degree of functional trait matching despite possessing the least extreme traits. Conversely, newts and snakes in southern populations show the greatest mismatch despite possessing exaggerated traits, with some snakes so resistant to TTX they would be unaffected by any sympatric newt. Nevertheless, individual variation was substantial, and appears to offer the opportunity for continued reciprocal selection in most populations. Overall, the three species of newts appear to be engaged in a TTX-mediated arms race with Th. couchii. These patterns are congruent with those seen between newts and Th. sirtalis, including the same latitudinal gradient in trait covariation, and the potential 'escape' from the arms race by snake predators. Such concordance in broad scale patterns across two distinct systems suggests common phenomena might structure geographic mosaics in similar ways.
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Affiliation(s)
- Jessica S Reimche
- Department of Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
| | - Edmund D Brodie
- Department of Biology, Utah State University, Logan, UT, USA
| | - Amber N Stokes
- Department of Biology, California State University, Bakersfield, CA, USA
| | - Erica J Ely
- Department of Biology, University of Nevada, Reno, NV, USA.,Department of Herpetology, California Academy of Sciences, San Francisco, CA, USA
| | - Haley A Moniz
- Department of Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
| | - Vicki L Thill
- Department of Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
| | - Joshua M Hallas
- Department of Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
| | - Michael E Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Edmund D Brodie
- Mountain Lake Biological Station and Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Chris R Feldman
- Department of Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
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13
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Sex linkage of the skeletal muscle sodium channel gene (SCN4A) explains apparent deviations from Hardy-Weinberg equilibrium of tetrodotoxin-resistance alleles in garter snakes (Thamnophis sirtalis). Heredity (Edinb) 2020; 124:647-657. [PMID: 32111979 DOI: 10.1038/s41437-020-0300-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/13/2020] [Accepted: 02/13/2020] [Indexed: 01/01/2023] Open
Abstract
The arms race between tetrodotoxin-bearing Pacific newts (Taricha) and their garter snake predators (Thamnophis) in western North America has become a classic example of coevolution, shedding light on predator-prey dynamics, the molecular basis of adaptation, and patterns of convergent evolution. Newts are defended by tetrodotoxin (TTX), a neurotoxin that binds to voltage-gated sodium channels (Nav proteins), arresting electrical activity in nerves and muscles and paralyzing would-be predators. However, populations of the common garter snake (T. sirtalis) have overcome this defense, largely through polymorphism at the locus SCN4A, which renders the encoded protein (Nav1.4) less vulnerable to TTX. Previous work suggests that SCN4A commonly shows extreme deviations from Hardy-Weinberg equilibrium (HWE) in these populations, which has been interpreted as the result of intense selection imposed by newts. Here we show that much of this apparent deviation can be attributed to sex linkage of SCN4A. Using genomic data and quantitative PCR, we show that SCN4A is on the Z chromosome in Thamnophis and other advanced snakes. Taking Z-linkage into account, we find that most apparent deviations from HWE can be explained by female hemizygosity rather than low heterozygosity. Sex linkage can affect mutation rates, selection, and drift, and our results suggest that Z-linkage of SCN4A may make significant contributions to the overall dynamics of the coevolutionary arms race between newts and snakes.
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14
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Mailho-Fontana PL, Jared C, Antoniazzi MM, Sciani JM, Pimenta DC, Stokes AN, Grant T, Brodie ED, Brodie ED. Variations in tetrodotoxin levels in populations of Taricha granulosa are expressed in the morphology of their cutaneous glands. Sci Rep 2019; 9:18490. [PMID: 31811169 PMCID: PMC6897900 DOI: 10.1038/s41598-019-54765-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 11/15/2019] [Indexed: 12/15/2022] Open
Abstract
Tetrodotoxin (TTX), one of the most toxic substances in nature, is present in bacteria, invertebrates, fishes, and amphibians. Marine organisms seem to bioaccumulate TTX from their food or acquire it from symbiotic bacteria, but its origin in amphibians is unclear. Taricha granulosa can exhibit high TTX levels, presumably concentrated in skin poison glands, acting as an agent of selection upon predatory garter snakes (Thamnophis). This co-evolutionary arms race induces variation in T. granulosa TTX levels, from very high to undetectable. Using morphology and biochemistry, we investigated differences in toxin localization and quality between two populations at the extremes of toxicity. TTX concentration within poison glands is related to the volume of a single cell type in which TTX occurs exclusively in distinctive secretory granules, suggesting a relationship between granule structure and chemical composition. TTX was detected in mucous glands in both populations, contradicting the general understanding that these glands do not secrete defensive chemicals and expanding currently held interpretations of amphibian skin gland functionality. Skin secretions of the two populations differed in low-mass molecules and proteins. Our results demonstrate that interpopulation variation in TTX levels is related to poison gland morphology.
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15
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Evidence of phenotypic correlation between exploration activity and resting metabolic rate among populations across an elevation gradient in a small rodent species. Behav Ecol Sociobiol 2019. [DOI: 10.1007/s00265-019-2740-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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16
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Perry BW, Card DC, McGlothlin JW, Pasquesi GIM, Adams RH, Schield DR, Hales NR, Corbin AB, Demuth JP, Hoffmann FG, Vandewege MW, Schott RK, Bhattacharyya N, Chang BSW, Casewell NR, Whiteley G, Reyes-Velasco J, Mackessy SP, Gamble T, Storey KB, Biggar KK, Passow CN, Kuo CH, McGaugh SE, Bronikowski AM, de Koning APJ, Edwards SV, Pfrender ME, Minx P, Brodie ED, Brodie ED, Warren WC, Castoe TA. Molecular Adaptations for Sensing and Securing Prey and Insight into Amniote Genome Diversity from the Garter Snake Genome. Genome Biol Evol 2018; 10:2110-2129. [PMID: 30060036 PMCID: PMC6110522 DOI: 10.1093/gbe/evy157] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2018] [Indexed: 12/26/2022] Open
Abstract
Colubridae represents the most phenotypically diverse and speciose family of snakes, yet no well-assembled and annotated genome exists for this lineage. Here, we report and analyze the genome of the garter snake, Thamnophis sirtalis, a colubrid snake that is an important model species for research in evolutionary biology, physiology, genomics, behavior, and the evolution of toxin resistance. Using the garter snake genome, we show how snakes have evolved numerous adaptations for sensing and securing prey, and identify features of snake genome structure that provide insight into the evolution of amniote genomes. Analyses of the garter snake and other squamate reptile genomes highlight shifts in repeat element abundance and expansion within snakes, uncover evidence of genes under positive selection, and provide revised neutral substitution rate estimates for squamates. Our identification of Z and W sex chromosome-specific scaffolds provides evidence for multiple origins of sex chromosome systems in snakes and demonstrates the value of this genome for studying sex chromosome evolution. Analysis of gene duplication and loss in visual and olfactory gene families supports a dim-light ancestral condition in snakes and indicates that olfactory receptor repertoires underwent an expansion early in snake evolution. Additionally, we provide some of the first links between secreted venom proteins, the genes that encode them, and their evolutionary origins in a rear-fanged colubrid snake, together with new genomic insight into the coevolutionary arms race between garter snakes and highly toxic newt prey that led to toxin resistance in garter snakes.
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Affiliation(s)
- Blair W Perry
- Department of Biology, University of Texas at Arlington, Arlington
| | - Daren C Card
- Department of Biology, University of Texas at Arlington, Arlington
| | - Joel W McGlothlin
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia
| | | | - Richard H Adams
- Department of Biology, University of Texas at Arlington, Arlington
| | - Drew R Schield
- Department of Biology, University of Texas at Arlington, Arlington
| | - Nicole R Hales
- Department of Biology, University of Texas at Arlington, Arlington
| | - Andrew B Corbin
- Department of Biology, University of Texas at Arlington, Arlington
| | - Jeffery P Demuth
- Department of Biology, University of Texas at Arlington, Arlington
| | - Federico G Hoffmann
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State.,Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, Starkville
| | - Michael W Vandewege
- Department of Biology, Institute for Genomics and Evolutionary Medicine, Temple University
| | - Ryan K Schott
- Department of Ecology and Evolutionary Biology, Department of Cell and Systems Biology, Centre for the Analysis of Genome Evolution & Function, University of Toronto, Ontario, Canada.,Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia
| | - Nihar Bhattacharyya
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
| | - Belinda S W Chang
- Department of Ecology and Evolutionary Biology, Department of Cell and Systems Biology, Centre for the Analysis of Genome Evolution & Function, University of Toronto, Ontario, Canada
| | - Nicholas R Casewell
- Alistair Reid Venom Research Unit, Parasitology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Gareth Whiteley
- Alistair Reid Venom Research Unit, Parasitology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Jacobo Reyes-Velasco
- Department of Biology, University of Texas at Arlington, Arlington.,Department of Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
| | | | - Tony Gamble
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA.,Bell Museum of Natural History, University of Minnesota, Saint Paul, MN, USA
| | - Kenneth B Storey
- Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada
| | - Kyle K Biggar
- Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada
| | | | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | | | - Anne M Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University
| | - A P Jason de Koning
- Department of Biochemistry and Molecular Biology, Department of Medical Genetics, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Scott V Edwards
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University
| | - Michael E Pfrender
- Department of Biological Sciences and Environmental Change Initiative, University of Notre Dame
| | - Patrick Minx
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis
| | | | | | - Wesley C Warren
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis
| | - Todd A Castoe
- Department of Biology, University of Texas at Arlington, Arlington
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17
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Hague MTJ, Toledo G, Geffeney SL, Hanifin CT, Brodie ED, Brodie ED. Large-effect mutations generate trade-off between predatory and locomotor ability during arms race coevolution with deadly prey. Evol Lett 2018; 2:406-416. [PMID: 30283691 PMCID: PMC6121790 DOI: 10.1002/evl3.76] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 07/10/2018] [Accepted: 07/13/2018] [Indexed: 01/06/2023] Open
Abstract
Adaptive evolution in response to one selective challenge may disrupt other important aspects of performance. Such evolutionary trade‐offs are predicted to arise in the process of local adaptation, but it is unclear if these phenotypic compromises result from the antagonistic effects of simple amino acid substitutions. We tested for trade‐offs associated with beneficial mutations that confer tetrodotoxin (TTX) resistance in the voltage‐gated sodium channel (NaV1.4) in skeletal muscle of the common garter snake (Thamnophis sirtalis). Separate lineages in California and the Pacific Northwest independently evolved TTX‐resistant changes to the pore of NaV1.4 as a result of arms race coevolution with toxic prey, newts of the genus Taricha. Snakes from the California lineage that were homozygous for an allele known to confer large increases in toxin resistance (NaV1.4LVNV) had significantly reduced crawl speed compared to individuals with the ancestral TTX‐sensitive channel. Heterologous expression of native snake NaV1.4 proteins demonstrated that the same NaV1.4LVNV allele confers a dramatic increase in TTX resistance and a correlated decrease in overall channel excitability. Our results suggest the same mutations that accumulate during arms race coevolution and beneficially interfere with toxin‐binding also cause changes in electrophysiological function of the channel that may affect organismal performance. This trade‐off was only evident in the predator lineage where coevolution has led to the most extreme resistance phenotype, determined by four critical amino acid substitutions. If these biophysical changes also translate to a fitness cost—for example, through the inability of T. sirtalis to quickly escape predators—then pleiotropy at this single locus could contribute to observed variation in levels of TTX resistance across the mosaic landscape of coevolution.
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Affiliation(s)
- Michael T J Hague
- Department of Biology University of Virginia Charlottesville Virginia 22903
| | - Gabriela Toledo
- Department of Biology University of Virginia Charlottesville Virginia 22903
| | - Shana L Geffeney
- Department of Biology Utah State University Uintah Basin Vernal Utah 84322
| | - Charles T Hanifin
- Department of Biology Utah State University Uintah Basin Vernal Utah 84322
| | - Edmund D Brodie
- Department of Biology Utah State University Logan Utah 84322
| | - Edmund D Brodie
- Department of Biology University of Virginia Charlottesville Virginia 22903
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18
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Davies KTJ. Digest: Know your poison: Predictable molecular changes confer toxin resistance in snakes. Evolution 2017; 71:1728-1729. [DOI: 10.1111/evo.13259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 04/17/2017] [Accepted: 04/21/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Kalina T. J. Davies
- School of Biological and Chemical Sciences; Queen Mary University of London; London E1 4NS United Kingdom
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