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Rosales-García RA, Rautsaw RM, Hofmann EP, Grünwald CI, Franz-Chavez H, Ahumada-Carrillo IT, Ramirez-Chaparro R, de la Torre-Loranca MA, Strickland JL, Mason AJ, Holding ML, Borja M, Castañeda-Gaytan G, Myers EA, Sasa M, Rokyta DR, Parkinson CL. Sequence Divergence in Venom Genes Within and Between Montane Pitviper (Viperidae: Crotalinae: Cerrophidion) Species is Driven by Mutation-Drift Equilibrium. J Mol Evol 2023; 91:514-535. [PMID: 37269364 PMCID: PMC10995822 DOI: 10.1007/s00239-023-10115-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 05/03/2023] [Indexed: 06/05/2023]
Abstract
Snake venom can vary both among and within species. While some groups of New World pitvipers-such as rattlesnakes-have been well studied, very little is known about the venom of montane pitvipers (Cerrophidion) found across the Mesoamerican highlands. Compared to most well-studied rattlesnakes, which are widely distributed, the isolated montane populations of Cerrophidion may facilitate unique evolutionary trajectories and venom differentiation. Here, we describe the venom gland transcriptomes for populations of C. petlalcalensis, C. tzotzilorum, and C. godmani from Mexico, and a single individual of C. sasai from Costa Rica. We explore gene expression variation in Cerrophidion and sequence evolution of toxins within C. godmani specifically. Cerrophidion venom gland transcriptomes are composed primarily of snake venom metalloproteinases, phospholipase A[Formula: see text]s (PLA[Formula: see text]s), and snake venom serine proteases. Cerrophidion petlalcalensis shows little intraspecific variation; however, C. godmani and C. tzotzilorum differ significantly between geographically isolated populations. Interestingly, intraspecific variation was mostly attributed to expression variation as we did not detect signals of selection within C. godmani toxins. Additionally, we found PLA[Formula: see text]-like myotoxins in all species except C. petlalcalensis, and crotoxin-like PLA[Formula: see text]s in the southern population of C. godmani. Our results demonstrate significant intraspecific venom variation within C. godmani and C. tzotzilorum. The toxins of C. godmani show little evidence of directional selection where variation in toxin sequence is consistent with evolution under a model of mutation-drift equilibrium. Cerrophidion godmani individuals from the southern population may exhibit neurotoxic venom activity given the presence of crotoxin-like PLA[Formula: see text]s; however, further research is required to confirm this hypothesis.
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Affiliation(s)
| | - Rhett M Rautsaw
- Department of Biological Sciences, Clemson University, 190 Collings St., Clemson, SC, 29634, USA
| | - Erich P Hofmann
- Department of Biological Sciences, Clemson University, 190 Collings St., Clemson, SC, 29634, USA
- Science Department, Cape Fear Community College, Wilmington, NC, 28401, USA
| | | | - Hector Franz-Chavez
- Herp.mx A.C., Colima, Mexico
- Biodiversa A. C., Chapala, Jalisco, 45900, Mexico
| | | | | | | | - Jason L Strickland
- Department of Biological Sciences, Clemson University, 190 Collings St., Clemson, SC, 29634, USA
- Department of Biology, University of South Alabama, Mobile, AL, 36688, USA
| | - Andrew J Mason
- Department of Biological Sciences, Clemson University, 190 Collings St., Clemson, SC, 29634, USA
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Matthew L Holding
- Department of Biological Sciences, Clemson University, 190 Collings St., Clemson, SC, 29634, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Miguel Borja
- Facultad de Ciencias Biológicas, Universdad Juárez del Estado de Durango, Gómez Palacio, Durango, 35010, Mexico
| | - Gamaliel Castañeda-Gaytan
- Facultad de Ciencias Biológicas, Universdad Juárez del Estado de Durango, Gómez Palacio, Durango, 35010, Mexico
| | - Edward A Myers
- Department of Biological Sciences, Clemson University, 190 Collings St., Clemson, SC, 29634, USA
| | - Mahmood Sasa
- Centro Investigaciones en Biodiversidad y Ecología Tropical and Instituto Clodomiro Picado, Universidad de Costa Rica, San José, Costa Rica
| | - Darin R Rokyta
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Christopher L Parkinson
- Department of Biological Sciences, Clemson University, 190 Collings St., Clemson, SC, 29634, USA.
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Hofmann EP, Rautsaw RM, Mason AJ, Strickland JL, Parkinson CL. Duvernoy's Gland Transcriptomics of the Plains Black-Headed Snake, Tantilla nigriceps (Squamata, Colubridae): Unearthing the Venom of Small Rear-Fanged Snakes. Toxins (Basel) 2021; 13:toxins13050336. [PMID: 34066626 PMCID: PMC8148590 DOI: 10.3390/toxins13050336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 12/13/2022] Open
Abstract
The venoms of small rear-fanged snakes (RFS) remain largely unexplored, despite increased recognition of their importance in understanding venom evolution more broadly. Sequencing the transcriptome of venom-producing glands has greatly increased the ability of researchers to examine and characterize the toxin repertoire of small taxa with low venom yields. Here, we use RNA-seq to characterize the Duvernoy’s gland transcriptome of the Plains Black-headed Snake, Tantilla nigriceps, a small, semi-fossorial colubrid that feeds on a variety of potentially dangerous arthropods including centipedes and spiders. We generated transcriptomes of six individuals from three localities in order to both characterize the toxin expression of this species for the first time, and to look for initial evidence of venom variation in the species. Three toxin families—three-finger neurotoxins (3FTxs), cysteine-rich secretory proteins (CRISPs), and snake venom metalloproteinases (SVMPIIIs)—dominated the transcriptome of T. nigriceps; 3FTx themselves were the dominant toxin family in most individuals, accounting for as much as 86.4% of an individual’s toxin expression. Variation in toxin expression between individuals was also noted, with two specimens exhibiting higher relative expression of c-type lectins than any other sample (8.7–11.9% compared to <1%), and another expressed CRISPs higher than any other toxin. This study provides the first Duvernoy’s gland transcriptomes of any species of Tantilla, and one of the few transcriptomic studies of RFS not predicated on a single individual. This initial characterization demonstrates the need for further study of toxin expression variation in this species, as well as the need for further exploration of small RFS venoms.
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Affiliation(s)
- Erich P. Hofmann
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA; (E.P.H.); (R.M.R.); (A.J.M.); (J.L.S.)
| | - Rhett M. Rautsaw
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA; (E.P.H.); (R.M.R.); (A.J.M.); (J.L.S.)
| | - Andrew J. Mason
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA; (E.P.H.); (R.M.R.); (A.J.M.); (J.L.S.)
| | - Jason L. Strickland
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA; (E.P.H.); (R.M.R.); (A.J.M.); (J.L.S.)
| | - Christopher L. Parkinson
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA; (E.P.H.); (R.M.R.); (A.J.M.); (J.L.S.)
- Department of Forestry and Environmental Conservation, Clemson University, Clemson, SC 29634, USA
- Correspondence:
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3
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Holding ML, Strickland JL, Rautsaw RM, Hofmann EP, Mason AJ, Hogan MP, Nystrom GS, Ellsworth SA, Colston TJ, Borja M, Castañeda-Gaytán G, Grünwald CI, Jones JM, Freitas-de-Sousa LA, Viala VL, Margres MJ, Hingst-Zaher E, Junqueira-de-Azevedo ILM, Moura-da-Silva AM, Grazziotin FG, Gibbs HL, Rokyta DR, Parkinson CL. Phylogenetically diverse diets favor more complex venoms in North American pitvipers. Proc Natl Acad Sci U S A 2021; 118:e2015579118. [PMID: 33875585 PMCID: PMC8092465 DOI: 10.1073/pnas.2015579118] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The role of natural selection in the evolution of trait complexity can be characterized by testing hypothesized links between complex forms and their functions across species. Predatory venoms are composed of multiple proteins that collectively function to incapacitate prey. Venom complexity fluctuates over evolutionary timescales, with apparent increases and decreases in complexity, and yet the causes of this variation are unclear. We tested alternative hypotheses linking venom complexity and ecological sources of selection from diet in the largest clade of front-fanged venomous snakes in North America: the rattlesnakes, copperheads, cantils, and cottonmouths. We generated independent transcriptomic and proteomic measures of venom complexity and collated several natural history studies to quantify dietary variation. We then constructed genome-scale phylogenies for these snakes for comparative analyses. Strikingly, prey phylogenetic diversity was more strongly correlated to venom complexity than was overall prey species diversity, specifically implicating prey species' divergence, rather than the number of lineages alone, in the evolution of complexity. Prey phylogenetic diversity further predicted transcriptomic complexity of three of the four largest gene families in viper venom, showing that complexity evolution is a concerted response among many independent gene families. We suggest that the phylogenetic diversity of prey measures functionally relevant divergence in the targets of venom, a claim supported by sequence diversity in the coagulation cascade targets of venom. Our results support the general concept that the diversity of species in an ecological community is more important than their overall number in determining evolutionary patterns in predator trait complexity.
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Affiliation(s)
- Matthew L Holding
- Department of Biological Sciences, Clemson University, Clemson, SC 29634;
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Jason L Strickland
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
| | - Rhett M Rautsaw
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
| | - Erich P Hofmann
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
| | - Andrew J Mason
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210
| | - Michael P Hogan
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Gunnar S Nystrom
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Schyler A Ellsworth
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Timothy J Colston
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Miguel Borja
- Facultad de Ciencias Biológicas, Universidad Juárez del Estado de Durango, C.P. 35010 Gómez Palacio, Dgo., Mexico
| | - Gamaliel Castañeda-Gaytán
- Facultad de Ciencias Biológicas, Universidad Juárez del Estado de Durango, C.P. 35010 Gómez Palacio, Dgo., Mexico
| | | | - Jason M Jones
- HERP.MX A.C., Villa del Álvarez, Colima 28973, Mexico
| | | | - Vincent Louis Viala
- Laboratório de Toxinologia Aplicada, Instituto Butantan, São Paulo 05503-900, Brazil
- Center of Toxins, Immune-Response and Cell Signaling, São Paulo 05503-900, Brazil
| | - Mark J Margres
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138
| | | | - Inácio L M Junqueira-de-Azevedo
- Laboratório de Toxinologia Aplicada, Instituto Butantan, São Paulo 05503-900, Brazil
- Center of Toxins, Immune-Response and Cell Signaling, São Paulo 05503-900, Brazil
| | - Ana M Moura-da-Silva
- Laboratório de Imunopatologia, Instituto Butantan, São Paulo 05503-900, Brazil
- Instituto de Pesquisa Clínica Carlos Borborema, Fundação de Medicina Tropical Doutor Heitor Vieira Dourado, Manaus 69040, Brazil
| | - Felipe G Grazziotin
- Laboratório de Coleções Zoológicas, Instituto Butantan, São Paulo 05503-900, Brazil
| | - H Lisle Gibbs
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210
| | - Darin R Rokyta
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Christopher L Parkinson
- Department of Biological Sciences, Clemson University, Clemson, SC 29634;
- Department of Forestry and Environmental Conservation, Clemson University, Clemson, SC 29634
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Margres MJ, Rautsaw RM, Strickland JL, Mason AJ, Schramer TD, Hofmann EP, Stiers E, Ellsworth SA, Nystrom GS, Hogan MP, Bartlett DA, Colston TJ, Gilbert DM, Rokyta DR, Parkinson CL. The Tiger Rattlesnake genome reveals a complex genotype underlying a simple venom phenotype. Proc Natl Acad Sci U S A 2021; 118:e2014634118. [PMID: 33468678 PMCID: PMC7848695 DOI: 10.1073/pnas.2014634118] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Variation in gene regulation is ubiquitous, yet identifying the mechanisms producing such variation, especially for complex traits, is challenging. Snake venoms provide a model system for studying the phenotypic impacts of regulatory variation in complex traits because of their genetic tractability. Here, we sequence the genome of the Tiger Rattlesnake, which possesses the simplest and most toxic venom of any rattlesnake species, to determine whether the simple venom phenotype is the result of a simple genotype through gene loss or a complex genotype mediated through regulatory mechanisms. We generate the most contiguous snake-genome assembly to date and use this genome to show that gene loss, chromatin accessibility, and methylation levels all contribute to the production of the simplest, most toxic rattlesnake venom. We provide the most complete characterization of the venom gene-regulatory network to date and identify key mechanisms mediating phenotypic variation across a polygenic regulatory network.
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Affiliation(s)
- Mark J Margres
- Department of Biological Sciences, Clemson University, Clemson, SC 29634;
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620
| | - Rhett M Rautsaw
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
| | - Jason L Strickland
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
- Department of Biology, University of South Alabama, Mobile, AL 36688
| | - Andrew J Mason
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
| | - Tristan D Schramer
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
| | - Erich P Hofmann
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
| | - Erin Stiers
- Department of Biological Sciences, Clemson University, Clemson, SC 29634
| | - Schyler A Ellsworth
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Gunnar S Nystrom
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Michael P Hogan
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Daniel A Bartlett
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Timothy J Colston
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Darin R Rokyta
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Christopher L Parkinson
- Department of Biological Sciences, Clemson University, Clemson, SC 29634;
- Department of Forestry and Environmental Conservation, Clemson University, Clemson, SC 29634
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5
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Rautsaw RM, Hofmann EP, Margres MJ, Holding ML, Strickland JL, Mason AJ, Rokyta DR, Parkinson CL. Intraspecific sequence and gene expression variation contribute little to venom diversity in sidewinder rattlesnakes ( Crotalus cerastes). Proc Biol Sci 2019; 286:20190810. [PMID: 31266424 DOI: 10.1098/rspb.2019.0810] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Traits can evolve rapidly through changes in gene expression or protein-coding sequences. However, these forms of genetic variation can be correlated and changes to one can influence the other. As a result, we might expect traits lacking differential expression to preferentially evolve through changes in protein sequences or morphological adaptation. Given the lack of differential expression across the distribution of sidewinder rattlesnakes ( Crotalus cerastes), we tested this hypothesis by comparing the coding regions of genes expressed in the venom gland transcriptomes and fang morphology. We calculated Tajima's D and FST across four populations comparing toxin and nontoxin loci. Overall, we found little evidence of directional selection or differentiation between populations, suggesting that changes to protein sequences do not underlie the evolution of sidewinder venom or that toxins are under extremely variant selection pressures. Although low-expression toxins do not have higher sequence divergence between populations, they do have more standing variation on which selection can act. Additionally, we found significant differences in fang length among populations. The lack of differential expression and sequence divergence suggests sidewinders-given their generalist diet, moderate gene flow and environmental variation-are under stabilizing selection which functions to maintain a generalist phenotype. Overall, we demonstrate the importance of examining the relationship between gene expression and protein-coding changes to understand the evolution of complex traits.
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Affiliation(s)
- Rhett M Rautsaw
- 1 Department of Biological Sciences, Clemson University , Clemson, SC 29634 , USA
| | - Erich P Hofmann
- 1 Department of Biological Sciences, Clemson University , Clemson, SC 29634 , USA
| | - Mark J Margres
- 1 Department of Biological Sciences, Clemson University , Clemson, SC 29634 , USA
| | - Matthew L Holding
- 1 Department of Biological Sciences, Clemson University , Clemson, SC 29634 , USA.,3 Department of Biological Science, Florida State University , Tallahassee, FL 32306 , USA
| | - Jason L Strickland
- 1 Department of Biological Sciences, Clemson University , Clemson, SC 29634 , USA
| | - Andrew J Mason
- 1 Department of Biological Sciences, Clemson University , Clemson, SC 29634 , USA
| | - Darin R Rokyta
- 3 Department of Biological Science, Florida State University , Tallahassee, FL 32306 , USA
| | - Christopher L Parkinson
- 1 Department of Biological Sciences, Clemson University , Clemson, SC 29634 , USA.,2 Department of Forestry and Environmental Conservation, Clemson University , Clemson, SC 29634 , USA
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Hofmann EP, Nicholson KE, Luque-Montes IR, Köhler G, Cerrato-Mendoza CA, Medina-Flores M, Wilson LD, Townsend JH. Cryptic Diversity, but to What Extent? Discordance Between Single-Locus Species Delimitation Methods Within Mainland Anoles (Squamata: Dactyloidae) of Northern Central America. Front Genet 2019; 10:11. [PMID: 30804976 PMCID: PMC6378269 DOI: 10.3389/fgene.2019.00011] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 01/11/2019] [Indexed: 01/10/2023] Open
Abstract
Single-locus molecular barcoding is a useful method for identifying overlooked and undescribed biodiversity, providing the groundwork for further systematic study and taxonomic investigation. A variety of methods for delimiting species from barcoding libraries have been developed and applied, allowing for rapid estimates of species diversity in a broad range of taxa. However, tree-based and distance-based analyses can infer different group assignments, potentially over- or underestimating the number of putative species groups. Here, we explore diversity of mainland species of anole lizards from the Chortís Block biogeographical province of northern Central America using a DNA barcoding approach, generating and analyzing cytochrome oxidase subunit I (COI) sequences for over 400 samples assignable to 33 of 38 (86.8%) native and one introduced mainland species. We subsequently tested the effects different models of nucleotide substitution, different species-delimitation algorithms, and reducing our dataset had on species delimitation estimates. We performed of two distance-based (ABGD, RESL) and three tree-based (bPTP, mPTP, GMYC) analyses on both the full dataset and a dataset consisting only of unique halotypes. From 34 nominal taxa, analyses of the full dataset recovered between 34 and 64 operational taxonomic units (OTUs), while analyses of the reduced dataset inferred between 36 and 59. Reassigning individuals to either mPTP-inferred or ABGD clustered (7.2% threshold) groups improved the detection of a barcoding gap across three different models of nucleotide substitution, removing overlap between intra- and interspecific distances. Our results highlight the underestimated diversity of mainland Chortís Block anoles, but the lack of congruence between analyses demonstrates the importance of considering multiple analytical methods when dealing with single-locus datasets. We recommend future studies consider the effects of different models of nucleotide substitution on proposed barcoding gaps, as well as the effect reducing a dataset to unique haplotypes may have on proposed diversity estimates.
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Affiliation(s)
- Erich P. Hofmann
- Department of Biology, Indiana University of Pennsylvania, Indiana, PA, United States
- Department of Biological Sciences, Clemson University, Clemson, SC, United States
| | - Kirsten E. Nicholson
- Department of Biology, Central Michigan University, Mount Pleasant, MI, United States
| | | | - Gunther Köhler
- Senckenberg Forschungsinstitut und Naturmuseum, Frankfurt, Germany
| | - César A. Cerrato-Mendoza
- Federación Hondureña de Deportes de Montaña Y Escalada, Departamento de Francisco Morazán, Tegucigalpa, Honduras
| | - Melissa Medina-Flores
- Federación Hondureña de Deportes de Montaña Y Escalada, Departamento de Francisco Morazán, Tegucigalpa, Honduras
| | - Larry David Wilson
- Centro Zamorano de Biodiversidad, Escuela Agrícola Panamericana Zamorano, Departamento de Francisco Morazán, Tegucigalpa, Honduras
| | - Josiah H. Townsend
- Department of Biology, Indiana University of Pennsylvania, Indiana, PA, United States
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Hofmann EP, Rautsaw RM, Strickland JL, Holding ML, Hogan MP, Mason AJ, Rokyta DR, Parkinson CL. Comparative venom-gland transcriptomics and venom proteomics of four Sidewinder Rattlesnake (Crotalus cerastes) lineages reveal little differential expression despite individual variation. Sci Rep 2018; 8:15534. [PMID: 30341342 PMCID: PMC6195556 DOI: 10.1038/s41598-018-33943-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/03/2018] [Indexed: 11/24/2022] Open
Abstract
Changes in gene expression can rapidly influence adaptive traits in the early stages of lineage diversification. Venom is an adaptive trait comprised of numerous toxins used for prey capture and defense. Snake venoms can vary widely between conspecific populations, but the influence of lineage diversification on such compositional differences are unknown. To explore venom differentiation in the early stages of lineage diversification, we used RNA-seq and mass spectrometry to characterize Sidewinder Rattlesnake (Crotalus cerastes) venom. We generated the first venom-gland transcriptomes and complementary venom proteomes for eight individuals collected across the United States and tested for expression differences across life history traits and between subspecific, mitochondrial, and phylotranscriptomic hypotheses. Sidewinder venom was comprised primarily of hemorrhagic toxins, with few cases of differential expression attributable to life history or lineage hypotheses. However, phylotranscriptomic lineage comparisons more than doubled instances of significant expression differences compared to all other factors. Nevertheless, only 6.4% of toxins were differentially expressed overall, suggesting that shallow divergence has not led to major changes in Sidewinder venom composition. Our results demonstrate the need for consensus venom-gland transcriptomes based on multiple individuals and highlight the potential for discrepancies in differential expression between different phylogenetic hypotheses.
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Affiliation(s)
- Erich P Hofmann
- Clemson University, Department of Biological Sciences, Clemson, SC, 29634, USA
| | - Rhett M Rautsaw
- Clemson University, Department of Biological Sciences, Clemson, SC, 29634, USA
| | - Jason L Strickland
- Clemson University, Department of Biological Sciences, Clemson, SC, 29634, USA
- University of Central Florida, Department of Biology, Orlando, FL, 32816, USA
| | - Matthew L Holding
- Clemson University, Department of Biological Sciences, Clemson, SC, 29634, USA
- Florida State University, Department of Biological Science, Tallahassee, FL, 32306, USA
| | - Michael P Hogan
- Florida State University, Department of Biological Science, Tallahassee, FL, 32306, USA
| | - Andrew J Mason
- Clemson University, Department of Biological Sciences, Clemson, SC, 29634, USA
| | - Darin R Rokyta
- Florida State University, Department of Biological Science, Tallahassee, FL, 32306, USA
| | - Christopher L Parkinson
- Clemson University, Department of Biological Sciences, Clemson, SC, 29634, USA.
- Clemson University, Department of Forestry and Environmental Conservation, Clemson, SC, 29634, USA.
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8
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Luque-Montes I, Austin JD, Weinfurther KD, Wilson LD, Hofmann EP, Townsend JH. An integrative assessment of the taxonomic status of putative hybrid leopard frogs (Anura: Ranidae) from the Chortís Highlands of Central America, with description of a new species. SYST BIODIVERS 2018. [DOI: 10.1080/14772000.2017.1415232] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Ileana Luque-Montes
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611, USA
- Department of Biology, Indiana University of Pennsylvania, Indiana, Pennsylvania 15705–1081, USA
| | - James D. Austin
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611, USA
| | - Kayla D. Weinfurther
- Department of Biology, Indiana University of Pennsylvania, Indiana, Pennsylvania 15705–1081, USA
| | - Larry David Wilson
- Centro Zamorano de Biodiversidad, Escuela Agrícola Panamericana Zamorano, Departamento Francisco Morazán, Honduras
| | - Erich P. Hofmann
- Department of Biology, Indiana University of Pennsylvania, Indiana, Pennsylvania 15705–1081, USA
| | - Josiah H. Townsend
- Department of Biology, Indiana University of Pennsylvania, Indiana, Pennsylvania 15705–1081, USA
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9
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Hofmann EP, Townsend JH. Origins and biogeography of the Anolis crassulus subgroup (Squamata: Dactyloidae) in the highlands of Nuclear Central America. BMC Evol Biol 2017; 17:267. [PMID: 29268694 PMCID: PMC5740896 DOI: 10.1186/s12862-017-1115-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 12/14/2017] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Recent studies have begun to reveal the complex evolutionary and biogeographic histories of mainland anoles in Central America, but the origins and relationships of many taxa remain poorly understood. One such group is the Anolis (Norops) crassulus species subgroup, which contains ten morphologically similar highland taxa, the majority of which have restricted distributions. The nominal taxon A. crassulus has a disjunct distribution from Chiapas, Mexico, through Guatemala, in the highlands of El Salvador, and in the Chortís Highlands of Honduras. We test the relationships of these species using multiple mitochondrial and nuclear loci in concatenated and multispecies coalescent frameworks, in an effort to both resolve long-standing taxonomic confusion and present new insights into the evolution and biogeography of these taxa. RESULTS Sequences of multiple mitochondrial and nuclear loci were generated for eight of the ten species of the Anolis crassulus species subgroup. We analyzed phylogenetic relationships and estimated divergence times and ancestral ranges of the subgroup, recovering a monophyletic subgroup within Anolis. Within the nominal taxon Anolis crassulus, we recovered multiple genetically distinct lineages corresponding to allopatric populations, and show that the Chortís Highland lineage split from the others over 13 MYA. Additionally, distinct mitochondrial lineages are present within the taxa A. heteropholidotus and A. morazani, and importantly, samples of A. crassulus and A. sminthus previously used in major anole phylogenetic analyses are not recovered as conspecific with those taxa. We infer a Chortís Highland origin for the ancestor of this subgroup, and estimate cladogenesis of this subgroup began approximately 22 MYA. CONCLUSIONS Our results provide new insights into the evolution, biogeography, and timing of diversification of the Anolis crassulus species subgroup. The disjunctly distributed Anolis crassulus sensu lato represents several morphologically conserved, molecularly distinct anoles, and several other species in the subgroup contain multiple isolated lineages.
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Affiliation(s)
- Erich P. Hofmann
- Department of Biology, Indiana University of Pennsylvania, Indiana, PA 15705-1081 USA
- Present Address: Department of Biological Sciences, Clemson University, Clemson, SC 29634 USA
| | - Josiah H. Townsend
- Department of Biology, Indiana University of Pennsylvania, Indiana, PA 15705-1081 USA
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