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Jowers MJ, Smart U, Sánchez-Ramírez S, Murphy JC, Gómez A, Bosque RJ, Sarker GC, Noonan BP, Faria JF, Harris DJ, da Silva NJ, Prudente ALC, Weber J, Kok PJR, Rivas GA, Jadin RC, Sasa M, Muñoz-Mérida A, Moreno-Rueda G, Smith EN. Unveiling underestimated species diversity within the Central American Coralsnake, a medically important complex of venomous taxa. Sci Rep 2023; 13:11674. [PMID: 37468518 DOI: 10.1038/s41598-023-37734-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 06/27/2023] [Indexed: 07/21/2023] Open
Abstract
Coralsnakes of the genus Micrurus are a diverse group of venomous snakes ranging from the southern United States to southern South America. Much uncertainty remains over the genus diversity, and understanding Micrurus systematics is of medical importance. In particular, the widespread Micrurus nigrocinctus spans from Mexico throughout Central America and into Colombia, with a number of described subspecies. This study provides new insights into the phylogenetic relationships within M. nigrocinctus by examining sequence data from a broad sampling of specimens from Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, and Panama. The recovered phylogenetic relationships suggest that M. nigrocinctus is a species complex originating in the Pliocene and composed of at least three distinct species-level lineages. In addition, recovery of highly divergent clades supports the elevation of some currently recognized subspecies to the full species rank while others may require synonymization.
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Affiliation(s)
- Michael J Jowers
- CIBIO/InBIO (Centro de Investigação em Biodiversidade e Recursos Genéticos), Universidade do Porto, Campus Agrario De Vairão, 4485-661, Vairão, Portugal.
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, 4485-661, Vairão, Portugal.
- Departamento de Zoología, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain.
| | - Utpal Smart
- Department of Biology, Texas State University, 601 University Dr., San Marcos, TX, 78666, USA
| | - Santiago Sánchez-Ramírez
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks, Toronto, ON, M5S 3B2, Canada
| | - John C Murphy
- Science and Education, Field Museum, 1400 S. Lake Shore Drive, Chicago, IL, 60605, USA
| | - Aarón Gómez
- Facultad de Microbiología, Instituto Clodomiro Picado, Universidad de Costa Rica, San José, Costa Rica
| | - Renan J Bosque
- Department of Biological Sciences, Southwestern Oklahoma State University, Weatherford, OK, 73096, USA
| | - Goutam C Sarker
- Department of Biology and Amphibian and Reptile Diversity Research Center, University of Texas at Arlington, Arlington, TX, 76019, USA
- Department of Biology, Cottey College, 1000 W. Austin Blvd, Nevada, MO, 64772, USA
| | - Brice P Noonan
- Department of Biology, The University of Mississippi, Oxford, MS, 38677, USA
| | - J Filipe Faria
- CIBIO/InBIO (Centro de Investigação em Biodiversidade e Recursos Genéticos), Universidade do Porto, Campus Agrario De Vairão, 4485-661, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, 4485-661, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, 4099-002, Porto, Portugal
| | - D James Harris
- CIBIO/InBIO (Centro de Investigação em Biodiversidade e Recursos Genéticos), Universidade do Porto, Campus Agrario De Vairão, 4485-661, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, 4485-661, Vairão, Portugal
| | - Nelson Jorge da Silva
- Pontifícia Universidade Católica de Goiás - Programa de Pós-Graduação em Ciências Ambientais e Saúde, Goiânia, Goiás, 74605140, Brazil
| | - Ana L C Prudente
- Laboratório de Herpetologia, Coordenação de Zoologia, Museu Paraense Emílio Goeldi (MPEG), Belém, Pará, Brazil
- Programa de Pós-Graduação em Zoologia (UFPA/MPEG) and Biodiversidade e Evolução (MPEG), Belém, Pará, Brazil
| | - John Weber
- Department of Geology, Grand Valley State University, Allendale, MI, 49401, USA
| | - Philippe J R Kok
- Department of Ecology and Vertebrate Zoology, Faculty of Biology and Environmental Protection, University of Łódź, 12/16 Banacha Str, 90-237, Lodz, Poland
- Department of Life Sciences, The Natural History Museum, London, SW7 5BD, UK
| | - Gilson A Rivas
- Museo de Biología, Facultad Experimental de Ciencias, Universidad del Zulia, Maracaibo, Venezuela
| | - Robert C Jadin
- Department of Biology and Museum of Natural History, University of Wisconsin Stevens Point, Stevens Point, WI, 54481, USA
| | - Mahmood Sasa
- Facultad de Microbiología, Instituto Clodomiro Picado, Universidad de Costa Rica, San José, Costa Rica
- Museo de Zoología, Centro de Investigación en Biodiversidad y Ecología Tropical, Universidad de Costa Rica, San José, Costa Rica
| | - Antonio Muñoz-Mérida
- CIBIO/InBIO (Centro de Investigação em Biodiversidade e Recursos Genéticos), Universidade do Porto, Campus Agrario De Vairão, 4485-661, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, 4485-661, Vairão, Portugal
| | - Gregorio Moreno-Rueda
- Departamento de Zoología, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain
| | - Eric N Smith
- Department of Biology and Amphibian and Reptile Diversity Research Center, University of Texas at Arlington, Arlington, TX, 76019, USA
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2
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Georgalis GL, Scheyer TM. Lizards and snakes from the earliest Miocene of Saint-Gérand-le-Puy, France: an anatomical and histological approach of some of the oldest Neogene squamates from Europe. BMC Ecol Evol 2021; 21:144. [PMID: 34256702 PMCID: PMC8278609 DOI: 10.1186/s12862-021-01874-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 06/28/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The earliest Miocene (Aquitanian) represents a crucial time interval in the evolution of European squamates (i.e., lizards and snakes), witnessing a high diversity of taxa, including an array of extinct forms but also representatives of extant genera. We here conduct a taxonomical survey along with a histological/microanatomical approach on new squamate remains from the earliest Miocene of Saint-Gérand-le-Puy, France, an area that has been well known for its fossil discoveries since the nineteenth century. RESULTS We document new occurrences of taxa, among which, the lacertid Janosikia and the anguid Ophisaurus holeci, were previously unknown from France. We provide a detailed description of the anatomical structures of the various cranial and postcranial remains of lizards and snakes from Saint-Gérand-le-Puy. By applying micro-CT scanning in the most complete cranial elements of our sample, we decipher previously unknown microanatomical features. We report in detail the subsurface distribution and 3D connectivity of vascular channels in the anguid parietal. The fine meshwork of channels and cavities or sinuses in the parietal of Ophisaurus could indicate some thermoregulatory function, as it has recently been demonstrated for other vertebrate groups, providing implications for the palaeophysiology of this earliest Miocene anguine lizard. CONCLUSIONS A combination of anatomical and micro-anatomical/histological approach, aided by micro-CT scanning, enabled the documentation of these new earliest Miocene squamate remains. A distinct geographic expansion is provided for the extinct anguine Ophisaurus holeci and the lacertid Janosikia (the closest relative of the extant insular Gallotia from the Canary Islands).
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Affiliation(s)
- Georgios L Georgalis
- University of Zurich, Palaeontological Institute and Museum, Karl Schmid-Strasse 4, 8006, Zurich, Switzerland.
| | - Torsten M Scheyer
- University of Zurich, Palaeontological Institute and Museum, Karl Schmid-Strasse 4, 8006, Zurich, Switzerland
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3
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Cleuren SGC, Hocking DP, Evans AR. Fang evolution in venomous snakes: Adaptation of 3D tooth shape to the biomechanical properties of their prey. Evolution 2021; 75:1377-1394. [PMID: 33904594 DOI: 10.1111/evo.14239] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 04/10/2021] [Accepted: 04/12/2021] [Indexed: 11/27/2022]
Abstract
Venomous snakes are among the world's most specialized predators. During feeding, they use fangs to penetrate the body tissues of their prey, but the success of this penetration depends on the shape of these highly specialized teeth. Here, we examined the evolution of fang shape in a wide range of snakes using 3D geometric morphometrics (3DGM) and cross-sectional tooth sharpness measurements. We investigated the relationship of these variables with six diet categories based on the prey's biomechanical properties, and tested for evolutionary convergence using two methods. Our results show that slender elongate fangs with sharp tips are used by snakes that target soft-skinned prey (e.g., mammals), whereas fangs become more robust and blunter as the target's skin becomes scaly (e.g., fish and reptiles) and eventually hard-shelled (e.g., crustaceans), both with and without correction for evolutionary allometry. Convergence in fang shape is present, indicating that fangs of snakes with the same diet are more similar than those of closely related species with different diets. Establishing the relationship between fang morphology and diet helps to explain how snakes became adapted to different lifestyles, while also providing a proxy to infer diet in lesser known species or extinct snakes from the fossil record.
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Affiliation(s)
- Silke G C Cleuren
- School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia
| | - David P Hocking
- School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Clayton, Victoria, 3800, Australia.,Geosciences, Museums Victoria, Melbourne, Victoria, 3001, Australia
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4
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Westeen EP, Durso AM, Grundler MC, Rabosky DL, Davis Rabosky AR. What makes a fang? Phylogenetic and ecological controls on tooth evolution in rear-fanged snakes. BMC Evol Biol 2020; 20:80. [PMID: 32646372 PMCID: PMC7346461 DOI: 10.1186/s12862-020-01645-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 06/22/2020] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Fangs are a putative key innovation that revolutionized prey capture and feeding in snakes, and - along with their associated venom phenotypes - have made snakes perhaps the most medically-significant vertebrate animals. Three snake clades are known for their forward-positioned fangs, and these clades (Elapidae, Viperidae, and Atractaspidinae) contain the majority of snakes that are traditionally considered venomous. However, many other snakes are "rear-fanged": they possess potentially venom-delivering teeth situated at the rear end of the upper jaw. Quantification of fang phenotypes - and especially those of rear-fanged species - has proved challenging or impossible owing to the small size and relative rarity of many such snakes. Consequently, it has been difficult to understand the evolutionary history of both venom and prey-capture strategies across extant snakes. We quantified variation in the dentition of 145 colubriform ("advanced") snake species using microCT scanning and compared dental characters with ecological data on species' diet and prey capture method(s) to understand broader patterns in snake fang evolution. RESULTS Dental traits such as maxilla length, tooth number, and fang size show strong phylogenetic signal across Colubriformes. We find extreme heterogeneity and evolutionary lability in the rear-fanged phenotype in colubrid (colubrine, dipsadine, and natricine lineages) and lamprophiid snakes, in contrast to relative uniformity in the front fanged phenotypes of other groups (vipers and, to a lesser extent, elapids). Fang size and position are correlated with venom-use in vipers, elapids, and colubrid snakes, with the latter group shifting fangs anteriorly by shortening the entire maxillary bone. We find that maxilla length and tooth number may also be correlated with the evolution of dietary specialization. Finally, an ancestral state reconstruction suggests that fang loss is a recurring phenomenon in colubrid snakes, likely accompanied by shifts in diet and prey capture mode. CONCLUSIONS Our study provides a framework for quantifying the complex morphologies associated with venom use in snakes. Our results suggest that fang phenotypes, and particularly the rear-fanged phenotype, in snakes are both diverse and labile, facilitating a wide range of ecological strategies and contributing to spectacular radiations of these organisms in tropical and subtropical biomes worldwide.
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Affiliation(s)
- Erin P Westeen
- Department of Environmental Science, Policy, and Management & Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA.
- Department of Ecology and Evolutionary Biology & Museum of Zoology, University of Michigan, Ann Arbor, MI, USA.
| | - Andrew M Durso
- Department of Biological Sciences, Florida Gulf Coast University, Ft. Myers, FL, USA
| | - Michael C Grundler
- Department of Ecology and Evolutionary Biology & Museum of Zoology, University of Michigan, Ann Arbor, MI, USA
| | - Daniel L Rabosky
- Department of Ecology and Evolutionary Biology & Museum of Zoology, University of Michigan, Ann Arbor, MI, USA
| | - Alison R Davis Rabosky
- Department of Ecology and Evolutionary Biology & Museum of Zoology, University of Michigan, Ann Arbor, MI, USA
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5
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Šmíd J, Tolley KA. Calibrating the tree of vipers under the fossilized birth-death model. Sci Rep 2019; 9:5510. [PMID: 30940820 PMCID: PMC6445296 DOI: 10.1038/s41598-019-41290-2] [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: 09/18/2018] [Accepted: 02/15/2019] [Indexed: 11/09/2022] Open
Abstract
Scaling evolutionary trees to time is essential for understanding the origins of clades. Recently developed methods allow including the entire fossil record known for the group of interest and eliminated the need for specifying prior distributions for node ages. Here we apply the fossilized birth-death (FBD) approach to reconstruct the diversification timeline of the viperines (subfamily Viperinae). Viperinae are an Old World snake subfamily comprising 102 species from 13 genera. The fossil record of vipers is fairly rich and well assignable to clades due to the unique vertebral and fang morphology. We use an unprecedented sampling of 83 modern species and 13 genetic markers in combination with 197 fossils representing 28 extinct taxa to reconstruct a time-calibrated phylogeny of the Viperinae. Our results suggest a late Eocene-early Oligocene origin with several diversification events following soon after the group's establishment. The age estimates inferred with the FBD model correspond to those from previous studies that were based on node dating but FBD provides notably narrower credible intervals around the node ages. Viperines comprise two African and an Eurasian clade, but the ancestral origin of the subfamily is ambiguous. The most parsimonious scenarios require two transoceanic dispersals over the Tethys Sea during the Oligocene.
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Affiliation(s)
- Jiří Šmíd
- South African National Biodiversity Institute, Kirstenbosch Research Centre, Cape Town, South Africa. .,Department of Botany and Zoology, University of Stellenbosch, Stellenbosch, Private Bag X1, South Africa. .,Department of Zoology, National Museum, Cirkusová, 1740, Prague, Czech Republic. .,Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, Prague, Czech Republic.
| | - Krystal A Tolley
- South African National Biodiversity Institute, Kirstenbosch Research Centre, Cape Town, South Africa.,Centre for Ecological Genomics and Wildlife Conservation, Department of Zoology, University of Johannesburg, Auckland Park, 2000, Johannesburg, South Africa
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6
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Fathinia B, Rastegar-Pouyani N, Rastegar-Pouyani E. Molecular phylogeny and historical biogeography of genera Eristicophis
and Pseudocerastes
(Ophidia, Viperidae). ZOOL SCR 2018. [DOI: 10.1111/zsc.12311] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Behzad Fathinia
- Department of Biology, Faculty of Science; Yasouj University; Yasouj Iran
| | - Nasrullah Rastegar-Pouyani
- Department of Biology, Faculty of Science; Razi University; Kermanshah Iran
- Iranian Plateau Herpetology Research Group (IPHRG), Faculty of Science; Razi University; Kermanshah Iran
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7
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Diversification in vipers: Phylogenetic relationships, time of divergence and shifts in speciation rates. Mol Phylogenet Evol 2016; 105:50-62. [DOI: 10.1016/j.ympev.2016.07.029] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Revised: 04/01/2016] [Accepted: 07/28/2016] [Indexed: 11/17/2022]
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8
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McCartney JA, Stevens NJ, O’Connor PM. The earliest colubroid-dominated snake fauna from Africa: perspectives from the Late Oligocene Nsungwe Formation of southwestern Tanzania. PLoS One 2014; 9:e90415. [PMID: 24646522 PMCID: PMC3960104 DOI: 10.1371/journal.pone.0090415] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 02/02/2014] [Indexed: 11/19/2022] Open
Abstract
The extant snake fauna has its roots in faunal upheaval occurring across the Paleogene-Neogene transition. On northern continents, this turnover is well established by the late early Miocene. However, this transition is poorly documented on southern landmasses, particularly on continental Africa, where no late Paleogene terrestrial snake assemblages are documented south of the equator. Here we describe a newly discovered snake fauna from the Late Oligocene Nsungwe Formation in the Rukwa Rift Basin of Tanzania. The fauna is small but diverse with eight identifiable morphotypes, comprised of three booids and five colubroids. This fauna includes Rukwanyoka holmani gen. et sp. nov., the oldest boid known from mainland Africa. It also provides the oldest fossil evidence for the African colubroid clade Elapidae. Colubroids dominate the fauna, comprising more than 75% of the recovered material. This is likely tied to local aridification and/or seasonality and mirrors the pattern of overturn in later snake faunas inhabiting the emerging grassland environments of Europe and North America. The early emergence of colubroid dominance in the Rukwa Rift Basin relative to northern continents suggests that the pattern of overturn that resulted in extant faunas happened in a more complex fashion on continental Africa than was previously realized, with African colubroids becoming at least locally important in the late Paleogene, either ahead of or as a consequence of the invasion of colubrids. The early occurrence of elapid snakes in the latest Oligocene of Africa suggests the clade rapidly spread from Asia to Africa, or arose in Africa, before invading Europe.
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Affiliation(s)
- Jacob A. McCartney
- Department of Anatomical Sciences, Health Sciences Center, Stony Brook University, Stony Brook, New York, United States of America
- Department of Biomedical Sciences, Irvine Hall, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, United States of America
- Center for Ecology and Evolutionary Studies, Irvine Hall, Ohio University, Athens, Ohio, United States of America
| | - Nancy J. Stevens
- Department of Biomedical Sciences, Irvine Hall, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, United States of America
- Center for Ecology and Evolutionary Studies, Irvine Hall, Ohio University, Athens, Ohio, United States of America
| | - Patrick M. O’Connor
- Department of Biomedical Sciences, Irvine Hall, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, United States of America
- Center for Ecology and Evolutionary Studies, Irvine Hall, Ohio University, Athens, Ohio, United States of America
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9
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Grooves to tubes: evolution of the venom delivery system in a Late Triassic "reptile". Naturwissenschaften 2011; 97:1117-21. [PMID: 21060984 DOI: 10.1007/s00114-010-0729-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 09/24/2010] [Accepted: 10/12/2010] [Indexed: 10/18/2022]
Abstract
Venom delivery systems occur in a wide range of extant and fossil vertebrates and are primarily based on oral adaptations. Teeth range from unmodified (Komodo dragons) to highly specialized fangs similar to hypodermic needles (protero- and solenoglyphous snakes). Developmental biologists have documented evidence for an infolding pathway of fang evolution, where the groove folds over to create the more derived condition. However, the oldest known members of venomous clades retain the same condition as their extant relatives, resulting in no fossil evidence for the transition. Based on a comparison of previously known specimens with newly discovered teeth from North Carolina, we describe a new species of the Late Triassic archosauriform Uatchitodon and provide detailed analyses that provide evidence for both venom conduction and document a complete structural series from shallow grooves to fully enclosed tubular canals. While known only from teeth, Uatchitodon is highly diagnostic in possessing compound serrations and for having two venom canals on each tooth in the dentition. Further, although not a snake, Uatchitodon sheds light on the evolutionary trajectory of venom delivery systems in amniotes and provide solid evidence for venom conduction in archosaur-line diapsids.
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10
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Lukoschek V, Scott Keogh J, Avise JC. Evaluating fossil calibrations for dating phylogenies in light of rates of molecular evolution: a comparison of three approaches. Syst Biol 2011; 61:22-43. [PMID: 21840843 DOI: 10.1093/sysbio/syr075] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Evolutionary and biogeographic studies increasingly rely on calibrated molecular clocks to date key events. Although there has been significant recent progress in development of the techniques used for molecular dating, many issues remain. In particular, controversies abound over the appropriate use and placement of fossils for calibrating molecular clocks. Several methods have been proposed for evaluating candidate fossils; however, few studies have compared the results obtained by different approaches. Moreover, no previous study has incorporated the effects of nucleotide saturation from different data types in the evaluation of candidate fossils. In order to address these issues, we compared three approaches for evaluating fossil calibrations: the single-fossil cross-validation method of Near, Meylan, and Shaffer (2005. Assessing concordance of fossil calibration points in molecular clock studies: an example using turtles. Am. Nat. 165:137-146), the empirical fossil coverage method of Marshall (2008. A simple method for bracketing absolute divergence times on molecular phylogenies using multiple fossil calibration points. Am. Nat. 171:726-742), and the Bayesian multicalibration method of Sanders and Lee (2007. Evaluating molecular clock calibrations using Bayesian analyses with soft and hard bounds. Biol. Lett. 3:275-279) and explicitly incorporate the effects of data type (nuclear vs. mitochondrial DNA) for identifying the most reliable or congruent fossil calibrations. We used advanced (Caenophidian) snakes as a case study; however, our results are applicable to any taxonomic group with multiple candidate fossils, provided appropriate taxon sampling and sufficient molecular sequence data are available. We found that data type strongly influenced which fossil calibrations were identified as outliers, regardless of which method was used. Despite the use of complex partitioned models of sequence evolution and multiple calibrations throughout the tree, saturation severely compressed basal branch lengths obtained from mitochondrial DNA compared with nuclear DNA. The effects of mitochondrial saturation were not ameliorated by analyzing a combined nuclear and mitochondrial data set. Although removing the third codon positions from the mitochondrial coding regions did not ameliorate saturation effects in the single-fossil cross-validations, it did in the Bayesian multicalibration analyses. Saturation significantly influenced the fossils that were selected as most reliable for all three methods evaluated. Our findings highlight the need to critically evaluate the fossils selected by data with different rates of nucleotide substitution and how data with different evolutionary rates affect the results of each method for evaluating fossils. Our empirical evaluation demonstrates that the advantages of using multiple independent fossil calibrations significantly outweigh any disadvantages.
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Affiliation(s)
- Vimoksalehi Lukoschek
- Department of Ecology and Evolutionary Biology, University of California at Irvine, Irvine, CA 92697, USA.
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11
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Morris SC. Predicting what extra-terrestrials will be like: and preparing for the worst. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:555-571. [PMID: 21220280 DOI: 10.1098/rsta.2010.0276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
It is difficult to imagine evolution in alien biospheres operating in any manner other than Darwinian. Yet, it is also widely assumed that alien life-forms will be just that: strange, un-nerving and probably repulsive. There are two reasons for this view. First, it is assumed that the range of habitable environments available to extra-terrestrial life is far wider than on Earth. I suggest, however, that terrestrial life is close to the physical and chemical limits of life anywhere. Second, it is a neo-Darwinian orthodoxy that evolution lacks predictability; imagining what extra-terrestrial life would look like in any detail is a futile exercise. To the contrary, I suggest that the outcomes of evolution are remarkably predictable. This, however, leads us to consider two opposites, both of which should make our blood run cold. The first, and actually extremely unlikely, is that alien biospheres will be strikingly similar to our terrestrial equivalent and that in such biospheres intelligence will inevitably emerge. The reasons for this revolve around the ubiquity of evolutionary convergence, the determinate structure of the Tree of Life and molecular inherency. But if something like a human is an inevitability, why do I also claim that the first possibility is 'extremely unlikely'? Simply because the other possibility is actually the correct answer. Paradoxically, we and our biosphere are completely alone. So which is worse? Meeting ourselves or meeting nobody?
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Affiliation(s)
- Simon Conway Morris
- Department of Earth Sciences, Downing Street, University of Cambridge, Cambridge CB2 3EQ, UK.
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12
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Sanders KL, Hamidy A, Head JJ, Gower DJ. Phylogeny and divergence times of filesnakes (Acrochordus): inferences from morphology, fossils and three molecular loci. Mol Phylogenet Evol 2010; 56:857-67. [PMID: 20434568 DOI: 10.1016/j.ympev.2010.04.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 04/16/2010] [Accepted: 04/22/2010] [Indexed: 11/15/2022]
Abstract
Acrochordus is a species-poor but highly distinctive aquatic snake genus currently distributed from India to the western edge of the Pacific. We provide the first phylogeny for the three extant species using Bayesian and parsimony analyses of one mitochondrial and two nuclear gene sequences. Acrochordus javanicus is strongly recovered as sister to A. arafurae+A. granulatus, counter to expectations from superficial ecology, external phenotype and former taxonomy. We review and revise key fossil calibrations for dating snake divergences. Bayesian relaxed-clock analysis of the two nuclear loci yields deep interspecific divergences among extant species that occurred during the Miocene approximately 16 and approximately 20Mya (million years ago), pre-dating at least two of the three other living marine snake lineages. New morphological data for A. arafurae, and our molecular timescale, provide support for the placement of fossil taxon A. dehmi within the Acrochordus crown group, as sister to A. javanicus among nominate species. Finally, Acrochordus phylogeny provides an improved basis for taxon selection and character polarization in higher snake phylogenetics. Our study highlights the three Acrochordus species as old and highly distinct lineages that comprise an important component of the threatened Indo-Australian biodiversity.
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Affiliation(s)
- Kate L Sanders
- Darling Building School of Earth and Environmental Sciences, University of Adelaide, Adelaide 5005, Australia.
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13
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Abstract
Snake bite is a common and frequently devastating environmental and occupational disease, especially in rural areas of tropical developing countries. Its public health importance has been largely ignored by medical science. Snake venoms are rich in protein and peptide toxins that have specificity for a wide range of tissue receptors, making them clinically challenging and scientifically fascinating, especially for drug design. Although the full burden of human suffering attributable to snake bite remains obscure, hundreds of thousands of people are known to be envenomed and tens of thousands are killed or maimed by snakes every year. Preventive efforts should be aimed towards education of affected communities to use proper footwear and to reduce the risk of contact with snakes to a minimum through understanding of snakes' behaviour. To treat envenoming, the production and clinical use of antivenom must be improved. Increased collaboration between clinicians, epidemiologists, and laboratory toxinologists should enhance the understanding and treatment of envenoming.
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Affiliation(s)
- David A Warrell
- Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
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14
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Conway Morris S. The predictability of evolution: glimpses into a post-Darwinian world. Naturwissenschaften 2009; 96:1313-37. [PMID: 19784612 DOI: 10.1007/s00114-009-0607-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/17/2009] [Accepted: 08/27/2009] [Indexed: 01/01/2023]
Abstract
The very success of the Darwinian explanation, in not only demonstrating evolution from multiple lines of evidence but also in providing some plausible explanations, paradoxically seems to have served to have stifled explorations into other areas of investigation. The fact of evolution is now almost universally yoked to the assumption that its outcomes are random, trends are little more than drunkard's walks, and most evolutionary products are masterpieces of improvisation and far from perfect. But is this correct? Let us consider some alternatives. Is there evidence that evolution could in anyway be predictable? Can we identify alternative forms of biological organizations and if so how viable are they? Why are some molecules so extraordinarily versatile, while others can be spoken of as "molecules of choice"? How fortuitous are the major transitions in the history of life? What implications might this have for the Tree of Life? To what extent is evolutionary diversification constrained or facilitated by prior states? Are evolutionary outcomes merely sufficient or alternatively are they highly efficient, even superb? Here I argue that in sharp contradistinction to an orthodox Darwinian view, not only is evolution much more predictable than generally assumed but also investigation of its organizational substrates, including those of sensory systems, which indicates that it is possible to identify a predictability to the process and outcomes of evolution. If correct, the implications may be of some significance, not least in separating the unexceptional Darwinian mechanisms from underlying organizational principles, which may indicate evolutionary inevitabilities.
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Affiliation(s)
- Simon Conway Morris
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK.
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15
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Kelly CMR, Barker NP, Villet MH, Broadley DG. Phylogeny, biogeography and classification of the snake superfamily Elapoidea: a rapid radiation in the late Eocene. Cladistics 2009; 25:38-63. [DOI: 10.1111/j.1096-0031.2008.00237.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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16
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Global richness patterns of venomous snakes reveal contrasting influences of ecology and history in two different clades. Oecologia 2008; 159:617-26. [PMID: 19101733 DOI: 10.1007/s00442-008-1244-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Accepted: 11/13/2008] [Indexed: 10/21/2022]
Abstract
Recent studies addressing broad-scale species richness gradients have proposed two main primary drivers: contemporary climate and evolutionary processes (differential balance between speciation and extinction). Here, we analyze the global richness patterns of two venomous snake clades, Viperidae and Elapidae. We used ordinary least squares multiple regression (OLS) and partial regression analysis to investigate to what extent actual evapotranspiration (AET; summarizing current environmental conditions) and biogeographical regions (representing evolutionary effects) were associated with species richness. For viperids, AET explained 45.6% of the variance in richness whereas the effect of this variable for elapids was almost null (0.5%). On the other hand, biogeographic regions were the best predictors of elapid richness (56.5%), against its relatively small effect (25.9%) in viperid richness. Partial regressions also revealed similar patterns for independent effects of climate and history in both clades. However, the independent historical effect in Elapidae decreased from 45.2 to 17.8% when we excluded Australia from the analyses, indicating that the strong historical effect that had emerged for the global richness pattern was reflecting the historical process of elapid radiation into Australia. Even after excluding Australia, the historical signal in elapid richness in the rest of the globe was still significant and much higher than that observed in viperid richness at a global scale (2.7% after controlling for AET effects). Differences in the evolutionary age of these two clades can be invoked to explain these contrasting results, in that viperids probably had more time for diversification, generating richness responses to environmental gradients, whereas the pattern of distribution of elapid richness can be more directly interpreted in an evolutionary context. Moreover, these results show the importance of starting to adopt deconstructive approaches to species richness, since the driving factors of these patterns may vary from group to group according to their evolutionary history.
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17
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A nesting of vipers: Phylogeny and historical biogeography of the Viperidae (Squamata: Serpentes). Mol Phylogenet Evol 2008; 49:445-59. [PMID: 18804544 DOI: 10.1016/j.ympev.2008.08.019] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 08/01/2008] [Accepted: 08/28/2008] [Indexed: 11/23/2022]
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18
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Vonk FJ, Admiraal JF, Jackson K, Reshef R, de Bakker MAG, Vanderschoot K, van den Berge I, van Atten M, Burgerhout E, Beck A, Mirtschin PJ, Kochva E, Witte F, Fry BG, Woods AE, Richardson MK. Evolutionary origin and development of snake fangs. Nature 2008; 454:630-3. [DOI: 10.1038/nature07178] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Accepted: 06/19/2008] [Indexed: 11/10/2022]
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19
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Sanders KL, Lee MSY, Leys R, Foster R, Keogh JS. Molecular phylogeny and divergence dates for Australasian elapids and sea snakes (hydrophiinae): evidence from seven genes for rapid evolutionary radiations. J Evol Biol 2008; 21:682-95. [PMID: 18384538 DOI: 10.1111/j.1420-9101.2008.01525.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One of the most prolific radiations of venomous snakes, the Australo-Melanesian Hydrophiinae includes approximately 100 species of Australasian terrestrial elapids plus all approximately 60 species of viviparous sea snakes. Here, we estimate hydrophiine relationships based on a large data set comprising 5800 bp drawn from seven genes (mitochondrial: ND4, cytb, 12S, 16S; nuclear: rag1, cmos, myh). These data were analysed using parsimony, likelihood and Bayesian methods to better resolve hydrophiine phylogeny and provide a timescale for the terrestrial and marine radiations. Among oviparous forms, Cacophis, Furina and Demansia are basal to other Australian elapids (core oxyuranines). The Melanesian Toxicocalamus and Aspidomorphus group with Demansia, indicating multiple dispersal events between New Guinea and Australia. Oxyuranus and Pseudonaja form a robust clade. The small burrowing taxa form two separate clades, one consisting of Vermicella and Neelaps calanotus, and the other including Simoselaps, Brachyurophis and Neelaps bimaculatus. The viviparous terrestrial elapids form three separate groups: Acanthophis, the Rhinoplocephalus group and the Notechis-Hemiaspis group. True sea snakes (Hydrophiini) are robustly united with the Notechis-Hemiaspis group. Many of the retrieved groupings are consistent with previous molecular and morphological analyses, but the polyphyly of the viviparous and burrowing groups, and of Neelaps, are novel results. Bayesian relaxed clock analyses indicate very recent divergences: the approximately 160 species of the core Australian radiation (including sea snakes) arose within the last 10 Myr, with most inter-generic splits dating to between 10 and 6 Ma. The Hydrophis sea snake lineage is an exceptionally rapid radiation, with > 40 species evolving within the last 5 Myr.
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Affiliation(s)
- K L Sanders
- School of Earth and Environmental Sciences, University of Adelaide, Adelaide, Australia.
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20
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Sanders KL, Lee MSY. Molecular evidence for a rapid late-Miocene radiation of Australasian venomous snakes (Elapidae, Colubroidea). Mol Phylogenet Evol 2007; 46:1165-73. [PMID: 18222097 DOI: 10.1016/j.ympev.2007.11.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 10/17/2007] [Accepted: 11/21/2007] [Indexed: 11/25/2022]
Affiliation(s)
- Kate L Sanders
- Darling Building, School of Earth and Environmental Sciences, University of Adelaide, Adelaide 5005, Australia.
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21
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Jackson K. The evolution of venom-conducting fangs: Insights from developmental biology. Toxicon 2007; 49:975-81. [PMID: 17337027 DOI: 10.1016/j.toxicon.2007.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 12/30/2006] [Accepted: 01/15/2007] [Indexed: 11/30/2022]
Abstract
The present study of the origin of the various types of fang represented among colubroid snakes (i.e., tubular, grooved, and ungrooved) attempts to reconcile the morphology of adult fangs with current phylogenetic hypotheses. Observations of growth series of developing tubular fangs were hypothesised to shed light on the evolutionary origin of fangs in snakes. While molecular phylogenies and evolutionary studies of venom proteins and of other anatomical components of the venom-delivery system reconstruct a consistent evolutionary scenario, the character of a tubular venom-conducting fang does not fit in this scenario. The present review offers a series of possible scenarios to resolve this anomaly. Of these, a new idea argues that a heterochronic mechanism (alteration of the timing of developmental events) may provide the answer that the ungrooved and grooved teeth of colubrid snakes evolved from an ancestral tubular fang by means of attachment of replacement tubular fangs to the maxilla at an earlier developmental stage than usual (precocial ankylosis).
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Affiliation(s)
- Kate Jackson
- Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, Ont., Canada M5S 3G5.
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