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Ludington AJ, Hammond JM, Breen J, Deveson IW, Sanders KL. New chromosome-scale genomes provide insights into marine adaptations of sea snakes (Hydrophis: Elapidae). BMC Biol 2023; 21:284. [PMID: 38066641 PMCID: PMC10709897 DOI: 10.1186/s12915-023-01772-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 11/20/2023] [Indexed: 12/18/2023] Open
Abstract
BACKGROUND Sea snakes underwent a complete transition from land to sea within the last ~ 15 million years, yet they remain a conspicuous gap in molecular studies of marine adaptation in vertebrates. RESULTS Here, we generate four new annotated sea snake genomes, three of these at chromosome-scale (Hydrophis major, H. ornatus and H. curtus), and perform detailed comparative genomic analyses of sea snakes and their closest terrestrial relatives. Phylogenomic analyses highlight the possibility of near-simultaneous speciation at the root of Hydrophis, and synteny maps show intra-chromosomal variations that will be important targets for future adaptation and speciation genomic studies of this system. We then used a strict screen for positive selection in sea snakes (against a background of seven terrestrial snake genomes) to identify genes over-represented in hypoxia adaptation, sensory perception, immune response and morphological development. CONCLUSIONS We provide the best reference genomes currently available for the prolific and medically important elapid snake radiation. Our analyses highlight the phylogenetic complexity and conserved genome structure within Hydrophis. Positively selected marine-associated genes provide promising candidates for future, functional studies linking genetic signatures to the marine phenotypes of sea snakes and other vertebrates.
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Affiliation(s)
- Alastair J Ludington
- School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia.
| | - Jillian M Hammond
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, NSW, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research and Murdoch Children's Research Institute, Darlinghurst, Australia
| | - James Breen
- Indigenous Genomics, Telethon Kids Institute, Adelaide, Australia
- John Curtin School of Medical Research, College of Health & Medicine, Australian National University, Canberra, Australia
| | - Ira W Deveson
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, NSW, Australia
- Centre for Population Genomics, Garvan Institute of Medical Research and Murdoch Children's Research Institute, Darlinghurst, Australia
- Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Kate L Sanders
- School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia.
- The South Australian Museum, Adelaide, Australia.
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2
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Martin SB, De Silva MLI, Pathirana E, Rajapakse RPVJ. Polyphyly of the Dinurinae Looss, 1907 (Digenea: Hemiuridae) and resurrection of the Mecoderinae Skrjabin & Guschanskaja, 1954 based on novel collection of Tubulovesicula laticaudi Parukhin, 1969 from marine elapid snakes in Sri Lanka. Parasitol Int 2023; 97:102776. [PMID: 37437775 DOI: 10.1016/j.parint.2023.102776] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/27/2023] [Accepted: 07/06/2023] [Indexed: 07/14/2023]
Abstract
With one exception, the only known hemiurid trematodes that do not use teleost fishes as definitive hosts instead occur in marine elapid snakes. These comprise six species across four genera and three subfamilies, and so presumably indicate at least three independent invasions of marine snakes from teleost fishes. Here, one of these taxa, Tubulovesicula laticaudi Parukhin, 1969 (= T. orientalis Chattopadhyaya, 1970 n. syn.) is reported from Sri Lanka, collected from Shaw's sea snake Hydrophis curtus (Shaw) (Elapidae: Hydrophiinae: Hydrophinii), the annulated sea snake H. cyanocinctus Daudin and the yellow sea snake H. spiralis (Shaw) off Nayaru in the Bay of Bengal, and from H. spiralis in Portugal Bay, Gulf of Mannar. Novel molecular data, for COI mtDNA and ITS2 and 28S rDNA, are the first for a species of Tubulovesicula Yamaguti, 1934. Nominally, Tubulovesicula belongs in the Dinurinae Looss, 1907, but in phylogenetic analyses based on 28S rDNA, our sequences for T. laticaudi resolved relatively distant from that for representatives of Dinurus Looss, 1907, the type-genus, rendering the subfamily polyphyletic. Tubulovesicula laticaudi resolved closest to data for the type-species of the Plerurinae Gibson & Bray, 1979, but that subfamily is also polyphyletic. These findings lead us to re-evaluate an alternative classification considered by Gibson & Bray (1979). We propose restricting the Dinurinae for forms with a permanent sinus-organ (Dinurus, Ectenurus Looss, 1907; Erilepturus Woolcock, 1935; Paradinurus Vigueras, 1958; Qadriana Bilqees, 1971) and resurrect the Mecoderinae Skrjabin & Guschanskaja, 1954 for forms with a temporary sinus-organ (Mecoderus Manter, 1940, Allostomachicola Yamaguti, 1958, Stomachicola Yamaguti, 1934 and Tubulovesicula).
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Affiliation(s)
- Storm Blas Martin
- Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, Murdoch, Western Australia 6150, Australia.
| | - M L I De Silva
- Divsion of Parasitology, Department of Veterinary Pathobiology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Sri Lanka; Department of Aquatic Bioresources, Faculty of Urban and Aquatic Bioresources, University of Sri Jayawardenepura, Gangodawila, Nugegoda, Sri Lanka.
| | - Erandi Pathirana
- Department of Aquatic Bioresources, Faculty of Urban and Aquatic Bioresources, University of Sri Jayawardenepura, Gangodawila, Nugegoda, Sri Lanka
| | - R P V J Rajapakse
- Divsion of Parasitology, Department of Veterinary Pathobiology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Sri Lanka
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3
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Shine R, Shine TG, Brown GP, Udyawer V. Sexual dimorphism in aipysurine sea snakes (Elapidae, Hydrophiinae). R Soc Open Sci 2023; 10:231261. [PMID: 38094274 PMCID: PMC10716647 DOI: 10.1098/rsos.231261] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/20/2023] [Indexed: 01/11/2024]
Abstract
The transition from terrestrial to aquatic life by hydrophiine elapid snakes modified targets of natural selection and likely affected sexual selection also. Thus, the shift to marine life also might have affected sexual dimorphism. Our measurements of 419 preserved specimens of six species of aipysurine snakes (genera Emydocephalus and Aipysurus) revealed sexual dimorphism in mean adult snout-vent length (SVL), body width relative to SVL, lengths and widths of heads and tails relative to SVL, and eye diameter relative to head length. Females averaged larger than males in all taxa, and generally were wider-bodied with shorter and wider tails and smaller eyes. For other traits, sexual dimorphism varied among species: for example, relative head length ranged from male-biased to female-biased, and head shape (width relative to length) was highly dimorphic only in A. laevis. The transition to marine life may have eliminated male-male combat (reducing selection for large males) and favoured visual rather than pheromone-based mate-searching (favouring larger eyes in males). Variation in head-size dimorphism may reflect intersexual niche partitioning, with different taxa following different trajectories. Repeated evolutionary transitions from terrestrial to aquatic life in snakes provide a powerful opportunity to explore selective forces on sexually dimorphic traits.
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Affiliation(s)
- R. Shine
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - T. G. Shine
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - G. P. Brown
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - V. Udyawer
- Australian Institute of Marine Science, Darwin, Northern Territory 0810, Australia
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4
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Tiatragul S, Brennan IG, Broady ES, Keogh JS. Australia's hidden radiation: Phylogenomics analysis reveals rapid Miocene radiation of blindsnakes. Mol Phylogenet Evol 2023; 185:107812. [PMID: 37207892 DOI: 10.1016/j.ympev.2023.107812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 03/24/2023] [Accepted: 05/10/2023] [Indexed: 05/21/2023]
Affiliation(s)
- Sarin Tiatragul
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, Canberra 2601, ACT, Australia.
| | - Ian G Brennan
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, Canberra 2601, ACT, Australia.
| | - Elizabeth S Broady
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, Canberra 2601, ACT, Australia.
| | - J Scott Keogh
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, Canberra 2601, ACT, Australia.
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5
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Figueroa A, Low MEY, Lim KKP. Singapore's herpetofauna: updated and annotated checklist, history, conservation, and distribution. Zootaxa 2023; 5287:1-378. [PMID: 37518684 DOI: 10.11646/zootaxa.5287.1.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Indexed: 08/01/2023]
Abstract
Given Singapore's location at the confluence of important maritime trading routes, and that it was established as a British East India Company trading post in 1819, it is unsurprising that Singapore has become one of the centres of natural history collecting and research in Southeast Asia. Despite its small size, Singapore is home to a diverse herpetofauna assemblage and boasts a rich herpetological history. The first systematic studies of Singapore's herpetofauna (within the Linnaean binomial framework) date back to Stamford Raffles and the naturalists hired by him who first came to the island in 1819. Specimens that were collected during and after this time were deposited in museums worldwide. Over time, 39 species from Singapore were described as new to science. Due to the entrepôt nature of Singapore with its associated purchasing and trading of specimens (both alive and dead), poor record-keeping, and human introductions, numerous extraneous species from outside of Singapore were reported to occur on the island. Such issues have left a complicated legacy of ambiguous records and taxonomic complications concerning the identity of Singapore's species-rich herpetofauna, many of which were only resolved in the past 30-40 years. By compiling a comprehensive collection of records and publications relating to the herpetofauna of Singapore, we construct an updated and more accurate listing of the herpetofauna of Singapore. Our investigation culminated in the evaluation of 309 species, in which we compiled a final species checklist recognising 166 species (149 native and 17 non-native established species). Among the 149 native species are two caecilians, 24 frogs, one crocodilian, 13 turtles (three visitors), 34 lizards, and 75 snakes. Of the 17 non-native species are five frogs, four turtles, six lizards, and two snakes. The remaining 143 species represent species to be excluded from Singapore's herpetofauna species checklist. For each of the 309 species examined, we provide species accounts and explanatory annotations. Furthermore, we discuss Singapore's herpetofauna from a historical and conservation perspective. Immediate deforestation and nationwide urbanisation following colonisation completely eliminated many species from throughout much of the country and restricted them to small, degraded forest patches. We hope this publication highlights the importance of publishing observations and serves as a valuable resource to future researchers, naturalists, biological consultants, and policy makers in initiating studies on species ecology, distribution, status, and promoting conservation efforts to safeguard Singapore's herpetofauna.
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Affiliation(s)
| | - Martyn E Y Low
- Lee Kong Chian Natural History Museum; 2 Conservatory Drive; Singapore 117377.
| | - Kelvin K P Lim
- Lee Kong Chian Natural History Museum; 2 Conservatory Drive; Singapore 117377.
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6
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Dehghani R, Monzavi SM, Mehrpour O, Shirazi FM, Hassanian-Moghaddam H, Keyler DE, Wüster W, Westerström A, Warrell DA. Medically important snakes and snakebite envenoming in Iran. Toxicon 2023; 230:107149. [PMID: 37187227 DOI: 10.1016/j.toxicon.2023.107149] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/01/2023] [Accepted: 05/02/2023] [Indexed: 05/17/2023]
Abstract
Snakebite is a common health condition in Iran with a diverse snake fauna, especially in tropical southern and mountainous western areas of the country with plethora of snake species. The list of medically important snakes, circumstances and effects of their bite, and necessary medical care require critical appraisal and should be updated regularly. This study aims to review and map the distributions of medically important snake species of Iran, re-evaluate their taxonomy, review their venomics, describe the clinical effects of envenoming, and discuss medical management and treatment, including the use of antivenom. Nearly 350 published articles and 26 textbooks with information on venomous and mildly venomous snake species and snakebites of Iran, were reviewed, many in Persian (Farsi) language, making them relatively inaccessible to an international readership. This has resulted in a revised updated list of Iran's medically important snake species, with taxonomic revisions of some, compilation of their morphological features, remapping of their geographical distributions, and description of species-specific clinical effects of envenoming. Moreover, the antivenom manufactured in Iran is discussed, together with treatment protocols that have been developed for the hospital management of envenomed patients.
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Affiliation(s)
- Ruhollah Dehghani
- Department of Environmental Health, Kashan University of Medical Sciences, Kashan, Iran; Social Determinants of Health Research Center, Kashan University of Medical Sciences, Kashan, Iran
| | - Seyed Mostafa Monzavi
- Medical Toxicology Center, Mashhad University of Medical Sciences, Mashhad, Iran; Social Determinants of Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Omid Mehrpour
- Medical Toxicology and Drug Abuse Research Center, Birjand University of Medical Sciences, Birjand, Iran; Rocky Mountain Poison and Drug Center, Denver Health and Hospital Authority, Denver, CO, USA.
| | - Farshad M Shirazi
- Arizona Poison and Drug Information Center, University of Arizona, Tucson, AZ, USA
| | - Hossein Hassanian-Moghaddam
- Social Determinants of Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Clinical Toxicology, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Daniel E Keyler
- Department of Experimental & Clinical Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - Wolfgang Wüster
- Molecular Ecology and Evolution at Bangor, School of Natural Sciences, Bangor University, Bangor, UK
| | | | - David A Warrell
- Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
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7
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Hosseinian Yousefkhani SS, Yasser A, Naser M, Rezaie-Atagholipour M, Askari Hesni M, Yousefabadi F, Rastegar Pouyani E. Genetic diversity among sea snakes of the genus Hydrophis (Elapidae, Reptilia) in the Persian Gulf and Gulf of Oman. Zookeys 2023; 1158:121-131. [PMID: 37215695 PMCID: PMC10193271 DOI: 10.3897/zookeys.1158.101347] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/01/2023] [Indexed: 05/24/2023] Open
Abstract
Sea snakes of the genus Hydrophis are important components of animal diversity in Iranian waters of the Persian Gulf and Gulf of Oman. Ten species of Hydrophis have been identified from the these waters and, in this study, genetic structure of seven species was compared with other populations in the eastern Indian Ocean and the West Pacific. We found that six species (H.platurus, H.cyanocinctus, H.spiralis, H.schistosus, H.gracilis, and H.lapemiodes) show high genetic similarity with conspecific populations in the Indian Ocean and Australia. However, H.curtus from southern Iran shows a high level of genetic differentiation from conspecific populations in Sri Lanka and Indonesia (0.6% and 6% genetic distance from Sri Lankan samples for 16S and COI gene fragments, respectively). Variation between Iranian and Southeast Asian populations may reflect new genetic lineages and suggest the need of further morphological evaluations to re-evaluate their taxonomic position.
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Affiliation(s)
| | - Amaal Yasser
- Marine Science Centre, University of Basrah, Basra, Iraq
- Australian Rivers Institute, Griffith University, 170 Kessels Road, Nathan, Queensland 4111, Australia
| | - Murtada Naser
- Marine Science Centre, University of Basrah, Basra, Iraq
- Australian Rivers Institute, Griffith University, 170 Kessels Road, Nathan, Queensland 4111, Australia
| | - Mohsen Rezaie-Atagholipour
- School of Environment and Science, Griffith University, 170 Kessels Road, Nathan, Queensland, 4111, Australia
| | - Majid Askari Hesni
- Qeshm Environmental Conservation Institute (QECI), Qeshm Island, Hormozgan Province, Iran
| | - Fariba Yousefabadi
- Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman Province, Iran
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8
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Sherratt E, Nash-Hahn T, Nankivell JH, Rasmussen AR, Hampton PM, Sanders KL. Macroevolution in axial morphospace: innovations accompanying the transition to marine environments in elapid snakes. R Soc Open Sci 2022; 9:221087. [PMID: 36569233 PMCID: PMC9768463 DOI: 10.1098/rsos.221087] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Sea snakes in the Hydrophis-Microcephalophis clade (Elapidae) show exceptional body shape variation along a continuum from similar forebody and hindbody girths, to dramatically reduced girths of the forebody relative to hindbody. The latter is associated with specializations on burrowing prey. This variation underpins high sympatric diversity and species richness and is not shared by other marine (or terrestrial) snakes. Here, we examined a hypothesis that macroevolutionary changes in axial development contribute to the propensity, at clade level, for body shape change. We quantified variation in the number and size of vertebrae in two body regions (pre- and post-apex of the heart) for approximately 94 terrestrial and marine elapids. We found Hydrophis-Microcephalophis exhibit increased rates of vertebral evolution in the pre- versus post-apex regions compared to all other Australasian elapids. Unlike other marine and terrestrial elapids, axial elongation in Hydrophis-Microcephalophis occurs via the preferential addition of vertebrae pre-heart apex, which is the region that undergoes concomitant shifts in vertebral number and size during transitions along the relative fore- to hindbody girth axis. We suggest that this macroevolutionary developmental change has potentially acted as a key innovation in Hydrophis-Microcephalophis by facilitating novel (especially burrowing) prey specializations that are not shared with other marine snakes.
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Affiliation(s)
- Emma Sherratt
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
| | - Tamika Nash-Hahn
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - James H. Nankivell
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
| | - Arne R. Rasmussen
- The Royal Danish Academy, Institute of Conservation, 1435 Copenhagen, Denmark
| | - Paul M. Hampton
- Department of Biology, Colorado Mesa University, Grand Junction, CO 81501, USA
| | - Kate L. Sanders
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
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9
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Deepak V, Cooper N, Poyarkov NA, Kraus F, Burin G, Das A, Narayanan S, Streicher JW, Smith SJ, Gower DJ. Multilocus phylogeny, natural history traits and classification of natricine snakes (Serpentes: Natricinae). Zool J Linn Soc 2021. [DOI: 10.1093/zoolinnean/zlab099] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Natricine snakes are geographically widespread, species rich (with ~250 extant species) and both morphologically and ecologically diverse. We present a multilocus DNA sequence phylogeny for 249 natricine specimens representing 189 named species, including 69 specimens and 21 species not previously sampled. Our inferred Bayesian and maximum likelihood trees form the basis for evaluations of genus-level classification, historical biogeography, lineage diversification, and dietary, habit and reproductive-mode diversity and evolution, although several, mostly deeper, relationships remain poorly resolved. The optimal trees support natricine origins in Asia, with dispersals to Australo-Melanesia, sub-Saharan Africa (including Seychelles Archipelago, excluding Aldabra), Europe and North Africa and into North and Central America. Viviparity appears to have evolved independently three times in Natricinae but was not significantly associated with an aquatic habit. We found limited associations between habit and diet categories. We propose generic reallocations for four natricine species and highlight other points of uncertainty in natricine classification.
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Affiliation(s)
- V Deepak
- Department of Life Sciences, Natural History Museum, London, UK
- Senckenberg Dresden, Königsbrücker Landstraße, Dresden, Germany
| | - Natalie Cooper
- Department of Life Sciences, Natural History Museum, London, UK
| | - Nikolay A Poyarkov
- Department of Vertebrate Zoology, Biological Faculty, M. V. Lomonosov Moscow State University, Moscow, Russia
- Joint Russian–Vietnamese Tropical Research and Technological Center, Nghia Do, Cau Giay, Hanoi, Vietnam
| | - Fred Kraus
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Gustavo Burin
- Department of Life Sciences, Natural History Museum, London, UK
| | - Abhijit Das
- Wildlife Institute of India, Chandrabani, Dehradun, India
| | - Surya Narayanan
- Suri Sehgal Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), Srirampura, Bangalore, Karnataka, India
| | | | - Sarah-Jane Smith
- Department of Life Sciences, Natural History Museum, London, UK
- Imperial College London, South Kensington, London, UK
| | - David J Gower
- Department of Life Sciences, Natural History Museum, London, UK
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10
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Fujishima K, Sasai T, Hibino Y, Nishizawa H. Morphology, Diet, and Reproduction of Coastal Hydrophis Sea Snakes (Elapidae: Hydrophiinae) at Their Northern Distribution Limit. Zoolog Sci 2021; 38:405-415. [PMID: 34664915 DOI: 10.2108/zs210010] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/31/2021] [Indexed: 11/17/2022]
Abstract
The Ryukyu Archipelago represents the northern distribution limit for hydrophiine sea snakes, the largest group of marine reptiles. Ryukyuan sea snakes may have developed distinct local adaptations in morphology and ecology, but they have been poorly studied. We examined preserved specimens of 111 Hydrophismelanocephalusand 61 Hydrophis ornatusfrom the Ryukyu Archipelago to obtain data on morphology, diet, and reproduction. Sexual size dimorphism was detected in H. melanocephalus (mean ± standard deviation of adult snout-vent length: SVL, females 1062 ± 141 mm vs. males 959 ± 96 mm) but not in H. ornatus. Female H. melanocephalus had larger head widths and shorter tail lengths relative to SVL compared to males. Relative girth was low in neonates of both species (1.0-1.3), but increased in adults to about 1.7-2.6 in H. melanocephalus and 1.3-1.8 in female H. ornatus. Stomach contents of H. melanocephalus consisted of ophichthid and congrid eels, a sand diver, and gobies, whereas in H. ornatus, gobies and a goat fish were found. Litter size of three reproductive H. melanocephalus ranged from five to seven, and parturition seems to occur from August to October. Litter size of six H. ornatus ranged from two to seven, and was correlated with maternal SVL. Parturition in H. ornatus probably occurs around November. Different selective forces related to locomotion, feeding and predation risk, which influence the pregnant mother and neonates, may have resulted in having few, long but slender offspring that show positive allometric growth in hind-body girth.
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Affiliation(s)
- Kanta Fujishima
- Graduate School of Informatics, Kyoto University, Yoshida Hommachi, Kyoto 606-8501, Japan,
| | - Takahide Sasai
- Graduate School of Engineering and Science, University of the Ryukyus, Nishihara-cho, Okinawa 903-0213, Japan.,Okinawa Churashima Foundation, Motobu-cho, Okinawa 905-0206, Japan
| | - Yusuke Hibino
- Kitakyushu Museum of Natural History and Human History, Kitakyushu, Fukuoka 805-0071, Japan
| | - Hideaki Nishizawa
- Graduate School of Informatics, Kyoto University, Yoshida Hommachi, Kyoto 606-8501, Japan
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11
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Sasai T, Yamamoto T, Oka SI, Toda M. Addition of the Sea Snake, Hydrophis stokesii (Reptilia: Squamata: Elapidae), to the Herpetofauna of Japan. Current Herpetology 2021. [DOI: 10.5358/hsj.40.190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Takahide Sasai
- Okinawa Churashima Research Center, 888 Ishikawa, Motobu, Okinawa 905–0206, JAPAN
| | - Takumi Yamamoto
- Graduate School of Engineering and Science, University of the Ryukyus, Nishihara, Okinawa 903–0213, JAPAN
| | - Shin-ichiro Oka
- Okinawa Churashima Research Center, 888 Ishikawa, Motobu, Okinawa 905–0206, JAPAN
| | - Mamoru Toda
- Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903–0213, JAPAN
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Li A, Wang J, Sun K, Wang S, Zhao X, Wang T, Xiong L, Xu W, Qiu L, Shang Y, Liu R, Wang S, Lu Y. Two reference-quality sea snake genomes reveal their divergent evolution of adaptive traits and venom systems. Mol Biol Evol 2021; 38:4867-4883. [PMID: 34320652 PMCID: PMC8557462 DOI: 10.1093/molbev/msab212] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
True sea snakes (Hydrophiini) are among the last and most successful clades of vertebrates that show secondary marine adaptation, exhibiting diverse phenotypic traits and lethal venom systems. To better understand their evolution, we generated the first chromosome-level genomes of two representative Hydrophiini snakes, Hydrophis cyanocinctus and H. curtus. Through comparative genomics we identified a great expansion of the underwater olfaction-related V2R gene family, consisting of more than 1,000 copies in both snakes. A series of chromosome rearrangements and genomic structural variations were recognized, including large inversions longer than 30 megabase (Mb) on sex chromosomes which potentially affect key functional genes associated with differentiated phenotypes between the two species. By integrating multiomics we found a significant loss of the major weapon for elapid predation, three-finger toxin genes, which displayed a dosage effect in H. curtus. These genetic changes may imply mechanisms that drove the divergent evolution of adaptive traits including prey preferences between the two closely related snakes. Our reference-quality sea snake genomes also enrich the repositories for addressing important issues on the evolution of marine tetrapods, and provide a resource for discovering marine-derived biological products.
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Affiliation(s)
- An Li
- Department of Critical Care Medicine, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, 200072, China.,School of Pharmacy, Second Military Medical University, Shanghai, 200433, China
| | - Junjie Wang
- Department of Critical Care Medicine, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, 200072, China
| | - Kuo Sun
- School of Pharmacy, Second Military Medical University, Shanghai, 200433, China
| | - Shuocun Wang
- School of Medicine, Shanghai University, Shanghai, 200444, China
| | - Xin Zhao
- Department of Critical Care Medicine, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, 200072, China
| | - Tingfang Wang
- School of Medicine, Shanghai University, Shanghai, 200444, China
| | - Liyan Xiong
- School of Medicine, Shanghai University, Shanghai, 200444, China
| | - Weiheng Xu
- School of Pharmacy, Second Military Medical University, Shanghai, 200433, China
| | - Lei Qiu
- School of Pharmacy, Second Military Medical University, Shanghai, 200433, China
| | - Yan Shang
- Department of Respiratory and Critical Care Medicine, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China
| | - Runhui Liu
- School of Pharmacy, Second Military Medical University, Shanghai, 200433, China
| | - Sheng Wang
- Department of Critical Care Medicine, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, 200072, China
| | - Yiming Lu
- Department of Critical Care Medicine, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, 200072, China.,School of Pharmacy, Second Military Medical University, Shanghai, 200433, China.,School of Medicine, Shanghai University, Shanghai, 200444, China
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13
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Borczyk B, Paśko Ł, Kusznierz J, Bury S. Sexual dimorphism and skull size and shape in the highly specialized snake species, Aipysurus eydouxii (Elapidae: Hydrophiinae). PeerJ 2021; 9:e11311. [PMID: 33976986 PMCID: PMC8063874 DOI: 10.7717/peerj.11311] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 07/18/2018] [Accepted: 03/29/2021] [Indexed: 11/25/2022] Open
Abstract
Background Snakes exhibit sexual dimorphism in both head size and shape. Such differences are often attributed to different reproductive roles and feeding habits. We aim to investigate how sexual dimorphism is displayed in the highly specialised fish-egg-eating snake, Aipysurus eydouxii, by analysing two complementary features: body size and skull morphology. Methods We used data on body length, weight, and skull shape from 27 measurements of 116 males and females of A. eydouxii. We investigated both sexual dimorphism and allometric (multivariate and bi-variate) properties of skull growth in the analysed data set. Results We found that although there was female-biased sexual size dimorphism in body length, females were not heavier than males, contrary to what is commonly observed pattern among snakes. Moreover, females tend to possess relatively smaller heads than males. However, we only found very subtle differences in skull shape reflected in nasal width, mandibular fossa, quadrate crest and quadrate length. Discussion We suggest that the feeding specialisation in A. eydouxii does not allow for an increase in body thickness and the size of the head above a certain threshold. Our results may be interpreted as support for prey-size divergence as a factor driving skull dimorphism since such species in which the sexes do not differ in prey size also shows very subtle or no differences in skull morphology.
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Affiliation(s)
- Bartosz Borczyk
- Department of Evolutionary Biology and Conservation of Vertebrates, University of Wroclaw, Wrocław, Poland
| | - Łukasz Paśko
- Department of Evolutionary Biology and Conservation of Vertebrates, University of Wroclaw, Wrocław, Poland
| | - Jan Kusznierz
- Department of Evolutionary Biology and Conservation of Vertebrates, University of Wroclaw, Wrocław, Poland
| | - Stanisław Bury
- Department of Comparative Anatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, Kraków, Poland
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14
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Tan CH, Tan KY. De Novo Venom-Gland Transcriptomics of Spine-Bellied Sea Snake ( Hydrophis curtus) from Penang, Malaysia-Next-Generation Sequencing, Functional Annotation and Toxinological Correlation. Toxins (Basel) 2021; 13:toxins13020127. [PMID: 33572266 PMCID: PMC7915529 DOI: 10.3390/toxins13020127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 12/30/2020] [Revised: 01/31/2021] [Accepted: 02/02/2021] [Indexed: 01/26/2023] Open
Abstract
Envenomation resulted from sea snake bite is a highly lethal health hazard in Southeast Asia. Although commonly caused by sea snakes of Hydrophiinae, each species is evolutionarily distinct and thus, unveiling the toxin gene diversity within individual species is important. Applying next-generation sequencing, this study investigated the venom-gland transcriptome of Hydrophis curtus (spine-bellied sea snake) from Penang, West Malaysia. The transcriptome was de novo assembled, followed by gene annotation and sequence analyses. Transcripts with toxin annotation were only 96 in number but highly expressed, constituting 48.18% of total FPKM in the overall transcriptome. Of the 21 toxin families, three-finger toxins (3FTX) were the most abundantly expressed and functionally diverse, followed by phospholipases A2. Lh_FTX001 (short neurotoxin) and Lh_FTX013 (long neurotoxin) were the most dominant 3FTXs expressed, consistent with the pathophysiology of envenomation. Lh_FTX001 and Lh_FTX013 were variable in amino acid compositions and predicted epitopes, while Lh_FTX001 showed high sequence similarity with the short neurotoxin from Hydrophis schistosus, supporting cross-neutralization effect of Sea Snake Antivenom. Other toxins of low gene expression, for example, snake venom metalloproteinases and L-amino acid oxidases not commonly studied in sea snake venom were also identified, enriching the knowledgebase of sea snake toxins for future study.
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Affiliation(s)
- Choo Hock Tan
- Venom Research and Toxicoogy Lab, Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
- Correspondence:
| | - Kae Yi Tan
- Protein and Interactomics Lab, Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia;
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15
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Ludington AJ, Sanders KL. Demographic analyses of marine and terrestrial snakes (Elapidae) using whole genome sequences. Mol Ecol 2020; 30:545-554. [PMID: 33170980 DOI: 10.1111/mec.15726] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 10/13/2020] [Accepted: 11/03/2020] [Indexed: 11/27/2022]
Abstract
The question of whether spatial aspects of evolution differ in marine versus terrestrial realms has endured since Ernst Mayr's 1954 essay on marine speciation. Marine systems are often suggested to support larger and more highly connected populations, but quantitative comparisons with terrestrial systems have been lacking. Here, we compared the population histories of marine and terrestrial elapid snakes using the pairwise sequentially Markovian coalescent (PSMC) model to track historical fluctuations in species' effective population sizes (Ne ) from individual whole-genome sequences. To do this we generated a draft genome for the olive sea snake (Aiysurus laevis) and analysed this alongside six published elapid genomes and their sequence reads (marine species Hydrophis curtus, H. melanocephalus and Laticauda laticaudata; terrestrial species Pseudonaja textilis, Naja Naja and Notechis scutatus). Counter to the expectation that marine species should show higher overall Ne and less pronounced fluctuations in Ne , our analyses reveal demographic patterns that are highly variable among species and do not clearly correspond to major ecological divisions. At deeper time intervals, the four marine elapids appear to have experienced relatively stable Ne , while each terrestrial species shows a prominent upturn in Ne starting at ~4 million years ago (Ma) followed by an equally strong decline. However, over the last million years, all seven species show strong and divergent fluctuations. Estimates of Ne in the most recent intervals (~10 kya) are lowest in two of four marine species (H. melanocephalus and Laticauda), and do not correspond to contemporary range sizes in marine or terrestrial taxa.
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Affiliation(s)
- Alastair J Ludington
- School of Biological Science, The University of Adelaide, Adelaide, South Australia, Australia
| | - Kate L Sanders
- School of Biological Science, The University of Adelaide, Adelaide, South Australia, Australia
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16
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Seiko T, Kishida T, Toyama M, Hariyama T, Okitsu T, Wada A, Toda M, Satta Y, Terai Y. Visual adaptation of opsin genes to the aquatic environment in sea snakes. BMC Evol Biol 2020; 20:158. [PMID: 33243140 PMCID: PMC7690139 DOI: 10.1186/s12862-020-01725-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 07/04/2020] [Accepted: 11/22/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Evolutionary transitions from terrestrial to aquatic life history cause drastic changes in sensory systems. Indeed, the drastic changes in vision have been reported in many aquatic amniotes, convergently. Recently, the opsin genes of the full-aquatic sea snakes have been reported. However, those of the amphibious sea snakes have not been examined in detail. RESULTS Here, we investigated opsin genes and visual pigments of sea snakes. We determined the sequences of SWS1, LWS, and RH1 genes from one terrestrial, three amphibious and four fully-aquatic elapids. Amino acid replacements at four and one spectra-tuning positions were found in LWS and RH1, respectively. We measured or predicted absorption of LWS and RH1 pigments with A1-derived retinal. During their evolution, blue shifts of LWS pigments have occurred stepwise in amphibious sea snakes and convergently in both amphibious and fully-aquatic species. CONCLUSIONS Blue shifted LWS pigments may have adapted to deep water or open water environments dominated by blue light. The evolution of opsins differs between marine mammals (cetaceans and pinnipeds) and sea snakes in two fundamental ways: (1) pseudogenization of opsins in marine mammals; and (2) large blue shifts of LWS pigments in sea snakes. It may be possible to explain these two differences at the level of photoreceptor cell composition given that cone and rod cells both exist in mammals whereas only cone cells exist in fully-aquatic sea snakes. We hypothesize that the differences in photoreceptor cell compositions may have differentially affected the evolution of opsins in divergent amniote lineages.
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Affiliation(s)
- Takashi Seiko
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193 Japan
| | - Takushi Kishida
- Wildlife Research Center, Kyoto University, 2-24 Tanaka Sekiden-cho, Sakyo, Kyoto 606-8203 Japan
| | - Mina Toyama
- Department of Biology, Faculty of Medicine, Hamamatsu University School of Medicine, Handayama, Hamamatsu Japan
| | - Takahiko Hariyama
- Department of Biology, Faculty of Medicine, Hamamatsu University School of Medicine, Handayama, Hamamatsu Japan
| | - Takashi Okitsu
- Laboratory of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita, Higashinada, Kobe, 658-8558 Japan
| | - Akimori Wada
- Laboratory of Organic Chemistry for Life Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita, Higashinada, Kobe, 658-8558 Japan
| | - Mamoru Toda
- Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213 Japan
| | - Yoko Satta
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193 Japan
| | - Yohey Terai
- Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193 Japan
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17
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Galbraith JD, Ludington AJ, Suh A, Sanders KL, Adelson DL. New Environment, New Invaders-Repeated Horizontal Transfer of LINEs to Sea Snakes. Genome Biol Evol 2020; 12:2370-2383. [PMID: 33022046 PMCID: PMC7846101 DOI: 10.1093/gbe/evaa208] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [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] [Accepted: 09/29/2020] [Indexed: 12/12/2022] Open
Abstract
Although numerous studies have found horizontal transposon transfer (HTT) to be widespread across metazoans, few have focused on HTT in marine ecosystems. To investigate potential recent HTTs into marine species, we searched for novel repetitive elements in sea snakes, a group of elapids which transitioned to a marine habitat at most 18 Ma. Our analysis uncovered repeated HTTs into sea snakes following their marine transition. The seven subfamilies of horizontally transferred LINE retrotransposons we identified in the olive sea snake (Aipysurus laevis) are transcribed, and hence are likely still active and expanding across the genome. A search of 600 metazoan genomes found all seven were absent from other amniotes, including terrestrial elapids, with the most similar LINEs present in fish and marine invertebrates. The one exception was a similar LINE found in sea kraits, a lineage of amphibious elapids which independently transitioned to a marine environment 25 Ma. Our finding of repeated horizontal transfer events into marine snakes greatly expands past findings that the marine environment promotes the transfer of transposons. Transposons are drivers of evolution as sources of genomic sequence and hence genomic novelty. We identified 13 candidate genes for HTT-induced adaptive change based on internal or neighboring HTT LINE insertions. One of these, ADCY4, is of particular interest as a part of the KEGG adaptation pathway “Circadian Entrainment.” This provides evidence of the ecological interactions between species influencing evolution of metazoans not only through specific selection pressures, but also by contributing novel genomic material.
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Affiliation(s)
| | | | - Alexander Suh
- Department of Ecology and Genetics-Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Sweden.,Department of Organismal Biology-Systematic Biology, Evolutionary Biology Centre, Uppsala University, Sweden.,School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Kate L Sanders
- School of Biological Sciences, University of Adelaide, Australia
| | - David L Adelson
- School of Biological Sciences, University of Adelaide, Australia
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18
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Kim IH, Yi CH, Park J, Kim MS, Cho IY, Kim JG, Park D. Rediscovery of the yellow-bellied sea snake (Hydrophis platurus) in South Korea (Squamata: Elapidae). Journal of Asia-Pacific Biodiversity 2020. [DOI: 10.1016/j.japb.2020.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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19
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Affiliation(s)
- Jing Zhang
- West China School of Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Chaochao Yan
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
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20
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Segall M, Cornette R, Godoy‐Diana R, Herrel A. Exploring the functional meaning of head shape disparity in aquatic snakes. Ecol Evol 2020; 10:6993-7005. [PMID: 32760507 PMCID: PMC7391336 DOI: 10.1002/ece3.6380] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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: 03/02/2020] [Revised: 03/30/2020] [Accepted: 04/22/2020] [Indexed: 12/26/2022] Open
Abstract
Phenotypic diversity, or disparity, can be explained by simple genetic drift or, if functional constraints are strong, by selection for ecologically relevant phenotypes. We here studied phenotypic disparity in head shape in aquatic snakes. We investigated whether conflicting selective pressures related to different functions have driven shape diversity and explore whether similar phenotypes may give rise to the same functional output (i.e., many-to-one mapping of form to function). We focused on the head shape of aquatically foraging snakes as they fulfill several fitness-relevant functions and show a large amount of morphological variability. We used 3D surface scanning and 3D geometric morphometrics to compare the head shape of 62 species in a phylogenetic context. We first tested whether diet specialization and size are drivers of head shape diversification. Next, we tested for many-to-one mapping by comparing the hydrodynamic efficiency of head shape characteristic of the main axes of variation in the dataset. We 3D printed these shapes and measured the forces at play during a frontal strike. Our results show that diet and size explain only a small amount of shape variation. Shapes did not fully functionally converge as more specialized aquatic species evolved a more efficient head shape than others. The shape disparity observed could thus reflect a process of niche specialization.
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Affiliation(s)
- Marion Segall
- Department of HerpetologyAmerican Museum of Natural HistoryNew YorkNYUSA
- UMR CNRS/MNHN 7179Mécanismes adaptatifs et EvolutionParisFrance
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMHUMR 7636)CNRSESPCI Paris–PSL Research UniversityUniversité Paris DiderotSorbonne UniversitéParisFrance
| | | | - Ramiro Godoy‐Diana
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMHUMR 7636)CNRSESPCI Paris–PSL Research UniversityUniversité Paris DiderotSorbonne UniversitéParisFrance
| | - Anthony Herrel
- UMR CNRS/MNHN 7179Mécanismes adaptatifs et EvolutionParisFrance
- Evolutionary Morphology of VertebratesGhent UniversityGhentBelgium
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21
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Shine R, Goiran C, Shilton C, Meiri S, Brown GP. The life aquatic: an association between habitat type and skin thickness in snakes. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
An aquatic animal faces challenges not encountered by its terrestrial counterparts, promoting adaptive responses in multiple traits. For example, a thicker dermis might protect snakes when they are pushed against sharp objects by water currents, and might enable a snake to shed fouling organisms attached to its skin. We thus predicted that marine snakes should have thicker skin than terrestrial species, and that smaller sea snakes should have relatively thicker skin (because absolute, not relative, thickness determines vulnerability to fouling). Measurements of 192 snakes of 44 species supported those predictions. Many (but not all) sea snakes have skins 50% thicker than those of terrestrial and amphibious snake species, representing multiple independent evolutionary origins of thicker skin (in acrochordids, Laticauda sea kraits and both main clades of hydrophiine sea snakes). Marine snakes showed different allometries of skin thickness compared with their terrestrial counterparts; larger snakes had thicker skin within and among species of amphibious and terrestrial snakes, but larger aquatic snake species had thinner skin compared with smaller taxa. Interspecific variation in skin thickness was primarily due to increased collagen in the deep dermis, a physical barrier well suited to protecting against physical injury and to resisting penetration by epibionts.
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22
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Palci A, Seymour RS, Van Nguyen C, Hutchinson MN, Lee MSY, Sanders KL. Novel vascular plexus in the head of a sea snake (Elapidae, Hydrophiinae) revealed by high-resolution computed tomography and histology. R Soc Open Sci 2019; 6:191099. [PMID: 31598325 PMCID: PMC6774945 DOI: 10.1098/rsos.191099] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/01/2019] [Indexed: 05/03/2023]
Abstract
Novel phenotypes are often linked to major ecological transitions during evolution. Here, we describe for the first time an unusual network of large blood vessels in the head of the sea snake Hydrophis cyanocinctus. MicroCT imaging and histology reveal an intricate modified cephalic vascular network (MCVN) that underlies a broad area of skin between the snout and the roof of the head. It is mostly composed of large veins and sinuses and converges posterodorsally into a large vein (sometimes paired) that penetrates the skull through the parietal bone. Endocranially, this blood vessel leads into the dorsal cerebral sinus, and from there, a pair of large veins depart ventrally to enter the brain. We compare the condition observed in H. cyanocinctus with that of other elapids and discuss the possible functions of this unusual vascular network. Sea snakes have low oxygen partial pressure in their arterial blood that facilitates cutaneous respiration, potentially limiting the availability of oxygen to the brain. We conclude that this novel vascular structure draining directly to the brain is a further elaboration of the sea snakes' cutaneous respiratory anatomy, the most likely function of which is to provide the brain with an additional supply of oxygen.
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Affiliation(s)
- Alessandro Palci
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
| | - Roger S. Seymour
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Cao Van Nguyen
- Institute of Oceanography, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Mark N. Hutchinson
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
| | - Michael S. Y. Lee
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
| | - Kate L. Sanders
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
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23
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Sherratt E, Sanders KL, Watson A, Hutchinson MN, Lee MSY, Palci A. Heterochronic Shifts Mediate Ecomorphological Convergence in Skull Shape of Microcephalic Sea Snakes. Integr Comp Biol 2019; 59:616-624. [DOI: 10.1093/icb/icz033] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Abstract
Morphological variation among the viviparous sea snakes (Hydrophiinae), a clade of fully aquatic elapid snakes, includes an extreme “microcephalic” ecomorph that has a very small head atop a narrow forebody, while the hind body is much thicker (up to three times the forebody girth). Previous research has demonstrated that this morphology has evolved at least nine times as a consequence of dietary specialization on burrowing eels, and has also examined morphological changes to the vertebral column underlying this body shape. The question addressed in this study is what happens to the skull during this extreme evolutionary change? Here we use X-ray micro-computed tomography and geometric morphometric methods to characterize cranial shape variation in 30 species of sea snakes. We investigate ontogenetic and evolutionary patterns of cranial shape diversity to understand whether cranial shape is predicted by dietary specialization, and examine whether cranial shape of microcephalic species may be a result of heterochronic processes. We show that the diminutive cranial size of microcephalic species has a convergent shape that is correlated with trophic specialization to burrowing prey. Furthermore, their cranial shape is predictable for their size and very similar to that of juvenile individuals of closely related but non-microcephalic sea snakes. Our findings suggest that heterochronic changes (resulting in pedomorphosis) have driven cranial shape convergence in response to dietary specializations in sea snakes.
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Affiliation(s)
- Emma Sherratt
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Kate L Sanders
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Amy Watson
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Mark N Hutchinson
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
| | - Michael S Y Lee
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
| | - Alessandro Palci
- South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
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24
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Sanz L, Quesada-bernat S, Ramos T, Casais-e-silva LL, Corrêa-netto C, Silva-haad JJ, Sasa M, Lomonte B, Calvete JJ. New insights into the phylogeographic distribution of the 3FTx/PLA2 venom dichotomy across genus Micrurus in South America. J Proteomics 2019; 200:90-101. [DOI: 10.1016/j.jprot.2019.03.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 03/24/2019] [Accepted: 03/25/2019] [Indexed: 01/01/2023]
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25
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Lillywhite HB, Menon GK. Structure and function of skin in the pelagic sea snake, Hydrophis platurus. J Morphol 2019; 280:544-554. [PMID: 30779371 DOI: 10.1002/jmor.20963] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/26/2019] [Accepted: 01/29/2019] [Indexed: 12/12/2022]
Abstract
We describe and interpret the functional morphology of skin of the Yellow-bellied sea snake, Hydrophis platurus. This is the only pelagic sea snake, and its integument differs from what is known for other species of snakes. In gross appearance, the scales of H. platurus consist of non-overlapping, polygonal knobs with flattened outer surfaces bearing presumptive filamentous sensillae. The deep recesses between scales ('hinge') entrap and wick water over the body surface, with mean retention of 5.1 g/cm of skin surface, similar to that determined previously for the roughened, spiny skin of marine file snakes, Acrochordus granulatus. This feature possibly serves to maintain the skin wet when the dorsal body protrudes above water while floating on calm oceanic slicks where they forage. In contrast with other snakes, including three species of amphibious, semi-marine sea kraits (Laticauda spp.), the outer corneous β-protein layer consists of a syncytium that is thinner than seen in most other species. The subjacent α-layer is also thin, and lipid droplets and lamellar bodies are seen among the immature, cornifying α-cells. A characteristic mesos layer, comprising the water permeability barrier, is either absent or very thin. These features are possibly related to (1) permeability requirements for cutaneous gas exchange, (2) reduced gradient for water efflux compared with terrestrial environments, (3) less need for physical protection in water compared with terrestrial ground environments, and (4) increased frequency of ecdysis thought to be an anti-fouling mechanism. The lipogenic features of the α-layer possibly compensate for the reduced or absent mesos layer, or produce layers of cells that comprise what functionally might be termed a mesos layer, but where the organization of barrier lipids nonetheless appears less robust than what is characteristically seen in squamates.
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Affiliation(s)
| | - Gopinathan K Menon
- Department of Ornithology and Mammalogy, California Academy of Sciences, Golden Gate Park, San Franisco, California
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26
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Tan CH, Tan KY, Ng TS, Sim SM, Tan NH. Venom Proteome of Spine-Bellied Sea Snake ( Hydrophis curtus) from Penang, Malaysia: Toxicity Correlation, Immunoprofiling and Cross-Neutralization by Sea Snake Antivenom. Toxins (Basel) 2018; 11:E3. [PMID: 30583590 DOI: 10.3390/toxins11010003] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 12/14/2018] [Accepted: 12/19/2018] [Indexed: 11/16/2022] Open
Abstract
The venom proteome of Hydrophis curtus (synonym: Lapemis hardwickii) from Penang, Malaysia was investigated with nano-electrospray ionization-liquid chromatography tandem mass spectrometry (ESI-LCMS/MS) of the reverse-phase high-performance liquid chromatography (HPLC) venom fractions. Thirty distinct protein forms were identified as toxins from ten families. The three major protein families were phospholipase A2 (PLA2, 62.0% of total venom proteins), three-finger toxin (3FTX, 26.33%) and cysteine-rich secretory protein (CRiSP, 9.00%). PLA2 comprises diverse homologues (11 forms), predominantly the acidic subtypes (48.26%). 3FTX composed of one short alpha-neurotoxin (SNTX, 22.89%) and four long alpha-neurotoxins (LNTX, 3.44%). Both SNTX and LNTX were lethal in mice (intravenous LD50 = 0.10 and 0.24 μg/g, respectively) but the PLA2 were non-lethal (LD50 >1 μg/g). The more abundant and toxic SNTX appeared to be the main driver of venom lethality (holovenom LD50 = 0.20 μg/g). The heterologous Sea Snake Antivenom (SSAV, Australia) effectively cross-neutralized the venom (normalized potency = 9.35 mg venom neutralized per g antivenom) and the two neurotoxins in vivo, with the LNTX being neutralized more effectively (normalized potency = 3.5 mg toxin/g antivenom) than SNTX (normalized potency = 1.57 mg/g). SSAV immunorecognition was strong toward PLA2 but moderate-to-weak toward the alpha-neurotoxins, indicating that neutralization of the alpha-neurotoxins should be further improved.
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Nitschke CR, Hourston M, Udyawer V, Sanders KL. Rates of population differentiation and speciation are decoupled in sea snakes. Biol Lett 2018; 14:rsbl.2018.0563. [PMID: 30333264 DOI: 10.1098/rsbl.2018.0563] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 09/14/2018] [Indexed: 11/12/2022] Open
Abstract
Comparative phylogeography can inform many macroevolutionary questions, such as whether species diversification is limited by rates of geographical population differentiation. We examined the link between population genetic structure and species diversification in the fully aquatic sea snakes (Hydrophiinae) by comparing mitochondrial phylogeography across northern Australia in 16 species from two closely related clades that show contrasting diversification dynamics. Contrary to expectations from theory and several empirical studies, our results show that, at the geographical scale studied here, rates of population differentiation and speciation are not positively linked in sea snakes. The eight species sampled from the rapidly speciating Hydrophis clade have weak population differentiation that lacks geographical structure. By contrast, all eight sampled Aipysurus-Emydocephalus species show clear geographical patterns and many deep intraspecific splits, but have threefold slower speciation rates. Alternative factors, such as ecological specialization, species duration and geographical range size, may underlie rapid speciation in sea snakes.
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Affiliation(s)
- Charlotte R Nitschke
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Mathew Hourston
- The Department of Primary Industries and Regional Development, Perth, Western Australia, Australia
| | - Vinay Udyawer
- Australian Institute of Marine Science, Darwin, Northern Territory 0810, Australia
| | - Kate L Sanders
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
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Durban J, Sasa M, Calvete JJ. Venom gland transcriptomics and microRNA profiling of juvenile and adult yellow-bellied sea snake, Hydrophis platurus, from Playa del Coco (Guanacaste, Costa Rica). Toxicon 2018; 153:96-105. [DOI: 10.1016/j.toxicon.2018.08.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/13/2018] [Accepted: 08/29/2018] [Indexed: 02/08/2023]
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Bell CD, Gonzalez LA. Exploring the utility of “next-generation” sequence data on inferring the phylogeny of the South American Valeriana (Valerianaceae). Mol Phylogenet Evol 2018; 123:44-49. [DOI: 10.1016/j.ympev.2018.02.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 02/14/2018] [Accepted: 02/14/2018] [Indexed: 10/18/2022]
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Neale V, Smout MJ, Seymour JE. Spine-bellied sea snake (Hydrophis curtus) venom shows greater skeletal myotoxicity compared with cardiac myotoxicity. Toxicon 2018; 143:108-117. [PMID: 29355573 DOI: 10.1016/j.toxicon.2018.01.009] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/31/2017] [Accepted: 01/16/2018] [Indexed: 10/18/2022]
Abstract
For the first time the impedance-based xCELLigence real-time cell analysis system was used to measure the myotoxicity of sea snake venom. With a focus on the spine-bellied sea snake (Hydrophis curtus), the venom of four sea snake species and three terrestrial snake species were compared for myotoxicity against a human skeletal muscle cell line (HSkMC). Hydrophis curtus venom was also tested on a human cardiac muscle cell line (HCM). Surprisingly, all four sea snake venoms tested on HSkMC produced an initial 100-280% rise in xCELLigence cell index that peaked within the first two hours before falling. The cell index rise of H. curtus venom was correlated with the WST-1 cell proliferation assay, which demonstrated an increase in mitochondrial metabolism. The myotoxicity of H. curtus was 4.7-8.2 fold less potent than the other sea snakes tested, the Australian beaked sea snake (Hydrophis zweifeli), the elegant sea snake (Hydrophis elegans) and the olive sea snake (Aipysurus laevis). If our cell-based results translate to H. curtus envenomations, this implies that H. curtus would be less myotoxic than the other three. Yet the myotoxicity of H. curtus venom to cardiac muscle cells was nine times weaker than for skeletal muscle cells, providing evidence that the venom has a selective effect on skeletal muscle cells. This evidence, combined with the slow-acting nature of the venom, supports a digestive role for sea snake myotoxins.
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Affiliation(s)
- Vanessa Neale
- College of Public Health, Medical and Veterinary Sciences, James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia; Australian Institute of Tropical Health and Medicine (AITHM) and Centre for Biodiscovery and Molecular Development of Therapeutics (CBMDT), James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia.
| | - Michael J Smout
- Australian Institute of Tropical Health and Medicine (AITHM) and Centre for Biodiscovery and Molecular Development of Therapeutics (CBMDT), James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia.
| | - Jamie E Seymour
- Australian Institute of Tropical Health and Medicine (AITHM) and Centre for Biodiscovery and Molecular Development of Therapeutics (CBMDT), James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia.
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Neale V, Sotillo J, Seymour JE, Wilson D. The Venom of the Spine-Bellied Sea Snake (Hydrophis curtus): Proteome, Toxin Diversity and Intraspecific Variation. Int J Mol Sci 2017; 18:ijms18122695. [PMID: 29231898 PMCID: PMC5751296 DOI: 10.3390/ijms18122695] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [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: 11/10/2017] [Revised: 11/26/2017] [Accepted: 11/27/2017] [Indexed: 11/19/2022] Open
Abstract
The spine-bellied sea snake (Hydrophis curtus) is known to cause human deaths, yet its venom composition has not yet been proteomically characterised. An in-depth proteomic analysis was performed on H. curtus venom from two different seasons, January and June, corresponding to adults and subadults, respectively. Venoms from adult and subadult H. curtus individuals were compared using reversed-phase high-performance liquid chromatography (RP-HPLC), matrix-assisted laser desorption ionisation-time of flight (MALDI-TOF) mass spectrometry and liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS) to detect intraspecific variation, and the molecular weight data obtained with ESI-MS were used to assess toxin diversity. RP-HPLC and LC-ESI-MS/MS were used to characterise the venom proteome and estimate the relative abundances of protein families present. The most abundant protein family in January and June venoms is phospholipase A2 (PLA2: January 66.7%; June 54.5%), followed by three-finger toxins (3FTx: January 30.4%; June 40.4%) and a minor component of cysteine-rich secretory proteins (CRISP: January 2.5%; June 5%). Trace amounts of snake venom metalloproteinases (SVMP), C-type lectins and housekeeping and regulatory proteins were also found. Although the complexity of the venom is low by number of families present, each family contained a more diverse set of isoforms than previously reported, a finding that may have implications for the development of next-generation sea snake antivenoms. Intraspecific variability was shown to be minor with one obvious exception of a 14,157-Da protein that was present in some January (adult) venoms, but not at all in June (subadult) venoms. There is also a greater abundance of short-chain neurotoxins in June (subadult) venom compared with January (adult) venom. These differences potentially indicate the presence of seasonal, ontogenetic or sexual variation in H. curtus venom.
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Affiliation(s)
- Vanessa Neale
- College of Public Health, Medical and Veterinary Sciences, James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia.
- Australian Institute of Tropical Health and Medicine (AITHM) and Centre for Biodiscovery and Molecular Development of Therapeutics (CBMDT), James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia.
| | - Javier Sotillo
- Australian Institute of Tropical Health and Medicine (AITHM) and Centre for Biodiscovery and Molecular Development of Therapeutics (CBMDT), James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia.
| | - Jamie E Seymour
- Australian Institute of Tropical Health and Medicine (AITHM) and Centre for Biodiscovery and Molecular Development of Therapeutics (CBMDT), James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia.
| | - David Wilson
- Australian Institute of Tropical Health and Medicine (AITHM) and Centre for Biodiscovery and Molecular Development of Therapeutics (CBMDT), James Cook University, McGregor Road, Smithfield, Cairns 4878, Australia.
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Lukoschek V. Congruent phylogeographic patterns in a young radiation of live-bearing marine snakes: Pleistocene vicariance and the conservation implications of cryptic genetic diversity. DIVERS DISTRIB 2017. [DOI: 10.1111/ddi.12687] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Vimoksalehi Lukoschek
- ARC Centre of Excellence for Coral Reef Studies; James Cook University; Townsville Qld Australia
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Heatwole H, Grech A, Marsh H. Paleoclimatology, Paleogeography, and the Evolution and Distribution of Sea Kraits (Serpentes; Elapidae;Laticauda). Herpetological Monographs 2017. [DOI: 10.1655/herpmonographs-d-16-00003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Harold Heatwole
- School of Earth and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Alana Grech
- Department of Environmental Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Helene Marsh
- College of Marine and Environmental Sciences, Centre for Tropical Water and Aquatic Ecosystem Research, James Cook University, Townsville, Queensland 4811, Australia
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Brischoux F, Cotté C, Lillywhite HB, Bailleul F, Lalire M, Gaspar P. Oceanic circulation models help to predict global biogeography of pelagic yellow-bellied sea snake. Biol Lett 2017; 12:rsbl.2016.0436. [PMID: 27555651 DOI: 10.1098/rsbl.2016.0436] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 08/04/2016] [Indexed: 11/12/2022] Open
Abstract
It is well recognized that most marine vertebrates, and especially tetrapods, precisely orient and actively move in apparently homogeneous oceanic environments. Here, we investigate the presumptive role of oceanic currents in biogeographic patterns observed in a secondarily marine tetrapod, the yellow-bellied sea snake (Hydrophis [Pelamis] platurus). State-of-the-art world ocean circulation models show how H. platurus, the only pelagic species of sea snake, can potentially exploit oceanic currents to disperse and maintain population mixing between localities that spread over two-thirds of the Earth's circumference. The very close association of these snakes with surface currents seems to provide a highly efficient dispersal mechanism that allowed this species to range extensively and relatively quickly well beyond the central Indo-Pacific area, the centre of origin, abundance and diversity of sea snakes. Our results further suggest that the pan-oceanic population of this species must be extraordinarily large.
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Affiliation(s)
- François Brischoux
- Centre d'Etudes Biologiques de Chizé, CEBC-CNRS UMR 7372, 79360 Villiers en Bois, France
| | - Cédric Cotté
- LOCEAN Laboratory, Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, 4 place Jussieu, 75005 Paris, France
| | - Harvey B Lillywhite
- Department of Biology, University of Florida, Gainesville, FL 32611-8525, USA
| | - Frédéric Bailleul
- South Australian Research and Development Institute (Aquatic Sciences), 2 Hamra Avenue, West Beach, Adelaide, South Australia 5024, Australia
| | - Maxime Lalire
- Department of Marine Ecosystems, Satellite Oceanography Division, Collecte Localisation Satellites, 31520 Ramonville, France
| | - Philippe Gaspar
- Department of Marine Ecosystems, Satellite Oceanography Division, Collecte Localisation Satellites, 31520 Ramonville, France
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Crowe-Riddell JM, Snelling EP, Watson AP, Suh AK, Partridge JC, Sanders KL. The evolution of scale sensilla in the transition from land to sea in elapid snakes. Open Biol 2017; 6:rsob.160054. [PMID: 27278646 PMCID: PMC4929937 DOI: 10.1098/rsob.160054] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/13/2016] [Indexed: 11/12/2022] Open
Abstract
Scale sensilla are small tactile mechanosensory organs located on the head scales of many squamate reptiles (lizards and snakes). In sea snakes and sea kraits (Elapidae: Hydrophiinae), these scale organs are presumptive scale sensilla that purportedly function as both tactile mechanoreceptors and potentially as hydrodynamic receptors capable of sensing the displacement of water. We combined scanning electron microscopy, silicone casting of the skin and quadrate sampling with a phylogenetic analysis to assess morphological variation in sensilla on the postocular head scale(s) across four terrestrial, 13 fully aquatic and two semi-aquatic species of elapids. Substantial variation exists in the overall coverage of sensilla (0.8-6.5%) among the species sampled and is broadly overlapping in aquatic and terrestrial lineages. However, two observations suggest a divergent, possibly hydrodynamic sensory role of sensilla in sea snake and sea krait species. First, scale sensilla are more protruding (dome-shaped) in aquatic species than in their terrestrial counterparts. Second, exceptionally high overall coverage of sensilla is found only in the fully aquatic sea snakes, and this attribute appears to have evolved multiple times within this group. Our quantification of coverage as a proxy for relative 'sensitivity' represents the first analysis of the evolution of sensilla in the transition from terrestrial to marine habitats. However, evidence from physiological and behavioural studies is needed to confirm the functional role of scale sensilla in sea snakes and sea kraits.
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Affiliation(s)
- Jenna M Crowe-Riddell
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Edward P Snelling
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, Gauteng 2193, South Africa
| | - Amy P Watson
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Anton Kyuseop Suh
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Julian C Partridge
- School of Animal Biology and Oceans Institute, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Kate L Sanders
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
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Abstract
Advances in the last decade combining transcriptomics with established proteomics methods have made possible rapid identification and quantification of protein families in snake venoms. Although over 100 studies have been published, the value of this information is increased when it is collated, allowing rapid assimilation and evaluation of evolutionary trends, geographical variation, and possible medical implications. This review brings together all compositional studies of snake venom proteomes published in the last decade. Compositional studies were identified for 132 snake species: 42 from 360 (12%) Elapidae (elapids), 20 from 101 (20%) Viperinae (true vipers), 65 from 239 (27%) Crotalinae (pit vipers), and five species of non-front-fanged snakes. Approximately 90% of their total venom composition consisted of eight protein families for elapids, 11 protein families for viperines and ten protein families for crotalines. There were four dominant protein families: phospholipase A2s (the most common across all front-fanged snakes), metalloproteases, serine proteases and three-finger toxins. There were six secondary protein families: cysteine-rich secretory proteins, l-amino acid oxidases, kunitz peptides, C-type lectins/snaclecs, disintegrins and natriuretic peptides. Elapid venoms contained mostly three-finger toxins and phospholipase A2s and viper venoms metalloproteases, phospholipase A2s and serine proteases. Although 63 protein families were identified, more than half were present in <5% of snake species studied and always in low abundance. The importance of these minor component proteins remains unknown.
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Tan CH, Wong KY, Tan KY, Tan NH. Venom proteome of the yellow-lipped sea krait, Laticauda colubrina from Bali: Insights into subvenomic diversity, venom antigenicity and cross-neutralization by antivenom. J Proteomics 2017; 166:48-58. [DOI: 10.1016/j.jprot.2017.07.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 06/28/2017] [Accepted: 07/02/2017] [Indexed: 12/19/2022]
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Bessesen BL, Galbreath GJ. A new subspecies of sea snake, Hydrophis platurus xanthos, from Golfo Dulce, Costa Rica. Zookeys 2017:109-123. [PMID: 29200918 PMCID: PMC5672566 DOI: 10.3897/zookeys.686.12682] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [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: 03/12/2017] [Accepted: 06/27/2017] [Indexed: 11/18/2022] Open
Abstract
We describe a distinctive new subspecies of sea snake from the occasionally anoxic inner-basin waters of Golfo Dulce, Costa Rica, based on combined data garnered between 2010 and 2017 for 154 specimens, 123 free-ranging and 31 museum-held. The yellow sea snake, Hydrophisplaturusxanthos Bessesen & Galbreath, subsp. n., is diagnosed by a notably smaller body size and nearly uniform yellow coloration, which contrasts with the black and yellow striae and tail spots or bands typical of the species. Within the modest geographic range (circa 320 km2), nearly all specimens possess both diagnostic character states. Bathymetrics appear to restrict genetic flow between this allopatric population and conspecifics in the broader Eastern Pacific. In perspicuous contrast to typical H.platurus, H.p.xanthos shows no association with drift lines, and feeds at night in turbulent waters, assuming a sinusoidal ambush posture never previously reported for the species. This evolutionarily significant unit (ESU) warrants taxonomic recognition and active protection.
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Affiliation(s)
- Brooke L Bessesen
- Joyce Corrigan Memorial Care Center, 455 N. Galvin Parkway, Phoenix Zoo, Phoenix, AZ, USA
| | - Gary J Galbreath
- Biological Sciences, 2205 Tech Drive, Northwestern University, Evanston, IL, USA.,Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, IL, USA
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Gillett AK, Ploeg R, Flint M, Mills PC. Postmortem examination of Australian sea snakes ( Hydrophiinae): Anatomy and common pathologic conditions. J Vet Diagn Invest 2017; 29:593-611. [PMID: 28545324 DOI: 10.1177/1040638717710056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [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: 11/15/2022] Open
Abstract
There is limited published information about disease in wild sea snakes and no standardized guideline for postmortem examination of sea snakes. Identifying causes of morbidity and mortality of marine vertebrate species has been pivotal to understanding disease factors implicated in stranding events and assisting with the formulation of conservation plans. Additionally, postmortem findings can provide valuable information on life history traits and the ecology of these reclusive species. Sick, moribund, or dead sea snakes are intermittently washed ashore along Australian and international beaches and provide an opportunity to examine a subset of the population and identify causes of population decline. We present an illustrated description of sea snake anatomy and describe a systematic approach to postmortem examination of sea snakes. We describe common pathologic conditions identified from clinical and postmortem examinations of stranded Australian sea snakes from southeast Queensland. Notable pathologic conditions include traumatic injury, inflammatory conditions, parasitic infections, and neoplasia.
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Affiliation(s)
- Amber K Gillett
- Vet-MARTI, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia (Gillett, Flint, Mills).,Australia Zoo Wildlife Hospital, Beerwah, Queensland, Australia (Gillett).,IDEXX Laboratories, East Brisbane, Queensland, Australia (Ploeg).,School of Forest Resources and Conservation, The Florida Aquarium's Center for Conservation, University of Florida, Apollo Beach, FL (Flint)
| | - Richard Ploeg
- Vet-MARTI, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia (Gillett, Flint, Mills).,Australia Zoo Wildlife Hospital, Beerwah, Queensland, Australia (Gillett).,IDEXX Laboratories, East Brisbane, Queensland, Australia (Ploeg).,School of Forest Resources and Conservation, The Florida Aquarium's Center for Conservation, University of Florida, Apollo Beach, FL (Flint)
| | - Mark Flint
- Vet-MARTI, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia (Gillett, Flint, Mills).,Australia Zoo Wildlife Hospital, Beerwah, Queensland, Australia (Gillett).,IDEXX Laboratories, East Brisbane, Queensland, Australia (Ploeg).,School of Forest Resources and Conservation, The Florida Aquarium's Center for Conservation, University of Florida, Apollo Beach, FL (Flint)
| | - Paul C Mills
- Vet-MARTI, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia (Gillett, Flint, Mills).,Australia Zoo Wildlife Hospital, Beerwah, Queensland, Australia (Gillett).,IDEXX Laboratories, East Brisbane, Queensland, Australia (Ploeg).,School of Forest Resources and Conservation, The Florida Aquarium's Center for Conservation, University of Florida, Apollo Beach, FL (Flint)
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Lillywhite HB, Lillywhite SM. Ontogenetic shifts of heart position in snakes. J Morphol 2017; 278:1105-1113. [PMID: 28470824 DOI: 10.1002/jmor.20697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 04/10/2017] [Accepted: 04/16/2017] [Indexed: 11/07/2022]
Abstract
Heart position relative to total body length (TL) varies among snakes, with anterior hearts in arboreal species and more centrally located hearts in aquatic or ground-dwelling species. Anterior hearts decrease the cardiac work associated with cranial blood flow and minimize drops in cranial pressure and flow during head-up climbing. Here, we investigate whether heart position shifts intraspecifically during ontogenetic increases in TL. Insular Florida cottonmouth snakes, Agkistrodon conanti, are entirely ground-dwelling and have a mean heart position that is 33.32% TL from the head. In contrast, arboreal rat snakes, Pantherophis obsoleta, of similar lengths have a mean heart position that is 17.35% TL from the head. In both species, relative heart position shifts craniad during ontogeny, with negative slopes = -.035 and -.021% TL/cm TL in Agkistrodon and Pantherophis, respectively. Using a large morphometric data set available for Agkistrodon (N = 192 individuals, 23-140 cm TL), we demonstrate there is an anterior ontogenetic shift of the heart position within the trunk (= 4.56% trunk length from base of head to cloacal vent), independent of head and tail allometry which are both negative. However, in longer snakes > 100 cm, the heart position reverses and shifts caudally in longer Agkistrodon but continues toward the head in longer individuals of Pantherophis. Examination of data sets for two independent lineages of fully marine snakes (Acrochordus granulatus and Hydrophis platurus), which do not naturally experience postural gravity stress, demonstrate both ontogenetic patterns for heart position that are seen in the terrestrial snakes. The anterior migration of the heart is greater in the terrestrial species, even if TL is standardized to that of the longer P. obsoleta, and compensates for about 5 mmHg gravitational pressure head if they are fully upright.
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Affiliation(s)
- Harvey B Lillywhite
- Department of Biology, University of Florida, Gainesville, Florida, 32611-8525
| | - Steven M Lillywhite
- IMPA (Instituto de Matemática Pura e Aplicada), Estrada Dona Castorina, 110, Rio de Janeiro, RJ, 22460-320, Brazil
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Calvete JJ. Venomics: integrative venom proteomics and beyond*. Biochem J 2017; 474:611-34. [DOI: 10.1042/bcj20160577] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 12/31/2016] [Accepted: 01/03/2017] [Indexed: 01/15/2023]
Abstract
Venoms are integrated phenotypes that evolved independently in, and are used for predatory and defensive purposes by, a wide phylogenetic range of organisms. The same principles that contribute to the evolutionary success of venoms, contribute to making the study of venoms of great interest in such diverse fields as evolutionary ecology and biotechnology. Evolution is profoundly contingent, and nature also reinvents itself continuosly. Changes in a complex phenotypic trait, such as venom, reflect the influences of prior evolutionary history, chance events, and selection. Reconstructing the natural history of venoms, particularly those of snakes, which will be dealt with in more detail in this review, requires the integration of different levels of knowledge into a meaningful and comprehensive evolutionary framework for separating stochastic changes from adaptive evolution. The application of omics technologies and other disciplines have contributed to a qualitative and quantitative advance in the road map towards this goal. In this review we will make a foray into the world of animal venoms, discuss synergies and complementarities of the different approaches used in their study, and identify current bottlenecks that prevent inferring the evolutionary mechanisms and ecological constraints that molded snake venoms to their present-day variability landscape.
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Dabruzzi T, Sutton MA, Fangue NA, Bennett WA. Evidence for Control of Cutaneous Oxygen Uptake in the Yellow-Lipped Sea Krait Laticauda colubrina (Schneider, 1799). J HERPETOL 2016; 50:621-6. [DOI: 10.1670/15-037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Udyawer V, Read M, Hamann M, Heupel MR, Simpfendorfer CA. Importance of Shallow Tidal Habitats as Refugia from Trawl Fishing for Sea Snakes. J HERPETOL 2016; 50:527-33. [DOI: 10.1670/15-026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kim IH, Park J, Kaplan RH, Lee JN, Park D. Chinese sea snake (Laticauda semifasciata) misidentified as slender-necked sea snake in previous published account in Korea. ACTA ACUST UNITED AC 2016. [DOI: 10.1186/s41610-016-0002-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Rezaie-Atagholipour M, Ghezellou P, Hesni MA, Dakhteh SMH, Ahmadian H, Vidal N. Sea snakes (Elapidae, Hydrophiinae) in their westernmost extent: an updated and illustrated checklist and key to the species in the Persian Gulf and Gulf of Oman. Zookeys 2016; 622:129-164. [PMID: 27843383 PMCID: PMC5096412 DOI: 10.3897/zookeys.622.9939] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [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: 07/19/2016] [Accepted: 09/11/2016] [Indexed: 11/26/2022] Open
Abstract
The Persian Gulf is known as the westernmost distribution limit for sea snakes, except for Hydrophis platurus (Linnaeus, 1766) that reaches southeastern Africa. Previous identification guides for sea snakes of the Persian Gulf and its adjacent waters in the Gulf of Oman were based on old data and confined mostly to written descriptions. Therefore, a series of field surveys were carried out in 2013 and 2014 through Iranian coastal waters of both gulfs to provide a comprehensive sampling of sea snakes in the area. This paper presents an illustrated and updated checklist and identification tool for sea snakes in the Persian Gulf and Gulf of Oman, which are based on new material and a review of the literature. This checklist includes ten species of marine hydrophiines, of which one, Microcephalophis cantoris (Günther, 1864), is a new record for the area. All specimens examined herein are deposited and available at the Zoological Museum of Shahid Bahonar University of Kerman, Kerman province, Iran.
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Affiliation(s)
- Mohsen Rezaie-Atagholipour
- Environmental Management Office, Qeshm Free Area Organization, Qeshm Island, P. O. Box 7951614465, Hormozgan Province, Iran
| | - Parviz Ghezellou
- Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Tehran, Iran
| | - Majid Askari Hesni
- Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman Province, Iran
| | - Seyyed Mohammad Hashem Dakhteh
- Environmental Management Office, Qeshm Free Area Organization, Qeshm Island, P. O. Box 7951614465, Hormozgan Province, Iran
| | | | - Nicolas Vidal
- ISYEB, UMR7205 MNHN-CNRS-UPMC-EPHE, Muséum national d’Histoire naturelle, Département Systématique et Evolution, CP30 25 rue Cuvier 75005 Paris, France
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Figueroa A, McKelvy AD, Grismer LL, Bell CD, Lailvaux SP. A Species-Level Phylogeny of Extant Snakes with Description of a New Colubrid Subfamily and Genus. PLoS One 2016; 11:e0161070. [PMID: 27603205 PMCID: PMC5014348 DOI: 10.1371/journal.pone.0161070] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 07/28/2016] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND With over 3,500 species encompassing a diverse range of morphologies and ecologies, snakes make up 36% of squamate diversity. Despite several attempts at estimating higher-level snake relationships and numerous assessments of generic- or species-level phylogenies, a large-scale species-level phylogeny solely focusing on snakes has not been completed. Here, we provide the largest-yet estimate of the snake tree of life using maximum likelihood on a supermatrix of 1745 taxa (1652 snake species + 7 outgroup taxa) and 9,523 base pairs from 10 loci (5 nuclear, 5 mitochondrial), including previously unsequenced genera (2) and species (61). RESULTS Increased taxon sampling resulted in a phylogeny with a new higher-level topology and corroborate many lower-level relationships, strengthened by high nodal support values (> 85%) down to the species level (73.69% of nodes). Although the majority of families and subfamilies were strongly supported as monophyletic with > 88% support values, some families and numerous genera were paraphyletic, primarily due to limited taxon and loci sampling leading to a sparse supermatrix and minimal sequence overlap between some closely-related taxa. With all rogue taxa and incertae sedis species eliminated, higher-level relationships and support values remained relatively unchanged, except in five problematic clades. CONCLUSION Our analyses resulted in new topologies at higher- and lower-levels; resolved several previous topological issues; established novel paraphyletic affiliations; designated a new subfamily, Ahaetuliinae, for the genera Ahaetulla, Chrysopelea, Dendrelaphis, and Dryophiops; and appointed Hemerophis (Coluber) zebrinus to a new genus, Mopanveldophis. Although we provide insight into some distinguished problematic nodes, at the deeper phylogenetic scale, resolution of these nodes may require sampling of more slowly-evolving nuclear genes.
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Affiliation(s)
- Alex Figueroa
- Department of Biological Sciences, University of New Orleans, New Orleans, LA, United States of America
| | - Alexander D. McKelvy
- Department of Biology, The Graduate School and Center, City University of New York, New York, NY, United States of America
- Department of Biology, 6S-143, College of Staten Island, 2800 Victory Boulevard, Staten Island, NY, United States of America
| | - L. Lee Grismer
- Department of Biology, La Sierra University, 4500 Riverwalk Parkway, Riverside, CA, United States of America
| | - Charles D. Bell
- Department of Biological Sciences, University of New Orleans, New Orleans, LA, United States of America
| | - Simon P. Lailvaux
- Department of Biological Sciences, University of New Orleans, New Orleans, LA, United States of America
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Sanz L, Pla D, Pérez A, Rodríguez Y, Zavaleta A, Salas M, Lomonte B, Calvete JJ. Venomic Analysis of the Poorly Studied Desert Coral Snake, Micrurus tschudii tschudii, Supports the 3FTx/PLA₂ Dichotomy across Micrurus Venoms. Toxins (Basel) 2016; 8:E178. [PMID: 27338473 DOI: 10.3390/toxins8060178] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/17/2016] [Accepted: 06/01/2016] [Indexed: 12/11/2022] Open
Abstract
The venom proteome of the poorly studied desert coral snake Micrurus tschudii tschudii was unveiled using a venomic approach, which identified ≥38 proteins belonging to only four snake venom protein families. The three-finger toxins (3FTxs) constitute, both in number of isoforms (~30) and total abundance (93.6% of the venom proteome), the major protein family of the desert coral snake venom. Phospholipases A2 (PLA2s; seven isoforms, 4.1% of the venom proteome), 1–3 Kunitz-type proteins (1.6%), and 1–2 l-amino acid oxidases (LAO, 0.7%) complete the toxin arsenal of M. t. tschudii. Our results add to the growing evidence that the occurrence of two divergent venom phenotypes, i.e., 3FTx- and PLA2-predominant venom proteomes, may constitute a general trend across the cladogenesis of Micrurus. The occurrence of a similar pattern of venom phenotypic variability among true sea snake (Hydrophiinae) venoms suggests that the 3FTx/PLA2 dichotomy may be widely distributed among Elapidae venoms.
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Lee MSY, Sanders KL, King B, Palci A. Diversification rates and phenotypic evolution in venomous snakes (Elapidae). R Soc Open Sci 2016; 3:150277. [PMID: 26909162 PMCID: PMC4736917 DOI: 10.1098/rsos.150277] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 12/08/2015] [Indexed: 05/19/2023]
Abstract
The relationship between rates of diversification and of body size change (a common proxy for phenotypic evolution) was investigated across Elapidae, the largest radiation of highly venomous snakes. Time-calibrated phylogenetic trees for 175 species of elapids (more than 50% of known taxa) were constructed using seven mitochondrial and nuclear genes. Analyses using these trees revealed no evidence for a link between speciation rates and changes in body size. Two clades (Hydrophis, Micrurus) show anomalously high rates of diversification within Elapidae, yet exhibit rates of body size evolution almost identical to the general elapid 'background' rate. Although correlations between speciation rates and rates of body size change exist in certain groups (e.g. ray-finned fishes, passerine birds), the two processes appear to be uncoupled in elapid snakes. There is also no detectable shift in diversification dynamics associated with the colonization of Australasia, which is surprising given that elapids appear to be the first clade of venomous snakes to reach the continent.
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Affiliation(s)
- Michael S. Y. Lee
- Earth Sciences Section, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
- School of Biological Sciences, Flinders University, PO Box 2100, Adelaide, SA 5001, Australia
- Author for correspondence: Michael S. Y. Lee e-mail:
| | - Kate L. Sanders
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Benedict King
- School of Biological Sciences, Flinders University, PO Box 2100, Adelaide, SA 5001, Australia
| | - Alessandro Palci
- Earth Sciences Section, South Australian Museum, North Terrace, Adelaide, SA 5000, Australia
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
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