The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Kate L. Sanders - One of the best experts on this subject based on the ideXlab platform.
-
horizontal transfer and southern migration the tale of Hydrophiinae s marine journey
bioRxiv, 2021Co-Authors: J D Galbraith, Kate L. Sanders, Alastair J Ludington, Richard Edwards, Alexander Suh, David L AdelsonAbstract:Transposable elements (TEs), also known as jumping genes, are sequences able to move or copy themselves within a genome. As TEs move throughout genomes they can be exapted as coding and regulatory elements, or can promote genetic rearrangement. In so doing TEs act as a source of genetic novelty, hence understanding TE evolution within lineages is key in understanding adaptation to their environment. Studies into the TE content of lineages of mammals such as bats have uncovered horizontal transposon transfer (HTT) into these lineages, with squamates often also containing the same TEs. Despite the repeated finding of HTT into squamates, little comparative research has examined the evolution of TEs within squamates. The few broad scale studies in Squamata which have been conducted found both the diversity and total number of TEs differs significantly across the entire order. Here we examine a diverse family of Australo-Melanesian snakes (Hydrophiinae) to examine if this pattern of variable TE content and activity holds true on a smaller scale. Hydrophiinae diverged from Asian elapids ~15-25 Mya and have since rapidly diversified into 6 amphibious, ~60 marine and ~100 terrestrial species which fill a broad range of ecological niches. We find TE diversity and expansion differs between hydrophiines and their Asian relatives and identify multiple HTTs into Hydrophiinae, including three transferred into the ancestral hydrophiine likely from marine species. These HTT events provide the first tangible evidence that Hydrophiinae reached Australia from Asia via a marine route.
-
Novel vascular plexus in the head of a sea snake (Elapidae, Hydrophiinae) revealed by high-resolution computed tomography and histology
Royal Society open science, 2019Co-Authors: Alessandro Palci, Roger S. Seymour, Cao Van Nguyen, Mark Hutchinson, Michael S. Y. Lee, Kate L. SandersAbstract: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.
-
Underwater hearing in sea snakes (Hydrophiinae): first evidence of auditory evoked potential thresholds.
The Journal of experimental biology, 2019Co-Authors: Lucille Chapuis, Caroline C Kerr, Shaun P Collin, Nathan S Hart, Kate L. SandersAbstract:The viviparous sea snakes (Hydrophiinae) are a secondarily aquatic radiation of more than 60 species that possess many phenotypic adaptations to marine life. However, virtually nothing is known of the role and sensitivity of hearing in sea snakes. This study investigated the hearing sensitivity of the fully marine sea snake Hydrophis stokesii by measuring auditory evoked potential (AEP) audiograms for two individuals. AEPs were recorded from 40 Hz (the lowest frequency tested) up to 600 Hz, with a peak in sensitivity identified at 60 Hz (163.5 dB re. 1 µPa or 123 dB re. 1 µm s-2). Our data suggest that sea snakes are sensitive to low-frequency sounds but have relatively low sensitivity compared with bony fishes and marine turtles. Additional studies are required to understand the role of sound in sea snake life history and further assess these species' vulnerability to anthropogenic noise.
-
ultrastructural evidence of a mechanosensory function of scale organs sensilla in sea snakes Hydrophiinae
Royal Society Open Science, 2019Co-Authors: Jenna M Croweriddell, Ruth Williams, Lucille Chapuis, Kate L. SandersAbstract:The evolution of epidermal scales was a major innovation in lepidosaurs, providing a barrier to dehydration and physical stress, while functioning as a sensitive interface for detecting mechanical stimuli in the environment. In snakes, mechanoreception involves tiny scale organs (sensilla) that are concentrated on the surface of the head. The fully marine sea snakes (Hydrophiinae) are closely related to terrestrial hydrophiine snakes but have substantially more protruding (dome-shaped) scale organs that often cover a larger portion of the scale surface. Various divergent selection pressures in the marine environment could account for this morphological variation relating to detection of mechanical stimuli from direct contact with stimuli and/or indirect contact via water motion (i.e. 'hydrodynamic reception'), or co-option for alternate sensory or non-sensory functions. We addressed these hypotheses using immunohistochemistry, and light and electron microscopy, to describe the cells and nerve connections underlying scale organs in two sea snakes, Aipysurus laevis and Hydrophis stokesii. Our results show ultrastructural features in the cephalic scale organs of both marine species that closely resemble the mechanosensitive Meissner-like corpuscles that underlie terrestrial snake scale organs. We conclude that the scale organs of marine hydrophiines have retained a mechanosensory function, but future studies are needed to examine whether they are sensitive to hydrodynamic stimuli.
-
First records of sea snakes (Elapidae: Hydrophiinae) diving to the mesopelagic zone (>200 m)
Austral Ecology, 2019Co-Authors: Jenna M. Crowe-riddell, Arne Redsted Rasmussen, Blanche D'anastasi, James H. Nankivell, Kate L. SandersAbstract:Viviparous sea snakes (Elapidae: Hydrophiinae) are fully marine reptiles distributed in the tropical and subtropical waters of the Indian and Pacific Oceans. Their known maximum diving depth ranges between 50 and 100 m and this is thought to limit their ecological ranges to shallow habitats. We report two observations, from industry-owned remotely operated vehicles, of hydrophiine sea snakes swimming and foraging at depths of approximately 250 m in the Browse Basin on Australia's North West Shelf, in 2014 and 2017. These observations show that sea snakes are capable of diving to the dim-lit, cold-water mesopelagic zone, also known as the 'twilight' zone. These record-setting dives raise new questions about the thermal tolerances, diving behaviour and ecological requirements of sea snakes. In addition to significantly extending previous diving records for sea snakes, these observations highlight the importance of university-industry collaboration in surveying understudied deep-sea habitats.
Juan J. Calvete - One of the best experts on this subject based on the ideXlab platform.
-
venomic analysis of the poorly studied desert coral snake micrurus tschudii tschudii supports the 3ftx pla2 dichotomy across micrurus venoms
Toxins, 2016Co-Authors: Libia Sanz, Davinia Pla, Bruno Lomonte, María Salas, Alfonso Zavaleta, Alicia Perez, Yania Rodriguez, Juan J. CalveteAbstract: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.
-
Venomic Analysis of the Poorly Studied Desert Coral Snake, Micrurus tschudii tschudii, Supports the 3FTx/PLA2 Dichotomy across Micrurus Venoms
Toxins, 2016Co-Authors: Libia Sanz, Davinia Pla, Bruno Lomonte, María Salas, Alfonso Zavaleta, Alicia Perez, Yania Rodriguez, Juan J. CalveteAbstract: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.
-
snake venomics of two poorly known Hydrophiinae comparative proteomics of the venoms of terrestrial toxicocalamus longissimus and marine hydrophis cyanocinctus
Journal of Proteomics, 2012Co-Authors: Libia Sanz, Juan J. Calvete, Fred Kraus, Parviz Ghezellou, Owen Paiva, Teatulohi Matainaho, Alireza Ghassempour, Hamidreza Goudarzi, David J WilliamsAbstract:Abstract The venom proteomes of Toxicocalamus longissimus and Hydrophis cyanocinctus , a fossorial and a marine species, respectively, of the Hydrophiinae genus of Elapidae, were investigated by Edman degradation of RP-HPLC isolated proteins, and de novo MS/MS sequencing of in-gel derived tryptic peptide ions. The toxin arsenal of T. longissimus is made up of 1–2 type-I PLA 2 molecules, which account for 6.5% of the venom proteins, a minor PIII-SVMP (1.4% of the venom toxins), and ~ 20 members of the 3FTx family comprising 92% of the venom proteome. Seventeen proteins (5 type-I PLA 2 s and 12 3FTxs) were found in the venom of H. cyanocinctus . Three-finger toxins and type-I PLA 2 proteins comprise, respectively, 81% and 19% of its venom proteome. The simplicity of the H. cyanocinctus venom proteome is highlighted by the fact that only 6 venom components (3 short-chain neurotoxins, two long-chain neurotoxins, and one PLA 2 molecule) exhibit relative abundances > 5%. As expected from its high neurotoxin abundance, the LD 50 for mice of H. cyanocinctus venom was fairly low, 0.132 μg/g (intravenous) and 0.172 μg/g (intraperitoneal). Our data indicate that specialization towards a lethal cocktail of 3FTx and type-I PLA 2 molecules may represent a widely adopted trophic solution throughout the evolution of Elapidae. Our results also points to a minimization of the molecular diversity of the toxin arsenal of the marine snake Hydrophis cyanocinctus in comparison to the venom proteome of its terrestrial relatives, and highlight that the same evolutionary solution, economy of the toxin arsenal, has been convergently adopted by different taxa in response to opposite selective pressures, loss and gain of neurotoxicity.
Michael S. Y. Lee - One of the best experts on this subject based on the ideXlab platform.
-
Novel vascular plexus in the head of a sea snake (Elapidae, Hydrophiinae) revealed by high-resolution computed tomography and histology
Royal Society open science, 2019Co-Authors: Alessandro Palci, Roger S. Seymour, Cao Van Nguyen, Mark Hutchinson, Michael S. Y. Lee, Kate L. SandersAbstract: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.
-
evaluating the drivers of indo pacific biodiversity speciation and dispersal of sea snakes elapidae Hydrophiinae
Journal of Biogeography, 2016Co-Authors: Michael S. Y. Lee, Kanishka D B Ukuwela, Anslem De Silva, Bryan G Fry, Arne Redsted Rasmussen, Parviz Ghezellou, Mohsen Rezaieatagholipour, Kate L. SandersAbstract:Aim: There are several competing hypotheses to explain the high species richness of the Indo-Australian Archipelago (IAA) marine biodiversity hotspot centred within Southeast (SE) Asia. We use phylogenetic methods to provide a novel perspective on this problem using viviparous sea snakes, a group with high species richness in the IAA that is highly distinct from other taxa previously studied, both phylogenetically (Reptilia, Amniota) and biologically (e.g.viviparity and direct development). Location: Indian Ocean and the West Pacific. Methods: We used likelihood and Bayesian methods to reconstruct a multi-locus time-calibrated phylogeny for c.70% of viviparous sea snake species, many sampled from multiple localities in Australasia, Southeast Asia and the Indian Ocean. We then compared rates and temporal concordance of inferred vicariance and dispersal events between marine basins using several approaches including new Bayesian analyses that allow for clade-specific and event-specific dispersal rates. Results: Phylogenetic analyses and novel Bayesian biogeographical reconstructions indicate that viviparous sea snakes underwent rapid speciation after colonizing SE Asia c.3 million years ago. Most of the SE Asian sea snake diversity is the result of insitu speciation, most consistent with the 'centre of origin' and 'centre of refuge' models for biodiversity hotspots. There is also speciation at the periphery, or entirely outside SE Asia; however, contrary to predictions of the 'accumulation' and 'overlap' models, these new outlying taxa do not preferentially disperse back into SE Asia. Instead, lineages are equally likely to disperse either into or away from SE Asia. Main conclusion: The high diversity of sea snakes in SE Asia (and hence the IAA) is mostly explained by insitu speciation rather than accumulation or overlap. Most speciation events are contemporaneous with sea level changes that generated and dissolved barriers between marine basins during the last 2.5 million years.
-
multilocus phylogeny and recent rapid radiation of the viviparous sea snakes elapidae Hydrophiinae
Molecular Phylogenetics and Evolution, 2013Co-Authors: Kate L. Sanders, Michael S. Y. Lee, Terry Bertozzi, Arne Redsted RasmussenAbstract:Abstract The viviparous sea snakes (Hydrophiinae: Hydrophiini) comprise a young but morphologically and ecologically diverse clade distributed throughout the Indo-Pacific. Despite presenting a very promising model for marine diversification studies, many relationships among the 62 species and 16 genera in Hydrophiini remain unresolved. Here, we extend previous taxonomic and genomic sampling for Hydrophiini using three mitochondrial fragments and five nuclear loci for multiple individuals of 39 species in 15 genera. Our results highlight many of the impediments to inferring phylogenies in recent rapid radiations, including low variation at all five nuclear markers, and conflicting relationships supported by mitochondrial and nuclear trees. However, concatenated Bayesian and likelihood analyses, and a multilocus coalescent tree, recovered concordant support for primary clades and several previously unresolved inter-specific groupings. The Aipysurus group is monophyletic, with egg-eating specialists forming separate, early-diverging lineages. All three monotypic semi-aquatic genera (Ephalophis, Parahydrophis and Hydrelaps) are robustly placed as early diverging lineages along the branch leading to the Hydrophis group, with Ephalophis recovered as sister to Parahydrophis. The molecular phylogeny implies extensive evolutionary convergence in feeding adaptations within the Hydrophis group, especially the repeated evolution of small-headed (microcephalic) forms. Microcephalophis (Hydrophis) gracilis is robustly recovered as a relatively distant sister lineage to all other sampled Hydrophis group species, here termed the ‘core Hydrophis group’. Within the ‘core Hydrophis group’, Hydrophis is recovered as broadly paraphyletic, with several other genera nested within it (Pelamis, Enhydrina, Astrotia, Thalassophina, Acalyptophis, Kerilia, Lapemis, Disteira). Instead of erecting multiple new genera, we recommend dismantling the latter (mostly monotypic) genera and recognising a single genus, Hydrophis Latreille 1802, for the core Hydrophis group. Estimated divergence times suggest that all Hydrophiini last shared a common ancestor ∼6 million years ago, but that the majority of extant lineages diversified over the last ∼3.5 million years. The core Hydrophis group is a young and rapidly speciating clade, with 26 sampled species and 9 genera and dated at only ∼1.5–3 million years old.
-
molecular evidence that the deadliest sea snake enhydrina schistosa elapidae Hydrophiinae consists of two convergent species
Molecular Phylogenetics and Evolution, 2013Co-Authors: Kanishka D B Ukuwela, Michael S. Y. Lee, Anslem De Silva, Bryan G Fry, Kate L. SandersAbstract:Abstract We present a striking case of phenotypic convergence within the speciose and taxonomically unstable Hydrophis group of viviparous sea snakes. Enhydrina schistosa, the ‘beaked sea snake’, is abundant in coastal and inshore habitats throughout the Asian and Australian regions, where it is responsible for the large majority of recorded deaths and injuries from sea snake bites. Analyses of five independent mitochondrial and nuclear loci for populations spanning Australia, Indonesia and Sri Lanka indicate that this ‘species’ actually consists of two distinct lineages in Asia and Australia that are not closest relatives. As a result, Australian “E. schistosa” are elevated to species status and provisionally referred to Enhydrina zweifeli. Convergence in the characteristic ‘beaked’ morphology of these species is probably associated with the wide gape required to accommodate their spiny prey. Our findings have important implications for snake bite management in light of the medical importance of beaked sea snakes and the fact that the only sea snake anti-venom available is raised against Malaysian E. schistosa.
-
uncoupling ecological innovation and speciation in sea snakes elapidae Hydrophiinae hydrophiini
Journal of Evolutionary Biology, 2010Co-Authors: Kate L. Sanders, Michael S. Y. LeeAbstract:The viviparous sea snakes (Hydrophiini) are by far the most successful living marine reptiles, with ∼60 species that comprise a prominent component of shallow-water marine ecosystems throughout the Indo-West Pacific. Phylogenetically nested within the ∼100 species of terrestrial Australo-Melanesian elapids (Hydrophiinae), molecular timescales suggest that the Hydrophiini are also very young, perhaps only ∼8–13 Myr old. Here, we use likelihood-based analyses of combined phylogenetic and taxonomic data for Hydrophiinae to show that the initial invasion of marine habitats was not accompanied by elevated diversification rates. Rather, a dramatic three to six-fold increase in diversification rates occurred at least 3–5 Myr after this transition, in a single nested clade: the Hydrophis group accounts for ∼80% of species richness in Hydrophiini and ∼35% of species richness in (terrestrial and marine) Hydrophiinae. Furthermore, other co-distributed lineages of viviparous sea snakes (and marine Laticauda, Acrochordus and homalopsid snakes) are not especially species rich. Invasion of the oceans has not (by itself) accelerated diversification in Hydrophiini; novelties characterizing the Hydrophis group alone must have contributed to its evolutionary and ecological success.
Arne Redsted Rasmussen - One of the best experts on this subject based on the ideXlab platform.
-
First records of sea snakes (Elapidae: Hydrophiinae) diving to the mesopelagic zone (>200 m)
Austral Ecology, 2019Co-Authors: Jenna M. Crowe-riddell, Arne Redsted Rasmussen, Blanche D'anastasi, James H. Nankivell, Kate L. SandersAbstract:Viviparous sea snakes (Elapidae: Hydrophiinae) are fully marine reptiles distributed in the tropical and subtropical waters of the Indian and Pacific Oceans. Their known maximum diving depth ranges between 50 and 100 m and this is thought to limit their ecological ranges to shallow habitats. We report two observations, from industry-owned remotely operated vehicles, of hydrophiine sea snakes swimming and foraging at depths of approximately 250 m in the Browse Basin on Australia's North West Shelf, in 2014 and 2017. These observations show that sea snakes are capable of diving to the dim-lit, cold-water mesopelagic zone, also known as the 'twilight' zone. These record-setting dives raise new questions about the thermal tolerances, diving behaviour and ecological requirements of sea snakes. In addition to significantly extending previous diving records for sea snakes, these observations highlight the importance of university-industry collaboration in surveying understudied deep-sea habitats.
-
evaluating the drivers of indo pacific biodiversity speciation and dispersal of sea snakes elapidae Hydrophiinae
Journal of Biogeography, 2016Co-Authors: Michael S. Y. Lee, Kanishka D B Ukuwela, Anslem De Silva, Bryan G Fry, Arne Redsted Rasmussen, Parviz Ghezellou, Mohsen Rezaieatagholipour, Kate L. SandersAbstract:Aim: There are several competing hypotheses to explain the high species richness of the Indo-Australian Archipelago (IAA) marine biodiversity hotspot centred within Southeast (SE) Asia. We use phylogenetic methods to provide a novel perspective on this problem using viviparous sea snakes, a group with high species richness in the IAA that is highly distinct from other taxa previously studied, both phylogenetically (Reptilia, Amniota) and biologically (e.g.viviparity and direct development). Location: Indian Ocean and the West Pacific. Methods: We used likelihood and Bayesian methods to reconstruct a multi-locus time-calibrated phylogeny for c.70% of viviparous sea snake species, many sampled from multiple localities in Australasia, Southeast Asia and the Indian Ocean. We then compared rates and temporal concordance of inferred vicariance and dispersal events between marine basins using several approaches including new Bayesian analyses that allow for clade-specific and event-specific dispersal rates. Results: Phylogenetic analyses and novel Bayesian biogeographical reconstructions indicate that viviparous sea snakes underwent rapid speciation after colonizing SE Asia c.3 million years ago. Most of the SE Asian sea snake diversity is the result of insitu speciation, most consistent with the 'centre of origin' and 'centre of refuge' models for biodiversity hotspots. There is also speciation at the periphery, or entirely outside SE Asia; however, contrary to predictions of the 'accumulation' and 'overlap' models, these new outlying taxa do not preferentially disperse back into SE Asia. Instead, lineages are equally likely to disperse either into or away from SE Asia. Main conclusion: The high diversity of sea snakes in SE Asia (and hence the IAA) is mostly explained by insitu speciation rather than accumulation or overlap. Most speciation events are contemporaneous with sea level changes that generated and dissolved barriers between marine basins during the last 2.5 million years.
-
molecules and morphology reveal overlooked populations of two presumed extinct australian sea snakes aipysurus Hydrophiinae
PLOS ONE, 2015Co-Authors: Kate L. Sanders, Tina Schroeder, Michael L Guinea, Arne Redsted RasmussenAbstract:The critically endangered leaf-scaled (Aipysurus foliosquamaI) and short-nosed (A. apraefrontalis) sea snakes are currently recognised only from Ashmore and Hibernia reefs ~600km off the northwest Australian coast. Steep population declines in both species were documented over 15 years and neither has been sighted on dedicated surveys of Ashmore and Hibernia since 2001. We examine specimens of these species that were collected from coastal northwest Australian habitats up until 2010 (A.foliosquama) and 2012 (A. apraefrontalis) and were either overlooked or treated as vagrants in conservation assessments. Morphological variation and mitochondrial sequence data confirm the assignment of these coastal specimens to A. foliosquama (Barrow Island, and offshore from Port Hedland) and A.apraefrontalis (Exmouth Gulf, and offshore from Roebourne and Broome). Collection dates, and molecular and morphological variation between coastal and offshore specimens, suggest that the coastal specimens are not vagrants as previously suspected, but instead represent separate breeding populations. The newly recognised populations present another chance for leaf-scaled and short-nosed sea snakes, but coastal habitats in northwest Australia are widely threatened by infrastructure developments and sea snakes are presently omitted from environmental impact assessments for industry. Further studies are urgently needed to assess these species’ remaining distributions, population structure, and extent of occurrence in protected areas.
-
multilocus phylogeny and recent rapid radiation of the viviparous sea snakes elapidae Hydrophiinae
Molecular Phylogenetics and Evolution, 2013Co-Authors: Kate L. Sanders, Michael S. Y. Lee, Terry Bertozzi, Arne Redsted RasmussenAbstract:Abstract The viviparous sea snakes (Hydrophiinae: Hydrophiini) comprise a young but morphologically and ecologically diverse clade distributed throughout the Indo-Pacific. Despite presenting a very promising model for marine diversification studies, many relationships among the 62 species and 16 genera in Hydrophiini remain unresolved. Here, we extend previous taxonomic and genomic sampling for Hydrophiini using three mitochondrial fragments and five nuclear loci for multiple individuals of 39 species in 15 genera. Our results highlight many of the impediments to inferring phylogenies in recent rapid radiations, including low variation at all five nuclear markers, and conflicting relationships supported by mitochondrial and nuclear trees. However, concatenated Bayesian and likelihood analyses, and a multilocus coalescent tree, recovered concordant support for primary clades and several previously unresolved inter-specific groupings. The Aipysurus group is monophyletic, with egg-eating specialists forming separate, early-diverging lineages. All three monotypic semi-aquatic genera (Ephalophis, Parahydrophis and Hydrelaps) are robustly placed as early diverging lineages along the branch leading to the Hydrophis group, with Ephalophis recovered as sister to Parahydrophis. The molecular phylogeny implies extensive evolutionary convergence in feeding adaptations within the Hydrophis group, especially the repeated evolution of small-headed (microcephalic) forms. Microcephalophis (Hydrophis) gracilis is robustly recovered as a relatively distant sister lineage to all other sampled Hydrophis group species, here termed the ‘core Hydrophis group’. Within the ‘core Hydrophis group’, Hydrophis is recovered as broadly paraphyletic, with several other genera nested within it (Pelamis, Enhydrina, Astrotia, Thalassophina, Acalyptophis, Kerilia, Lapemis, Disteira). Instead of erecting multiple new genera, we recommend dismantling the latter (mostly monotypic) genera and recognising a single genus, Hydrophis Latreille 1802, for the core Hydrophis group. Estimated divergence times suggest that all Hydrophiini last shared a common ancestor ∼6 million years ago, but that the majority of extant lineages diversified over the last ∼3.5 million years. The core Hydrophis group is a young and rapidly speciating clade, with 26 sampled species and 9 genera and dated at only ∼1.5–3 million years old.
-
independent innovation in the evolution of paddle shaped tails in viviparous sea snakes elapidae Hydrophiinae
Integrative and Comparative Biology, 2012Co-Authors: Kate L. Sanders, Arne Redsted Rasmussen, Johan ElmbergAbstract:The viviparous sea snakes (Hydrophiinae) comprise ∼90% of living marine reptiles and display many physical and behavioral adaptations for breathing, diving, and achieving osmotic balance in marine ...
Libia Sanz - One of the best experts on this subject based on the ideXlab platform.
-
venomic analysis of the poorly studied desert coral snake micrurus tschudii tschudii supports the 3ftx pla2 dichotomy across micrurus venoms
Toxins, 2016Co-Authors: Libia Sanz, Davinia Pla, Bruno Lomonte, María Salas, Alfonso Zavaleta, Alicia Perez, Yania Rodriguez, Juan J. CalveteAbstract: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.
-
Venomic Analysis of the Poorly Studied Desert Coral Snake, Micrurus tschudii tschudii, Supports the 3FTx/PLA2 Dichotomy across Micrurus Venoms
Toxins, 2016Co-Authors: Libia Sanz, Davinia Pla, Bruno Lomonte, María Salas, Alfonso Zavaleta, Alicia Perez, Yania Rodriguez, Juan J. CalveteAbstract: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.
-
snake venomics of two poorly known Hydrophiinae comparative proteomics of the venoms of terrestrial toxicocalamus longissimus and marine hydrophis cyanocinctus
Journal of Proteomics, 2012Co-Authors: Libia Sanz, Juan J. Calvete, Fred Kraus, Parviz Ghezellou, Owen Paiva, Teatulohi Matainaho, Alireza Ghassempour, Hamidreza Goudarzi, David J WilliamsAbstract:Abstract The venom proteomes of Toxicocalamus longissimus and Hydrophis cyanocinctus , a fossorial and a marine species, respectively, of the Hydrophiinae genus of Elapidae, were investigated by Edman degradation of RP-HPLC isolated proteins, and de novo MS/MS sequencing of in-gel derived tryptic peptide ions. The toxin arsenal of T. longissimus is made up of 1–2 type-I PLA 2 molecules, which account for 6.5% of the venom proteins, a minor PIII-SVMP (1.4% of the venom toxins), and ~ 20 members of the 3FTx family comprising 92% of the venom proteome. Seventeen proteins (5 type-I PLA 2 s and 12 3FTxs) were found in the venom of H. cyanocinctus . Three-finger toxins and type-I PLA 2 proteins comprise, respectively, 81% and 19% of its venom proteome. The simplicity of the H. cyanocinctus venom proteome is highlighted by the fact that only 6 venom components (3 short-chain neurotoxins, two long-chain neurotoxins, and one PLA 2 molecule) exhibit relative abundances > 5%. As expected from its high neurotoxin abundance, the LD 50 for mice of H. cyanocinctus venom was fairly low, 0.132 μg/g (intravenous) and 0.172 μg/g (intraperitoneal). Our data indicate that specialization towards a lethal cocktail of 3FTx and type-I PLA 2 molecules may represent a widely adopted trophic solution throughout the evolution of Elapidae. Our results also points to a minimization of the molecular diversity of the toxin arsenal of the marine snake Hydrophis cyanocinctus in comparison to the venom proteome of its terrestrial relatives, and highlight that the same evolutionary solution, economy of the toxin arsenal, has been convergently adopted by different taxa in response to opposite selective pressures, loss and gain of neurotoxicity.
