Adult Snakes Research Articles

Comparative analysis of newborn and adult Bothrops jararaca snake venoms

Different clinical manifestations have been reported to occur in patients bitten by newborn and adult Bothrops jararaca snakes. Herein, we studied the chemical composition and biological activities of B. jararaca venoms and their immunoneutralization by commercial antivenin at these ontogenetic stages. Important differences in protein profiles were noticed both in SDS-PAGE and two-dimensional electrophoresis. Newborn venom showed lower proteolytic activity on collagen and fibrinogen, diminished hemorrhagic activity in mouse skin and hind paws, and lower edematogenic, ADPase and 5′-nucleotidase activities. However, newborn snake venom showed higher l-amino oxidase, hyaluronidase, platelet aggregating, procoagulant and protein C activating activities. The adult venom is more lethal to mice than the newborn venom. In vitro and in vivo immunoneutralization tests showed that commercial Bothrops sp antivenin is less effective at neutralizing newborn venoms. These findings indicate remarkable differences in biological activities of B. jararaca venom over its development. We suggest that not only venom from adult specimens, but also from specimens at other ontogenetic stages should be included in the venom pool used for raising antibodies. Thus, Bothrops antivenin can efficaciously neutralize proteins lacking in the adult venom pool, especially those that promote more intense hemostatic disturbances in victims of newborn snakes.

Correlated geographic variation in predation risk and antipredator behaviour within a wide‐ranging snake species (Notechis scutatus, Elapidae)

AbstractGeographic variation in antipredator behaviour within wide‐ranging species may be driven by both genetic and environmental influences. We quantified antipredator responses in neonatal (laboratory born, n = 555) and adult (field caught, n = 346) tiger snakes (Notechis scutatus) from 11 mainland and island sites in southern Australia. We used these data to test predictions from Bonnet et al.'s hypothesis that the vigour of antipredator responses in this species reflects behavioural plasticity (in turn, driven by an individual snake's exposure to predators during its lifetime) rather than by genetic variation in this trait. We used the number of predator taxa in each area as an index of predator risk. As predicted, adult snakes from predator‐rich areas had more vigorous defensive responses when handled, whereas neonatal behaviour (although also variable among populations) was unrelated to predator species richness. Adult males bit more readily than adult females (as expected from the greater predation exposure of males during mate searching) but no such sex difference was evident in neonates. Although alternative models remain possible, our data are most consistent with the hypothesis that geographic divergence in antipredator tactics within this species primarily reflects developmentally plastic responses to local predation risk.

Molecular cloning and characterization of a type 3 iodothyronine deiodinase in the pine snake Pituophis deppei

The three distinct but related isotypes of the iodothyronine deiodinase family: D1, D2, and D3, have been amply studied in vertebrate homeotherms and to a lesser extent in ectotherms, particularly in reptiles. Here, we report the molecular and kinetic characteristics of both the native and the recombinant hepatic D3 from the pine snake Pituophis deppei (PdD3). The complete PdD3 cDNA (1680 bp) encodes a protein of 287 amino acids (aa), which is the longest type 3 deiodinase so far cloned. PdD3 shares 78% identity with chicken and 71% with its other orthologs. Interestingly, the hinge domain in D3s, including PdD3, is rich in proline. This structural feature is shared with D1s, the other inner-ring deiodinases, and deserves further study. The kinetic characteristics of both native and recombinant PdD3 were similar to those reported for D3 in other vertebrates. True K m values for T 3 IRD were 9 and 11 nM for native and recombinant PdD3, respectively. Both exhibited a requirement for a high concentration of cofactor (40 mM DTT), insensitivity to inhibition by PTU (>2 mM), and bisubstrate, sequential-type reaction kinetics. In summary, the present data demonstrate that the liver of the adult pine snake P. deppei expresses D3. Furthermore, this is the first report of the cloning and expression of a reptilian D3 cDNA. The finding of hepatic D3 expression in the adult pine snake P. deppei is consistent with results in adult piscine species in which the dietary T 3 content seems to regulate liver deiodinase expression. Thus, our present results support the proposal that hepatic D3 in adult vertebrates plays a sentinel role in avoiding an inappropriate overload of exogenous T 3 secondary to feeding in those species that devour the whole prey.

Born Knowing: Tentacled Snakes Innately Predict Future Prey Behavior

BackgroundAquatic tentacled snakes (Erpeton tentaculatus) can take advantage of their prey's escape response by startling fish with their body before striking. The feint usually startles fish toward the snake's approaching jaws. But when fish are oriented at a right angle to the jaws, the C-start escape response translates fish parallel to the snake's head. To exploit this latter response, snakes must predict the future location of the fish. Adult snakes can make this prediction. Is it learned, or are tentacled snakes born able to predict future fish behavior?Methods and FindingsLaboratory-born, naïve snakes were investigated as they struck at fish. Trials were recorded at 250 or 500 frames per second. To prevent learning, snakes were placed in a water container with a clear transparency sheet or glass bottom. The chamber was placed over a channel in a separate aquarium with fish below. Thus snakes could see and strike at fish, without contact. The snake's body feint elicited C-starts in the fish below the transparency sheet, allowing strike accuracy to be quantified in relationship to the C-starts. When fish were oriented at a right angle to the jaws, naïve snakes biased their strikes to the future location of the escaping fish's head, such that the snake's jaws and the fish's translating head usually converged. Several different types of predictive strikes were observed.ConclusionsThe results show that some predators have adapted their nervous systems to directly compensate for the future behavior of prey in a sensory realm that usually requires learning. Instead of behavior selected during their lifetime, newborn tentacled snakes exhibit behavior that has been selected on a different scale—over many generations. Counter adaptations in fish are not expected, as tentacled snakes are rare predators exploiting fish responses that are usually adaptive.

Habitat Selection of the Terciopelo (Serpentes: Viperidae: Bothrops asper) in a Lowland Rainforest in Costa Rica

Abstract Despite their high diversity and importance as top predators in many ecosystems, the ecology of many snakes remains poorly understood. This situation is especially true at low latitudes, as few attempts have been made to quantify patterns of space usage by tropical snake species. Here, we describe macro- and microhabitat use by the abundant pit viper Bothrops asper in the lowlands of Costa Rica. Specifically, we used radiotelemetry to monitor nine female and four male adult snakes at La Selva Biological Station between 2004 and 2006. We determined macrohabitat usage and availability on the basis of the movements of individual snakes and analyzed selection using compositional analysis. Microhabitat was quantified by a series of structural characteristics, and groups of locations were compared using multivariate ANOVA and discriminant function analysis. In our study, B. asper demonstrated a positive selection for swamp habitat and avoidance of human-disturbed areas by both male and female snakes. M...

Orthoreovirus Infection and Concurrent Cryptosporidiosis in Rough Green Snakes (Opheodrys Aestivus): Pathology and Identification of a Novel Orthoreovirus Strain via Polymerase Chain Reaction and Sequencing

Reoviruses are nonenveloped, segmented, double-stranded RNA viruses capable of infecting a wide range of invertebrate, vertebrate, fungus, and plant hosts. Though sporadic infection has been reported in a variety of reptilian species, infection of rough green snakes (Opheodrys aestivus) has not been previously described. Five wild-caught, adult rough green snakes were obtained by a zoological institution. Clinical deterioration was first noted in all snakes after 3 weeks in quarantine. Despite treatment, clinical decline progressed, and all 5 snakes died or were euthanized by 48 days post-arrival. Moderate, multifocal, acute, necrotizing hepatitis with hepatocellular syncytia was diagnosed in 1 snake. Two additional snakes had severe, diffuse, subacute to chronic pancreatitis. All 5 snakes had gastroenteric cryptosporidiosis. Electron microscopic examination of liver from the snake with hepatic lesions revealed scattered hepatocytes containing 1 or more intranuclear clusters of approximately 90 nm in diameter viral particles arranged in loose arrays. Polymerase chain reaction (PCR) amplification of a segment of the reovirus RNA-dependent RNA polymerase gene was performed on RNA extracted from tissues of all 5 snakes. PCR amplification of samples extracted from the snake with hepatic lesions resulted in a 109-base pair (bp) product. Phylogenetic analyses indicated the virus was a novel strain distinct from other reoviruses at a level consistent with species difference. The source of infection was unknown. PCR amplification of samples extracted from the other 4 snakes was negative.

Biochemical comparison of venoms from young Colombian Crotalus durissus cumanensis and their parents

Crotalus durissus cumanensis, a rattlesnake endemic to Colombia and Venezuela, is considered one of the most lethal snake species in Latin America. The aim of the present study was to compare the protein content and biological activity of the venom obtained from eight specimens of C. durissus cumanensis, namely two adults from different localities of Colombia and six offspring born in captivity. Protein profiles of crude venoms were analyzed by SDS-PAGE and RP-HPLC, and biological activities were evaluated for lethality, edema, defibrination, hemolytic and coagulant activities to assess individual venoms of adults and a pool of young snake venoms. Transient edema appeared rapidly after venom inoculation, whereas hemorrhagic effect was not observed. Differences in protein profiles, lethality, hemolytic, coagulant and defibrinating activities between both adult snake venoms were observed; those from the mother snake exhibited higher activities. Venoms from young snakes were similar to the one obtained from the mother, but the coagulant effect was stronger in offspring venoms. Notably, biological effects of the father snake venom were not comparable to those previously described for C. durissus cumanensis from Venezuela and C. durissus terrificus from Brazil, confirming the high variability of the venom from Crotalus species.

When do meadow vipers (Vipera ursinii) become sexually dimorphic? – ontogenetic patterns of sexual size dimorphisms

Contrary to an increasing number of papers that document sexual dimorphism in size (and/or shape) in adults, studies dealing with sex differences in newborn and juvenile snakes are surprisingly scarce. Data about ontogenetic shifts in sexual dimorphism are generally lacking and hence, it is unclear whether sex differences are set at birth or arise post-natally. In this study, we analyzed patterns of sexual dimorphism in body size, head dimensions and tail length (TL) among newborn, subadult and adult meadow vipers (Vipera ursinii) from the Bjelasica Mt. in Montenegro. Patterns of sexual size dimorphisms differed among traits. There was no significant difference in head dimension of males and females, but adult snakes were sexually dimorphic in body size. Sexual differences in TL were evident since birth but changed in degree throughout ontogeny. Neonate meadow vipers presented highly significant inter-litter variation in the sexual dimorphism of all traits we have measured. Such family effects may have an important influence on extent of inter-sexual differences in snakes and should be included in analyses of sexual dimorphism.

Movements by adult cutthroat trout in a lotic system: implications for watershed‐scale management

Abstract Movements by adult cutthroat trout, Oncorhynchus clarkii (Richardson), were assessed from autumn to summer in the Salt River watershed, Wyoming‐Idaho, USA by radio telemetry. Adult cutthroat trout were captured during September and October 2005 in the main stem of the Salt River, surgically implanted with radio transmitters, and tracked through to August 2006. Adult cutthroat trout were relatively sedentary and resided primarily in pools from October to March, but their movement rates increased during April. Higher movement rates were observed among tagged fish during May and early June. Among 43 fish residing in the Salt River during April 2006, 44% remained in the river, 37% moved into mountain tributaries and 19% moved into spring streams during the spawning season. Fish did not use segments of mountain tributaries or the upstream Salt River where fish passage was blocked by anthropogenic barriers or the channel was dewatered during summer. Almost all the fish that moved into spring streams used spring streams where pools and gravel–cobble riffles had been constructed by landowners. The results suggest that adult Snake River cutthroat move widely during May and early June to use spawning habitat in mountain tributaries and improved spring streams. Maintaining the ability of adult fish to move into mountain streams with spawning habitat, preserving spawning habitat in accessible mountain tributaries and removing barriers to upstream movements, and re‐establishing summer stream flows in mountain tributaries affected by dams appear to be habitat management alternatives to preserve the Snake River cutthroat trout fishery in the Salt River.

Post mortem identification of Kalicephalus colubri colubri (Nematoda: Diaphanocephalidae) in a captive Mole snake (Pseudaspis cana) in South Africa : clinical communication

Necropsy examination of a captive emaciated, dehydrated adult female Mole snake (Pseudaspis cana) in October 2007 revealed multiple cutaneous abscesses. Other findings included renal and hepatic atrophy, hepatic haemosiderosis, multifocal granulomatous hepatitis associated with acid-fast bacteria as well as pulmonary congestion and oedema. Large numbers of the nematode Kalicephalus colubri colubri were recovered from the oesophagus and stomach, representing the 1st reported case of K. colubri from a Mole snake in South Africa. The lesions caused by K. c. colubri were insignificant, but the presence of worms may have contributed to weight loss.

Spatial ecology of hatchling water pythons (Liasis fuscus) in tropical Australia

Abstract:Young snakes are rarely seen in the field and little is known about their habits, mostly because they are too small for radio-telemetry (the primary method for studying snake spatial ecology). However, the offspring of some larger species can be fitted with transmitters and we investigated the spatial ecology and habitat use of ten hatchling water pythons (Liasis fuscus: Pythonidae) in the floodplain of the Adelaide River, tropical Australia. Patterns of habitat use in the late wet season and during the dry season were similar to those of adults tracked in the same vicinity in an earlier study. Soon after release the young snakes moved to the floodplain, avoiding pasture areas. Diurnal refuge sites were typically in the base of grass clumps or below the soil surface, especially in sites with thick vegetation and deep, wide soil cracks. Adult snakes are more sedentary but move longer absolute distances (mean ± SE = 252 ± 50 m wk−1) than hatchlings (66.3 ± 41 m wk−1). However, hatchling snakes moved longer distances relative to body size (84.4 ± 1.1 body lengths wk−1) than did the previously studied adults (66.0 ± 1.1 body lengths wk−1). Mean and minimum body temperatures of the hatchlings were correlated with mean and minimum air temperatures, respectively.

Activity Patterns of a Neotropical Ambush Predator: Spatial Ecology of the Fer‐de‐lance (Bothrops asper, Serpentes: Viperidae) in Costa Rica

ABSTRACTPatterns of movement and space usage are important components of the ecology of any organism. Among snakes, this information is often lacking even for species that are abundant, ecologically important, and/or relevant to human health. We used radiotelemetry to examine the spatial ecology and behavior of the fer‐de‐lance (Bothrops asper), a highly venomous pit viper that is ubiquitous throughout much of Central America. Sixteen adult snakes were tracked over 2 yr in lowland rainforest of Costa Rica to determine home range, movement patterns, and foraging behavior. Consistent with previous descriptions, B. asper was found to be a highly nocturnal ambush predator, exhibiting virtually no activity during the day. Overall home range was determined using both minimum convex polygon (mean size = 5.95 ha) and 95 and 50 percent kernel density (mean size = 3.71 and 0.370 ha, respectively); home range size did not differ between males and females by any estimation method. Movement pattern was largely aseasonal and unrelated to any observed environmental conditions other than the daily low temperature. Most movements consisted of short (< 10 m) movements between daytime shelter and nocturnal ambush sites within a given area, interspersed with longer distance (> 50 m) movements to new foraging areas. Compositional analysis of habitat usage indicated an avoidance of developed areas and selection of swamp habitat. Most snakes had several activity cores (50% kernel density), the majority which were in or near swamps. These patterns suggest that space and habitat usage of fer‐de‐lance may be related to foraging strategy.

Snake Population Venomics: Proteomics-Based Analyses of Individual Variation Reveals Significant Gene Regulation Effects on Venom Protein Expression in Sistrurus Rattlesnakes

Studies of the molecular basis of adaptations seek to understand the relative importance of structural changes in proteins versus gene regulation effects as determinants of phenotype. Amino acid substitutions in gene coding sequences are well documented as causes of variation in snake venom proteins, whereas the importance of gene regulation effects on venom protein abundance and composition is less well known. Here, we use a proteomics-based approach to infer the effects of gene regulation on protein expression by comparing the relative abundance of specific, known venom proteins among different individuals in each of two species of Sistrurus rattlesnakes. Variation in the presence or absence, and in the relative amounts, of proteins was high in both species across all major protein families. Based on our empirical criteria for inferring regulatory effects (presence-absence of specific proteins and/or more than threefold variation in abundance) between 51% and 83% of S. catenatus individuals and between 40% and 63% of S. miliarius individuals showed evidence for gene regulation across the four most abundant proteins (disintegrins, phospholipase A(2)'s, serine proteinases, and snake venom metalloproteases). Thus, the effects of gene regulation should be considered an important cause of variation in the composition of whole venoms at the intraspecific level. They also suggest the need for testing the adaptive hypothesis for venom plasticity in relation to prey consumed by adult snakes. Finally, the venom variability reported may have an impact in the treatment of bite victims, highlighting the necessity of using pooled venoms as a substrate for antivenom production.

Habitat selection and range size of grass snakes Natrix natrix in an agricultural landscape in southern England

AbstractThe range sizes and habitat preferences of nine adult European grass snakes (Natrix natrix) were determined from radio-tracking data obtained within a landscape of mixed deciduous woodland and pastoral fields in southern England. These data were analysed using RANGES7v0.81 software. Concave polygons resulted in overall individual range size estimates that varied between 0.18-9.41 ha. However, for individuals that were radio-tracked for more than one season, annual range size estimates ranged between 1.29 ha and 3.56 ha and some snakes shifted their range between seasons. Grass snakes showed a strong preference for habitat boundaries and interfaces and an avoidance of woodland, and fields that were used for grazing. The attributes common to habitats that snakes preferred were a combination of basking site availability and a close proximity to relatively dense vegetation that offered potential protection from predators. The attributes common to habitats that snakes avoided were a lack of basking sites in woodland, and cover, in fields. Grass snakes selected banks as hibernation sites, the majority of which were within woodland.

Intraguild predation, thermoregulation, and microhabitat selection by snakes

Intraguild (IG) predation, the killing and eating of potential competitors, can be a powerful force within faunal assemblages. If both the IG predator and its prey prefer similar microhabitats in spatially structured environments, avoidance of the predator may relegate IG prey to suboptimal habitats. In southeastern Australia, the broad-headed snake (Hoplocephalus bungaroides )i s an endangered species sympatric with the small-eyed snake (Cryptophis nigrescens), an abundant and geographically widespread species known to eat other snakes. Both of these nocturnal ectotherms shelter diurnally beneath thermally distinctive ‘‘hot rocks,’’ which are in limited supply. When selecting shelter sites, broad-headed snakes thus face a trade-off between predation risk and habitat quality. In laboratory experiments, we allowed broad-headed snakes to choose between retreat sites differing in thermal regimes, in scent cues from predators, and in the actual presence of the predator. Broad-headed snakes displayed an aversion to sites with live predators and predator scent, yet nonetheless frequently selected those sites to obtain thermal benefits. In trials with live predators, adult broad-headed snakes shared hot rocks with small-eyed snakes, but most juveniles did not; data from a 16-year field study likewise suggest that broad-headed snakes only cohabit with small-eyed snakes if the two snakes are similar in body size. Our results suggest that thermoregulatory considerations are sufficient to prompt juvenile (but not adult) broad-headed snakes to risk IG predation, emphasizing the importance of microhabitat quality and body size in mediating IG predator–prey interactions. Key words: disturbance, endangered species, habitat selection, predation risk, refuge, snakes. [Behav Ecol]

Food habits of Brazilian boid snakes: overview and new data, with special reference to Corallus hortulanus

AbstractThis study examines the diet of eight boid snakes: Boa c. constrictor, Boa c. amarali, Corallus caninus, C. hortulanus, Epicrates cenchria, E. crassus, E. assisi and Eunectes murinus mainly by analyzing the gut contents of preserved museum specimens, and includes a literature review to present an overview of the diet of Brazilian boids. Mammals constitute the primary prey consumed by the majority of the species. Birds are also frequently consumed by C. hortulanus and Boa contrictor, and are the most important prey for B. c. amarali. Ectotherms (mostly lizards) were only consumed by immature snakes. Such prey is rarely consumed by B. c. amarali and not recorded for Epicrates and Eunectes species in our dissections. C. caninus is likely a mammal specialist and Epicrates prey on birds more opportunistically. The niche overlap index varied from 0.27-0.52 for species occurring in the same bioma and geographic range but it is possible this overlap is lower as most sympatric species explore different macrohabitat. C. hortulanus exhibited a significant relationship between prey size and predator head size; this relationship did not differ among mature and immature snakes. In comparison to immature individuals heavier adult snakes fed on heavier prey items however, the ratio between prey/predator mass decreased with increase in predator mass (or size). Most boids exploit diurnal and nocturnal preys, probably using both sit-and-wait and active tactics. They feed on the ground but boas and C. hortulanus and possibly E. cenchria also exploit arboreal prey.

Habitat Use and Seasonal Activity Patterns of the Great Plains Ratsnake (Elaphe guttata emoryi) in Central Texas

The Great Plains ratsnake (Elaphe guttata emoryi) is a poorly known species of the central and southern United States. We captured 24 Great Plains ratsnakes over 3 years at Fort Hood, Texas, and used radiotelemetry to determine habitat use and seasonal activity patterns of five adult male snakes. Great Plains ratsnakes showed an affinity for human-made structures with the majority of locations in rock structures used to control erosion. When compared to random sites, snake-selected sites were in areas of increased structure with more trees and ground cover and closer to habitat edges. Despite Great Plains ratsnakes having been documented preying on nests of arboreal birds, tracked snakes were found almost exclusively at or below ground level. Snakes were active year round and did not exhibit distinct hibernation times or sites. Snakes exhibited a bimodal pattern of activity with peaks in late spring and autumn, most likely due to temperature constraints.

Oviduct Adenocarcinoma in Some Species of Captive Snakes

This article reports 5 cases of oviduct adenocarcinoma in adult captive snakes from Smithsonian's National Zoological Park. This neoplasm was found in 1 of each of the following species: emerald tree boa (Corallus caninus), Amazonian tree boa (Corallus enydris enydris), Burmese rock python (Python molurus bivittatus), Northern pine snake (Pituophis melanoleucus melanoleucus), and corn snake (Elaphe guttata). Grossly, tan to red firm masses were found within oviducts in 3 cases. In an additional 2 cases, the primary tumor was detected only histologically. Microscopically, neoplasms were papillary, and often extended transmurally. The neoplastic cells were polygonal and organized in acini or cords, with often abundant fibrovascular stroma. Hemorrhages and necrosis were present in all cases. Inflammation, myxomatous material, desmoplasia, and bacteria were often observed. Histologic evidence of metastasis was present in all cases. Solid metastases were seen in all animals except the Northern pine snake and involved several organs including the liver, lung, and heart. Emboli of neoplastic cells were observed in all animals but the Burmese rock python and corn snake.

Exploring Hypotheses about the Loss of the Rattle in Rattlesnakes: How Arboreal Is the Isla Santa Catalina Rattleless Rattlesnake, Crotalus catalinensis?

Rattle loss in the Isla Santa Catalina (Baja California Sur, México) rattlesnake, Crotalus catalinensis, was hypothesized to be a stealth adaptation for hunting for birds within the vegetation. Recently, however, it was shown that birds are rarely captured by C. catalinensis, while a semi-arboreal mouse is very important in its diet. It was thus suggested that the loss of the rattle could be a stealth adaptation for hunting for mice within the vegetation. But both these hypotheses imply a high degree of arboreality in C. catalinensis, and there is no detailed study on microhabitat use in this species. Here we use field data recently obtained (2005 to 2008) to test the hypothesis of a high degree of arboreality in C. catalinensis. During nine visits to Isla Santa Catalina we searched for snakes in suitable habitats. Of 92 observations in which the snakes were exposed, in seven occasions (7.6%) they were on the vegetation. There was no difference between sexes or between young and adult snakes in the frequency of use of vegetation. Thus, C. catalinensis is a primarily terrestrial rattlesnake which uses the vegetation only occasionally, similar to its sister species Crotalus ruber. Results of a previous phase of our studies at Isla Santa Catalina are similar to those presented herein. These results make the hypothesis of the loss of the rattle as a stealth adaptation for hunting on the vegetation very unlikely, since such a low frequency of use of vegetation may not function as a selective agent that could lead to an adaptive loss of the rattle.

Snake Venomics of the Lancehead Pitviper Bothrops asper: Geographic, Individual, and Ontogenetic Variations

We report the comparative proteomic characterization of the venoms of adult and newborn specimens of the lancehead pitviper Bothrops asper from two geographically isolated populations from the Caribbean and the Pacific versants of Costa Rica. The crude venoms were fractionated by reverse-phase HPLC, followed by analysis of each chromatographic fraction by SDS-PAGE, N-terminal sequencing, MALDI-TOF mass fingerprinting, and collision-induced dissociation tandem mass spectrometry of tryptic peptides. The two B. asper populations, separated since the late Miocene or early Pliocene (8-5 mya) by the Guanacaste Mountain Range, Central Mountain Range, and Talamanca Mountain Range, contain both identical and different (iso)enzymes from the PLA 2, serine proteinase, and SVMP families. Using a similarity coefficient, we estimate that the similarity of venom proteins between the two B. asper populations may be around 52%. Compositional differences between venoms among different geographic regions may be due to evolutionary environmental pressure acting on isolated populations. To investigate venom variability among specimens from the two B. asper populations, the reverse-phase HPLC protein profiles of 15 venoms from Caribbean specimens and 11 venoms from snakes from Pacific regions were compared. Within each B. asper geographic populations, all major venom protein families appeared to be subjected to individual variations. The occurrence of intraspecific individual allopatric variability highlights the concept that a species, B. asper in our case, should be considered as a group of metapopulations. Analysis of pooled venoms of neonate specimens from Caribbean and Pacific regions with those of adult snakes from the same geographical habitat revealed prominent ontogenetic changes in both geographical populations. Major ontogenetic changes appear to be a shift from a PIII-SVMP-rich to a PI-SVMP-rich venom and the secretion in adults of a distinct set of PLA 2 molecules than in the neonates. In addition, the ontogenetic venom composition shift results in increasing venom complexity, indicating that the requirement for the venom to immobilize prey and initiate digestion may change with the size (age) of the snake. Besides ecological and taxonomical implications, the geographical venom variability reported here may have an impact in the treatment of bite victims and in the selection of specimens for antivenom production. The occurrence of intraspecies variability in the biochemical composition and symptomatology after envenomation by snakes from different geographical location and age has long been appreciated by herpetologist and toxinologists, though detailed comparative proteomic analysis are scarce. Our study represents the first detailed characterization of individual and ontogenetic venom protein profile variations in two geographical isolated B. asper populations, and highlights the necessity of using pooled venoms as a statistically representative venom for antivenom production.