Natrix Tessellata Research Articles

Testing the competitive exclusion principle using various niche parameters in a native (Natrix maura) and an introduced (N. tessellata) colubrid

AbstractDespite the increase of animal and plant introductions worldwide and the strong augmentation of the reptile trade, few invasive snake populations have been studied. Dice snakes (Natrix tessellata) were introduced to the shores of Lake Geneva (Switzerland) in the early 1920s, and are now well established. This region of introduction was previously inhabited by Viperine snakes (N. maura). Ever since these two species have been under monitoring (which began in 1996) the Viperine snake population has shown drastic decline. We examine here the possibility of trophic competition by analysing diet composition, prey size and trophic niche overlap. Spatial distribution is also assessed in order to address the question of spatial competitive exclusion. We found very similar diets, and thus a high trophic niche overlap, indicating no partitioning of the trophic resource. No arguments in favour of spatial competitive exclusion were found. Our study suggests that trophic competition may occur between the two natricines and that it may give an explanation for the drastic decline of the Viperine snake in this area. Other pathways potentially playing a role in the exclusion of the Viperine snake are discussed.

Helminth parasites of the Grass Snake, Natrix natrix, and the Dice Snake, Natrix tessellata (Serpentes: Colubridae), from Turkey

Twenty-one grass snakes, Natrix natrix, and 24 dice snakes, Natrix tessellata, from Turkey were examined for helminths. Natrix natrix harbored 5 species of Digenea: Astiotrema monticelli, Encyclometra colubrimurorum, Macrodera longicollis, Paralepoderma cloacicola, and Telorchis assula; 2 species of Cestoda: Ophiotaenia europaea and Spirometra erinaceieuropae; and 2 species of Nematoda: Rhabdias fuscovenosa and larvae of Eustrongylides excisus. Natrix tessellata snakes harbored 1 species of Digenea, Telorchis assula; 1 species of Cestoda, Ophiotaenia europaea; and 2 species of Nematoda, Rhabdias fuscovenosa and larvae of Eustrongylides excisus. Turkey is a new locality record for A. monticelli, P. cloacicola, T. assula, O. europaea, S. erinaceieuropae, larvae of E. excisus and R. fuscovenosa.

Comparative Diets of Three Populations of an Aquatic Snake (Natrix Tessellata, Colubridae) from Mediterranean Streams with Different Hydric Regimes

The Dice Snake (Natrix tessellata) is an aquatic colubrid that is known for having a basically piscivorous diet and a female-biased sexual size dimorphism (larger females). The feeding habits of three populations of N. tessellata from Mediterranean streams in central Italy were studied. The three streams differed in terms of their water regimes, one being seasonal and two being perennial. More than 2,000 snake individuals were handled for food items, and 1,200 prey items were collected. The percent of fed snakes was significantly influenced by the study area and by the interaction term between study area and season (i.e., by the hydric regime). Fishes accounted for over 90% of the snake diets at all study areas, the most common prey species being cyprinids. Overall, the three snake populations had similar taxonomic diet composition. There was a significant ontogenetic change in diets in all populations. There were also significant intersexual differences in prey composition, with the females taking more Scardinius erythrophtalmus fishes and more anurans, and the males more Leuciscus s. muticellus. The various fish species found at the three study areas (15 species) were classified in terms of six independent ecological characteristics in order to investigate what factors make a given prey species suited or not for Dice Snakes. It appeared that N. tessellata selected mainly fish species that were gregarious, small to medium sized, active foraging, diurnal, and not using mud as preferred substratum. We also found that the seasonal desiccation of the stream-bed of one study area caused a shift in the diet composition of these snakes, with males and juveniles being the categories where the seasonal dietary shift was more evident. Males preyed especially on the fishes S. erythrophtalmus and Leuciscus cephalus, and the juveniles preyed upon Leuciscus s. muticellus, whereas in spring their primary prey was Alburnus a. alborella.

Directional asymmetry and correlation of tail injury with left-side dominance occur in Serpentes (Sauropsida)

Recent evidence on directional asymmetry (DA) in species of the paraphyletic assemblage “Lacertilia” indicates a possible biological significance of this phenomenon, and we tested its occurrence in Serpentes by examining bilateral morphological characters, such as the numbers of supralabial and infralabial scutes and the diameter of the eyes, on both sides of museum specimens of seven species: Coronella austriaca, Elaphe longissima, Hierophis viridiflavus, Natrix natrix, Natrix tessellata, Platyceps saharicus, and Vipera aspis. Significant DA (not antisymmetry) occurred in at least one sex of four species and in two characters: H. viridiflavus—the number of infralabial scutes in males; N. tessellata—the diameter of the eyes in males; P. saharicus—the number of infralabial scutes in males and the diameter of the eyes in females; and V. aspis—the number of infralabial scutes in the pooled sexes. In N. tessellata and P. saharicus the DA varied geographically. Rank correlation between the DA of different characters, positive or negative, was significant in one character pair in each of three species. In the largest sample (N. tessellata males from the Levant), tail injury correlated with morphological left-dominant asymmetry (a greater number on the left) of infralabial scutes. Four of ten morphologically left-dominant males, but only 1 of 37 symmetrical or right-dominant males, had an injured tail. The syndrome of morphological DA with functional handicap may be genotypical or phenotypical. Our results support three earlier conclusions: bilateral characters should be examined on both sides of an animal; asymmetry should be analyzed separately in each sex; and the accident proneness of left-handed Homo sapiens merits re-evaluation in view of the apparently wide-spread accident proneness in left-biased Sauropsida (exclusive of Aves).

Helminth parasites of reptiles (Reptilia) in Romania

Necropsy of 82 specimens of reptiles (snakes, lizards, and turtles) was performed between 2002 and 2006 to determine the helminth fauna. We examined 7 species of reptiles: Natrix natrix (n=25), Natrix tessellata (n=20), Vipera berus (n=5), Coluber caspius (n=12), Anguis fragilis (n=2), Lacerta agilis (n=10), and Emys orbicularis (n=8). Overall prevalence of helminthic infections in Romanian reptiles was 81.71%. In snakes, the most prevalent group of helminths was trematodes. The helminth species, their prevalence, intensity, and abundance are shown in Table 1. In two reptile species, all individuals were infected with helminths (N. natrix and E. orbicularis). The lowest prevalence of helminthic infection was in C. caspius. Three digenean trematodes, namely, Leptophallus nigrovenosus, Metaleptophallus gracillimus, and Spirhapalum polesianum, and three nematodes, Entomelas entomelas, Strongyloides mirzai, and Hexametra quadricornis, are new records for Romania. N. natrix has a new host record for infection with nematode genus Eustrongylides.

Severe Granulomatous Lesions in Several Organs from Eustrongylides Larvae in a Free-ranging Dice Snake, Natrix tessellata

During an extensive study regarding the epidemiology of larval Eustrongylides infestation in a free-ranging endangered population of dice snakes (Natrix tessellata) from Histria, Romania, an adult female was euthanized to evaluate pathologic changes. Parasites appeared as nodules at various locations: in subcutaneous connective tissues, on the serosae of the intestines and liver. Histologic sections revealed nematode larvae surrounded by a capsule, forming a parasitic granuloma with 3 layers: macrophage layer, lymphocyte layer, and fibrous capsule. Differences between newly formed and mature granulomas consisted mainly in the eosinophilic infiltration. Other types of parasitic granulomas of reptiles are discussed in comparison with our findings.

Asymmetry and population characteristics in dice snakes (Natrix tessellata): an interpopulation comparison

Asymmetry and population characteristics in dice snakes (Natrix tessellata): an interpopulation comparison

Individual reproductive success and clutch-size of a population of the semi-aquatic snake Natrix tessellata from central Italy : are smaller males and larger females advantaged ?

Succès reproducteur individuel et taille de ponte dans une population de la couleuvre semi-aquatique Natrix tessellata en Italie centrale : les plus petits mâles et les plus grandes femelles sont-ils avantagés ? — Le succès de la formation des couples et de la reproduction de Natrix tessellata, serpent semi-aquatique, a été étudié dans le centre de l’Italie. Le succès des appariements a été établi en suivant par radiopistage 10 mâles et 12 femelles durant la période d’accouplement et en comptant combien chaque individu avait de partenaires sexuels en fonction de sa taille corporelle (longueur museauanus). Les femelles étaient significativement plus grandes que les mâles. Deux patrons opposés de succès individuel ont été mis en évidence dans la population : un succès d’appariement plus grand pour les plus petits mâles et pour les plus grandes femelles. De fait, chez les mâles, il y avait une relation significative entre la taille du mâle et le nombre de femelles avec lesquelles il s’accouplait tandis que les plus grandes femelles étaient courtisées et s’accouplaient avec un plus grand nombre de mâles. La taille maternelle était positivement liée au nombre d’oeufs pondus.

New evidence for the occurrence of the Dice Snake, Natrix tessellata (Laurenti, 1768) on Cyprus

Two subadult specimens of the Dice Snake (Natrix tessellata), collected in 1960 at Gönyeli-Nicosia, northern Cyprus, were recovered from the Zoological Collection of the Aegean University at Bornova-Izmir, Turkey. They challenge the view that the only existing voucher specimen of this species from Cyprus could have wrong locality data or was brought to the island by man.

Increased frequency of scale anomalies and loss of genetic variation in serially bottlenecked populations of the dice snake, Natrix tessellata

Documented demographic bottlenecks resultingfrom introductions of the dice snake to severallakes in Switzerland provide a rare opportunityto study the effect of serial bottlenecks onthe genetic properties of Natrixtessellata populations. We investigated twointroduced populations using informationderived from eight microsatellite markers. Bothintroduced populations had significantlyreduced levels of allelic diversity relative tonon-bottlenecked populations. The severity ofthe bottlenecks was underlined by thesignificant reduction in observed and expectedheterozygosity. The loss of allelic diversityand observed heterozygosity was stronger in theserially bottlenecked population than in thepopulation that was bottlenecked only once.From previous studies, scale anomalies wereknown to be more common in introducedpopulations relative to native populations. Weinvestigated whether the higher occurrence ofscale anomalies in introduced populations isassociated with individual heterozygosity andmean genomic diversity d 2. We founda significant relationship between theoccurrence of scale anomalies and individualheterozygosity but no significant relationshipbetween scale anomalies and the microsatellitespecific measurement, d 2, was found.Because of their known history, introducedpopulations in Switzerland may serve as a modelto demonstrate the effect of severe populationbottlenecks on genetic variability anddevelopmental stability in N. tessellata.The results therefore help to device strategiesfor the management and protection of endangerednatural N. tessellata populations.

Isolation and characterization of microsatellite loci in the dice snake (Natrix tessellata)

Isolation and characterization of microsatellite loci in the dice snake (<i>Natrix tessellata</i>)

Isolation and characterization of microsatellite loci in the dice snake (Natrix tessellata)

Molecular EcologyVolume 9, Issue 12 p. 2192-2193 Isolation and characterization of microsatellite loci in the dice snake (Natrix tessellata) B. Gautschi, Corresponding Author B. Gautschi Institut für Umweltwissenschaften, Universität Zürich-Irchel, Winterthurerstraße 190, CH-8057 Zürich, Switzerland, B. Gautschi. Fax: +41 1635 57 11; E-mail:babagaut@uwinst.unizh.ch§Former address: Experimentelle Ökologie, ETH Zürich, ETH Zentrum-NW, CH-8092 Zürich, SwitzerlandSearch for more papers by this authorA. Widmer, Corresponding Author A. Widmer Geobotanisches Institut, ETH Zürich, Zollikerstraße 107, CH-8008 Zürich, Switzerland, B. Gautschi. Fax: +41 1635 57 11; E-mail:babagaut@uwinst.unizh.ch§Former address: Experimentelle Ökologie, ETH Zürich, ETH Zentrum-NW, CH-8092 Zürich, SwitzerlandSearch for more papers by this authorJ. Koella, Corresponding Author J. Koella Laboratoire d’Ecologie, CC237, Université Pierre & Marie Curie, CNRS UMR 7625, 7 Quai St Bernard, 75252 Paris, France B. Gautschi. Fax: +41 1635 57 11; E-mail:babagaut@uwinst.unizh.ch§Former address: Experimentelle Ökologie, ETH Zürich, ETH Zentrum-NW, CH-8092 Zürich, SwitzerlandSearch for more papers by this author B. Gautschi, Corresponding Author B. Gautschi Institut für Umweltwissenschaften, Universität Zürich-Irchel, Winterthurerstraße 190, CH-8057 Zürich, Switzerland, B. Gautschi. Fax: +41 1635 57 11; E-mail:babagaut@uwinst.unizh.ch§Former address: Experimentelle Ökologie, ETH Zürich, ETH Zentrum-NW, CH-8092 Zürich, SwitzerlandSearch for more papers by this authorA. Widmer, Corresponding Author A. Widmer Geobotanisches Institut, ETH Zürich, Zollikerstraße 107, CH-8008 Zürich, Switzerland, B. Gautschi. Fax: +41 1635 57 11; E-mail:babagaut@uwinst.unizh.ch§Former address: Experimentelle Ökologie, ETH Zürich, ETH Zentrum-NW, CH-8092 Zürich, SwitzerlandSearch for more papers by this authorJ. Koella, Corresponding Author J. Koella Laboratoire d’Ecologie, CC237, Université Pierre & Marie Curie, CNRS UMR 7625, 7 Quai St Bernard, 75252 Paris, France B. Gautschi. Fax: +41 1635 57 11; E-mail:babagaut@uwinst.unizh.ch§Former address: Experimentelle Ökologie, ETH Zürich, ETH Zentrum-NW, CH-8092 Zürich, SwitzerlandSearch for more papers by this author First published: 19 August 2003 https://doi.org/10.1046/j.1365-294X.2000.105320.xCitations: 59Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume9, Issue12December 2000Pages 2192-2193 RelatedInformation

Somites et prolongements somitiques impliqués dans la formation des membres chez les reptiles. L'amélie chez les serpents

Summary A new study was carried out on an increased number of young embryos of Reptile taxa either with well developed limbs or limbless to complete the previous observations devoted to the relationships between the somatic extensions and the formation of limb buds. Results are summarized in table I. In the embryos of Reptiles, the somites involved in limb formation send ventral processes in the somatopleural territory of the future limb and the limb develops only in front of these somatic extensions. In lizards with well developed limbs, there are always eight somites (S6–S13, S1 being the first postotic somite) which send ventral processes in the somatopleure and are thus involved in anterior limb formation. In serpentiform lizards such as Anguis fragilis, Ophisaurus apodus, Scelotes brevipes, only four or five somites (S6–S9 or S6–S10) form ventral extensions; the limb bud develops only in front of these somites, and its size is thus reduced from this early stage. Macroscopic and histological studies of young embryos belonging to four species of snakes (Natrix natrix, Natrix tessellata, Natrix maura and Vipera aspis) shows that none of the thoracic somites of the series S6–S13 form ventral extensions. Several observations suggest that in Reptiles with well developed limbs, the somitic extensions may initiate limb development by liberating a growth factor of the FGF family. In snake embryos, which are devoid of somitic extensions, no growth factor would be liberated and thus no anterior limb would develop. In some species, some pelvian somites form short extensions, which induce a feeble pelvian thickening or a rudimentary posterior limb bud (e.g. Boidae). It is an embryonic mechanism which is responsible for the limbless condition in Snakes.

Development of the plerocercoid I of Ophiotaenia europaea in reptiles

The existence of a two-host life-cycle in ophiotaeniid proteocephalideans was tested experimentally using Ophiotaenia europaea as a model. Three species of reptiles, Natrix natrix, Natrix tessellata and Lacerta viridis, were fed with experimentally infected copepods containing a large number of infective plerocercoids I. A few plerocercoids, most of which were dead, corresponding morphologically to the plerocercoid II developmental stage of O. europaea, were found encysted in the intestinal wall of N. natrix (8 days p.i.), N. tessellata (5 and 150 days p.i.) and L. viridis (40 days p.i.), while no plerocercoids or adult worms were recovered from their intestines. The results indicate that the infective plerocercoid I of O. europaea cannot undergo further development when ingested directly by the final host (a reptile), and that environmental temperature stimuli cannot initiate a reverse plerocercoid migration to the gut followed by strobilization.

Thermal ecology and reproductive cyclicity of the snake Natrix tessellata in south-eastern Austria and central Italy: a comparative study

Abstract Aspects of thermal ecology and reproductive cyclicity are compared in two populations of the dice snake (Natrix tessellata), a semi-aquatic natricine species widely distributed across Europe. One population was studied near Leibnitz, Styria (south-eastern Austria), and the other one was studied in the Mounts of Tolfa near Rome (Latium, central Italy). The climate was strongly colder in the Austrian than in the Italian site. Snakes of both populations were similar in various traits, including average body temperature, higher mean body temperature of gravid than non-gravid individuals, significantly higher substratum temperatures selected by gravid than by non-gravid individuals, trends of relationships between body, air and substratum temperatures, average length of reproductive females, and average preparturition mass of reproductive females. However, Austrian snakes were found in water significantly less often than their Italian conspecifics (although in both populations nearly all individuals occurred close to water bodies), and showed a lower frequency of reproduction (biannual rather than annual) than Italian ones. The presented data are discussed in the light of suboptimal occupation of the colder area by Austrian snakes, and conservative rigidity of natural history and ecological traits of such a widespread species as N. tessellata.

Skin resistance to water loss in colubrid snakes: Ecological and taxonomical correlations

:Rates of cutaneous water loss (CWL) in terrestrial snakes may be affected by the temperature and humidity prevailing in the habitat, the activity pattern of the snake, and the taxonomic position of the species. To find out whether variation in snake CWL is mainly due to the physical conditions characterizing a particular habitat, or whether it is better attributed to taxonomic position, we measured CWL and skin resistance to water loss (Rs) in four species of colubrid snakes. These species inhabit different climatic regions (from mesic Mediterranean to dry and hot desert) and habitats (semi-aquatic and terrestrial), and have different daily activities (diurnal and crepuscular-nocturnal). CWL and Rs were correlated more with aridity of habitat rather than with taxonomy. CWL rates of the non-desert species were higher, and their Rs lower than those obtained from desert species. The highest rates of CWL (0.98 mg cm−2 h−1) and the lowest Rs (117 s cm−1) were found in the water snake Natrix tessellata, whereas the lowest CWL (0.13 mg cm−2 h−1) and the highest Rs (1088 s cm−1) were found in the stripeless form of Psammophis schokari, which inhabits desert biotopes. Intermediate values were found in Coluber rubriceps and the striped form of Psammophis, both inhabiting mesic Mediterranean areas. CWL and Rs of Spalerosophis diadema,a species inhabiting arid desert biotopes, were not significantly different from those of the semi-aquatic Natrix. The apparent discrepancy between the low Rs found in Spalerosophis and the high aridity of its habitat can be attributed to the crepuscular-nocturnal activity of this species. The environmental conditions to which Spalerosophis is exposed during its activity in the desert nights are milder and much more moderate than those encountered by diurnal snakes. CWL and Rs reflect, therefore, not the apparent aridity of the habitat but the real ecological niche of the species, i.e.,the actual climatic conditions prevailing during the activity time of the species.

Inhibition of Hemorrhagic Effects of Crotalus atrox Venom by Natrix tessellata Embryos

Inhibition of Hemorrhagic Effects of Crotalus atrox Venom by Natrix tessellata Embryos

Snake yolk sac as a site for in vivo organ incubation: A new method in the research of snake embryo development

AbstractThe snake embryo yolk sac served as a culture medium for the development of isolated reptilian organs. Isolated upper jaws of Natrix tessellata and Vipera palaestinae embryos at the early stages of jaw organogenesis were implanted into the yolk, close to the yolk sac blood vessels of Natrix tessellata embryos in order to determine natural conditions for long‐term incubation of organ culture. Tissues were incubated in the yolk for approximately 1 month until 1 day before host embryo hatching. Histological inspection showed full morphological differentiation of all tissues including scales, bones, teeth, glands, and connective tissue. The biochemical marker phosphodiesterase showed the typical developmental pattern in the main oral gland, Duvernoy's gland, and was comparable to the same gland in the host embryo. Vipera implants developed almost normally, except for differentiation of the skin which remained in the stage of one to two cell undifferentiated layers. Natrix was chosen for these experiments owing to the special chemical composition of its yolk that allows the penetration of blood vessels. This characteristic is probably crucial for the success of angiogenesis, which in turn is an essential condition for tissue survival. The ability of the yolk to support normal differentiation of isolated organs provides a valuable tool for the long‐term incubation experiments that are indispensable in order to achieve maximal tissue differentiation. © Wiley‐Liss, Inc.

A potent antihemorrhagin in the serum of the non-poisonous water snake Natrix tessellata: isolation, characterization and mechanism of neutralization

The main natural antihemorrhagic factor (NtAH), which inhibits the hemorrhagic activity of Bothrops asper snake venom, was isolated from the serum of the non-poisonous water snake Natrix tessellata by ammonium sulfate precipitation at 35–55%, Sephadex G-75 gel filtration, ion exchange chromatography on DEAE-Sepharose and CM-Sepharose and hydrophobic Phenyl-Sepharose chromatography. The purified protein showed one band with an isoelectric point of 4.5 and a molecular mass of about 880 kDa. The antihemorrhagic activity was stable between pH 5.5–11.7 and up to 50°C, but lost activity after 20 min at 60°C. It did not form a precipitin line with the main hemorrhagin of Bothrops asper snake venom (BaH1), nor with the whole venom, which suggests that the antihemorrhagic factor is not an immunoglobulin. The mechanism of neutralization by the isolated antihemorrhagic factor NtAH did not include digestion of the hemorrhagic toxin BaH1. Chromatography of NtAH with active 125I-labeled BaH1 toxin as well as ELISA experiments demonstrated that the mechanism of neutralization involves formation of an inactive soluble complex between the natural NtAH of the non-poisonous water snake and the main hemorrhagin of Bothrops asper venom.

The Boxgrove, England, middle Pleistocene herpetofauna: Paleogeographic, evolutionary, stratigraphic, and paleoecological relationships

Triturus vulgaris (smooth newt), Triturus helveticus or T. vulgaris (palmate or smooth newt), Triturus sp. (newt), Pelobates fuscus (common spadefoot), Bufo bufo (common toad), Bufo calamita (natte...