Natrix Tessellata Research Articles

Infection of Dice Snake (Reptilia, Colubridae) with Larvae of Eustrongylides excisus (Nematoda, Dioctophymatidae) in the Middle and Lower Dnipro River Basin

Dice snakes can be a paratenic host for a stage IV of Eustrongylides excisus, Jägerskiöld, 1909 larva due to specific diet of the snakes. The infection rate of E. excisus in Natrix tessellata (Laurenti, 1768) was studied in the basin of the middle and the lower Dnipro River in 2013–2017. We searched for nematodes in snakes from four sites: Prydniprovska Thermal Power Station, Majorova Balka, Zaporizhzhia; National Nature Park Velykyi Luh. The snakes from all studied areas had high prevalence of infection (more than 90 %). The lowest level of intensity (2.50 ± 0.60) and abundance (2.27 ± 0.58) were in ecosystems near Prydniprovska ТPP. There was no significant difference between infection parameters in snakes from other groups. Capsules with larva localized in the gastrointestinal tract, liver, muscles, and lung. The most infected organ was the liver, statistical analysis showed significant differences with other organs. The lowest infection was found in the lung. Environmental pollution of the Dnipro River waters with pesticides and other pollutants accompanied by a climate change may influence on the E. excisus life cycle that needs additional studies.

Preliminary overview of body condition variation among dice snake populations from transboundary Lake Prespa

Preliminary overview of body condition variation among dice snake populations from transboundary Lake Prespa

Видовой состав, численность и биотопическое размещение змей (Serpentes) на южном макросклоне хребта Навагир (Абрауский полуостров) и некоторые вопросы их охраны

Seven species of snakes were revealed in 1997–1998, six of which (Natrix tessellata, N. natrix, Zamenis longissimus, Hierophis caspius, Platyceps najadum, and Elaphe sauromatus) were in the lower part of the slope, in the area of mediterranean vegetation. In 2001– 2003, the first three species were revealed only, and their numbers significantly decreased, reaching a maximum in the middle part of the slope, in the zone of transition from mediterranean vegetation to broad-leaved forests. In 1999–2000, the recreational load on the coastal area sharply rose, which probably was the cause for the species composition reduction and changes of the spatial distribution in snakes.

It takes two to tango – Phylogeography, taxonomy and hybridization in grass snakes and dice snakes (Serpentes: Natricidae: Natrix natrix, N. tessellata)

Using two mitochondrial DNA fragments and 13 microsatellite loci, we examined the phylogeographic structure and taxonomy of two codistributed snake species (Natrix natrix,N. tessellata) in their eastern distribution area, with a focus on Turkey. We found evidence for frequent interspecific hybridization, previously thought to be extremely rare, and for backcrosses. This underscores that closely related sympatric species should be studied together because otherwise the signal of hybridization will be missed. Furthermore, the phylogeographic patterns of the two species show many parallels, suggestive of a shared biogeographic history. In general, the phylogeographies follow the paradigm of southern richness to northern purity, but the dice snake has some additional lineages in the south and east in regions where grass snakes do not occur. For both species, the Balkan Peninsula and the Caucasus region served as glacial refugia, with several mitochondrial lineages occurring in close proximity. Our results show that the mitochondrial divergences in both species match nuclear genomic differentiation. Yet, in the former glacial refugia of grass snakes there are fewer nuclear clusters than mitochondrial lineages, suggesting that Holocene range expansions transformed the glacial hotspots in melting pots where only the mitochondrial lineages persisted, bearing witness of former diversity. On the other hand, the deep mitochondrial divergences inN. tessellataacross its entire range indicate that more than one species could be involved, even though lacking microsatellite data outside of Turkey prevent firm conclusions. On the contrary, our microsatellite and mitochondrial data corroborate thatN. megalocephalais invalid and not differentiated from sympatric populations ofN. natrix. For Cypriot grass snakes, our analyses yielded conflicting results. A critical assessment of the available evidence suggests thatN. natrixis a genetically impoverished recent invader on Cyprus and taxonomically not distinct from a subspecies also occurring in western Anatolia and the southern Balkans. Based on combined mitochondrial and nuclear genomic evidence we propose that for grass snakes the following subspecies should be recognized in our study region: (1)Natrix natrix vulgarisLaurenti, 1768, southeastern Central Europe and northern Balkans; (2)Natrix natrix moreotica(Bedriaga, 1882), southern Balkans, western Anatolia, and Cyprus; and (3)Natrix natrix scutata(Pallas, 1771), eastern Anatolia, Caucasus region, Iran, northeastern distribution range (from eastern Poland and Finland to Kazakhstan and the Lake Baikal region). Thus,Natrix natrix cypriaca(Hecht, 1930) becomes a junior synonym ofN. n. moreoticaandNatrix natrix persa(Pallas, 1814) becomes a junior synonym ofN. n. scutata. Due to insufficient material, we could not resolve the status ofNatrix natrix syriaca(Hecht, 1930) from the Gulf of İskenderun, southeastern Turkey.

Snake Conservation State in the Reserves of the Volga Basin

There are 23 nature reserves in the Volga basin, all of them in the Russian Federation. According to our data and open access literature sources, ten out of the eleven species of snakes that are reliably known to be found in the Volga basin, inhabit and, therefore, are protected in 22 reserves. No snakes have been recorded in the Vishersky Reserve. One species inhabits the nature reserves “Basegi” and “Tsentralno-Lesnoy”, two species – in the reserves “Bolshaya Kokshaga”, “Darvinsky”, “Kaluzhskie zaseki”, “Kologrivsky forest”, “Nurgush”, “Prioksko-terrasny”, in the reserves “Bashkirsky”, “Visimsky”, “Volzhsko-Kamsky”, “Kerzhensky”, “Mordovsky”, “Oksky”, “Prisursky”, “Shulgan-Tash” and “Yuzhno-Uralsky” there are 3 species each, the reserves “Zhigulevsky” and “Volga forest-steppe” – 4 species each, in the reserves “Astrakhansky” and “Bogdinsko-Baskunchaksky” – 5 species each, in the reserve “Chornye Zemli” – 7 species. Eryx jaculus was not found in the reserves of the Volga basin. Species Eryx miliaris inhabits two reserves, Natrix natrix – 20, Natrix tessellata – 2, Coronella austriaca – 11, Elaphe dione – 4, Elaphe sauromates – 2, Hierophis caspius – 3, Malpolon monspessulanus – 1, Vipera berus – 19, Vipera renardi – 2. The latter species is represented in both reserves (Volga forest-steppe and Astrakhansky) only by the nominative subspecies Vipera r. renardi, and in the Volga Basin, by the endemic subspecies V. r. bashkirovi, which has no conservation status in regional reserves. Three species of snakes are the least prosperous in terms conservation in the Volga basin: Eryx jaculus, Eryx miliaris, and Vipera renardi.

Snakes of the Volga basin in the Red Data Books of Differnt Levels

Currently, 11 species of snakes are reliably known to be found in the Volga River basin. Vipera renardi has been assigned the Vulnerable (VU) category on the IUCN Red List of Threatened Species. The authors analyze the representation of snakes in the Volga basin in the latest editions of the Red Data Book (RDB) of the Republic of Kazakhstan, the RDB of the Russian Federation and the RDBs of Russian Oblasts, which are fully or partially related to the Volga basin. The species Hierophis caspius is included in the list of protected species in the RDB of Kazakhstan in the interfluve of the Volga and the Urals. The RDB of the Russian Federation considers rare and threatened three ophidiofauna species of the Volga basin: Eryx jaculus, Eryx miliaris, and Elaphe sauromates. Coronella austriaca is the most listed species in the Red Data Books of the constituent entities of Russia in the Volga Basin (35 Red Data Books); it is widespread but rare. The RDB of the Republic of Kalmykia protects the world’s northernmost population of Eryx jaculus. The RDBs of the Republic of Bashkortostan and Samara Oblast protect the world’s northernmost populations of Natrix tessellata, the RDB of Tatarstan protects the world’s northernmost population of Vipera renardi. The RDB of Volgograd Oblast protects the world’s northernmost population of Hierophis caspius, and the RDB of Samara Oblast – the northernmost population of Elaphe dione in Europe. Anthropogenic transformation of habitats, traffic-related deaths and actual killing of snakes are the main limiting factors in the RDBs. The authors believe that an effective measure of conservation is the creation of protected areas in the habitats of species, and, first of all, the preservation of winter brumation sites.

Death‐feigning propensity varies within dice snake populations but not with sex or colour morph

AbstractOnce cornered by a predator, prey can try to intimidate the assailant or repel it, with irritating sprays for example. If seized, they may scratch, bite or struggle to cause the predator to release its grip. At the other extreme, they can adopt passive behaviours such as death feigning (DF, i.e. thanatosis). DF is observed widely across the animal kingdom; it usually involves a combination of displays such as immobility, supination, leg‐folding, mouth opening and release of nauseating secretions. When displaying DF, individuals are highly vulnerable and effectively bet on the attitude of the predator; this risky choice is presumably under positive selection. We explored how propensity for DF varies among and within populations of dice snakes (Natrix tessellata). We also considered the influence of sex, body size, reproductive status, colour morph and presence of injuries (N = 2760 snakes; five populations). DF propensity differed among populations, possibly due to variation in local predation pressures. Larger snakes displayed DF more frequently and carried more signs of probable past predation attempts (scars and recent injuries). We found no sex effect on antipredator behaviour. Gravid females used DF less frequently compared with non‐gravid females. Differential expression of DF across populations, body sizes and reproductive status suggests that this complex behaviour was selected to respond to environmental and intrinsic factors. Future studies should explore which elements affect duration, intensity and success of DF in defence against various predators.

Bithynian snake bombs

Bithynian snake bombs

Population size estimation based upon zero-truncated, one-inflated and sparse count data

Estimating the size of a hard-to-count population is a challenging matter. In particular, when only few observations of the population to be estimated are available. The matter gets even more complex when one-inflation occurs. This situation is illustrated with the help of two examples: the size of a dice snake population in Graz (Austria) and the number of flare stars in the Pleiades. The paper discusses how one-inflation can be easily handled in likelihood approaches and also discusses how variances and confidence intervals can be obtained by means of a semi-parametric bootstrap. A Bayesian approach is mentioned as well and all approaches result in similar estimates of the hidden size of the population. Finally, a simulation study is provided which shows that the unconditional likelihood approach as well as the Bayesian approach using Jeffreys’ prior perform favorable.

Показатели лейкоцитарной системы крови ужа водяного Natrix tessellata Северного и Восточного Прикаспия

Показатели лейкоцитарной системы крови ужа водяного Natrix tessellata Северного и Восточного Прикаспия

Различия признаков внешней морфологии молодых и взрослых змей семейства Colubridae (Reptilia)

Characteristics of the meristic features of the external morphology of young and adult snakes (the Colubridae family) of three species, namely, the grass snake Natrix natrix, the dice snake N. tessellata and the Pallas’ coluber Elaphe dione, living in the Samara region, are described. For the first time, a comparative analysis was carried out of a number of morphological characters of uneven-aged snakes, namely: newborns obtained in laboratory conditions, juvenile specimens, and adult snakes captured in nature. It was revealed that those morphological features which remained unchanged during the snake's life (the number of Ventr., Scd., Lab. and Temp. scales) significantly differred in specimens of laboratory and natural origin. Statistically significant differences were also found between young and adult specimens of the dice snake from nature.

Albinism in Natrix tessellata (Serpentes: Natricidae)

Albinism in Natrix tessellata (Serpentes: Natricidae). The Dice Snake, Natrix tessellata, varies in color and pattern, and has several color morphs. Except for melanism, color aberrations are quite rare in the species. Of the two published records of albinism in N. tessellata, the first, from the mid–19th century in Italy is dubious; the second is from Israel. Herein, albinism in juvenile N. tessellata from Slovakia is documented, and the occurrence of albinism in all species of European snakes is discussed.

Effect of Capture, Phenotype, and Physiological Status on Blood Glucose and Plasma Corticosterone Levels in Free-Ranging Dice Snakes.

AbstractTheoretically, animals integrate intrinsic and extrinsic factors to respond appropriately to the wide range of stressors they encounter during their life span. We examined how stress response varies between sexes and among morphotypes in wild dice snakes (Natrix tessellata). We also considered reproductive and feeding status and antipredator behavior. We used two indicators of stress (glucose [GLUC] and corticosterone [CORT] levels) at eight sampling time intervals (immediately after capture, up to 17 h after) and a large sample size ( snakes). Concentrations of both markers increased sharply after capture (an equivalent of predation). This acute phase occurred earlier for GLUC (30 min) compared to CORT (60 min). Then the values plateaued to very high levels without decline over time, indicating prolonged saturation of the hypothalamus-pituitary-adrenal axis. In contrast to our expectations, we found no effect of sex, morphotype, or reproductive status. Yet the CORT stress response of those individuals displaying death-feigning (DF)antipredator behavior was attenuated compared to those that did not. Low stress hormones levels may facilitate the expression of DF (high levels supporting fleeing behavior). The presence of partially digested material in the stomach was associated with higher blood GLUC during the plateau. Assaying blood GLUC requires very little blood but was as good as CORT at gauging acute stress response. The prolonged plateau suggests that captivity should be minimized during field studies.

Local industrial pollution induces astrocyte cytoskeleton rearrangement in the dice snake brain: GFAP as a biomarker

The present study was designed to evaluate the responsiveness of modulation of glial fibrillary acidic protein (GFAP) content and its fragmentation in the snake brain as a biomarker of local industrial pollution of aquatic ecosystems. Despite GFAP being a well known cytoskeleton marker of astrocytes’ reactivity in the brain of vertebrates, its expression in the snake brain remains insufficiently described. The GFAP expression and its fragmentation were detected using the immunoblot method in the snake brain. ROS level was determined with dichlorofluorescein diacetate fluorescence. The content of the glial fibrillary acidic protein (GFAP) of filament (cytoskeleton) and soluble (cytosol) fractions in the brain of dice snake Natrix tessellata from three ecosystems with different rates of industrial pollution were studied (two polluted and one clean control site). Characteristic increase in GFAP fragmentation was noted for the snakes from both the researched polluted sites. Significant increase in the content of the GFAP cleaved polypeptide fragments induced by industrial pollution exposure was confirmed in the snakes’ brains. Meaningful GFAP fragmentation was determined in snake brain astrocytes as an increase in cleaved fragments of 47–35 kDa molecular weight for both soluble and cytoskeletal GFAP fractions. We found significant abnormality in the ratio of the GFAP soluble fraction to the cytoskeletal one in contaminant-exposed dice snakes. It should testify to significant metabolic disturbance in nerve cells of the dice snakes. Furthermore, growth of reactive oxygen species level as the main cause of oxidative stress was determined in brains of the snakes exposed to environmental toxicity. Thus, astrocyte cytoskeleton disorders are associated with pollutant-induced redox imbalance in the snake brain. Despite the limited data on glial cell biology in the reptilian brain, the observed results prove that snake astrocytes can respond to the environmental toxicity using typical astroglial response. The presented results evidence that monitoring of molecular characteristics of glial cytoskeleton in dice snakes could be used as reliable biomarker of neurotoxicity and adverse effects of industrial pollution. Further studies are required to elucidate the role of astrocyte cytoskeleton in the response against neurotoxic contaminants.

Spatio-Temporal Dynamics of a Semi-Aquatic Reptile Community in Caspian Reed Bed Ecosystems

Reed bed ecosystems are crucial for the survival of complex animal communities in Europe and Western Asia, but have been subjected to considerable decline, especially in beds in eutrophic shallow lakes, throughout Europe during the last decades. In Western Asia, however, these ecosystems are still wide and ecologically intact, and support highly biodiverse communities of species, including some highly threatened taxa. Here, we studied the spatio-temporal community dynamics of semi-aquatic reptiles in a wide reed bed biotope in Azerbaijan, and present conservation considerations for its optimal management for the survival of the authochtonous reptile species. Three reptile species (two snakes, Natrix natrix and Natrix tessellata, and one turtle Emys orbicularis persica) were found in the study area. Activity intensity was not even throughout the years, and was significantly more related to ambient temperatures in 2016 than in 2017. Interestingly, amphipod abundance was also significantly different between years, and correlated well with the differences in activity patterns observed in a turtle species. There were complex spatio-temporal patterns exhibited by the reptile species at the study area, with an excess of reptile individuals in the high density reed bed habitat during summertime whereas there was an excess of individuals in the open reed bed habitat in spring and autumn. This evidence suggests that there should be seasonal interhabitat movements of reptiles at the study area, and that the reed beds are not perceived as a homogeneous habitat by reptiles. Several hypotheses are presented to explain these unexpected spatio-temporal patterns by reptiles in reed beds. Our study clearly shows that, in order to enhance the conservation of reptiles, it is important to keep a mosaic of areas with dense reed stands (high density of young stems) and of open reed stands (lower density of older stems), thus increasing habitat heterogeneity and favouring small-scale ecological key-structures.

Bioaccumulation of heavy metals in the dice snake Natrix tessellata (Reptilia, Colubridae) from ecosystems of different anthropogenic loads in modern conditions of the steppe Dnieper area

We studied the peculiarities of bioaccumulation and distribution of heavy metals (cadmium, lead, zinc and copper) in the bone tissue, liver and kidneys of the dice snake Natrix tessellata (Laurenti, 1768) inhabited ecosystems under different anthropogenic loads in 2015-2016. Mature individuals were caught in anthropogenically transformed ecosystems of the sanitary-protective zone of the Dniprovska Thermal Power Plant (SPZ DTPP) (48.402°N, 35.111°E, n = 7), coastal ecosystems of the National Nature Park «Velykyi Luh» (47.443°N, 35.149°E, n = 8) and in the Maiorka gully ecosystems (48.260°N, 35.170°E, n = 7). The gross content of metals in the organs of N. tessellata was determined after their dry ashing in a muffle furnace. Determination of the trace elements was performed by atomic absorption spectrophotometry. Among the studied trace elements, zinc has the highest concentrations in the liver, kidneys and bones of N. tessellata. The kidneys and liver are characterized by such amount of concentrations: Zn> Cu> Pb> Cd, but bone tissue has the following ratio Zn> Pb> Cu> Cd. The highest concentration of cadmium is found in the kidneys, and the lowest one – in the bones of snakes. There are the highest contents of lead and copper in the snakes’ liver, but the lowest in the kidneys and bones. The lead bioaccumulations in organs of snakes from different ecosystems are dissimilar. Zinc content in bones is higher than in kidneys and liver, but the lowest concentration is found in the kidneys. It has been found that the highest contents of toxic metals (Cd, Pb) were in the kidneys and liver of the snakes dwelled in the SPZ DTPP ecosystems in comparison with both studied natural ecosystems. In addition, snakes caught in anthropogenically transformed ecosystems of SPZ DTPP are characterised by increased zinc content in all studied organs and enlarged copper concentration in the kidneys. Considering the obtained results on the metals bioaccumulation, the dice snake can be considered as a potential bio-indicator of environmental pollution by heavy metals.

Population and ecological characteristics of the dice snake, Natrixtessellata(Laurenti, 1768), in lower portions of the Vrbanja River(Republic of Srpska, Bosnia and Herzegovina)

Despite their comparative richness and accessibility in the Republic of Srpska and in Bosnia and Herzegovina in general, population studies of reptiles have not been performed in Srpska until recently. For example, one of the most common snake species in this area is the dice snake; nevertheless, previous studies have only reported its distribution. The aim of the present study was to analyze characteristics of the dice snake population along the Vrbanja River. Animals were processed during 2011 throughout their activity period. In total, 199 individuals of all ages were collected. We observed substantial differences in numbers of animals captured in different habitat types classified according to the level of anthropogenic influence. Unexpectedly, the largest number of snakes was captured in the zone with the highest anthropogenic influence, while the smallest number was observed in the zone with no anthropogenic pressures. The above is probably connected with the observed greater number of their most common prey, as well as the absence of raptors in areas with human impact. In the surveyed area, dice snakes feed predominantly on cyprinid fishes, and their reproductive traits are in accord with literature data.

Living with aliens: Suboptimal ecological condition in semiaquatic snakes inhabiting a hot spot of allodiversity

The presence of alien species can embody a form of disturbance for natural communities and the concomitant presence of alien species at different levels within the trophic chain may compromise ecosystem functionality. We studied the ecology of two species of snake (Natrix tessellata and N. natrix) in a system of five ponds with a high number of alien species at a Mediterranean area in central Italy. We evaluated the potential perturbations to ecological traits of snakes due to the presence of alien species, including their body size, population density, and food habits. We compared the studied populations' body size to that estimated in conspecific populations studied elsewhere, including populations at close distance from the study site. Distance sampling and Capture-Mark-Recapture techniques were used to calculate the population density. Diet was estimated using stomach contents and stable isotope ratios (δ15N and δ13C), using Bayesian stable isotope mixing models to estimate the contribution of food sources and species' isotopic niche spaces. Few prey items were found in the stomach contents of either species, with Ameiurus melas as the main prey. Based on isotope niche analyses, N. tessellata diet consisted of only alien species, and N. natrix diet mostly relied on alien species (>80%). Stomach contents revealed high overlap between the two species, although isotopes showed a random resource use (i.e. low isotopic niche space overlap). Overall, we caught a low number of individuals, indicating small population sizes. Moreover, snakes at the study site were comparatively smaller in size than most other populations found in the literature and almost all the recorded individuals were in very poor condition or injured by ingested alien prey. We suggest that the presence of rich allodiversity has negatively affected the snakes’ fitness by decreasing their foraging performance, increasing their risk of being preyed upon, or through other mechanisms.

Do different diets affect oxidative stress biomarkers and metal bioaccumulation in two snake species?

In this study we examined possible differences in heavy metal accumulation and oxidative stress parameters in the liver and muscle of two semi-aquatic snakes: grass snake (Natrix natrix) and dice snake (N. tessellata), that inhabit the same environment but differ in prey diversity. The obtained results revealed some interspecies, inter-tissue, prey-snake and prey-prey differences in heavy metal concentrations. Grass snakes pray contained significantly higher concentrations of Al, Cr and Fe as compared to food of dice snakes. Both investigated snakes accumulated generally lower concentrations of metals than their prey, indicating that they are not at risk of contaminant biomagnification. A significant interspecies difference in accumulation was observed only for Cu and Mn concentrations. On the other hand, analysis of oxidative stress biomarkers showed clear differences between the investigated snake species and the two investigated tissues. The liver of grass snake had increased superoxide dismutase, glutathione reductase and glutathione-S-transferase activities in comparison to dice snake. In muscle, a reverse trend was observed for the activities of these three enzymes, as well as for glutathione peroxidase activity. The higher number of significant correlations observed between oxidative stress biomarkers and heavy metal concentrations in grass snake points to upregulation of the antioxidative system (AOS), which resulted in a lower TBARS concentration. Results show that while the investigated snake species did not differ significantly in the accumulated metals, their defense mechanisms were different. This reveals the complexity of the AOS and points to the cooperation of different AOS components in individuals from natural populations.

PRZEGLĄD „NOWYCH” GATUNKÓW PŁAZÓW I GADÓW WYSTĘPUJĄCYCH W POLSCE

W ostatnich latach doszło do aktualizacji wiedzy o gatunkach płazów i gadów występujących na terenie Polski. Okazało się, że dla części z nich brak jest w pełni jednoznacznych danych dotyczących ich rozmieszczenia, pochodzenia czy także statusu taksonomicznego. W niniejszej pracy podsumowujemy obecny stan wiedzy na temat „nowych” gatunków oraz przedstawiamy propozycję zmian na liście gatunków chronionych. Rzekotka wschodnia i padalec kolchidzki są gatunkami rodzimymi i powinny zostać objęte odpowiednio ochroną ścisłą i częściową. Do czasu zaktualizowania stosownego Rozporządzenia sugerujemy wprowadzenie tych gatunków na wojewódzkie listy gatunków chronionych. Status dalszych czterech (żaby bałkańskiej, ropuchy B. variabilis, murówki zwyczajnej oraz zaskrońca rybołowa) jest niepewny i wymaga dalszych badań. Do czasu wyjaśnienia statusu zaskrońca rybołowa powinien on zostać usunięty z listy gatunków chronionych.