Dice snake

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Dice snake
Natrix tessellata capturing a Gobius fish - 20060710.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Genus: Natrix
Species:
N. tessellata
Binomial name
Natrix tessellata
(Laurenti, 1768)
Natrix tessellata distribution map.svg
Distribution of the Natrix tessellata
Synonyms

Coronella tessellata Laurenti, 1768
Coluber tessellatus Bonnaterre, 1790
Tropidonotus tessellatus, part., Wagler, 1830
Natrix tessellata Bonaparte, 1834
Tropidonotus tessellatus Boulenger, 1893 [2]

Contents

Natrix tessellata Schlange frist Fisch.jpg
Natrix tessellata

The dice snake (Natrix tessellata) is a Eurasian nonvenomous snake belonging to the family Colubridae, subfamily Natricinae. It is also called water snake. [3]

Brief description

Illustration of dice snake (top) and grass snake (Natrix natrix) including underside Durigen, 1897, T07.JPG
Illustration of dice snake (top) and grass snake ( Natrix natrix ) including underside
A dice snake in Umbria, Italy Dicesnake umbriaitaly.jpg
A dice snake in Umbria, Italy

Females are bigger than males. Their typical size is 1.0–1.3 m (39–51 in) long. Their color may vary from greyish green to brownish or almost black, with dark spots on the back. The belly is sometimes vividly coloured in yellow or orange, with black spots, very similar to dice, hence the name.

Biology

Living mainly near rivers, streams and lakes, it frequently feeds on fish. Sometimes, it feeds also on amphibians such as frogs, toads, and tadpoles.

Classified as nonvenomous, N. tessellata produces a potent antihemorrhagin in its serum [4] and has been said to produce a neurotoxin through a gland in its mouth. [5] As a defence, it spreads a very bad-smelling secretion from its cloaca. Another defence mechanism is thanatosis, playing dead.

During the mating season (March–May), they congregate in large groups. Egg-laying is usually in July, and one clutch consists of 10–30 eggs. The young snakes hatch in early September.

N. tessellata Natrix tessellata frombosnia.jpg
N. tessellata
Dice snake observed along Caspian Sea in northern Iran Sea Snake.jpg
Dice snake observed along Caspian Sea in northern Iran

Dice snakes hibernate from October to April in dry holes near the water.

Distribution

The dice snake is found throughout much of Eurasia: Afghanistan, Albania, Armenia, Austria, Azerbaijan, Bosnia and Herzegovina, Bulgaria, China, Croatia, Cyprus, Czech Republic, France, Georgia, Germany, Greece, Hungary, India, Iran, Iraq, Israel, Italy, Jordan, Kazakhstan, Kyrgyzstan, Lebanon, Montenegro, North Macedonia, Pakistan, Poland, [6] Romania, Russia, Serbia, Slovakia, Slovenia, Switzerland, Syria, Tajikistan, Turkmenistan, Turkey, Ukraine, Uzbekistan, and Yemen. The species is also present in Egypt.

Research projects

Czech Nature Conservation Agency

The Dice Snake is considered Critically Endangered in the Czech Republic, mostly due to destruction of habitats and the introduction of an invasive species, the American mink. In order to combat this, the Czech Nature Conservation Agency began a project in 2007 to figure out what factors determine the distribution of the Dice Snake. The predictive model suggested that the most influential factors were watercourses and bodies, average annual temperatures, altitude, slope inclination, and precipitation seasonality. At the conclusion of the study, researchers proposed that the next route of study should be focused on areas that should but don't contain Dice Snake populations based on the predictive model. These areas might become the focus for conservation/migration efforts. [7]

Fluctuating Asymmetry in Urban Dice Snake Populations

Urbanization is one of the greatest reasons that habitats for Dice Snake populations are on the decline. As a result, some Dice Snake populations have been forced to live in artificial lakeside habitats. A study published in 2023 researched the effects of urban living on the Dice Snake and found that urban environmental factors influence the fluctuating asymmetry, body condition, and size of dice snake populations.

Fluctuating asymmetry (FA), a measure of developmental instability, was found to be significantly influenced by local environmental variables. Specifically, larger harbors were associated with poorer body condition in dice snakes. This correlation suggests that larger harbors may harbor higher pollutant concentrations or increased human disturbance, leading to adverse effects on snake health and fitness. Proximity to main roads was identified as a significant factor influencing the level of fluctuating asymmetry in dice snake populations. Snakes living closer to main roads exhibited higher levels of asymmetry, indicating potential negative effects of road-related factors on snake development and health.

The study concluded that conservation efforts should focus on mitigating the negative impacts of urbanization on dice snake populations. Strategies may include reducing pollutant release into the environment, exploring alternative road materials to minimize the adverse effects of roads, and implementing measures to reduce human disturbance in snake habitats. [8]

Population Bottlenecks and Resulting Loss of Genetic Variation

Another study in 2001 studied the effect of bottlenecks on the Dice Snake population when Dice Snakes were introduced into several lakes in Switzerland. A bottleneck on a population is "an event that drastically reduces the size of a population" [9]

The study followed two introduced populations, one that was serially bottlenecked and one that was only bottlenecked once. Both populations had much less allelic diversity and resulting heterozygosity (due to inbreeding) than populations that had never been bottlenecked, but the one that was serially bottlenecked displayed a greater severity of these conditions.

Scale anomalies were another factor that was studied during this project. Scale anomalies are often a sign of developmental stress, and the introduced populations had a greater frequency of scale anomalies than normal. The occurrence of scale anomalies correlated with the degree of bottlenecking and individual heterozygosity. Developmental stability, reflected in the ability to withstand environmental and genetic perturbations, is indirectly linked to individual fitness. Studies on other snake species indicate a negative relationship between scale anomalies and traits such as locomotion speed and growth rate, which affect survival.

Researchers argue that population decline should be prevented and large populations maintained in order to conserve allelic diversity and genetic variability. But the root problem of habitat destruction must be addressed as well. Habitat protection and restoration are crucial for protecting natural populations of Dice Snake. Demographic and genetic monitoring of populations can aid in detecting declines and assessing genetic variability. Introduction of new genes from different populations can enhance genetic variability, but careful selection of source populations is essential to avoid harming existing populations and outbreeding depression. [10]

Parasitic Threat

One of the most numerous populations lives in the vicinity of the ruins of Histria, in the Dobruja region, Romania. This population has been recently discovered to be threatened by a parasitic nematode of the genus Eustrongylides . Since 2005, the population from Histria has been receiving researchers' attention. For example, a joint Romanian–Swedish–Czech research program is focused on population biology studies and parasitic threats of this unique coastal population. An overview on Biology, Distribution and Conservation is given by Mebert (2011). [11]

Related Research Articles

Small populations can behave differently from larger populations. They are often the result of population bottlenecks from larger populations, leading to loss of heterozygosity and reduced genetic diversity and loss or fixation of alleles and shifts in allele frequencies. A small population is then more susceptible to demographic and genetic stochastic events, which can impact the long-term survival of the population. Therefore, small populations are often considered at risk of endangerment or extinction, and are often of conservation concern.

<span class="mw-page-title-main">Population bottleneck</span> Effects of a sharp reduction in numbers on the diversity and robustness of a population

A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as genocide, specicide, widespread violence or intentional culling. Such events can reduce the variation in the gene pool of a population; thereafter, a smaller population, with a smaller genetic diversity, remains to pass on genes to future generations of offspring. Genetic diversity remains lower, increasing only when gene flow from another population occurs or very slowly increasing with time as random mutations occur. This results in a reduction in the robustness of the population and in its ability to adapt to and survive selecting environmental changes, such as climate change or a shift in available resources. Alternatively, if survivors of the bottleneck are the individuals with the greatest genetic fitness, the frequency of the fitter genes within the gene pool is increased, while the pool itself is reduced.

<span class="mw-page-title-main">Founder effect</span> Effect in population genetics

In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, using existing theoretical work by those such as Sewall Wright. As a result of the loss of genetic variation, the new population may be distinctively different, both genotypically and phenotypically, from the parent population from which it is derived. In extreme cases, the founder effect is thought to lead to the speciation and subsequent evolution of new species.

<span class="mw-page-title-main">Genetic diversity</span> Total number of genetic characteristics in a species

Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species and can be attributed to the span of survival for a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary.

<span class="mw-page-title-main">Fire salamander</span> Species of amphibian

The fire salamander is a common species of salamander found in Europe.

<span class="mw-page-title-main">Laysan finch</span> Species of bird

The Laysan finch is a species of Hawaiian honeycreeper, that is endemic to the Northwestern Hawaiian Islands. It is one of four remaining finch-billed Hawaiian honeycreepers and is closely related to the smaller Nihoa finch. The Laysan finch is named for Laysan, the island to which it was endemic on its discovery. It was subsequently introduced to a few other atolls, and its historical range included some of the main islands.

The Allee effect is a phenomenon in biology characterized by a correlation between population size or density and the mean individual fitness of a population or species.

<span class="mw-page-title-main">Minimum viable population</span> Smallest size a biological population can exist without facing extinction

Minimum viable population (MVP) is a lower bound on the population of a species, such that it can survive in the wild. This term is commonly used in the fields of biology, ecology, and conservation biology. MVP refers to the smallest possible size at which a biological population can exist without facing extinction from natural disasters or demographic, environmental, or genetic stochasticity. The term "population" is defined as a group of interbreeding individuals in similar geographic area that undergo negligible gene flow with other groups of the species. Typically, MVP is used to refer to a wild population, but can also be used for ex situ conservation.

<span class="mw-page-title-main">Conservation genetics</span> Interdisciplinary study of extinction avoidance

Conservation genetics is an interdisciplinary subfield of population genetics that aims to understand the dynamics of genes in a population for the purpose of natural resource management, conservation of genetic diversity, and the prevention of species extinction. Scientists involved in conservation genetics come from a variety of fields including population genetics, research in natural resource management, molecular ecology, molecular biology, evolutionary biology, and systematics. The genetic diversity within species is one of the three fundamental components of biodiversity, so it is an important consideration in the wider field of conservation biology.

Genetic viability is the ability of the genes present to allow a cell, organism or population to survive and reproduce. The term is generally used to mean the chance or ability of a population to avoid the problems of inbreeding. Less commonly genetic viability can also be used in respect to a single cell or on an individual level.

<span class="mw-page-title-main">Aesculapian snake</span> Species of snake

The Aesculapian snake, is a species of nonvenomous snake native to Europe, a member of the Colubrinae subfamily of the family Colubridae. Growing up to 2 metres (6.6 ft) in length, it is among the largest European snakes, similar in size to the four-lined snake and the Montpellier snake. The Aesculapian snake has been of cultural and historical significance for its role in ancient Greek, Roman and Illyrian mythology and derived symbolism.

Genetic variability is either the presence of, or the generation of, genetic differences. It is defined as "the formation of individuals differing in genotype, or the presence of genotypically different individuals, in contrast to environmentally induced differences which, as a rule, cause only temporary, nonheritable changes of the phenotype". Genetic variability in a population is important for biodiversity.

Inbreeding depression is the reduced biological fitness that has the potential to result from inbreeding. Biological fitness refers to an organism's ability to survive and perpetuate its genetic material. Inbreeding depression is often the result of a population bottleneck. In general, the higher the genetic variation or gene pool within a breeding population, the less likely it is to suffer from inbreeding depression, though inbreeding and outbreeding depression can simultaneously occur.

Extinction vortices are a class of models through which conservation biologists, geneticists and ecologists can understand the dynamics of and categorize extinctions in the context of their causes. This model shows the events that ultimately lead small populations to become increasingly vulnerable as they spiral toward extinction. Developed by M. E. Gilpin and M. E. Soulé in 1986, there are currently four classes of extinction vortices. The first two deal with environmental factors that have an effect on the ecosystem or community level, such as disturbance, pollution, habitat loss etc. Whereas the second two deal with genetic factors such as inbreeding depression and outbreeding depression, genetic drift etc.

The striped nerite, scientific name Theodoxus transversalis, is a species of small freshwater snail with an operculum, an aquatic gastropod mollusk in the family Neritidae, the nerites.

Genetic erosion is a process where the limited gene pool of an endangered species diminishes even more when reproductive individuals die off before reproducing with others in their endangered low population. The term is sometimes used in a narrow sense, such as when describing the loss of particular alleles or genes, as well as being used more broadly, as when referring to the loss of a phenotype or whole species.

<span class="mw-page-title-main">Ornate box turtle</span> Subspecies of turtle

The ornate box turtle is one of only two terrestrial species of turtles native to the Great Plains of the United States. It is one of the two different subspecies of Terrapene ornata. It is the state reptile of Kansas and Nebraska. It is currently listed as threatened in Illinois and is of concern and protected in six Midwestern states.

A genetic isolate is a population of organisms with little genetic mixing with other organisms within the same species due to geographic isolation or other factors that prevent reproduction. Genetic isolates form new species through an evolutionary process known as speciation. All modern species diversity is a product of genetic isolates and evolution.

<span class="mw-page-title-main">Barred grass snake</span> Species of snake

The barred grass snake is a non-venomous colubrid snake from Western Europe, living in and close to water. It was included within the grass snake species, Natrix natrix, until August 2017, when genetic analysis led to its reclassification as a separate species.

References

  1. Mebert, K.; Amr, Z.S.S.; Al Johany, A.M.H.; Aloufi, A.A.H.; Jiang, J.; Meyer, A.; Sterijovski, B.; Baha El Din, S.; Pleguezuelos, J.; Sá-Sousa, P.; Corti, C.; Ajtic, R.; Tuniyev, S.; Orlov, N.L.; Ananjeva, N.B.; Cogălniceanu, D.; Andrén, C.; Crnobrnja-Isailović, J.; Aghasyan, A.; Avci, A.; Tuniyev, B.; Lymberakis, P.; Wilkinson, J.; Üzüm, N.; Podloucky, R.; Kaya, U.; Vogrin, M.; Pérez Mellado, V.; Cheylan, M.; Nettmann, H.K.; De Haan, C.C.; Schmidt, B.; Lau, M.; Borkin, L.; Milto, K.; Golynsky, E.; Belouskova, A.; Rustamov, A; Nuridjanov, D.; Munkhbayar, K. (2021). "Natrix tessellata". IUCN Red List of Threatened Species . 2021: e.T157256A745071. doi: 10.2305/IUCN.UK.2021-2.RLTS.T157256A745071.en . Retrieved 21 February 2022.
  2. Boulenger, G.A. 1893. Catalogue of the Snakes in the British Museum (Natural History), Volume I. London. pp. 233-234
  3. Guicking, Daniela; Joger, Ulrich; Wink, Michael (25 August 2009). "Cryptic diversity in a Eurasian water snake (Natrix tessellata, Serpentes: Colubridae): Evidence from mitochondrial sequence data and nuclear ISSR-PCR fingerprinting". Organisms Diversity & Evolution. 9 (3): 201–214. doi: 10.1016/j.ode.2009.03.001 .
  4. Borkow, Gadi; Gutierrez, Jose Maria; Ovadia, Michael (December 1994). "A potent antihemorrhagin in the serum of the non-poisonous water snake Natrix tessellata: isolation, characterization and mechanism of neutralization". Biochimica et Biophysica Acta (BBA) - General Subjects. 1201 (3): 482–490. doi:10.1016/0304-4165(94)90080-9. PMID   7803481.
  5. "Wildest Europe - Swimming Snake". www.facebook.com. Discovery Channel UK. Retrieved 2018-03-17.[ unreliable source? ]
  6. Vlcek, Petr; Bartlomiej Najbar and Daniel Jablonski. (2010) First records of the Dice Snake (Natrix tessellata) from the North-Eastern part of the Czech Republic and Poland. Archived 2010-04-14 at the Wayback Machine Herpetology Notes3:23-26
  7. Chmelař, Jan; Civiš, Petr; Fischer, David; Frynta, Daniel; Jeřábková, Lenka; Rudolfová, Veronika; Rehák, Ivan (28 December 2023). "Protecting isolated reptile populations outside their main area of distribution: a predictive model of the Dice snake, Natrix tessellata, distribution in the Czech Republic". Biodiversity Data Journal. 11. doi: 10.3897/BDJ.11.e114790 . PMID   38188184.
  8. Mészáros, Boglárka; Bürgés, József; Tamás, Mónika; Gál, Blanka; Bohus, Attila; Schmera, Dénes (December 2023). "Effects of the urban environment on the developmental stability, size and body condition of dice snakes (Natrix tessellata) living in artificial lakeside habitats". Ecological Indicators. 156: 111117. doi:10.1016/j.ecolind.2023.111117.
  9. "population bottleneck". Scitable. Nature Education.
  10. Gautschi, Barbara; Widmer, Alex; Joshi, Jasmin; Koella, Jacob C. (September 2002). "Increased frequency of scale anomalies and loss of genetic variation in serially bottlenecked populations of the dice snake, Natrix tessellata". Conservation Genetics. 3 (3): 235–245. doi:10.1023/A:1019924514465.
  11. Mebert, Konrad (2011). The Dice Snake, Natrix Tessellata: Biology, Distribution and Conservation of a Palaearctic Species. DGHT. ISBN   978-3-9812565-4-3.[ page needed ]