Alpine salamander
Alpine salamander | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Amphibia |
Order: | Urodela |
Family: | Salamandridae |
Genus: | Salamandra |
Species: | S. atra
|
Binomial name | |
Salamandra atra Laurenti , 1768 | |
The alpine salamander (Salamandra atra) is a black salamander that can be found in the French Alps, and through the mountainous range in Europe.[2] It is a member of the genus Salamandra. Their species name, atra, may be derived from the Latin ater, meaning dull black.[3] The salamanders' coloration has evolved over time, as some species are completely monochrome black and others have yellow spotting and marks.[4][5][6][7] Their life expectancy is at least 10 years. There are four subspecies of the alpine salamander, with varied distribution and physical coloration.[8] Unlike other salamanders, whose larvae are developed in water, the alpine salamander and its subspecies are a fully terrestrial species in life and gestation.[8] They give birth to live young.[9]
Alpine salamanders produce toxic compounds from their skin.[8] These compounds may protect them from both predator and microbial threats.[10][11][12][13]
Description
Alpine salamanders are often small in size, and dark brown or black.[8] Members of the subspecies are not wholly black or brown monochrome, but rather have mosaic or spotted patterns.[8] Members of the subspecies Salamandra atra aurorae have bright splotches on its dorsal side and head. The color is often bright yellow, but can range to shades of white or even gray.[8] Distribution of the pigment is dependent on the distribution of certain cells, so may be smooth and even or patchy.[8]
Female S. atra tend to be larger than the males, and can grow up to 151 millimeters, or around 5.9 inches.
Coloration
Most alpine salamanders that are either completely black (melanistic) or predominantly black have the dark pigment as a baseline, but the evolution behind this dark coloring has a winding history.[4] Scientists have studied the hypothesis of if the salamanders start completely black, or if they evolved like that over time.[5] DNA-evidence traced through maternal lineages suggest the latter: that salamanders evolved their black coloration over time.[5]
The yellow coloring on some alpine salamanders is thought to be an
Taxonomy and subspecies
- S. a. atra is a fully melanistic (black) subspecies from central, eastern and Dinaric Alps.[6] This subspecies is the most widespread.[16]
- S. a. pasubiensis, with fewer yellow spots than S. a. aurorae, lives in a different part of the Venetian Prealps.
- S. a. prenjensis lives on Prenj Mountain, part of the Dinaric Alps in Bosnia and Herzegovina. The validity of this subspecies is yet to be confirmed, and some scientists in the field debate if this salamander should be considered its own independent species.[8][18]
Genetic analysis suggests that the Corsican fire salamander (Salamandra corsica) is the closest related species, and the black-yellow coloration is an ancestral feature of alpine salamanders. Proposed colonization from south (Prealps) to Alps was carried out by the fully melanistic (derived feature) S. a. atra after the last retreat of the ice sheets.[18]
Habitat and distribution
Habitat
As terrestrial organisms, these salamanders live on land.[8][19] S. atra tend to live underneath stones or logs, or in rocky crevices in their mountainous habitat.[8] They also are diurnal, and most active in the day with periods of inactivity, rest, or sleep at night.[16] They will engage in nocturnal activity on a weather-dependent basis.[20] Ideal weather for alpine salamanders is rainy or post-rain, at temperatures between 3 and 18 °C (37.4 and 64.4 °F).[16]
Geographic distribution
The alpine salamander is found from the
Their range spans several nations, including: Slovenia, Croatia, Bosnia, Hersegovina, Montenegro, Kosovo, France, Italy, Austria.[citation needed]
Home range and territoriality
They thrive in forest environments that have
This high dependency on a quality nest site supports the theory that many terrestrial salamanders, including S. atra, engage in territorial behaviors.[21] Capture-recapture methods suggest that the species is very stationary;[23] 12 metres (39 ft) was the maximum observed distance traveled by one individual during the summer season. About 120 individuals per hectare were counted in most suitable areas with over 2000 individuals per hectare also observed, suggesting that this rather cryptic species is quite abundant.[17]
Territorial behavior
They employ
Females are more likely to return to their home site, while males are more emboldened to enter another male's territory.[21] Their fecal pellets allow them to both participate in homing behavior, or returning to their own site, and territoriality, and determine intruders on their territory or invade the spaces of others.[21]
Conservation
Alpine salamanders are not resilient to habitat changes— few terrestrial salamanders are— so risks of
One of the greatest dangers to alpine salamanders overall is commercial
Predators
Due to their toxicity,[10][11] as well as decreased concentration of animals at high altitudes,[28] researchers are unsure of consistent predators for alpine salamanders with limited observation.[8] These salamanders do move slowly, which could increase their risk of being caught.[28] Generally, predators of the broad category of toxic Salamandra species can include birds, rats and snakes, as well as other, larger carnivorous mammals like raccoons, minks, wild boars and foxes.[10]
One notable predator of S. atra is young
Feeding
Male and female alpine salamanders have relatively similar diets.[29] Some specific organisms they prey on include species such as beetles, snails, millipedes, and spiders,[30] but alpine salamanders display preferences among prey.[29] S. atra typically consume organisms from the Coleoptera and mollusca taxa.[29] These taxa are the most crucial component of their diet. They also tend to eat larger prey since they themselves are larger salamanders.[29] Such preference indicates a dimensional selectivity, in which the energy intake of prey consumption is maximized.[29] Though alpine salamanders have definite dietary preferences, they have a substantial amount of variation in their diet[29] that corresponds to their own optimized physical needs and prey-catching abilities.[citation needed]
Mating and interactions
Mating pattern
The alpine salamander engages in a promiscuous mating pattern,[20] meaning that they engage in multiple partner pairings. Males travel farther than females do, potentially to follow a scent emitted by females, and typically while still in their juvenile stage.[20] Female S. atra find and defend their shelters, which is a potential reason that they may stay more local than males.[20]
Male-male behavior
Males are more likely to engage in chasing other males, as well as actually fighting with each other.[31] Oftentimes, one male will mount the other, loosely grasp it with his forearms, and start rubbing his head on the other male.[31] The two males will switch roles, and in one studied interaction, continued like this for seven minutes before parting ways.[31] In a second documented fight, the behavior was more intense. When one member tried to leave, the other male chased it to re-engage.[31] This encounter lasted eight minutes. There is both photographic and video evidence of these behaviors.[31] Researchers are unsure if it is caused by territoriality, confusion on sexual identification and mistaken mating, or true combat.[31]
Gestation and reproduction
Alpine salamanders live in a sex ratio of 1:1.[32] Mating occurs on land. The male clasps the female at the forelegs, and fertilization is internal. S. atra are categorized as viviparous, meaning that their young are born alive and unlike many other amphibians, do not go through metamorphosis[8][9] They give birth to 2 young, sometimes 3 or 4. New young alpine salamanders may measure as long as 50 millimetres (2 in) at birth, with the mother measuring only 120 millimetres (4.7 in).[citation needed]
Female alpine salamanders have uteruses that are composed of a single luminal epithelial cell layer, connective tissue, and smooth muscle.[9] The uterine eggs are large and numerous, but, as a rule, only one fully develops in each uterus. The embryo is nourished on the yolk of the other eggs, which more or less dissolve to form a large mass of nutrient matter. The egg mass can be as long as between 25 mm and 40 mm long.[9] The embryo passes through three stages:[33]
- The first stage is when they are still enclosed within the egg and living on its own yolk.[33]
- The second stage is when they are free, within the vitelline mass, eating it directly with their mouths.[9][33]
- The final stage occurs when there is no more vitelline mass. The embryo is possessed of long external gills, which serve as an exchange of nutritive fluid through the maternal uterus, these gills functioning in the same way as the chorionic villi of the mammalian egg.[9][33]
Generally, at altitudes of 650–1,000 metres (2,130–3,280 ft) above sea level, a pregnancy lasts two years, and at altitudes of 1,400-1,700 m above sea level, the pregnancy lasts around three years, though anything within a 2-4 year range is considered standard.[9] Alpine salamander embryos are unique in how they are able to take in these nutrients through a long gestation.[9] A portion of the mother's uterine wall becomes nourishment after the salamanders have already eaten the unfertilized eggs,[9] (called oophagy or stage 1 and 2).[9] They then partake in epitheliophagy, or stage 3, where they ingest these zona trophica cells until birth, and have special tooth-like developments that allow it to do so without detriment to the mother.[9]
Physiology
Glands and toxins
As mentioned above, alpine salamanders have poison glands.[8] They are known to produce some alkaloid molecules and peptide products, and thus have a mustard-like scent associated with them.[10] Salamandra bioproduction is still a developing research area. Salamandarines are a chemical secretion produced by the skin of alpine salamanders, as well as some fire salamanders.[8][34] They are neurotoxins, and are synthesized via a biochemical pathway, completely independent of dietary intake.[8] This means that they make these chemicals within their bodies, not as a result of ingesting poisonous substances.The starting material for this nerve-block is most likely cholesterol, and it is about twice as potent as cyanide.[8] This pales in comparison to other toxins produced by salamanders, but S. atra do not only use this powerful substance to paralyze prey: they may have antimicrobial properties that protect them against bacterial and fungal infections.[8][35] Salamandorone is another biochemical compound produced by S. atra, and though it is less potent against prey it is the strongest antimicrobial weapon these salamanders have.[8][13][35]
There are two main categories of toxin studied, samandarine and samandarone.[8][11] There also exist many other compounds, as well as miscellaneous alkaloid secretions.[8] Both samandarine and samandarone are produced by S. atra species.[11] It is hypothesized that salamandarine is more commonly produced in alpine salamanders as a predator defense mechanism, and salamandorones are produced where there is greater infection risk.[8] There is also noted geographic variation in toxin production by alpine salamanders.[8]
Immunobiology and protection
Samandarone, a toxin they produce via skin secretion, has noted antimicrobial activity.[8] In one study, this toxin was present where there was infection risk, but at low concentration.[8] There is a wide arsenal of toxins produced by S. atra , many of which are antimicrobial or could be precursors to other protective molecules.[8] Nonetheless, the alpine salamander has been relatively lucky in avoiding infection with amphian chytrid fungus[35] compared to other amphibian species.[35][36] This dangerous fungal infection, caused by Batrachochytrium dendrobatidis (Bd) has decimated amphibian populations on every continent.[35] Bd is present in the Alps where alpine salamanders live, but in a study performed in 2012, there were no salamanders who tested positive when swabbed.[35] This may be because Bd infections are more common in species who spend more of their time in water, and since the alpine salamanders are terrestrial, they are less susceptible.[35] An alternate hypothesis proposes that S. atra are resistant via their skin microbiome or a produced molecule, thus granting them immunity.[35][37] This theory is untested, but considering how many salamanders excrete biological toxins, plausible.[35][37]
References
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- ^ "Salamandre noire unique - La Salamandre". Archived from the original on 2020-07-02.
- ^ "Atra meaning in English » DictZone Latin-English dictionary". dictzone.com. Retrieved 2022-12-05.
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- ^ a b "Salamandre noir". Karch.Ch (Swiss information center for amphibians and reptiles). Retrieved 29 June 2020.
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- ^ "Salamandra atra". AmphibiaWeb. 6 December 2018.
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- ^ a b Bonato, Fracasso. Movements, distribution pattern and density in a population of Salamandra atra aurorae (Caudata: Salamandridae). Amphibia-Reptilia 2003, 24, 251-260.
- ^ a b Bonato & Steinfartz. Evolution of the melanistic color in the Alpine salamander Salamandra atra as revealed by a new subspecies from the Venetian prealps. Italian Journal of Zoology 2001, 72, 253-260.
- ISSN 0906-7590.
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- ^ S2CID 89706693.
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- ^ Reinthaler-Lottermoser, Ursula; et al. (8 October 2018). "A new approach for surveying the Alpine Salamander (Salamandra atra) in Austria". Acta Herpetologic: 249–253.
- ^ a b c d e f g Luiselli, Luca; Anibaldi, Claudio; Capula, Massimo (August 12, 1994). "The diet of juvenile adders, Vipera berus, in an alpine habitat". Amphibia-Reptilia: 404–407 – via Brill.
- ^ ISSN 1424-2818.
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- ^ a b c d e f Di Nicola, Matteo Ricardo (November 2022). "Male-male interactions in Alpine salamanders, Salamandra atra atra Laurenti, 1768, with an overview of the main cases reported for the whole genus Salamandra Garsault, 1764". Herpetology Notes. 15: 601–604.
- ^ Body size, population structure and fecundity traits of Salamandra atra atra (Amphibia, Urodela, Salamandridae) population from the northeastern Italian Alps. Vol. 68. Luiselli, Andreone, Capizzi, Anibaldi: Italian Journal of Zoology. 2001. pp. 125–130.
- ^ a b c d Chisholm, Hugh, ed. (1911). . Encyclopædia Britannica. Vol. 1 (11th ed.). Cambridge University Press.
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External links
- Media related to Salamandra atra at Wikimedia Commons
- Data related to Salamandra atra at Wikispecies
- European Field Herping Community. "Picture gallery of S. a. atra, S. a. aurorae and S. a.pasubiensis subspecies". Archived from the original on 2015-09-24. Retrieved 2011-02-20.
- Emina Šunje. "Salamandra atra prenjensis". Archived from the original on 2021-04-27. Retrieved 2011-02-20. (in Bosnian)