Blue-spotted cross-tooth newt

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Blue-spotted cross-tooth newt
Blue-spotted newt (Ambystoma laterale)

Blue-spotted newt ( Ambystoma laterale )

Systematics
without rank: Amphibians (Lissamphibia)
Order : Tail amphibian (caudata)
Superfamily : Salamander relatives (Salamandroidea)
Family : Transverse newts (Ambystomatidae)
Genre : True transverse newts ( Ambystoma )
Type : Blue-spotted cross-tooth newt
Scientific name
Ambystoma laterale
Hallowell , 1856

The blue-spotted salamander ( Ambystoma laterale ), and blue-stain-toothed cross pig or Blaupunkt salamander called, is one in eastern North America common salamander from the family of cross-tooth newts (Ambystomatidae). It is the most northerly occurring species in the family in eastern North America and can still be found in areas of up to 55 ° north latitude .

Research history

The species was first scientifically described in 1856 by Edward Hallowell under the name Ambystoma laterale , which is still in use today . In 1868 Edward Drinker Cope interpreted Ambystoma laterale as a variety of the Jefferson transverse newt ( Ambystoma jeffersonianum ). At the same time he described a new species within the genus with Ambystoma platineum and particularly emphasized its similarity to Ambystoma jeffersonianum var. Laterale . Several years later, Cope partially revised his original opinion and now also assessed the species he newly described as a subspecies of the Jefferson cross-toothed newt. Cope's outline (only one species with three subspecies) was valid for several decades.

In 1934, Wesley Clanton described a population of these tailed amphibians from southern Michigan , in which he could distinguish two different forms, which he simply referred to as the "dark form" and the "light form". Both forms apparently paired with each other. To Clanton's surprise, the total population he studied showed some peculiarities in terms of gender distribution. Females were much more common than males, with the ratio between females and males varying between 2: 1 and 52: 1. The excess of females was apparently due to the "light form"; if only the "dark form" was considered, he always found a ratio of approximately 1: 1. In addition, Clanton found that the "light form" consisted of almost 100% female animals. Crossbreeding experiments showed him that when males and females of the "dark form" were mated, roughly the same number of female and male larvae of the "dark form" hatched from the eggs, while a mating of "light females" and "dark males" were exclusively female Copies of the "light form" produced. Although he suspected that the "light form" was a hybrid and considered the continued existence of the total population, he did not draw any conclusions about the taxonomic consequences of his observations.

With Ambystoma tremblayi , another very similar form was described as an independent species from southern Canada in 1943 . In 1954, Sherman A. Minton identified Clanton's "dark form" as Ambystoma laterale and gave it an independent species status again. He identified Clanton's "light form" as a hybrid between Ambystoma laterale and Ambystoma jeffersonianum .

It was not until the 1960s that Thomas M. Uzzell Jr. managed to untie the knot in several works. He was able to prove that the essentially purely female forms, which he assigned to two species ( Ambystoma platineum and Ambystoma tremblayi ), are animals with triploid chromosome sets (3n = 42) that are hybridized from two species ( Ambystoma laterale and Ambystoma jeffersonianum ) with normal gender distribution and diploid chromosome sets (2n = 28). Together with Sarah M. Goldblatt , he found evidence that Ambystoma tremblayi has two sets of chromosomes from Ambystoma laterale and one set of chromosomes from Ambystoma jeffersonianum , while the opposite is true for Ambystoma platineum .

Color drawing and furrows of the blue-spotted cross-tooth newt

features

Adult animals reach a total length of 7 to 14 centimeters, with about 40-50% being accounted for by the long tail. The males stay on average slightly smaller than the females and have a slightly longer tail in relation to the trunk. The trunk itself is segmented by 12-14 rib furrows.

The basic color on the back is black to gray-black, on the belly a little lighter. The back, abdomen and especially the lower areas of the flanks show a multitude of bluish-white spots. The eye-catching drawing of the flanks also gave the blue-spotted cross-toothed newt its scientific addition “ laterale ” (from the Latin “ lateralis ” - “side”).

The females of the triploid hybrid form Ambystoma tremblayi are slightly larger than the females of the diploid form, with a total length of up to 16 centimeters. The basic color is slightly lighter and is described as dark gray to gray-black. The bluish color drawing is less pronounced and diffuse.

Distribution, habitat, way of life

Distribution areas of the blue-spotted cross-tooth newt (magenta), the Jefferson cross-tooth newt (yellow) and the hybrids of both species (purple)

The blue-spotted cross-toothed newt occurs in the northeastern United States around the Great Lakes ( Minnesota , Michigan , Wisconsin , Indiana , Illinois , Ohio , New York ), Iowa and New Jersey, and the New England states of New Hampshire , Connecticut , Maine , Massachusetts and Vermont before. In southeastern Canada , the distribution area extends over the provinces of Ontario , Québec , the maritime provinces of Prince Edward Island , Nova Scotia and New Brunswick and the sub-province of Labrador . In the south, the range overlaps with that of the Jefferson cross-toothed newt. Here the hybrids of the two species dominate.

The populations are predominantly north of the so-called Wisconsin glacial line (glaciation limit of the last glacial period ; the Wisconsin glacial period corresponds to the Würm glacial period in the European Alpine region and the Weichselian glacial period in north and north-central Europe). Accordingly, it can be assumed that the blue-spotted cross-toothed newt first settled in its current range after the end of the last glacial period.

Humid deciduous and mixed forests and swampy scrubland are preferred as land habitats. During the day, the animals hide in rodent structures, under dead wood, fallen leaves or rocks, in order to search for food for insects , worms and snails at dusk and at night . The wintering takes place in frost-proof shelters on land. Small aquatic bodies such as ponds and ditches within forests serve as reproductive waters, which must not dry out too early in order to ensure larval development .

Reproduction and Individual Development

Blue-spotted newt ( Ambystoma laterale )

The mating season begins in spring, immediately after the end of the frost period. Triggered by the first spring rains, the blue-spotted cross-toothed newts migrate to their spawning grounds. Spawning then takes place within a few days ("explosive spawning"; compare, for example, common frog ). Mating takes place underwater and begins with mutual recognition of a partner. This is done on the one hand by releasing chemical attractants and on the other hand by nudging the flanks and the cloaca region. If a partner ready to mate has been recognized, the male clasps the female from the back with the front legs in the area of ​​the shoulder girdle (dorsal amplexus ). Subsequently, the male releases the female again from the clutch, moves further forward and deposits one or more spermatophores on the substrate, which are ingested by the female.

The eggs are laid within two days of mating. A female produces 120 to 300 (on average 216) gelatinous eggs per season. The eggs are usually deposited individually or in small clumps of two to four pieces on aquatic plants or plant remains in the water.

After three to four weeks, the larvae hatch and begin an aquatic way of life. They mainly feed on small crustaceans ( daphnia , ostracods ) and mosquito larvae. Metamorphosis takes place two to three months after hatching ; the rest of life takes place on land. After two years the animals finally become sexually mature. Males at this point have a head-trunk length of at least 42 mm. Sexually mature females are slightly larger with a head-trunk length of at least 51 mm.

Hybridization, Gynogenesis, and Kleptogenesis

Jefferson transverse newt ( Ambystoma jeffersonianum )
Ambystoma barbouri

In the course of time, in addition to Ambystoma platineum and Ambystoma tremblayi , other hybrid forms of the blue- spotted cross-tooth newt were identified; not only with the Jefferson cross-toothed newt ( Ambystoma jeffersonianum ), but also with other representatives of the genus such as the narrow-headed newt ( Ambystoma texanum ) and the eastern tiger salamander ( Ambystoma tigrinum ). The species group and its hybrids are also known as the " Ambystoma complex". Hybrids of the " Ambystoma complex" can each have a different degree of ploidy . In addition to diploid and triploid forms, tetraploid and even pentaploid forms can also occur. All of these hybrids are almost exclusively female and all have at least one set of Ambystoma laterale chromosomes .

In order to cope with the growing number of different hybrids, a simple coding was introduced, which symbolizes the individual chromosome sets of the parent taxa. Here correspond

  • "J" for Ambystoma jeffersonianum - (JJ)
  • "L" for Ambystoma laterale - (LL)
  • "T" for Ambystoma texanum - (TT) and
  • "Ti" for Ambystoma tigrinum - (TiTi)

the chromosome sets of the diploid, bisexual species involved. The triploid hybrids defined by Uzzell accordingly have the codes LLJ for Ambystoma tremblayi and LJJ for Ambystoma platineum . Locally, up to 70 percent of a population can consist of such hybrids.

The purely female populations, which have clonal - triploid sets of chromosomes , use the sperm of males of various Ambystoma species to stimulate oviposition, without however needing and passing on their genetic information (chromosomes). This phenomenon, discovered in transverse tooth newts in the 1960s, is also known as gynogenesis .

Investigations of the mitochondrial DNA (mtDNA) of the female hybrid populations show hardly any similarities with the mtDNA of the potential parent taxa. Instead, there is a close relationship with a population of Ambystoma barbouri ("BB") from Kentucky , away from the range of Ambystoma laterale and the hybrids associated with it. The differences in the mtDNA indicate that the all-female hybrids split off from this Ambystoma barbouri population about 2.4-3.9  Ma ago. In contrast, no traces of Ambystoma barbouri can be found in the chromosomal DNA of the hybrid forms . This indicates that the hybrids regularly incorporate chromosomal DNA from the “sperm donors” into their own DNA and thus more and more genetically assimilate to this over time. The term kleptogenesis (after the ancient Greek κλέφτης - kleptěs = "thief" and γένεσις - genesis = "birth") was proposed for this unusual form of reproduction . Since all hybrids have at least one set of Ambystoma laterale chromosomes , the blue-spotted newt appears to have played a key role in this process.

Danger

The entire population of this species is currently not considered threatened. In the Red List of the World Conservation of Nature Union , the blue-spotted cross-toothed newt is therefore listed as “not at risk” (“least concern”). In individual states in the north-east of the USA, on the other hand, the status of the species is classified as "special concern", "threatened" or "endangered". Reasons include the loss of near-natural forests and forest waters, clear cutting in forests and acid rain , which lowers the pH value in the larval habitats below a critical limit (around pH 4.5 to 5). Competition with single-sex populations (see above) could also inhibit local “normal populations” from spreading.

literature

  • J. Alan Holman: The Amphibians and Reptiles of Michigan - A Quaternary and Recent Faunal Adventure , Ambystoma laterale, pp. 31 ff., Wayne State University Press, 2012, ISBN 0814332390 , ( Online Version - Google books )

Individual evidence

  1. ↑ H. Zucchi & R. Gonschorek: On biology, especially on the behavioral biology of the axolotl Ambystoma mexicanum (Shaw, 1789) (Caudata: Ambystomatidae). In: Salamandra , Volume 19, Number 3, 1983, pp. 123-140, ( digitized version ).
  2. ^ Th. CH Cole: Dictionary of animal names: Latin-German-English German-Latin-English. 2nd edition, Springer Verlag, 2015, ISBN 978-3-662-44241-8 , p. 18, ( reading sample ).
  3. ^ F. Mutschmann: Diseases of the amphibians. 2nd edition, Enke Verlag, 2010, ISBN 978-3-8304-1097-3 , p. 18, ( reading sample ).
  4. ↑ KJ Ryan, JD Zydlewski & AJK Calhoun: Using Passive Integrated Transponder (PIT) Systems for Terrestrial Detection of Blue-Spottet Salamanders (Ambystoma laterale) in situ. In: Herpetological Conservation and Biology , Volume 9, Number 1, 2014, pp. 97-105, ( digitized ).
  5. ^ WE Duellman & SS Sweet: Distribution Patterns of Amphibians in the Nearctic Region of North America. In: WE Duellman (Ed.): Patterns of Distribution of Amphibians: A Global Perspective. Johns Hopkins University Press, 1999, ISBN 0-8018-6115-2 , pp 31-110, ( excerpt )
  6. ↑ E. Hallowell: Description of several species of Urodela, with remarks on the geographical distribution of the Caducibranchiate Division of these animals and their classification. In: Proceedings of the Academy of Natural Sciences of Philadelphia , Volume 8, 1856, pp. 6-11, ( digitized ).
  7. ^ ED Cope: A review of the species of the Amblystomidae. In: Proceedings of the Academy of Natural Sciences of Philadelphia , Volume 19, 1868, pp. 166-211, ( digitized version )
  8. ^ ED Cope: Check-list of North American Batrachia and Reptilia; with a systematic list of the higher groups, and an essay on geographical distribution. Based on the specimens contained in the US National Museum. In: Bulletin of the United States National Museum , Volume 1, 1875, pp. 1-104, ( digitized ).
  9. ^ A b W. Clanton: An unusual situation in the salamander Ambystoma jeffersonianum (Green). In: Occasional Papers of the Museum of Zoology - University of Michigan , Volume 290, 1934, pp. 1-14, ( digitized ).
  10. ↑ N.-M. Comeau: Une ambystome nouvelle. In: Annales de l'Association Canadienne-Française pour l'Avancement des Sciences , Volume 9, 1943, pp. 124-125.
  11. ↑ Sh. A. Minton: Salamanders of the Ambystoma jeffersonianum complex in Indiana. In: Herpetologica , Volume 10, Number 3, 1954, pp. 174-179.
  12. ↑ Th. M. Uzzell Jr. & SM Goldblatt: Serum Proteins of Salamanders of the Ambystoma jeffersonianum Complex, and the Origin of the Triploid Species of this Group. In: Evolution , Volume 21, Number 2, 1967, pp. 345-354, ( digitized ).
  13. ↑ WF Weller & WG Sprules: Taxonomic status of male salamanders of the Ambystoma jeffersonianum complex from an Ontario population, with the first record of the Jefferson salamander, A. jeffersonianum (Green), from Canada. In: Canadian Journal of Zoology , Volume 54, 1976, pp. 1270-1276, ( digitized ).
  14. ↑ FL Downs: Unisexual Ambystoma from the Bass Islands of Lake Erie. In: Occasional Papers of the Museum of Zoology - University of Michigan , number 685, 1978, 36 p., ( Digitized version ).
  15. ↑ a b c Th. M. Uzzell Jr .: Ambystoma laterale Hallowell - Blue-spotted Salamander. In: Catalog of American Amphibians and Reptiles (CAAR) , entry 48, 1967, pp. 48.1-48.2, ( https://repositories.lib.utexas.edu/handle/2152/44974 [digitized version ]).
  16. ↑ Th. M. Uzzell Jr .: Ambystoma tremblayi Comeau - Tremblay's salamander. In: Catalog of American Amphibians and Reptiles (CAAR) , entry 50, 1967, pp. 50.1-50.2, ( https://repositories.lib.utexas.edu/handle/2152/44978 [digitized]).
  17. ↑ a b c Ambystoma laterale in the IUCN Red List of Threatened Species 2015.4. Listed by: IUCN SSC Amphibian Specialist Group, 2015. Accessed March 6, 2019.
  18. ↑ JW Demastes, JM Eastman & JS East: Phylogeography of the Blue-spotted salamander Ambystoma laterale (Caudata: Ambystomatidae). In: American Midland Naturalist , Volume 157, 2009, pp. 149–161, ( digitized )
  19. ^ A b Massachusetts Division of Fisheries & Wildlife: Blue-Scoffs Salamander Fact Sheet. 2016, 6 p., ( Digitized version ).
  20. ↑ a b c H. M. Wilbur: The Ecological Relationship of the Salamander Ambystoma laterale to its All-Female, Gynogenetic Associate. In: Evolution , Volume 25, Number 1, 1971, pp. 168–179, ( digitized version )
  21. ↑ LA Lowcock, H. Griffith & RW Murphy: The Ambystoma laterale-jeffersonianum Complex in Central Ontario: Ploidy Structure, Sex Ratio, and Breeding Dynamics in a Bisexual-unisexual Community. In: Copeia , Volume 1991, Number 1, 1991, pp. 87-105, ( digitized version )
  22. ^ MG Bolek: Ambystoma laterale (Blue-spotted Salamander) Courtship and egg laying behavior. In: Herpetological Review , Volume 29, Number 3, 1998, p. 162, ( digitized version )
  23. ^ LD Houck & St. J. Arnold: Courtship and Mating Behavior. In: BGM Jamieson (ed.): Reproductive Biology and Phylogeny of Urodela , Science Publishers, Inc., 2003, ISBN 978-1-57808-271-1 , pp. 383-424, ( digitized ).
  24. ↑ a b H. M. Wilbur: Propagule Size, Number, and Dispersion Pattern in Ambystoma and Asclepias. In: The American Naturalist , Volume 111, Number 977, 1977, pp. 43-68, ( digitized ).
  25. ↑ LE Licht & JP Bogart: Growth and sexual maturation in diploid and polyploid salamanders (genus Ambystoma). In: Canadian Journal of Zoology , Volume 67, 1989, pp. 812-818, ( digitized ).
  26. ↑ S. Noël, J. Dumoulin, M. Ouellet, P. Galois & F.-J. Lapointe: Rapid Identification of Salamanders from the Jefferson Complex with Taxon-Specific Primers. In: Copeia , number 1, 2008, pp. 158–161, ( digitized version ).
  27. ↑ K. Bi, JP Bogart & J. Fu: The prevalence of genome replacement in unisexual salamanders of the genus Ambystoma (Amphibia, Caudata) revealed by nuclear gene genealogy. In: BMC Evolutionary Biology , Volume 8, Number 158, 2008, 9 pp. Doi : 10.1186 / 1471-2148-8-158 .
  28. ↑ JP Bogart & LE Licht: Reproduction and the origin of polyploids in hybrid salamanders of the genus Ambystoma. In: Canadian Journal of Genetics and Cytology , Volume 28, Number 4, 1986, pp. 605-617, ( digitized ).
  29. ^ A b J. P. Bogart & MW Klemens: Additional Distributional Records of Ambystoma laterale, A. jeffersonianum (Amphibia: Caudata) and Their Unisexual Kleptogens in Northeastern North America. In: American Museum Novitates , number 3627, 2008, 58 p., ( Digitized version )
  30. ↑ JP Bogart, K. Bi, J. Fu, DWA Noble & J. Niedzwiecki: Unisexual salamanders (genus Ambystoma) present a new reproductive mode for eukaryotes. In: Genome , Volume 50, 2007, pp. 119-136, ( digitized version ).
  31. ^ FJ Kutka & MD Bachmann: Acid sensitivity and water chemistry correlates of amphibian breeding ponds in northern Wisconsin USA. In: Hydrobiologia , Volume 208, 1990, pp. 153-160, ( digitalisat ).

Web links

Commons : Ambystoma laterale  - album with pictures, videos and audio files