Short-tailed dwarf hamster

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Short-tailed dwarf hamster
Roborowski hamster (Phodopus roborovskii)

Roborowski hamster ( Phodopus roborovskii )

Systematics
Order : Rodents (Rodentia)
Subordination : Mouse relatives (Myomorpha)
Superfamily : Mice-like (Muroidea)
Family : Burrowers (Cricetidae)
Subfamily : Hamster (Cricetinae)
Genre : Short-tailed dwarf hamster
Scientific name
Phodopus
Miller , 1910

The short-tailed dwarf hamsters ( Phodopus ) form a genus of hamsters and include the Roborowski dwarf hamster and the Djungarian dwarf hamster . Fossilized, they are known from the Pleistocene in Eurasia . They inhabit the forests, steppes and semi-deserts in Mongolia , in southern Siberia and in neighboring areas of China and Kazakhstan, and feed mainly on the seeds of plants.

Short-tailed dwarf hamsters are small hamsters with a short tail that does not protrude from the fur. They have special adaptations to extreme temperatures, such as hairy paws and a special thermoregulation .

Body features

External body features

The body of the short-tailed dwarf hamster is strong and the head-trunk length is 5.3 to 10.2 centimeters. At 4 to 14 millimeters, the tail length is usually less than a fifth and the thickly hairy tail is shorter than the hind paws. The features of the head are similar to those of other dwarf hamsters, but the snout is shorter, the neck is comparatively weak and the short, thin auricles are hairy. When bent forward, they do not reach the comparatively large eyes.

The paws of the short-tailed dwarf hamsters are short and wide. The fifth toe of the hind paw is not shortened and is only slightly shorter than the fourth. The first toe of the front paw has a blunt nail and the remaining toes have claws . In contrast to those of other hamsters, these are more than half as long as the corresponding toes, at least in winter. The soles of the front and rear paws are hairy up to the claws. The pads are smaller and not visible because of the thick hair.

The fur of the short-tailed dwarf hamster is gray to brown-yellow on the top and white on the underside. On the sides of the body, the fur on the underside runs upwards in three arcs. The sides of the muzzle, the upper lips, the lower part of the cheeks and flanks, the limbs, the tail and the belly are white. The Djungarian hamsters have a dark eel line . There is no dark spot on the chest. In contrast to other hamsters, the front wall of the cheek pouches is hairy. These are large and the females have eight teats .

skull

The facial skull of the short-tailed dwarf hamster is comparatively short. The zygomatic arches are widely spread, wider in the front than in the back, and they diverge steeply. The original surface of the masseter muscle on the upper jaw is well demarcated, covers the lower eye hole and extends further up and back to the front section of the zygomatic arch than in other hamsters.

Especially in the area of ​​the skull base , the skull is high and the brain capsule is comparatively high and extensive. There are no bone ridges between the frontal bone and the parietal bone . The wing pits of the sphenoid bone are wide and slightly deepened in a U-shape. The construction of the tympani is similar to that of the mouse hamster . They are small with elongated tubular front ends.

The lower jaw of the short-tailed dwarf hamster is characteristic of hamsters. The notch on the branches is deep and the processes, especially the muscular process and the angular process, are long. The bony cusp supporting the tooth sockets is comparatively weak and lies in front of the middle of the muscle process. The lower jaw body is relatively short and curved more steeply than in other hamsters.

denture

The cusps of the upper molars face each other. Even if they are slightly offset from one another, the furrows between them are closed. Only the furrow between the middle pair of cusps of the first molar can be open to the front and inward. The cusps of the lower molars are offset from one another. However, closed furrows are still present, even those between the middle pair of cusps of the first molar tooth and those between the front pair of cusps of the second molar tooth. The front cusps of the first upper molar tooth are comparatively large and of the same length. Compared to the following pair of cusps, they are arranged noticeably closer and clearly shifted outwards. The anterior cusps of the first lower molar, on the other hand, are more clearly separated from each other and the outer one is noticeably larger than the inner one.

The inner "collars" of the second and third upper molars tend to shrink, especially those of the third molar, while the outer ones are pronounced. The length of the third upper molar tooth corresponds approximately to half the length of the second upper molar tooth. Usually it is a little more. The length of the third lower molar tooth corresponds to about two thirds of the length of the second lower molar tooth.

Body skeleton

The hip bone of Phodopus's like the mouse hamsters relatively short with short iliac and weak distinctive iliac hump. The thigh bone is short and only slightly longer than that of mouse hamsters. Its neck is shortened so that the head appears more chair-shaped than that of other hamsters. The part of the fibula that lies against the shin is comparatively long. The humerus is not shortened. The ulna is long with a relatively short elbow process and a comparatively flat and wide furrow along the outer surface.

Cytogenetics

According Romanenko and colleagues (2007), the original adopted different karyotype of Phodopus with 40 chromosomes by chromosome 11 divisions and 15 chromosome fusions of the supposed original karyotype of mouse-like .

According to Schmid and coworkers (1986) and Haaf and coworkers (1987), the karyotype of the Roborowski dwarf hamster differs in seven or eight independent centric fusions, three inversions , a possible telomeric fusion, the amount of the constitutive heterochromatin and its DNA - base pair composition from the karyotype of the Djungarian dwarf hamster.

A comparison of the karyotypes of the short-tailed dwarf hamsters
  Roborowski dwarf hamster Djungarian hamsters
Number of chromosomes 34 28
Number of chromosome arms ( NF ) 59 51
Number of autosome arms (NF a ) 56 48

Way of life

The short-tailed dwarf hamsters feed primarily on the seeds of plants such as hair awl grass , saltpeter herbs , steppe stone herb and pea bushes . They are most active in the evening and early morning, but they are also somewhat active during the night. In contrast to other hamsters, they show a comparatively high tolerance towards conspecifics and both parents can be involved in rearing the young.

Distribution and Tribal History

The range of the short-tailed dwarf hamsters are the mountainous and flat forests , steppes and semi-deserts in Mongolia, in adjacent areas of China, in the east and northeast of Kazakhstan, in the south of the West Siberian lowlands , in Tuwa and in Dauria .

Fossilized , they are known from the Pleistocene of Europe , the Middle Pleistocene and / or the Young Pleistocene of Asia and the Holocene of Asia. Schaub (1930) assigns the short-tailed dwarf hamsters as some Cricetulus certain altpleistozäne fossils from caves Somerset to UK and other parts of Europe. According to Gromow and Jerbajewa (1995), finds in the Young Pleistocene strata of the Irtysh region are credible, but the assignment of finds from this time west to Europe is based on incorrect determinations.

According to molecular genetic studies, the short-tailed dwarf hamsters split up at the end of the Miocene . Fossils assigned to them are therefore missing for the entire Pliocene . The lack of fossils prevents the determination of an ecological or geographical event that led to the splitting off of the short-tailed dwarf hamsters. The relationship to other fossil hamsters is also not clear.

Systematics

External system

The short-tailed dwarf hamsters are probably basal to the middle hamsters and the hamsters of the Cricetus group . This is the conclusion molecular genetic studies of mitochondrial cytochrome - b - and 12S - rRNA genes and the nuclear vWF gene by Neumann and co-workers (2006). Measurements using a constant molecular clock show a split 8.5 to 9 million years ago and using a relaxed molecular clock a split 12.2 million years ago. According to studies of the 12S rRNA gene by Lebedew and co-workers (2003), the Tibetan dwarf hamsters may be their sister group .

Investigations of the nuclear GHR , BRCA1 , RAG1 and c-myc genes by Steppan and co-workers (2004) confirm the basal position of the short-tailed dwarf hamsters and reveal that they split off 13.5 to 14.1 million years ago when all four are considered Genes and a cleavage 12.4 million years ago when looking at only the GHR gene. Cytogenetic examinations using G-banding by Romanenko and colleagues (2007) also confirm the basal position.

According to investigations of the nuclear IRBP gene by Jansa and Weksler (2004), however, the short-tailed dwarf hamsters are possibly a sister group of the middle hamsters. Studies of the nuclear LCAT and vWF genes by Michaux and co-workers (2001) come to the same conclusion .

Internal system

Musser and Carleton (2005) distinguish three types of short-tailed dwarf hamsters:

  • the Roborowski hamster ( Phodopus roborovskii ) in Mongolia, in neighboring areas of China, in Tuva and in eastern Kazakhstan as well
  • the two species of the Djungarian hamster ( Phodopus sungorus group),
    • the Campbell's dwarf hamster ( Phodopus campbelli ) in Mongolia, in adjacent areas of China and in Dauria as well
    • the Djungarian hamster ( Phodopus sungorus ) in northeast Kazakhstan and in the south of the West Siberian lowlands.

In many systems , the Djungarian dwarf hamsters are united in one species. They differ more from the Roborowski dwarf hamster than other recognized genera of hamsters from one another. According to Neumann et al. , The genetic distance measured on the cytochrome b gene is 18.4 percent, measured on the 12S rRNA gene 5.2 percent and measured on the vWF gene 4.6 percent. Measurements using a constant molecular clock show a split 4.9 to 5.2 million years ago and using a relaxed molecular clock a split 6.9 million years ago. Morphological and cytogenetic differences are also large, and Neumann et al . Suggest that the Djungarian dwarf hamsters be placed in the independent genus Cricetiscus .

Name and meaning for people

Gerrit Smith Miller established the genus Phodopus in 1910 and determined Cricetulus bedfordiae , a subspecies of the Roborowski dwarf hamster, as a type species . The generic name is derived from ancient Greek phodos (φωδος, genitive of phos φως "burn mark ") and pous (πους "foot") and refers to the large, fused pad on the soles of the Roborowski dwarf hamster. German trivial names are "Kurzschwänzige Zwerghamster" (Flint, 1966; Piechocki, 1969) and "Kurzschwänzige Zwerghamster" (Niethammer, 1988).

Short-tailed dwarf hamsters can appear as pests on cropland, but everywhere their numbers are so small that the damage is insignificant. They are natural hosts of the pathogen of some for human infectious diseases. All species are kept as pets .

literature

Mainly used literature:

  • Igor Michailowitsch Gromow, Margarita Alexandrovna Jerbajewa: [The mammals of Russia and neighboring regions. Rabbits and rodents] . Publishing House of the Russian Academy of Sciences, Saint Petersburg 1995 ( zoometod.narod.ru - Russian: Млекопитающие фауны России и сопредельных территорий. Зайцеобразные зуцеобразные ).
  • Karsten Neumann, Johan Michaux, Wladimir Swjatoslawowitsch Lebedew, Nuri Yigit, Ercüment Çolak, Natalja W. Iwanowa, Andrei B. Poltoraus, Alexei Surow, Georgi Markow, Steffen Maak, Sabine Neumann, Rolf Gattermann: Molecular Phylogeny of the Subfamily Based on the Mitochondrial Cytochrome b and 12S rRNA Genes and the Nuclear vWF Gene . In: Molecular Phylogenetics and Evolution . tape 39 , no. 1 , 2006, p. 135–148 , doi : 10.1016 / j.ympev.2006.01.010 (English).
  • Patricia D. Ross: Phodopus roborovskii . In: Mammalian Species . No. 459 , 1994, ISSN  0076-3519 , pp. 1–4 (English, science.smith.edu [PDF; 528 kB ]).
  • Patricia D. Ross: Phodopus campbelli . In: Mammalian Species . No. 503 , 1995, ISSN  0076-3519 , pp. 1–7 (English, science.smith.edu [PDF; 908 kB ]).
  • Patricia D. Ross: Phodopus sungorus . In: Mammalian Species . No. 595 , 1998, ISSN  0076-3519 , pp. 1–9 (English, science.smith.edu [PDF; 1,2 MB ]).

Web links

Commons : Phodopus  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c Wladimir Evgenjewitsch Flint: The dwarf hamsters of the Palearctic fauna . In: The New Brehm Library . 2nd Edition. tape 366 . Westarp-Wissenschaften, Hohenwarsleben 2006, ISBN 3-89432-766-9 , here pp. 6–7 (first edition: 1966, reprint).
  2. ↑ a b c d e Neumann and co-workers, 2006.
  3. ↑ a b c d e Ronald M. Nowak: Walker's Mammals of the World . 6th edition. Johns Hopkins University Press, Baltimore / London 1999, ISBN 0-8018-5789-9 , here p. 1419 (English).
  4. ↑ a b c d e f g h i j k l m Gromow and Jerbajewa, 1995 ( " Phodopus " ).
  5. ↑ a b c Swetlana Anatoljewna Romanenko, Vitaly T. Volobouev, Polina Lwowna Perelman, Wladimir Swjatoslawowitsch Lebedew, Natalija A. Serdyukowa, Vladimir Alexandrovich Trifonow, Larissa Semenovna Biltuijewa, Malissa, Nie Wen-Hui, Patricia Bulatoslawowien. Nina Schamilowa Andrew Ferguson-Smith, Yang Feng-Tang, Alexander Sergejewitsch Grafodatski: Karyotype evolution and phylogenetic relationships of hamsters (Cricetidae, Muroidea, Rodentia) inferred from chromosomal painting and banding comparison . In: Chromosome Research . tape 15 , no. 3 , 2007, ISSN  0967-3849 , p. 283–297 , Tab. 1, Fig. 6, pp. 294–295 , doi : 10.1007 / s10577-007-1124-3 (English).
  6. ↑ Michael Schmid, Thomas Haaf, Heinz Weis, Werner Schempp: Chromosomal homologies in hamster species of the genus Phodopus (Rodentia, Cricetinae) . In: Cytogenetics and Cell Genetics . tape 43 , 1986, ISSN  0301-0171 , pp. 168-173 (English). → Quoted in: Ross, 1994 (“Genetics” p. 3).
  7. ↑ Thomas Haaf, Heinz Weis, Michael Schmid: A comparative cytogenetic study on the mitotic and meiotic chromosomes in hamster species of the genus Phodopus . In: Journal of Mammals . tape 52 , no. 5 , 1987, ISSN  1616-5047 , pp. 281-290 (English). → Quoted in: Ross, 1994 (“Genetics” p. 3).
  8. ↑ Ross, 1994 ("Genetics" p. 3).
  9. ↑ Ross, 1995 ("Genetics" p. 5); Ross, 1998 ("Genetics" p. 6).
  10. ↑ a b Jochen Niethammer: Wühler . In: Grzimek's Encyclopedia Mammals. Eleven-volume licensed edition of the original edition from 1988. Volume 5 , p. 206–265 , here p. 212 .
  11. ↑ Malcolm C. McKenna, Susan K. Bell: Classification of Mammals Above the Species Level . Columbia University Press, New York 1997, ISBN 0-231-11012-X , pp. 150 (English).
  12. ↑ Samuel Schaub: Quaternary and young teriary hamsters . In: Treatises of the Swiss Palaeontological Society . tape 49 , 1930, ISSN  1421-3311 , pp. 1-49 . → Quoted in: Ross, 1995 (“Fossil Records” p. 1).
  13. ↑ Wladimir Swjatoslawowitsch Lebedew, Natalja W. Iwanowa, NK Pawlowa, Andrei B. Poltoraus: Molecular phylogeny of the Palearctic hamsters . In: Alexander O. Awerjanow, Natalja Iossifowna Abramson (eds.): Systematics, Phylogeny and Paleontology of Small Mammals. Proceedings of the International Conference Devoted to the 90th Anniversary of Prof. IM Gromov . Pensoft / Publishing House of the Russian Academy of Sciences, Saint Petersburg 2003, p. 114–118 (Russian, abstract English). → Quoted in: Neumann and employees, 2006.
  14. ^ Scott J. Steppan, Ronald M. Adkins, Joel Anderson: Phylogeny and divergence-date estimates of rapid radiation in muroid rodents based on multiple nuclear genes . In: Systematic Biology . tape 53 , no. 4 , 2004, ISSN  1063-5157 , p. 533–553 , doi : 10.1080 / 10635150490468701 (English, bio.fsu.edu [PDF; 300 kB ]).
  15. ↑ Sharon A. Jansa, Marcelo Weksler: Phylogeny of muroid rodents: Relationships within and among major lineages as determined by IRBP gene sequences . In: Molecular Phylogenetics and Evolution . tape 31 , 2004, ISSN  1055-7903 , p. 256–276 , doi : 10.1016 / j.ympev.2003.07.002 (English, full text).
  16. ^ Johan Michaux, Aurelio Reyes, François Catzeflis: Evolutionary history of the most speciose mammals: Molecular phylogeny of muroid rodents . In: Molecular Biology and Evolution . tape 18 , no. 11 , 2001, ISSN  0737-4038 , p. 2017–2031 (English, mbe.oxfordjournals.org - abstract and full text).
  17. ^ A b Guy G. Musser, Michael D. Carleton: Superfamily Muroidea . In: Don E. Wilson, DeeAnn M. Reeder (Eds.): Mammal Species of the World . A Taxonomic and Geographic Reference . 3. Edition. Johns Hopkins University Press, Baltimore 2005, ISBN 0-8018-8221-4 , pp. 894–1531 , here pp. 1045–1046 (English, bucknell.edu - full text).
  18. ^ Gerrit Smith Miller: Two new genera of murine rodents . In: Smithsonian Miscellaneous Collections . tape 52 , 1910, ISSN  0096-8749 , p. 497-498 , here p. 498 (English). → Quoted in: Ross, 1998 (p. 1).
  19. ↑ Ross, 1994 ("Remarks" p. 3).
  20. ^ Rudolf Piechocki: Family Wühler . In: Irenäus Eibl-Eibesfeldt, Martin Eisentraut, Hans-Albrecht Freye, Bernhard Grzimek, Heini Hediger, Dietrich Heinemann, Helmut Hemmer, Adriaan Kortlandt, Hans Krieg, Erna Mohr, Rudolf Piechocki, Urs Rahm, Everard J. Slijper, Erich Thenius ( Ed.): Grzimeks animal life . Encyclopedia of the Animal Kingdom. Eleventh volume: Mammals 2 . Kindler-Verlag, Zurich 1969, p. 301-344 , here p. 306 .
  21. ↑ Sandra Honigs: Dwarf Hamsters. Biology. Attitude. Breeding . 2nd Edition. Natur- und Tierverlag, Münster 2005, ISBN 3-931587-96-7 , here p. 8 .