Mustela nivalis Linnaeus, 1766
|
publication ID |
https://doi.org/ 10.26879/581 |
|
persistent identifier |
https://treatment.plazi.org/id/1766284A-FFF3-DB5F-FE84-9EE8FEE3F9C4 |
|
treatment provided by |
Felipe |
|
scientific name |
Mustela nivalis Linnaeus, 1766 |
| status |
|
Mustela nivalis Linnaeus, 1766 View in CoL
Figures 11-13 View FIGURE 11 View FIGURE 12 View FIGURE 13
Specimens. Skull with damaged neurocranium, and present left P3-M1 and right P4-M1 (JSJ/Mnv/ 1); complete mandible with present p2 and p4-m2 (JSJ/Mnv/2).
Measurements. Skull (JSJ/Mnv/1): 1, 29.42 mm; 4, 9.45 mm; 6, 9.94 mm; 7, 4.82 mm; 8, 9.53 mm; 9, 11.78 mm; 10, 8.63 mm; 11, 6.27 mm; 12, 15.61 mm; 13, 2.71 mm; 14, 5.79 mm; 15, 9.12 mm; 16, 9.12 mm; 17, 3.12 mm; 18, 7.78 mm; 19, 7.12 mm; 25, 3.12 mm; 26, 9.09 mm; 32, 8.53 mm; P3-L, 1.77 mm; P3-Bp, 0.82 mm; P4-L, 3.34 mm (R), 3.32 mm (L); P4-Ba, 1.59 mm (R, L); P4-Bp, 1.09 mm (R), 1.11 mm (L); M1-L1, 1.29 mm (R), 1.31 mm (L); M1-L2, 0.84 mm (R), 0.81 mm (L); M1-L3, 1.02 mm (R), 1.05 mm (L); M1-B, 1.51 mm (R), 2.48 mm (L). Mandible (JSJ/Mnv/2): 1, 16.21 mm; 2, 15.08 mm; 3, 10.52 mm; 4, 10.42 mm; 5, 8.81 mm; 6, 4.71 mm; 7, 4.41 mm; 8, 1.97 mm; 9, 5.34 mm; 10, 7.48 mm; 11, 9.08 mm; 12, 2.65 mm; 13, 1.32 mm; 14, 2.73 mm; 15, 1.34 mm; 16, 1.29 mm; 17, 3.62 mm; 18, 5.42 mm; 19, 2.18 mm; p2-L, 1.19 mm; p2-B, 0.74 mm; p4-L, 1.96 mm; p4-Ba, 0.94 mm; p4-Bp, 1.05 mm; m1-L, 3.94 mm, m1-Ltri, 2.78 mm, m1-L-tal, 1.19 mm; m1-B-tri, 1.33 mm; m1-B-tal, 1.25 mm; m2-L, 0.88 mm; m2-B, 0.90 mm. See Appendices 3 and 4 for measured parts.
Remarks. The two remains belonged to a female (calvarium) ( Figure 11 View FIGURE 11 ) and a male (mandible), both adult. Males are always considerably larger, and the late Pleistocene populations were no exception. Apart from sexual dimorphism, Mustela nivalis body size also varies under the effect of many other factors: local habitats, climatic conditions, snow cover, prey density and many others ( Abramov and Baryshnikov, 2000; King and Powell, 2007). Mustela nivalis do not follow the Bergmann rule, and smaller individuals are usually found in cooler areas, while larger individuals occur in warmer places.
However, this is not as obvious as previously thought, and much more complicated. At present, Mu. nivalis has an extremely wide circumboreal and Holarctic distribution, with many subspecies and forms of different size and body proportions ( Marciszak and Socha, 2014, p. 260, figure 3). These differences are even larger than those between populations of Mu. erminea ( Heptner and Naumov, 1967; King and Powell, 2007). Mustela nivalis occurs throughout the European late Pleistocene, and detailed studies on the Polish material show that both sexes were on average significantly smaller than the modern individuals ( Figures 12- 13 View FIGURE 12 View FIGURE 13 ) ( Marciszak, 2012; Marciszak and Socha, 2014).
The calvarium is the only complete weasel skull from the Polish sites known till now. The skull from layer 13 of Nietoperzowa Cave, dated as MIS 5e and described by Wójcik (1974, p. 79-80, 85, tables I and V) and belonged in fact to a small female of Mu. erminea . The morphology of the specimen from Solna Jama Cave clearly indicates Mu. nivalis , and its measurements are even smaller than the smallest female measured from Poland. The total length of the skull is 29.40 mm, while the respective values for the recent Polish males is mean = 40.67 mm (range = 37.00–49.20, N = 115), and for the females is mean = 32.88 mm (range = 30.20–35.31, N = 65). This dwarf size, together with proportionally gracile build ( Figures 11-12 View FIGURE 11 View FIGURE 12 ) indicate that the specimen represents Mu. nivalis pygmaea ( Allen, 1933) , which now occurs only in Siberia (sensu Abramov and Baryshnikov, 2000).
The mandible individual from Solna Jama Cave is a medium-sized male, typical of postglacial period; it differs from the female in the more pronounced broadening of m1 crown at the base of protoconid. With its length of m1 3.94 mm, the male falls into the upper part of size range of the late Pleistocene males ( Figure 13 View FIGURE 13 ), but is considerably smaller than the modern Mu. nivalis from Poland (for males: mean = 4.60 mm, range = 4.02– 5.02, N = 283; for females: mean = 3.69 mm, range = 3.32–4.14, N = 114) ( Marciszak, 2012).
Remarks. The minute fossil form, described earlier by some authors, for example van den Brink (1957) or Allen (1933) as Mustela nivalis minuta ( Pomel, 1853) and Mu. rixosa Bangs, 1896 , are most probably only small, local variations of nivalis or the pygmaea form ( Wójcik, 1974; Marciszak, 2012). The dwarf individuals from the late Pleistocene reflect the evolutionary and ecological plasticity of the species. In the middle Pleistocene the climate cooling progressed due to the extensive glaciation. This, combined with the body structure ensuring only minimum protection against heat loss, meant that Mu. nivalis faced the need to adapt to the rapidly changing climatic conditions. This resulted in a progressive reduction of the body size and in most parts of Europe to dwarfing. This process reached its peak in the coolest periods of the late Pleistocene. The small mustelids reduced their size to an extent that was necessary and economic from the point of view of energy. They were small enough to move freely and hunt for rodents in a maze of underground corridors. At the same time they were large enough to effectively kill their prey, and the amount of food consumed ensured positive energy balance ( King, 1989; Szafrańska et al., 2006; King and Powell 2007). Today, the co-existence of
MARCISZAK, GORNIG, & STEFANIAK: MAMMALS FROM SOLNA JAMA CAVE small- and large-sized forms in some areas can be associated with adaptation to local habitats. The emergence of these ecotypes was a response to species-specific, local environmental conditions. Small individuals are found in mountainous regions (Alps, Carpathians, Caucasus), or in areas with a harsh (often continental) climate regime, such as Siberia ( Abramov and Baryshnikov, 2000). It has to do not only with thermoregulation and a limited number of potential prey, but also the reproduction strategy. Females of the small and dwarf subspecies are capable of producing and raising two litters within six months, whereas in the larger subspecies only one litter is produced during that time. Faster maturation of the females is a response to the short summer in the northern hemisphere ( Abramov and Baryshnikov, 2000).
King and Powell (2007) found a correlation between the duration of the snow cover and Mustela nivalis body size based on condylobasal length (CBL): the longer the snow cover lasts, the smaller the skull CBL. However, this relationship is much more complicated than previously thought. This is due to the fact that the low temperature, which is the main factor responsible for the fluctuations in weasel body size, it is not always related to the amount of precipitation and the duration of snow cover, as exemplified by the cold steppes of central Asia ( Hernández Fernández, 2001).
Today Mustela nivalis is a specialised hunter of small rodents, which can account for up to 90% and, during mass appearance, even close to 100% of food ( Jędrzejewska and Jędrzejewski, 2001; King and Powell, 2007). The abundance of rodents is subject to strong fluctuations. Like in Mu. erminea , the very pronounced sexual dimorphism of Mu. nivalis has to influence the prey size selection. The males, being larger and more powerful, often choose a larger-sized prey, such as a small Oryctolagus , Rattus or Cricetus cricetus , while the females feed mainly on vole-sized rodents ( Reichstein, 1993b; Jędrzejewska and Jędrzejewski, 2001; King and Powell, 2007).
The massiveness increase in the evolution of Mustela nivalis teeth, compared to the ermine, is less pronounced. This is due to the fact that Mu. nivalis specialises in hunting small rodents, whose size is generally comparable to the weasel size. The bones of these animals (especially the skull bones) are not too thick, so it is not necessary to have extremely massive teeth to pierce the hard bones of the prey. In contrast to Mu. nivalis , Mu. erminea (especially males) often kills prey much larger than itself (e.g., lagomorphs). Their thicker skeleton requires significantly more powerful jaws and teeth adapted to withstand the strong mechanical stress ( Heptner and Naumov, 1967; Reichstein, 1993a; King and Powell, 2007).
The large number of Mustela nivalis remains in some sites (Biśnik Cave, Stajnia Cave, Obłazowa 1 Cave, Aven 1 Abimés de la Fage, Istallöskö, Puskaporos) is associated with the activity of predators and humans ( Kormos, 1911; Jánossy, 1955; Hugueney, 1975; Marciszak, 2012). As a smaller animal, with smaller territories and greater density, as well as the lack of black tail tip to disconcert the attacker, Mu. nivalis falls prey to predators more often than Mu. erminea ( King and Powell, 2007) . Studies in the Białowieża Forest show that Mu. nivalis remains are found with an average frequency of 0.5% in pellets and faeces of birds and mammals. The registered mortality was 87% within 6 months ( Jedrzejewska and Jędrzejewski, 2001).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.