Editing Least weasel (section)

==Taxonomy and evolution==
The least weasel was given its scientific name ''Mustela nivalis'' by Carl Linnaeus in his [[12th edition of Systema Naturae]] in 1766; its [[specific name|epithet]] ''nivalis'' comes from the [[Latin]] word ''nix'' meaning "snow" because it grows a white coat during the winter season.<ref name=MS>{{cite journal |last1=Sheffield |first1=S. R. |last2=King |first2=C. M. |date=1994 |title=''Mustela nivalis'' |url=https://academic.oup.com/mspecies/article/doi/10.2307/3504183/2600691 |journal=Mammalian Species |issue=454 |pages=1–10 |doi=10.2307/3504183 |jstor=3504183}}</ref>{{rp|6}} The [[Type locality (biology)|type locality]] was [[Västerbotten]] in Sweden.<ref name=MS/>{{rp|1}} As an animal with a very wide distribution, the morphology of the least weasel varies geographically. The species was reviewed by Reichstein in 1957 and again by van Zyll de Jong in 1992 and Reig in 1997. Youngman (1982) placed it in the subgenus ''Mustela'' while Abramov (1999) considered it should be included in the subgenus ''Gale''. Based on skull characteristics, Reig (1997) proposed that the [[taxon]] should be split into four species, ''M. subpalmata'', ''M. rixosa'', ''M. vulgaris'' and ''M. eskimo''. Abrimov and Baryshinikov (2000) disagreed, recognising only ''M. subpalmata'' (the [[Egyptian weasel]]) as a separate species.<ref>{{cite book |title=Mammal Species of the World: A Taxonomic and Geographic Reference, Volume 12 |editor-last=Wilson |editor-first=Don E. |editor-last2=Reeder |editor-first2=DeeAnn M. |year=2005 |publisher=JHU Press |isbn=978-0-8018-8221-0 |pages=616–617 |url=https://books.google.com/books?id=JgAMbNSt8ikC&pg=PA1601}}</ref> However, Rodrigues ''et al''. (2016) recognized ''M. subpalmata'' as a distinct population of ''nivalis'' rather than a distinct species.<ref>{{Cite journal |last1=Rodrigues |first1=M. |last2=Bos |first2=A. R. |last3=Hoath |first3=R. |last4=Schembri |first4=P. J. |last5=Lymberakis |first5=P. |last6=Cento |first6=M. |last7=Ghawar |first7=W. |last8=Ozkurt |first8=S. O. |last9=Santos-Reis |first9=M. |last10=Merilä |first10=J. |last11=Fernandes|first11=Ca. |date=2016 |title=Taxonomic status and origin of the Egyptian weasel (''Mustela subpalmata'') inferred from mitochondrial DNA  |journal=Genetica  |volume=144 |issue=2 |pages=191–202 |doi=10.1007/s10709-016-9889-y |pmid=26961232 |s2cid=17450300}}</ref>

Within the genus ''Mustela'', the least weasel is a relatively unspecialised form, as evidenced by its [[pedomorphism|pedomorphic]] skull, which occurs even in large subspecies.<ref name=s972>{{Harvnb|Heptner|Sludskii|2002|p=972}}</ref> Its direct ancestor was ''Mustela praenivalis'', which lived in Europe during the [[Middle Pleistocene]] and [[Villafranchian]]. ''M. praenivalis'' itself was probably preceded by ''M. pliocaenica'' of the [[Pliocene]]. The modern species probably arose during the [[Late Pleistocene]].<ref name=k102>{{Harvnb|Kurtén|1968|pp=102–103}}</ref> The least weasel is the product of a process begun 5–7&nbsp;million years ago, when northern forests were replaced by open grassland, thus prompting an explosive evolution of small, burrowing rodents. The weasel's ancestors were larger than the current form, and underwent a reduction in size to exploit the new food source. The least weasel thrived during the [[Last Glacial Period|Ice Age]], as its small size and long body allowed it to easily operate beneath snow, as well as hunt in burrows. It probably crossed to North America through the [[Bering land bridge]] 200,000 years ago.<ref name=mac205>{{Harvnb|Macdonald|1992|p=205}}</ref>

===Subspecies===
The least weasel has a high geographic variation, a fact which has historically led to numerous disagreements among biologists studying its systematics. The least weasel's subspecies are divided into three categories:<ref name=s975>{{Harvnb|Heptner|Sludskii|2002|pp=975–978}}</ref>

* The ''pygmaea–rixosa'' group (small least weasels): Tiny weasels with short tails, [[Neoteny|pedomorphic]] skulls, and pelts that turn pure white in winter. They inhabit northern [[European Russia]], [[Siberia]], the [[Russian Far East]], [[Finland]], the northern [[Scandinavian Peninsula]], [[Mongolia]], northeastern [[China]], [[Japan]] and [[North America]].<ref name=s975/>
* The ''boccamela'' group (large least weasels): Very large weasels with large skulls, relatively long tails and lighter coloured pelts. Locally, they either do not turn white or only partially change colour in winter. They inhabit [[Transcaucasia]], from western [[Kazakhstan]] to [[Jetisu|Semirechye]] and in the flat deserts of [[Middle Asia]]. They are also found in Morocco, Algeria, and Tunisia.<ref name=s975/>
* The ''nivalis'' group (medium-sized least weasels): Medium-sized weasels, with tails of moderate length, representing a transitional form between the former two groups. They inhabit the middle and southern regions of European Russia, [[Crimea]], the [[Ciscaucasus]], western Kazakhstan, the southern and middle [[Urals]] and the montane parts of Middle Asia, except the [[Kopet Dag]].<ref name=s975/>

{| class="wikitable" width=80% font=90%
|- bgcolor="#115a6c"
!Subspecies
!Trinomial authority
!Description
!Range
!Synonyms
|----
|Common least weasel<br />''M. n. nivalis''
([[Nominate subspecies]])
[[File:Mustelanivalisnivalis.png|150 px]]
|Linnaeus, 1766
|A medium-sized subspecies with a tail of moderate length, constituting about 20–21% of its body length. In its summer fur, the upper body is a dark brownish or chestnut colour, while its winter fur is pure white. It is probably a transitional form between the small ''pygmaea'' and the large ''vulgaris''.<ref name=s982>{{Harvnb|Heptner|Sludskii|2002|p=982}}</ref>
|The middle regions of [[European Russia]], from the [[Baltic states]] to the middle and southern [[Urals]], northward approximately to the latitude of [[Saint Petersburg]] and [[Perm, Russia|Perm]], and south to the [[Kursk Oblast|Kursk]] and [[Voronezh Oblast]]s. Outside the [[former Soviet Union]], its range includes [[Northern Europe]] (except for [[Ireland]], [[Iceland]], [[Finland]] and parts of the [[Scandinavian Peninsula]]) and [[Hokkaidō]].
|<small>''caraftensis'' (Kishida, 1936)</small><br />
<small>''kerulenica'' (Bannikov, 1952)</small><br />
<small>''punctata'' (Domaniewski, 1926)</small><br />
<small>''yesoidsuna'' (Kishida, 1936)</small>
|----
|Allegheny least weasel<br />''M. n. allegheniensis''
|Rhoads, 1901
|Similar to ''M. n. rixosa'', but is larger, has a broad skull and darker coat, and is more adapted to live in [[deciduous]] forests<ref>{{cite journal |author=Rhoades, S. M. |year=1900 |title=A New Weasel from western Pennsylvania |journal=Proceedings of the Academy of Natural Sciences of Philadelphia |volume=52 |pages=751–754 |jstor=4062685}}</ref>
|The northeastern United States ([[Michigan]], [[Pennsylvania]], [[New York (state)|New York]], [[Virginia]], [[North Carolina]], [[Ohio]], [[Illinois]], [[Wisconsin]], [[West Virginia]], and [[Indiana]])
|
|----
|Transcaucasian least weasel<br />''M. n. boccamela''
[[File:Mustela-nivalis.jpg|150 px]]
|Bechstein, 1800
|A very large subspecies, with a long tail constituting about 30% of its body length. In its summer fur, the upper body is light brownish or chestnut with yellowish or reddish tints, with some individuals having a brownish dot on the corners of the mouth and sometimes on the chest and belly. The winter fur is not pure white, being usually dirty white with brown patches.<ref name=s980>{{Harvnb|Heptner|Sludskii|2002|p=980}}</ref>
|[[Transcaucasia]], [[southern Europe]], [[Asia Minor]] and probably western [[Iran]]
|<small>''italicus'' (Barrett-Hamilton, 1900)</small>
|----
|Plains least weasel<br />''M. n. campestris''
|Jackson, 1913
|
|The [[Great Plains]] of the United States ([[South Dakota]], [[Iowa]], [[Nebraska]], and [[Kansas]])
|
|----
|Caucasian least weasel<br />''M. n. caucasica''
|Barrett-Hamilton, 1900
|
|
|<small>''dinniki'' (Satunin, 1907)</small>
|----
|Alaskan least weasel<br />''M. n. eskimo''
|Stone, 1900
|A small subspecies. Resembles ''M. n. rixosa'', but has a duller colour, a larger skull and a shorter tail.<ref>{{cite journal |author=Swenk, M. H. |year=1926 |title=Notes on ''Mustela campestris'' Jackson, and on the American forms of Least Weasels |journal=Journal of Mammalogy |volume=7 |issue=4 |pages=313–330 |doi=10.2307/1373581 |jstor=1373581}}</ref>
|[[Alaska]], the [[Yukon]], and the [[Northwest Territories]]
|
|----
|Turkmenian least weasel<br />''M. n. heptneri''
|Morozova-Turova, 1953
|A very large subspecies with a long tail constituting about 25–30% of its body length. In its summer fur, the upper body is very light sandy brown or pale-yellowish. The fur is short, sparse and coarse, and does not turn white in winter.<ref name=s981>{{Harvnb|Heptner|Sludskii|2002|p=981}}</ref>
|The deserts and semi-deserts of southern [[Kazakhstan]] and [[Middle Asia]] from the [[Caspian Sea]] to [[Jetisu|Semirechye]], southern [[Tajikistan]], [[Koppet Dag]], [[Afghanistan]] and northeastern [[Iran]]
|
|----
|Japanese least weasel<br />''M. n. namiyei''
|Kuroda, 1921
|Smaller than ''M. n. rixosa'' and paler than ''M. n. eskimo''. Resembles ''M. n. pygmaea'', but the head and body are longer and the tail considerably longer.<ref>{{cite journal |author=Kuroda, N. |year=1921 |title=On three new mammals from Japan |journal=Journal of Mammalogy |volume=2 |issue=4 |pages=208–211 |doi=10.2307/1373554 |jstor=1373554 |url=https://www.biodiversitylibrary.org/part/90605}}</ref>
| Northern [[Honshū]] ([[Aomori Prefecture|Aomori]], [[Akita Prefecture|Akita]] and [[Iwate Prefecture|Iwate]] Prefectures)
|
|----
|Mediterranean least weasel<br />''M. n. numidica''
[[File:Mustelanivalisiberica.png|150 px]]
|Pucheran, 1855
|The largest subspecies
|[[Morocco]], [[Algeria]], [[Egypt]] (formerly thought to be a distinct species, the [[Egyptian weasel]]), [[Malta]], the [[Azores Islands]] and [[Corsica]]
|<small>''albipes'' (Mina Palumbo, 1868)</small><br />
<small>''algiricus'' (Thomas, 1895)</small><br />
<small>''atlas'' (Barrett-Hamilton, 1904)</small><br />
<small>''corsicanus'' (Cavazza, 1908)</small><br />
<small>''fulva'' (Mina Palumbo, 1908)</small><br />
<small>''galanthias'' (Bate, 1905)</small><br />
<small>''ibericus'' (Barrett-Hamilton, 1900)</small><br />
<small>''meridionalis'' (Costa, 1869)</small><br />
<small>''siculus'' (Barrett-Hamilton, 1900)</small>
<small>''subpalmata'' Hemprich & Ehrenberg, 1833</small>
|----
|Montane Turkestan least weasel<br />''M. n. pallida''
|Barrett-Hamilton, 1900
|A medium-sized subspecies with a tail constituting about 24% of its body length. The colour of the summer fur is light-brownish, while the winter fur is white.<ref name="s984">{{Harvnb|Heptner|Sludskii|2002|p=984}}</ref>
|The montane parts of [[Turkmenistan]], [[Uzbekistan]], [[Tajikistan]], [[Kazakhstan]] and [[Kirgizia]], as well as the Chinese parts of the same mountain systems and perhaps in the extreme eastern parts of [[Hindukush]]
|
|----
|Siberian least weasel<br />''M. n. pygmaea''
|J. A. Allen, 1903
|A very small subspecies, with a short tail which constitutes about 13% of its body length. In its summer coat, the dorsal colour is dark brown or reddish, while the winter fur is entirely white.<ref name="s978">{{Harvnb|Heptner|Sludskii|2002|p=978}}</ref>
|All of [[Siberia]] (except for southern and southeastern [[Transbaikalia]]); the northern and middle [[Urals]], northern Kazakhstan and the [[Russian Far East]], including [[Sakhalin]], the [[Kuril Islands]] and the [[Korean Peninsula]]; all of [[Mongolia]] (except for the eastern part), and probably northeastern [[China]]
|<small>''kamtschatica'' (Dybowksi, 1922)</small>
|----
|Bangs' least weasel<br />''M. n. rixosa''
[[image:Mustela nivalis (two, fighting).jpg|200 px]]
|Bangs, 1896
|The smallest subspecies and the smallest living [[mammal]]ian [[carnivore]] in the world. In its summer coat, the fur is dark reddish-brown, while the winter fur is pure white.<ref name=m14>{{Harvnb|Merriam|1896|pp=14–15}}</ref>
|[[Nunavut]], [[Labrador]], [[Quebec]], [[Minnesota]], [[North Dakota]], [[Montana]], [[Saskatchewan]], [[Alberta]], and [[British Columbia]]
|
|----
|Middle European least weasel<br />''M. n. vulgaris''
|Erxleben, 1777
|A somewhat larger subspecies than ''nivalis'' with a longer tail, which constitutes about 27% of its body length. In its summer fur, the upper body varies from being light brownish to dark chestnut, while the winter fur is white in its northern range and piebald in its southern range.<ref name=s983>{{Harvnb|Heptner|Sludskii|2002|p=983}}</ref>
|Southern European Russia from the latitude of southern Voronezh and Kursk districts, [[Crimea]], [[Ciscaucasia]], and the northern slopes of the main Caucasus, eastward to the [[Volga]]. Outside the former Soviet Union, its range includes Europe southward to the [[Alps]] and the [[Pyrenees]]. Introduced to [[New Zealand]].<ref name=long>Long, J. L. (2003). ''Introduced Mammals of the World: Their History, Distribution and Influence''. Cabi Publishing. pp. 271–272. {{ISBN|9780643099166}}</ref><ref>{{cite book |title=The Handbook of New Zealand Mammals |last=King |first=C. |year=2005 |publisher=Oxford University Press |isbn=0-19-558477-5 |page=287}}</ref>
|<small>''dumbrowskii'' (Matschie, 1901)</small><br />
<small>''hungarica'' (Vásárhelyi, 1942)</small><br />
<small>''minutus'' (Pomel, 1853)</small><br />
<small>''monticola'' (Cavazza, 1908)</small><br />
<small>''nikolskii'' (Semenov, 1899)</small><br />
<small>''occidentalis'' (Kratochvil, 1977)</small><br />
<small>''trettaui'' (Kleinschmidt, 1937)</small><br />
<small>''vasarhelyi'' (Kretzoi, 1942)</small>
|----
|}