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a b c d e f g h i j k l m n o p q r s t "Mammalian Species- Ursus arctos" (PDF). American Society of Mammalogists, Smith College. 23 April 1993. Archived from the original (PDF) on 31 March 2017. Whitaker, J. O., & Elman, R. (1996). National Audubon Society Field Guide to North American Mammals (p. 992). New York: Knopf. Hissa, R.; Siekkinen, J.; Hohtola, E.; Saarela, S.; Hakala, A.; Pudas, J. (1994). "Seasonal patterns in the physiology of the European brown bear ( Ursus arctos arctos) in Finland". Comparative Biochemistry and Physiology Part A: Physiology. 109 (#3): 781–791. doi: 10.1016/0300-9629(94)90222-4. PMID 8529017.
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Calvignac, Sebastien; Hughes, Sandrine; Hanni, Catherine (2009). "Genetic diversity of endangered brown bear ( Ursus arctos) populations at the crossroads of Europe, Asia and Africa". Diversity and Distributions. 15 (#5): 742–750. doi: 10.1111/j.1472-4642.2009.00586.x. S2CID 21666120.
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Clevenger, A. P.; Purroy, F. J.; Pelton, M. R. (1992). "Food habits of brown bears ( Ursus arctos) in the Cantabrian Mountains, Spain". Journal of Mammalogy. 73 (2): 415–421. doi: 10.2307/1382077. JSTOR 1382077. Kurtén, B. (1966). "Pleistocene bears of North America: Genus Tremarctos, spectacled bears". Acta Zoologica Fennica. 115: 1–96.
Brown Bears (Ursus arctos) | Alask - Nat Hab 13 Facts About Brown Bears (Ursus arctos) | Alask - Nat Hab
Hailer, F.; Kutschera, V. E.; Hallstrom, B. M.; Klassert, D.; Fain, S. R.; Leonard, J. A.; Arnason, U.; Janke, A. (2012). "Nuclear Genomic Sequences Reveal that Polar Bears Are an Old and Distinct Bear Lineage". Science. 336 (6, 079): 344–247. Bibcode: 2012Sci...336..344H. doi: 10.1126/science.1216424. hdl: 10261/58578. PMID 22517859. S2CID 12671275.
There are many methods used by scientists to define bear species and subspecies, as no one method is always effective. Brown bear taxonomy and subspecies classification has been described as "formidable and confusing," with few authorities listing the same specific set of subspecies. [28] Genetic testing is now perhaps the most important way to scientifically define brown bear relationships and names. Generally, genetic testing uses the word clade rather than species because a genetic test alone cannot define a biological species. Most genetic studies report on how closely related the bears are (or their genetic distance). There are hundreds of obsolete brown bear subspecies, each with its own name, so this can become confusing. Hall (1981) lists 86 different types, and even as many as 90 have been proposed. [29] [30] However, recent DNA analysis has identified as few as five main clades which contain all extant brown bears, [31] [32] while a 2017 phylogenetic study revealed nine clades, including one representing polar bears. [33] As of 2005 [update], 15 extant or recently extinct subspecies were recognized by the general scientific community. [34] [35] a b c d Dahle, B.; Swenson, J. E. (2003). "Seasonal range size in relation to reproductive strategies in brown bears Ursus arctos". Journal of Animal Ecology. 72 (#4): 660–667. doi: 10.1046/j.1365-2656.2003.00737.x. JSTOR 3505643. PMID 30893970. S2CID 67818528.
