Ursus (mammal)
Ursus | |
---|---|
From top to bottom: brown bear, American black bear, polar bear, Asian black bear | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Carnivora |
Family: | Ursidae |
Subfamily: | Ursinae |
Tribe: | Ursini |
Genus: | Ursus Linnaeus, 1758[1][2] |
Type species | |
Linnaeus , 1758
| |
Species | |
Synonyms | |
|
Ursus is a
Taxonomy and systematics
Extant species
Common name | Scientific name and subspecies | Range | Size and ecology | IUCN status and estimated population |
---|---|---|---|---|
American black bear | Ursus americanus , 1780
Pallas 16 subspecies
|
American Southwest and Mexico |
Size: Habitat: Diet: |
LC
|
Brown bear | Ursus arctos , 1758
Linnaeus 15 subspecies
|
Russia, Central Asia, China, Canada, the United States (mostly Alaska), Scandinavia, and the Carpathian region (especially Romania), Anatolia, and Caucasus |
Size: Habitat: Diet: |
LC
|
Polar bear | Phipps , 1774
2 subspecies
|
Arctic Circle and adjacent land masses as far south as Newfoundland. |
Size: Habitat: Diet: |
VU
|
Asian black bear | Ursus thibetanus , 1823
G. Cuvier 7 subspecies
|
Indian subcontinent, Korea, northeastern China, the Russian Far East, the Honshū and Shikoku islands of Japan, and Taiwan |
Size: Habitat: Diet: |
VU
|
A hybrid between grizzly bears and polar bears has also been recorded. Known commonly as a pizzly, prizzly, or grolar bear, the official name is simply "grizzly–polar bear hybrid".
Fossils
- †Ursus deningeri Richenau, 1904
- †Ursus dolinensis (Garcia & Arsuaga, 2001)
- †Ursus etruscus Cuvier, 1823
- †Ursus ingressus Rabeder, Hofreiter, Nagel & Withalm 2004
- †Ursus kudarensis Baryshnikov, 1985
- †Ursus minimus (Devèze & Bouillet, 1827)
- †Ursus pyrenaicus (Depéret, 1892)
- †Ursus rossicus Borissiak, 1930
- †Ursus savini (Andrews, 1922)
- †Ursus sackdillingensis Heller, 1955
- †Ursus spelaeus Rosenmüller, 1794
- †Ursus vitabilis? Gidley, 1913
Mating system ecology
The
Mating seasons fluctuate based on species dependent on geographical location.
The mating system is generally characterised by two main components, the search phase and the encounter phase.[13] During the breeding season, both males and females expand their home ranges to help increase the likelihood of finding potential mates.[12][14] Males, especially, adapt a roaming strategy, covering a large geographic range to find receptive females and tracking them via chemoreceptors.[12] Male bears are not considered to be territorial, but they do have large home ranges that may overlap with female home ranges, giving them access to a range of 3–15 females.[14]
Male-male competition
Males compete for females using contest competition, scramble competition and sperm competition as mechanisms for sexual selection.[12] The pre-copulatory mechanisms, including contest and scramble competition, are conditional mating tactics that are used based on an individual's phenotype.[11] Males that are larger in size compete more in physical contests to access potential mates, while males that are smaller or medium-sized use scramble competition as a strategy by increasing their ranges to encounter potential mates.[11] Age and size are positively correlated and as males mature, they grow in size and experience, monopolizing receptive females.[11] Observations of broken canines, cuts, wounds and scars demonstrate the costs associated with contests and the importance of physical intra-sexual conflict within polygamous mating systems.[12]
There is also post-copulatory male-male competition that has been documented in species within the genus Ursus. The presence of dual paternity within a litter implies that sperm competition may take place after copulation.[11][14]
Another male strategy observed by male bears is sexually selected infanticide.[13] This results in males killing the offspring of other males to directly and indirectly improve their own reproductive success.[13] This can directly influence their success by mating with the female when she re-enters oestrus or indirectly by lowering intra-sexual competition with other males and resources.[10]
Female mate choice
Female choice is based on the cost of searching for a mate and the quality of a mate.
Within Ursus, there may be a high variation within the mating strategies observed by both females and males, demonstrating overall plasticity depending on external factors.[10][11] This demonstrates the conditional mating tactics that male bears may consider based on their age and size,[11] as well as the counter-strategies of females, including sexually selected infanticide and cryptic female choice.[10]
References
- ^ "ADW: Ursus: CLASSIFICATION". animaldiversity.ummz.umich.edu. Retrieved 4 April 2018.
- OCLC 62265494.
- ^ "Brown Bear Fact Sheet". library.sandiegozoo.org. Archived from the original on 16 February 2018. Retrieved 4 April 2018.
- ^ "Polar Bear Fact Sheet". library.sandiegozoo.org. Archived from the original on 24 April 2016. Retrieved 4 April 2018.
- ^ "Definition of URSUS". www.merriam-webster.com. Retrieved 4 April 2018.
- ^ "Ursus | Define Ursus at Dictionary.com". Archived from the original on 2012-04-25. Retrieved 2014-03-17.
- ^ "Mexican black bear – Bear Conservation". www.bearconservation.org.uk. Retrieved 2018-01-29.
- ^ "West Mexico black bear – Bear Conservation". Retrieved 2018-01-29.
- ISBN 9780806152325.
- ^ ISSN 1365-2907.
- ^ ISSN 0008-4301.
- ^ S2CID 36614970.
- ^ PMID 16543170.
- ^ S2CID 54316843.
External links
- Data related to ursus at Wikispecies
- Media related to Ursus (genus) at Wikimedia Commons