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Post by King Kodiak on May 18, 2020 7:47:20 GMT -5
Looks like i basically hit it right on the money even before Tigerluver said it. Scroll up, i said it was most likely Ursus arctos arctos.
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Post by brobear on May 18, 2020 11:06:11 GMT -5
Looks like i basically hit it right on the money even before Tigerluver said it. Scroll up, i said it was most likely Ursus arctos arctos. Quote: It seems generally U. taubachensis specimens are part of U. priscus or U. artcos.
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Post by King Kodiak on Jun 12, 2020 7:05:48 GMT -5
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Post by brobear on Jun 12, 2020 8:01:52 GMT -5
Conclusions Brown bears on Hokkaido and the adjacent southern Kuril Islands experienced different maternal and paternal evolutionary histories. Our results indicate that sex-biased dispersal has played a significant role in the evolutionary history of the brown bear in continental populations and in peripheral insular populations, such as on Hokkaido, the southern Kuril Islands, and Sakhalin.
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Post by brobear on Aug 7, 2020 4:48:23 GMT -5
royalsocietypublishing.org/doi/10.1098/rspb.2017.1804 4. Discussion (a) Phylogenetic placement and evolutionary history of Himalayan and Tibetan brown bears Few genetic studies have been conducted of bears in the Tibetan Plateau and surrounding Himalaya region, and their evolutionary history remains enigmatic. Particularly little is known about the Himalayan brown bear (U. a. isabellinus). First, Masuda et al. [25] reported a 269 bp mtDNA control region sequence from a Gobi bear collected from the Great Gobi National Park in Mongolia, and suggested it was more closely related to Western European brown bears based on a neighbour-joining phylogenetic analysis. Later, Galbreath et al. [15] investigated homologous DNA fragments from two brown bears collected from the Deosai Plains of the western Himalayas. Their analyses demonstrated that the two Himalayan brown bears grouped together with the Gobi bear, confirming a close relationship between these two populations and a clear separation from European and Tibetan brown bears. Our results, providing more data and better resolution, demonstrate that the Himalayan brown bears, including the previously reported Gobi bear and Deosai bears, form a well-supported, sister lineage to all other extant brown bear clades included here. This result strongly supports Himalayan brown bears as a relict population that diverged early from other brown bear populations. The phylogenetic position of Tibetan brown bears (U. a. pruinosus), which form a sister clade to North American and Eurasian brown bears consistent with previous reports [10,17–19,25], indicates that the Tibetan and other Eurasian brown bears, as well as North American brown bears, are all descendants of a common ancestral lineage. It was proposed that the Tibetan brown bears migrated to the Tibetan Plateau from its source population—ancestral Eurasian brown bears—approximately 343 ka BP, and that they remained geographically isolated from this source population thereafter [10]. Our phylogenetic analyses strongly support this migration scenario. In our study, brown bear samples collected in the northwestern to western Himalayas were all identified as Himalayan brown bear, while the ones collected in the southeastern Himalayas and Tibetan Plateau were all identified as Tibetan brown bear (figure 1). The historical range of the Himalayan brown bear extends from the north and west of the Taklimakan Desert to the western Himalayas, while the historical range of the Tibetan brown bear lies in the Tibetan Plateau and the southeastern Himalayas [15]. While the Tibetan brown bears share a common ancestry with extant North American and Eurasian brown bears, the Himalayan brown bear appears to have originated from an ancient lineage that experienced long isolation in the mountains of central Asia, at least over the last 658 ka. Although the habitats of the two brown bear subspecies are geographically close, the high-altitude peaks of the Himalayan Mountains have likely impeded migration between these populations, and subsequently kept them as genetically distinct lineages. (b) Phylogenetic placement and evolutionary history of the Himalayan black bear The phylogenetic topology of Asian black bears is in agreement with a previous finding [61], except here we also include the rare Himalayan black bear (U. t. laniger), which forms a sister lineage to all other Asian black bears. Although sampling is limited, this result indicates that the Himalayan black bear originated from an ancient lineage and experienced long isolation in the Himalayan Mountains, a similar scenario to the divergence of the Himalayan brown bear lineage. However, the divergence time for the Himalayan black bear is younger, estimated at 475 ka BP, suggesting the isolation of Himalayan black bear occurred later than the isolation of the higher-altitude Himalayan brown bear. Reportedly, other described subspecies occur in the region, the Tibetan (U. t. thibetanus) and Indochinese (U. t. mupinensis) black bear, but whether these subspecies overlap is unclear given no modern revisionary work exists. Our phylogenetic relationships indicate that individuals from the Himalayas are genetically distant from other populations analysed, suggesting that little if any gene flow has occurred between this and other Asian black bear populations. Similar to the brown bear situation, the high mountains may also have separated the habitats of these black bear subspecies, possibly keeping U. t. laniger to the western Himalayas, and U. t. mupinensis and U. t. thibetanus to the east. Analyses of more individuals throughout the region and inclusion of nuclear DNA would be needed, however, to explore if this pattern is restricted to maternal gene flow only.
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Post by brobear on Dec 17, 2020 9:07:08 GMT -5
www.allgrizzly.org/evolution Evolution and the biogeography of evolution Evolutionary relations Evolutionary biogeography Evolution is a potentially all-encompassing topic that covers not only the descent and relatedness of species and other genetic variants, but also how they came to exhibit the distinctive form and function that reflect a unique niche. Essentially all of the ecological and biological disciplines are relevant to elucidating and explaining evolutionary outcomes and dynamics, including morphology, physiology, behavior, genetics, taxonomy, and phylogeny. All of these topics are explored on this web site with the intent of clarifying what makes grizzly bears unique, when they came to be that way, and why. The approach is necessarily comparative given that a defining notion of evolution is "niche," and that the emergence and maintenance of a niche is necessarily understood in context of other niches and the taxonomic entities that occupy them. Insofar as brown and grizzly bears are concerned (all of which are part of the species Ursus arctos), it's not too hard to describe features that make them and other bears truly unique. First is their large size, which by itself engenders all sorts of ecological and biological consequences--including a reduced reproductive rate. They are, as a group, the largest terrestrial carnivores around. Second is their obesity and related ability to accumulate fat stores. These stores provide bears with an unmatched ability to survive long periods of privation. This ability directly undergirds a third distinctive feature, which is a version of hibernation that allows them to maintain the health of muscles, bones, kidneys, and other organs while being essentially immobile and without sustenance in a den for (in the case of grizzly bears) 4-6 months of every year. The physiological processes associated with hibernation in bears are truly miraculous and as yet poorly understood in terms of root causal mechanisms. Hibernation is also closely intertwined with a fourth distinctive feature, which is the comparatively small poorly-developed young that females give birth to, possible only in the seclusion of a den. Finally, bears have the most flexible forelegs and paws of any large carnivore, which means that they have a well-developed ability to extract and manipulate foods with their paws. These flexuous forelimbs and paws are also powered by exceptionally powerful muscles. The muscles surmounting and surrounding the scapula of brown bears are particularly well-developed, hence their distinctive hump. As a complement, grizzlies also have claws uniquely configured to facilitate digging. The price of flexibility is the greater energetic costs of movement for bears and their comparatively lesser maximum running speed. This means that, although they can efficiently access all sorts of foods, including roots, rodents, spawning fish, insects, and berries, they are unable to pursue and capture most prey over any sort of distance. With this as an introduction, the scope of this section on Evolution is actually quite limited. Here I only attempt to describe patterns of relationship and descent among bears and the various subtaxa of brown bears, along with some biogeographical phenomena of the last Ice Age that help explain the emergence and varied distributions of different brown bear clades (more on clades can be found under Evolutionary relations). The many facets of the grizzly bear niche--all of relevance to an evolutionary perspective--are dealt with in other sections of this site, including Morphology, Physiology, History, and Foods.
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