Polar Bear Research Paper
The distinct evolutionary relationship and hybridization of brown bears (Ursus arctos) and polar bears (Ursus maritimus).
Fast morphological evolution has been seen over the years throughout mammals of the earth, as it is an important driver of specialization and speciation. Ursus, is the genus in the family of Ursidae (bears) that includes polar bears (Ursus arctos), black bears (Ursus americanus), and brown bears (Ursus maritimus). The polar bear and brown bear specifically are closely related. In fact, there are estimates that polar bears branched off from brown bears during the mid to late Pleistocene, becoming isolated on Siberian costal enclaves, an Arctic sea ice environment. (C. Lindqvist …show more content…
(Hailer et al. 2012) They roam the Arctic ice sheets, swim in coastal regions and have a fully carnivorous diet of seal flesh and blubber. Molecular and paleontological data indicate that the polar bear evolved less than a million years ago from a distinct other ursid, the brown bear. A brown bear has a complete omnivorous diet. (Slater et al. 2010) This is because they live in a completely different geographical region than polar bears. Brown bears can be found throughout mountains and forests of the Holarctic and in the Tundra. (PreuB et al. 2009) G. Slater et al. (2010) looked at dietary specializations using phylogenetic tests to estimate the rate that morphological specialization occurred in polar bears. It was observed that very fast evolution of semi-aquatic adaptations and dietary specialization produced cranial morphology that is weaker than that of brown bears primarily because of their different diets. The mean rate which was calculated for an ursid was rate= 0.024, +/- 0.007. The rate for a polar bear was, 0.059. This means that the rate of skull shape evolution was about double the mean that was observed for other parts of ursid phylogeny thus proving fast morphological evolution. (Slater et al. …show more content…
Fossil remains of polar bears are hard to find. This is because when majority of them die they are likely to be over sea ice, or scavenged by other animals. (C. Lindqvist et al. 2010). C. Lindqvist et al. (2010) also writes about a lower jawbone that is said to be the oldest polar bear remains ever found. Accelerator mass spectrometry was used to determine the age of a canine tooth left on the jaw. It was estimated to be approximately 130-110 ky old. It is said that this jawbone confirms that the polar bear was already a species at least 100 ky ago and was preserved due to the low temperatures and permafrost that was present during that time. Tests such as “next generation” sequencing technology and isotopes analyses of carbon and nitrogen of past and present environments were used. The date of a split between the brown bear and polar bear was concluded to be a mean of 152 ky. Isotope data collected also proved that the polar bear morphologically and physiologically adapted at a very rapid
Fast morphological evolution has been seen over the years throughout mammals of the earth, as it is an important driver of specialization and speciation. Ursus, is the genus in the family of Ursidae (bears) that includes polar bears (Ursus arctos), black bears (Ursus americanus), and brown bears (Ursus maritimus). The polar bear and brown bear specifically are closely related. In fact, there are estimates that polar bears branched off from brown bears during the mid to late Pleistocene, becoming isolated on Siberian costal enclaves, an Arctic sea ice environment. (C. Lindqvist …show more content…
(Hailer et al. 2012) They roam the Arctic ice sheets, swim in coastal regions and have a fully carnivorous diet of seal flesh and blubber. Molecular and paleontological data indicate that the polar bear evolved less than a million years ago from a distinct other ursid, the brown bear. A brown bear has a complete omnivorous diet. (Slater et al. 2010) This is because they live in a completely different geographical region than polar bears. Brown bears can be found throughout mountains and forests of the Holarctic and in the Tundra. (PreuB et al. 2009) G. Slater et al. (2010) looked at dietary specializations using phylogenetic tests to estimate the rate that morphological specialization occurred in polar bears. It was observed that very fast evolution of semi-aquatic adaptations and dietary specialization produced cranial morphology that is weaker than that of brown bears primarily because of their different diets. The mean rate which was calculated for an ursid was rate= 0.024, +/- 0.007. The rate for a polar bear was, 0.059. This means that the rate of skull shape evolution was about double the mean that was observed for other parts of ursid phylogeny thus proving fast morphological evolution. (Slater et al. …show more content…
Fossil remains of polar bears are hard to find. This is because when majority of them die they are likely to be over sea ice, or scavenged by other animals. (C. Lindqvist et al. 2010). C. Lindqvist et al. (2010) also writes about a lower jawbone that is said to be the oldest polar bear remains ever found. Accelerator mass spectrometry was used to determine the age of a canine tooth left on the jaw. It was estimated to be approximately 130-110 ky old. It is said that this jawbone confirms that the polar bear was already a species at least 100 ky ago and was preserved due to the low temperatures and permafrost that was present during that time. Tests such as “next generation” sequencing technology and isotopes analyses of carbon and nitrogen of past and present environments were used. The date of a split between the brown bear and polar bear was concluded to be a mean of 152 ky. Isotope data collected also proved that the polar bear morphologically and physiologically adapted at a very rapid