Irish Ancestry & Polar Bears

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From the BBC:


Scientists in the UK, Ireland and the US analysed the teeth and skeletons of 17 brown bears that were found at eight cave sites across Ireland.

The new research has been reported in the latest edition of Current Biology.

Previously, it was believed that today's polar bears were most closely related to brown bears living on islands off the coast of Alaska.

However, analysis of mitochondrial DNA - which is passed from mother to child - has shown the extinct Irish brown bears are the ancestors of all today's polar bears, the scientists said.

Their work provides evidence of the two species mating opportunistically during the past 100,000 years or more[...]


For more read here: www.bbc.co.uk/news/uk-scotland-highlands-islands-13965286

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Abstract

BACKGROUND:

Polar bears (Ursus maritimus) are among those species most susceptible to the rapidly changing arctic climate, and their survival is of global concern. Despite this, little is known about polar bear species history. Future conservation strategies would significantly benefit from an understanding of basic evolutionary information, such as the timing and conditions of their initial divergence from brown bears (U. arctos) or their response to previous environmental change.
RESULTS:

We used a spatially explicit phylogeographic model to estimate the dynamics of 242 brown bear and polar bear matrilines sampled throughout the last 120,000 years and across their present and past geographic ranges. Our results show that the present distribution of these matrilines was shaped by a combination of regional stability and rapid, long-distance dispersal from ice-age refugia. In addition, hybridization between polar bears and brown bears may have occurred multiple times throughout the Late Pleistocene.


CONCLUSIONS:

The reconstructed matrilineal history of brown and polar bears has two striking features. First, it is punctuated by dramatic and discrete climate-driven dispersal events. Second, opportunistic mating between these two species as their ranges overlapped has left a strong genetic imprint. In particular, a likely genetic exchange with extinct Irish brown bears forms the origin of the modern polar bear matriline. This suggests that interspecific hybridization not only may be more common than previously considered but may be a mechanism by which species deal with marginal habitats during periods of environmental deterioration.


Edwards et al., Ancient Hybridization and an Irish Origin for the Modern Polar Bear Matriline, Current Biology (2011), doi:10.1016/j.cub.2011.05.058.


www.sciencedirect.com/science/article/pii/S0960982211006452

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Jul 12, 2011 10:42:23 GMT -9 grrraaahhh said:

Abstract

BACKGROUND:

Polar bears (Ursus maritimus) are among those species most susceptible to the rapidly changing arctic climate, and their survival is of global concern. Despite this, little is known about polar bear species history. Future conservation strategies would significantly benefit from an understanding of basic evolutionary information, such as the timing and conditions of their initial divergence from brown bears (U. arctos) or their response to previous environmental change.
RESULTS:

We used a spatially explicit phylogeographic model to estimate the dynamics of 242 brown bear and polar bear matrilines sampled throughout the last 120,000 years and across their present and past geographic ranges. Our results show that the present distribution of these matrilines was shaped by a combination of regional stability and rapid, long-distance dispersal from ice-age refugia. In addition, hybridization between polar bears and brown bears may have occurred multiple times throughout the Late Pleistocene.


CONCLUSIONS:

The reconstructed matrilineal history of brown and polar bears has two striking features. First, it is punctuated by dramatic and discrete climate-driven dispersal events. Second, opportunistic mating between these two species as their ranges overlapped has left a strong genetic imprint. In particular, a likely genetic exchange with extinct Irish brown bears forms the origin of the modern polar bear matriline. This suggests that interspecific hybridization not only may be more common than previously considered but may be a mechanism by which species deal with marginal habitats during periods of environmental deterioration.


Edwards et al., Ancient Hybridization and an Irish Origin for the Modern Polar Bear Matriline, Current Biology (2011), doi:10.1016/j.cub.2011.05.058.


www.sciencedirect.com/science/article/pii/S0960982211006452

Discover Magazine Blogger Disagreement

blogs.discovermagazine.com/gnxp/2011/07/bearish-wisdom/