Population Genomics Reveal Recent Speciation and Rapid Evolutionary Adaptation in Polar Bears

Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyper-lipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show...

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Bibliographic Details
Main Authors: Liu, Shiping, Lorenzen, Eline D, Fumagalli, Matteo, Li, Bo, Harris, Kelley, Xiong, Zijun, Zhou, Long, Korneliussen, Thorfinn Sand, Somel, Mehmet, Babbitt, Courtney, Wray, Greg, Li, Jianwen, He, Weiming, Wang, Zhuo, Fu, Wenjing, Xiang, Xueyan, Morgan, Claire C, Doherty, Aoife, O’Connell, Mary J, McInerney, James O, Born, Erik W, Dalén, Love, Dietz, Rune, Orlando, Ludovic, Sonne, Christian, Zhang, Guojie, Nielsen, Rasmus, Willerslev, Eske, Wang, Jun
Format: Article in Journal/Newspaper
Language:unknown
Published: eScholarship, University of California 2014
Subjects:
Biological Sciences
Genetics
Heart Disease
Cardiovascular
Human Genome
Atherosclerosis
Adaptation
Physiological
Adipose Tissue
Animals
Apolipoproteins B
Arctic Regions
Biological Evolution
Fatty Acids
Gene Flow
Population
Genome
Ursidae
Medical and Health Sciences
Developmental Biology
Biomedical and clinical sciences
Arctic
brown bear
polar bear
Online Access:https://escholarship.org/uc/item/4fj7t28j
Description
Summary:Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyper-lipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show that the species diverged only 479-343 thousand years BP. We find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under strong positive selection are associated with cardiomyopathy and vascular disease, implying important reorganization of the cardiovascular system. One of the genes showing the strongest evidence of selection, APOB, encodes the primary lipoprotein component of low-density lipoprotein (LDL); functional mutations in APOB may explain how polar bears are able to cope with life-long elevated LDL levels that are associated with high risk of heart disease in humans.

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