A team of scientists at the Senckenberg Research Center for Biodiversity and Climate in Frankfurt, Germany, has reconstructed large parts of the male chromosome in polar bears (Ursus maritimus).

“In order to gain insights into the evolutionary development of polar bears, we use genetics instead of fossils,” said Prof Axel Janke, team leader and senior author of a paper published in the journal Genome Biology and Evolution.

“In this age of biological revolution, it is possible to sequence the entire genome of an organism rather quickly and cost-effectively. However, to date, such comprehensive genome projects have mostly been limited to female animals, neglecting the males’ special chromosome – the Y chromosome.”

“This is quite surprising, since the Y chromosome is an important part of the mammalian genome,” added study lead author Tobias Bidon. “It is the only genetic material that is passed on from male to male, thereby offering unique insights into the evolutionary history and population dynamics.”

The scientists were able to assign 1.9 million base pairs specifically to the polar bear Y chromosome.

They also found that around 100,000 years ago, the male polar bear lineages split and developed in two separate genetic groups.

“Today, individuals from both genetic groups can be found in various Arctic regions – from Alaska to Spitsbergen,” Mr Bidon explained.

“This confirms the idea that polar bears roam across vast distances and distribute their genetic material throughout the entire Arctic.”

“We will to use our bioinformatic approach to reconstruct large parts of the Y chromosome from other male genomes, in order to study paternal inheritance and migration from the male perspective,” Prof Janke said.

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Tobias Bidon et al. 2015. Genome-Wide Search Identifies 1.9 Mb from the Polar Bear Y Chromosome for Evolutionary Analyses. Genome Biol Evol 7 (7): 2010-2022; doi: 10.1093/gbe/evv103