Thaindian News

Washington, July 10 (ANI): A new study has indicated that seals can quickly respond to gain and loss of habitat under climate change.

The study was conducted by an international research team, including post-doctorate Dr Mark de Bruyn and collaborators from the US, South Africa and Italy, led by Professor Rus Hoelzel from the School of Biological and Biomedical Sciences, Durham University.

It revealed that Southern Elephant seals responded rapidly to climate and habitat change and established a new breeding site thousands of kilometres from existing breeding grounds.

The scientists found that when the Antarctic ice sheets of the Ross Sea Embayment retreated in the Holocene period 8,000 years ago, elephant seals adopted the emergent habitat and established a new population which flourished.

DNA sequences from the ancient remains of seals from the now extinct Antarctic colony showed high levels of genetic diversity, probably due to the very large population size sustained there.

According to Professor Rus Hoelzel, “We’ve shown how a highly mobile marine species responded to the gain and loss of new breeding habitat.

“The new habitat was quickly adopted, probably because seals migrate annually into Antarctic waters to feed. However, when the ice returned and the habitat was lost, only a small proportion returned to the original source population. The Antarctic population crashed and much diversity was lost,” he said.

This habitat was released after the retreat of the grounded ice sheet in the Ross Sea Embayment 7,500-8,000 years ago, and is within the range of modern foraging excursions from the Macquarie Island colony.

Using ancient mtDNA and evolutionary models, the research team tracked the population dynamics of the now extinct colony and the connectivity between this and modern breeding sites.

The team found clear signs of rapid expansion in the new colony 8,000 years ago.

This was followed by directional migration away, coupled with a loss of diversity 1,000 years ago, when the sea ice is thought to have expanded.

The data suggest that the new colony seals came initially from Macquarie Island, and that some returned there, but in much smaller numbers, when the new colony habitat was lost 7,000 years later.

“The seals that discovered the new breeding site had things good, because food was abundant and nearby, however when the ice returned, the new colony collapsed and only a few seals made it back to their original home,” Hoelzel said. (ANI)