Scientists exploring the depths of Antarctica's past have turned to an unexpected source—octopus DNA—to reveal a lost chapter in the continent's history. Approximately 100,000 years ago, the colossal western ice sheet of Antarctica is believed to have collapsed, temporarily connecting seas around the region. The surprising genetic evidence comes from Turquet's octopus, indicating a prolonged period of interbreeding following the ice sheet's collapse and subsequent isolation, as reported in Science.
This genetic record not only sheds light on Antarctica's ancient geography but also raises concerns about the potential for a significant rise in sea levels in the near future.
The collapse of the ice sheet allowed populations of Turquet's octopus (Pareledone turqueti) to intermingle for thousands of years. As the ice sheet reformed, these octopuses were once again isolated, leaving a genetic tale of their interconnected past.
The study, described as a "really creative approach" by geologist Andrea Dutton, unveils a critical period around 129,000 to 116,000 years ago, known as the last interglacial, marked by a warmer Earth and higher sea levels. The collapse of the West Antarctic Ice Sheet during this era is considered a potential driver for the elevated sea levels observed.
Biologists, seeking additional evidence for this collapse, turned to Turquet's octopus, a cephalopod inhabiting the waters around Antarctica. By analyzing the DNA of 96 octopuses collected over 33 years, the researchers identified distinct populations and built demographic models to simulate interbreeding scenarios.
The models indicated that before the ice ages, ocean currents connected four octopus populations in different regions around Antarctica. The collapse of the ice sheet led to isolation and genetic differentiation among these populations. The collapse scenario aligning with the observed genetic patterns suggested that interbreeding occurred between 139,000 and 54,000 years ago.
These findings align with geological evidence, strengthening the case for the collapse of the ice sheet during the last interglacial. The octopus genome data serves as compelling evidence, emphasizing the need to comprehend the current impact of climate conditions on the West Antarctic Ice Sheet.
The study underscores the urgency of addressing climate change, particularly in mitigating ocean warming caused by greenhouse gas emissions. Researchers emphasize the importance of taking immediate action to avoid the potential destabilization of the submerged portion of the ice sheet, highlighting that delaying emissions cuts is not an option.
More: https://www.science.org/content/article/lost-history-antarctica-revealed-octopus-dna
