A groundbreaking study utilizing the genetic history of the Turquet's octopus (Pareledone turqueti) has potentially unraveled a long-standing mystery surrounding the collapse of the West Antarctic ice sheet. The research, published in the journal Science, sheds light on when the ice sheet last collapsed and offers valuable information about future sea level rise in a warming climate.

Lead study author Sally Lau, a postdoctoral research fellow at James Cook University in Australia, expressed excitement about the project, explaining that DNA from living animals contains a wealth of information about their ancestors and acts as a unique "time capsule."

To piece together the puzzle, the research team sequenced the DNA of 96 Turquet's octopuses collected over the years from institutions worldwide and through fishing bycatch. By analyzing their genes, scientists were able to construct a comprehensive family tree going back millions of years.

The DNA analysis revealed fascinating insights about the octopus populations. The study found genetic connectivity between different populations of Turquet's octopuses in the Weddell, Amundsen, and Ross seas around 125,000 years ago, during a period known as the Last Interglacial. This suggested that the West Antarctic ice sheet had collapsed during that time, allowing the octopuses to occupy ice-bound areas on the seafloor.

Jan Strugnell, professor and director of the Centre for Sustainable Tropical Fisheries and Aquaculture at James Cook University, explained the significance of the West Antarctic ice sheet collapse. Not only is it a crucial contributor to global sea-level rise, but a complete collapse could raise sea levels by as much as 3 to 5 meters.

The findings also have implications for improving future sea-level rise projections. Understanding the configuration of the West Antarctic ice sheet during periods similar to today's global temperatures will provide valuable data for estimating future sea-level changes.

The choice of the Turquet's octopus for the study was strategic. Its relatively immobile nature means it is more likely to breed within its local populations, preserving distinct genetic characteristics. Additionally, the species is well-studied, enabling researchers to accurately determine DNA mutation rates and generation time for precise molecular dating.

While previous studies involving crustaceans and marine mollusks had detected genetic connectivity between the Ross and Weddell seas, this study stood out due to its high-resolution data and significant sample size. It effectively differentiated between the collapse of the ice sheet and gradual movement of octopuses around its edges.

Although this genetic approach couldn't pinpoint the exact timing or duration of the ice sheet collapse, future research using more advanced DNA analysis techniques and fresh octopus samples may provide further insights.

Andrea Dutton, a professor at the University of Wisconsin-Madison, and Robert M. DeConto, a professor at the University of Massachusetts Amherst, hailed the study as pioneering. They highlighted its potential importance in understanding historical climate change and whether it may be repeated given Earth's current temperature trajectory.

Douglas Crawford, a professor of marine biology and ecology at the University of Miami, praised the study as a careful and meticulous investigation. He noted that the study's sufficient sample size and vetted genetic markers lent credibility to its findings.

The use of octopus genomics to explore issues of historical climate change represents an innovative and exciting approach. Lau and her team expressed their eagerness to continue utilizing DNA as a tool to uncover further climate history mysteries across Antarctica.

The study opens up new avenues of research and highlights the critical role that DNA analysis can play in understanding Earth's climate history and predicting future environmental changes.

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