Thread by @lausally

We present genomic evidence showing the West Antarctic Ice Sheet collapsed during the #LastInterglacialPeriod!🇦🇶🌊🚨#popgen #icesheet #interdisciplinary
...the tipping point of future #WestAntarcticIceSheet collapse could be reached even under the #ParisAgreement (+1.5-2.0°C)

We used found population connectivity between Ross Sea and Weddell Sea in an #Antarctic #octopus, and dated it back to #LastInterglacialPeriod. This is only possible if #WestAntarcticIceSheet completely collapsed and opened seaway connecting 2 basins biorxiv.org/cgi/content/sh… 🧵/9

This is my PhD work with @JanStrugnell @NeridaWilson @nick_golledge @naish_tim PhillWatts @Cataribio @iracooke @DrShmoo FelixMark, KatrinLinse. This work was only possible with their help+many hrs my advisors @JanStrugnell @NeridaWilson @Cataribio spent troubleshooting w me🧑‍🎓1/9

During the #LastInterglacialPeriod (Marine Isotope Stage 5e ~129-116ka), the global air temp was +0.5-1.5°C warmer than #preindustrial, but the global sea level was 5-10m higher then today! So where did the water come from? 2/9

For a long time, it was uncertain if the #WestAntarcticIceSheet collapsed which would have contributed to the then-sea level rise during #LIG. But geological records were blurry and models gave conflicting results 3/9

In 2018, @JanStrugnell @NeridaWilson proposed this Q could be solved using #popgen 💡🧬sciencedirect.com/science/articl… 4/9

The ideal species needs to be a bentho, has a circum-Antarctic distribution, some phylogenetic structure + samples from Weddell, Ross, @AmundsenSea and East Antarctica. FYI most #Antarctic #benthos are not preserved for DNA and samples from Amundsen and East Ant are very rare 5/9

After a while, we nailed down the octopus Pareledone turqueti 🐙 as the best candidate to answer this Q! Most of the samples we curated were heavily degraded, but we used a #targetcapture method to retrieve genomic loci (ddRAD) with great success 6/9

We used a hypothesis-driven, hierarchical approach to specifically test if, and when, #WestAntarcticIceSheet collapsed in the past using #demographicmodels and other #popgen methods. Signatures of a complete WAIS collapse during LIG was clearly detectable in P. turqueti 7/9

Understanding that #WestAntarcticIceSheet completely collapsed during #LIG will help us to define the tipping point of future #WestAntarcticIceSheet collapse under #climatechange. This will also improve future global #sealevelrise projections under different climate scenarios 8/9

I hope you enjoy this paper as much as I have enjoyed working on it! This work was kindly supported by @saef_arc @arc_gov_au @Ant_Sci_Ltd @AntarcticSF @Science_Academy @AeRO_eResearch
@SuomenAkatemia @scar_instant CoSyst @jcu @CSTFA_JCU @MarineOmics
-End 9/9