b'Carnegie Science|Summer 2019 15A geochemical tool that can detect thekeel-creation through subduction. ButCarnegie Welcomes source of a mantle keels makeup wascomparison to diamonds mined from needed to help resolve this debate. Luckily,northern Canada does not show the sameMoises Exposito-Alonso, mantle keels have the ideal conditions forsulfur chemistry. The mantle keel in thisStaff Associatediamond formation and scientists can revealregion originated in some way that did notat Plant Biologya mantle keels origin by studying inclusionsincorporate surface material.from within the diamonds. The groups findings suggest that The research groups analysis ofthickening and stabilization of the mantle sulfur-rich minerals, called sulfides, inkeel beneath the West African continent diamonds mined in Sierra Leone indicateshappened when this section of mantle that the region experienced two subductionwas squeezed by collision with the sinking events through history. ocean floor material. This method of keel They determined this because thethickening and continent stabilization is chemistry of the sulfide mineral grains isnot responsible for forming the keel under only seen in samples from Earths surfacea portion of northern Canada. The sulfide more than 2.5 billion years agobeforeminerals inside Canadian diamonds do oxygen became so abundant in our planetsnot tell the researchers how this keel atmosphere. This means that the sulfur informed, only how it didnt.these mineral inclusions must have onceOur work shows that sulfide existed on the Earths surface and was theninclusions in diamonds are a powerful tool drawn down into the mantle by subduction. to investigate continent construction The teams comparison to diamondsprocesses, Smit concluded. from Botswana showed similar evidence ofEvolutionary geneticist Moises Exposito-Alonso is joining the Department of Plant Biology as a staff associate on September 1, 2019. He investigates whether and how plants will evolve to keep pace with climate change by conducting large-scale ecological and genome-sequencing experiments. He also develops computational methods to Carnegie staff scientist Stevederive fundamental principles of Shirey works in the field and in the lab to reconstructevolution, such as how fast natural Earths history.populations acquire new mutations Image courtesy Matthew Scott and how past climates shaped continental-scale biodiversity patterns. His goal is to use these first principles computations to forecast evolutionary outcomes of populations under climate change to anticipate potential future biodiversity losses. Exposito-Alonso is also interested in developing genome engineering methods that can help species adapt instead of becoming extinct.Exposito-Alonso earned his Ph.D. in ecological genomics in 2018 from the Max Planck Institute in Tbingen, Germany. He received an MSc degree in quantitative and population genetics from the University of Edinburgh, Scotland, and a B.S. in biology from the University of Seville, Spain. He was a postdoctoral fellow in statistical SUPPORT:The Gemological Institute ofgenetics at the University of America, the University of Alberta,California-Berkeley during 2019. the National Science Foundation, and Carnegie supported this work. It is a contribution to the Deep Carbon Observatory.'