 Siefert's work deals with understanding life's origins through microbial ecology and genomic and metabolic evolution.She has worked for 20 years in Cuatro Ciénegas, Mexico, a desert oasis protected by the Mexican government and known to exhibit endemism equal to the Galapagos.She is the first woman to serve as chairman of the Gordon Research Conference on the Origin of Life and the first female president (2008-2011) of .