Paula Welander

Assistant Professor
Stanford University
Department of Environmental Earth System Science

I am a microbiologist with interests in understanding the biosynthesis and physiological function of “molecular fossils” or biomarkers in extant bacteria. Biomarker signatures in ancient rocks have been used to reconstruct important events in the Earth’s past, such as the first appearance of major groups of organisms, the catastrophic loss of biodiversity and the evolution of cyanobacteria and oxygenic photosynthesis. Despite the significant implications biomarker studies have on our interpretation of microbial evolution and of the Earth’s ancient environment, our understanding of the phylogenetic distribution and physiological function of most of these molecules in modern bacteria is quite limited. My research utilizes a combination of bioinformatics, microbial genetics, physiology, and biochemistry to address three general questions that can be applied to any biomarker: 1) what is its phylogenetic distribution in modern bacteria? 2) what are its physiological roles in modern bacteria? 3) what is the evolutionary history of its biosynthetic pathway?