Department of Environmental Sciences

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Seminar Abstracts
Environmental Sciences Seminar Abstract            

  What can modern genomes tell us about the first 3 billion years of life on Earth?
Eric Alm

The Alm lab develops complementary computational and experimental methods for studying microbial ecology and evolution. Ongoing projects include the detection of selection in ancestral bacteria, the experimental evolution of marine Vibrio, and the refinement of the Tree of Life. Present day microbial genomes are the handiwork of over 3 billion years of evolution. Comparisons between these genomes enable stepping backwards through past evolutionary events, and can be formalized using binary tree models known as phylogenies. We have analyzed thousands of microbial gene families in an effort to reconstruct early events in life and biogeochemical history. We are also examining the the geochemical/ecologial factors that underlie community diversity, and the phylogenetic boundaries of natural ecological populations. As part of this effort, we have experimentally evolved various lineages of Vibrio splendidus strains on gradually increasing salinities. Interestingly, our approach yielded hypermutator strains at much higher rates than expected. By combining genome re-sequencing of the evolved strains with the analysis of their physiology and gene expression we hope to understand the scale and effect of small mutation events or hypermutation on bacterial stress tolerance and niche adaptation.

Last updated: 11/29/2011