PgmNr P2042: A gene’s view of a long-term evolution experiment with Escherichia coli.

Authors:
Rohan Maddamsetti ¹ ; Philip Hatcher ² ; Barry Williams ¹ ; Jeffrey Barrick ³ ; Richard Lenski ¹

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Institutes
1) Michigan State University, East Lansing, MI; 2) University of New Hampshire, Durham, NH; 3) University of Texas at Austin, Austin, TX.

Abstract:

In my dissertation research, I used genomic data from a long-term evolution experiment with Escherichia coli (LTEE) to answer two questions, among others. First, what do the evolutionary dynamics in the LTEE look like? Second, what kinds of genes evolve in the LTEE? These studies share the same cast of characters: pykF, iclR, spoT, nadR, topA, and malT. These genes make the strongest contribution to adaptive evolution in the LTEE. I use these genes to show that the evolutionary dynamics that play out in the LTEE involves two processes that are often difficult to tell apart: clonal interference and negative frequency-dependent selection. I then show that even though these genes evolve rapidly and repeatedly in the LTEE, they are well-conserved across E. coli isolates and have diverged slowly since the Salmonella–Escherichia split. In fact, adaptive evolution in the LTEE largely involves mutations at conserved protein residues within conserved core genes such as pykF. The apparent simplicity of LTEE belies considerable complexity, making the LTEE a powerful model system for evolutionary genomics.