Exobiology and Evolutionary Biology

Exploiting paleogenetics and experimental-evolution to reconstruct and recapitulate adaptive evolution (2)

PI: Eric Gaucher

The concept of experimental paleogenetics was proposed more than forty years ago as a way to exploit molecular sequence information in hopes of better understanding modern phenotypic diversity within a framework of ancient adaptation. Only recently, however, has computational reconstruction of ancestral sequences been supported by statistical models of character state inference and well-articulated phylogenies built from molecular sequence data. Laboratory resurrections of the inferred genes and proteins have, in turn, guided inferences regarding ancestral phenotypes based the behaviors of these ancient biomolecules. Beyond descriptions of ancient phenotypes and environments, paleogenetics provides the unique opportunity to 'replay’ the molecular tape of life. The research described in this proposal involves replacement of a modern component of the
E. coli protein translation machinery with its ancestral resurrected form through genomic integration. This research exploits the PI’s previous work with resurrected elongation factors and the known selective constraints governing the thermodynamic properties of extant proteins in their modern hosts. Recombinant E. coli expressing the ancient elongation factor will be subjected to long-term experimental-evolution studies to monitor the adaptation of the ancient biomolecule. The proposed experimental evolution of ancestral elongation factors provides an opportunity to both extend and experimentally validate the field of ancestral sequence reconstruction as a whole. The proposed research will have broad educational, scientific, and technological impact considering the growing interest in paleogenetics and its contributions to evolutionary theory, natural history and molecular evolution.