Postdoctoral Fellow

Early membrane cellular functions: new insights from phylogenetic comparisons

PI(s): Jonathan Lombard
Start Date: 15-Feb-2013
End Date: 31-Dec-2014
Keywords: macroevolution, genomics, comparative methods, phylogenetics, coevolution

The precise biological description of the last common ancestor of living organisms (the cenancestor) is necessary to understand previous evolution from the origins of life and subsequent changes in modern lineages. Most early evolutionary studies focus in the informational apparatus (replication, translation, etc), but the genome content in the cenancestor likely encoded many other metabolic and cellular functions. Therefore, I will focus in the infrequently addressed issue of the early evolution of membrane-related functions (energy metabolism, trans-membrane transport and signal recognition) using innovative phylogenomic approaches.
Frequent objections to the study of early evolution using molecular phylogenies argue that single-gene phylogenies most often lack phylogenetic signal and are blurred by horizontal gene transfers (HGT). However, it has been recently observed that proteins involved in common metabolic pathways often share congruent evolutionary histories for ancient events and thus, they can provide confident information of early enzyme evolution. Independently, efforts to better acknowledge HGTs in microbial evolution have led to implement network phylogenomic approaches that simultaneously represent divergent tree topologies instead of forcing the construction of unique bifurcating trees.
I propose an integrative synthetic approach combining classical phylogenetic approaches with in-depth biochemical bibliography research and recent network phylogenomic methods. This original protocol will highlight the congruencies and disparities among trees for a collection of membrane-related enzymes, and, therefore, will emphasize the evolutionary tendencies both in the case of horizontal transfers or vertical inheritance. I will also make my network-based methodology extendable to other biological questions, thus providing a supplementary tool for evolutionary analyses.