Author: Ingrid Billault-Chaumartin

A biochemical story on convergent evolution Introduction Convergent evolution is the process by which similar traits evolve independently in distantly related organisms, such as wings in bats and birds. This can target orthologous or unrelated genes, which gives a different view on the concept of convergent evolution : how much it is constrained to some pathways, or, reversely, how diverse the path to the same function can be. For convergent evolution to arise, different proteins must be assembled into an ordered, functional pathway. Currently, Three hypotheses shed light on the matter. Under the cumulative hypothesis, enzymes catalyzing the earlier reactions of a pathway must evolved first, because, otherwise, enzymes that perform the following steps would have no substrate to react with. Later steps would arise by duplication of the first enzyme. This suppose that intermediates are advantageous. Reversely, under the retrograde hypothesis, enzymes catalazing the later steps of a pathway would evolved first, and then gene duplication would give rise to the enzymes catalysing earlier steps. This suppose that intermediates could be produced non-enzymatically but doesn’t assume anything on their potential effect. Finally, the patchwork hypothesis states that a novel pathway will arise by the recruitment and rerouting of an alternative, …