Abstract:

Evolution is a tinkerer not an engineer: the term exaptation was coined to signify that old structures, that could be not significant in terms of fitness, get re-used when environmental conditions changed. Here I show that the average protein composition of G+C rich bacteria were exapted to the switch from anaerobic to aerobic conditions. Because the proteome composition is under the strong control of directional mutation pressure, this is an example of exaptation at the molecular level for which the underlying mechanism is documented.