Physics, physiology and evolutionary optimization of bacterial motility
Bacterial motility is among the quantitatively best-understood biological behaviors, at it has long served as a model of how physics can help to understand limits to bacterial ability to move and follow chemical gradients in the environment (chemotaxis). Here we will discuss how these physical limits might have shaped the evolution of bacterial motility and of the chemotaxis system. An equally important factor in the evolutionary optimization of biological pathways is the tradeoffs associated with investment of finite resources into different physiological functions, and we will see how this cost-benefit tradeoffs can explain the expression of motility genes in natural isolates as well as in the strains experimentally evolved under selection for motility. Finally, the ability of bacteria to compensate the loss of essential chemotaxis genes in the course of experimental evolution will be discussed.