Protein evolution under multiple opposing selective forces*

Evolution on a multidimensional adaptive landscape is the rule, not an exception in biological systems. When multiple opposing selection factors are simultaneously present or rapidly fluctuating in an environment, evolution is a genetic search on a convoluted fitness landscape with several pitfalls due to incompatibilities between genetic changes. Using a bacterial membrane protein as a model system, I will address (i) how evolutionary constraints on multiple fitness conditions arranged in a protein sequence and, (ii) how the rate and mechanism of protein evolution can vary under different (opposing or overlapping) selection conditions.