EVOLUTION ESCAPES RUGGED FITNESS LANDSCAPES BY GENE OR GENOME DOUBLING - THE BLESSING OF HIGHER DIMENSIONALITY

Evolution on rugged landscapes ceases when a local maximum is attained. This poses the problem of how evolution could approach or attain a global maximum, especially for large genomes for which quasispecies are ineffective. I show how increasing the dimensionality of the landscape, which occurs every time there is a gene or higher order duplication (up to polyploidy), may solve this problem. Epistasis or complementarity between the duplicated genes provides an all uphill pathway towards the global maximum. The evolution of hemoglobin and other dimeric and tetrameric proteins provides a testable case, since fitness is readily defined.