Abstract

Darwinian evolution proceeds in two steps. Firstly, there is variation: due to mutations, different members of a population may have differences in traits. Secondly, there is selection: if the variation in a trait allows an organism to have more viable offspring, to be ‘fitter’, then that trait will eventually come to dominate in the population. But is that variation generated in a uniform fashion, or could there be biases in the way it appears? Some general considerations of genotype-phenotype maps and evolutionary search suggest that A) Because of neutral mutations, the number of genotypes is typically much larger than the number of possible phenotypes and B) These genotypes are not uniformly distributed, but rather highly biased towards an exponentially small fraction of “frequent’ phenotypes that are therefore much more likely to arise by random mutations. These large differences in the rates at which traits can arrive through variation may direct evolution towards outcomes that are not simply the ‘fittest’. Instead it may be that the most ‘frequent’ are so much more likely to arrive, that they are the ones who survive.

see also The arrival of the frequent: how bias in genotype-phenotype maps can steer populations to local optima Steffen Schaper and Ard A. Louis PLoS ONE 9 (2): e86635 (2014)