Evolving a favorable distribution for mutation effects

Tandem-repeat DNA sequences appear to be singularly capable of yielding abundant repeat-number mutations with a potentially advantageous distribution of fitness effects. Although knowing the rates and relative proportions of deleterious, neutral and beneficial mutations is fundamental for understanding evolvability, analysis of adaptation routinely overlooks small-effect mutations arising in tandem repeats. Tandem-repeat DNA sequences appear to be singularly capable of yielding abundant repeat-number mutations with a potentially advantageous distribution of fitness effects. Although knowing the rates and relative proportions of deleterious, neutral and beneficial mutations are fundamental for understanding evolvability, analysis of adaptation routinely overlooks small-effect mutations arising in tandem repeats.