  Background: Acceleration of adaptation dynamics by stress-induced
hypermutation has been found experimentally. Evolved evolvability is a
prominent explanation. We investigate a more generally applicable explanation
by a physical constraint. Methods and Results: A generic thermodynamical
analysis of genetic information storage obviates physical constraints on the
integrity of genetic information. The capability to employ metabolic resources
is found as a major determinant of mutation probability in stored genetic
information. Incorporation into a non-recombinant, asexual adaptation toy model
predicts cases of markedly accelerated adaptation, driven by a transient
increase of mutation rate. No change in the mutation rate as a genetic trait is
required. The mutation rate of one and the same genotype varies dependent on
stress level. Implications: Stress-dependent mutation rates are physically
necessary and challenge a condition-independent genotype to mutation rate
mapping. This holds implications for evolutionary theory and pathogen and
cancer evolution.
