#40 · Systems biology

Mutation-selection dynamics localize quasispecies and bias evolution toward flat fitness

Three preprints address how stochastic variation shapes equilibrium distributions in mutation-selection and ecological systems. The first derives a general Hill-number relation for quasispecies localization under Eigen's model, applicable to viral diversity measures. The second shows that fluctuating species interactions displace equilibria, yielding a universal power law with exponent 2 and critical noise scaling as N^-1 in ecological networks. The third finds that mutation-selection dynamics on degenerate fitness manifolds drift toward low-curvature, flat regions in a minimal evolutionary model. The dominant thread is fluctuation-driven redistribution of population or abundance across constrained states. The ecological and evolutionary results address distinct systems and are not unified by a shared derivation in these items.