*N*, *u*, *s* | Population size, mutation rate, and mutation effect |

| Number of individuals in class *k* at time *t*, steady-state value |

λ = *u*/*s*, *τ* = *ts* | Rescaled mutation rate and time |

| Population frequency in class *k* at time *τ*, steady-state value |

*z*_{τ}, | Abbreviation for *x*_{0}(*τ*) and |

| Mean fitness: |

, | Deviations from steady state: , |

*S*_{λ}({*z*_{ρ}}) | Path integral action depending on the path {*z*_{ρ}} with 0 ≤ *ρ* ≤ *τ*. |

, | Extremal action and the associated path depending on the endpoints *z*_{τ}, *z*_{0} |

| Long time limit of with *z* = *z*_{τ} |

*P*_{τ}(*z*_{τ}|*z*_{0}) | Propagator from *z*_{0} to *z*_{τ} in time *τ* |

*P*(*z*) | Steady-state distribution of *z* |

*γ* | Rate of the ratchet in units of *s* |

*σ*^{2} | Variance of *x*_{0} depending on *Ns* and *λ* |

*ζ*^{2} | Rescaled variance of *x*_{0} depending on *λ* only: *ζ*^{2} = *Nse*^{λ}σ^{2} |

, | *k*th component of right and left eigenvectors with eigenvalue −*i* |

*a*_{i}(*τ*) | Projection of *δx*_{k} on |

*α* | Parameter of the effective potential confining *x*_{0} (traditionally *α* = 0.5−0.6) |