Thermodynamical interpretation of evolutionary dynamics on a fitness landscape in a evolution reactor, I.
A theory for describing evolution as adaptive walks by a finite population with M walkers (M > or = 1) on an anisotropic Mt. Fuji-type fitness landscape is presented, from a thermodynamical point of view. Introducing the 'free fitness' as the sum of a fitness term and an entropy term and 'evolutionary force' as the gradient of free fitness on a fitness coordinate, we demonstrate that the behavior of these theoretical walkers is almost consistent with the thermodynamical schemes. The major conclusions are as follows: (1) an adaptive walk (=evolution) is driven by an evolutionary force in the direction in which free fitness increases; (2) the expectation of the climbing rate obeys an equation analogous to the Einstein relation in Brownian motion; (3) the standard deviation of the climbing rate is a quantity analogous to the mean thermal energy of a particle, kT (x constant). In addition, on the interpretation that the walkers climb the landscape by absorbing 'fitness information' from the surroundings, we succeeded in quantifying the fitness information and formulating a macroscopic scheme from an informational point of view.
Computational Biology Research Center, National Institute of Advanced Industrial Science and Technology, 2-43 Aomi, Koto-ku, Tokyo 135-0064, Japan.
Takuyo
T
Aita
Shunichi
S
Morinaga
Yuzuru
Y
Husimi
D000220:Adaptation, Biological; D019143:Evolution, Molecular; D009716:Numerical Analysis, Computer-Assisted; D013816:Thermodynamics