The Bak-Sneppen evolutionary model can be used to analyse self-organization on
nucleotide content of evolving species.
Applying two-parameter Kimura model of substitution enables changes of the nucleotide
fractions in time.
We established fitness parameter as a deviation of the genomic nucleotide fraction
from its equilibrium value (0,25 and the food chain had the same dynamics as in
Bak-Sneppen model in spite of its asymmetrical neighborhood.
The new findings are: the higher is the value of the threshold fitness, the more
frequent are large fluctuations in number of species with strongly differentiated
nucleotide content; and it is more often the case that the oldest species,
which survive the food-chain competition, might have specific nucleotide fraction
making possible generating long genes.