Recombination and Error Thresholds in Finite Populations

This paper introduces the notions of `quasi-species' and `error threshold' from molecular evolutionary biology. The error threshold is a critical mutation rate beyond which the effect of selection on the population changes drastically. We reproduce, using GAs --- and hence finite populations --- some interesting results obtained with an analytical model --- using infinite populations --- from the evolutionary biology literature. A reformulation of a previous analytical expression , which explicitly indicates the extent of the reduction in the error threshold as we move from infinite to finite populations, is derived. Error thresholds are shown to be lower for finite populations. Moreover, as in the infinite case, for low mutation rates recombination can reduce the diversity of the population and enhance overall fitness. For high mutation rates, however, recombination can push the population over the error threshold, and thereby cause a loss of genetic information. These results may be ..