MOLECULAR EVOLUTION MODELED AS A FRACTAL POISSON-PROCESS IN AGREEMENTWITH MAMMALIAN SEQUENCE COMPARISONS

The fractal doubly stochastic Poisson process (FDSPP) model of molecul ar evolution, like other doubly stochastic Poisson models, agrees with the high estimates for the index of dispersion found from sequence co mparisons. Unlike certain previous models, the FDSPP also predicts a p ositive geometric correlation between the index of dispersion and the mean number of substitutions. Such a relationship is statistically pro ven herein using comparisons between 49 mammalian genes. There is no c haracteristic rate associated with molecular evolution according to th is model, but there is a scaling relationship in rates according to a fractal dimension of evolution. The FDSPP is a suitable replacement fo r the homogeneous Poisson process in tests of the lineage dependence o f rates and in estimating confidence intervals for divergence times. A s opposed to other fractal models, this model can be interpreted in te rms of Darwinian selection and drift.