  Rich information on the prebiotic evolution is still stored in contemporary
genomic data. The statistical mechanism at the sequence level may play a
significant role in the prebiotic evolution. Based on statistical analysis of
genome sequences, it has been observed that there is a close relationship
between the evolution of the genetic code and the organisation of genomes. A
biodiversity space for species is constructed based on comparing the
distributions of codons in genomes for different species according to
recruitment order of codons in the prebiotic evolution, by which a closely
relationship between the evolution of the genetic code and the tree of life has
been confirmed. On one hand, the three domain tree of life can be reconstructed
according to the distance matrix of species in this biodiversity space, which
supports the three-domain tree rather than the eocyte tree. On the other hand,
an evolutionary tree of codons can be obtained by comparing the distributions
of the 64 codons in genomes, which agrees with the recruitment order of codons
on the roadmap. This is a simple phylogenomic method to study the origins of
metazoan, the evolution of primates, etc. This study should be regarded as an
exploratory attempt to explain the diversification of the three domains of life
by statistical mechanism in prebiotic sequence evolution. It is indicated that
the number of bases in the triplet codons might be explained statistically by
the number of strands in the triplex DNAs. The adaptation of life to the
changing environment might be due to assembly of redundant genomes at the
sequence level.
