As is the case with other evolutionary phenomena, there is no way to formally demonstrate that the suggested pathways are indeed the actual ways things came to be. The recently discovered noncontiguous sequences in eukaryotic DNA that encode messenger RNA may reflect an ancient, rather than a new, distribution of information in DNA and that eukaryotes evolved independently of prokaryotes. In short, Margulis' endosymbiosis theory is, like all other Darwinist macro-evolutionary theory, driven by similarities and naturalistic Darwinist necessity. The amount is to be determined by the geological record and biological experimentation. But there is no vertical radiation.
Vertical radiation is only by fiat creation.
A root-species may give rise to several species by horizontal radiation, through the process of the unraveling of gene potentialities or recombination. Horizontal radiation could account for much which now passes as evidence for the theory of evolution. The gaps in the geological record are gaps because vertical progress takes place only by creation.