Prokaryotic diversity, electrified DNA, lightning waveforms, abiotic gene transfer, and the Drake equation: assessing the hypothesis of lightning-driven evolution.

In a review article in this journal [1], I discussed the feasibility of lightning-triggered electroporation and electrofusion acting as purely (bio)physical mechanisms of horizontal gene transfer and thus contributing to biological evolution, particularly among the prokaryotes. I would like to thank the authors of all commentaries on this article [2–6], and here I try to address the most important issues raised in them. Golberg [2] stresses that for different bacteria, the range of electric fields strengths causing reversible electroporation with ability for DNA uptake generally differs, and so does the range of electric field strengths causing irreversible electroporation with DNA release. This is true for prokaryotic organisms in general (both bacteria and archaea), and consequently, in the area where some prokaryotic species are electroporated irreversibly, others may be electroporated reversibly, avoiding the need for DNA to travel from the area where it is released from an irreversibly porated prokaryote to the area where it can enter a reversibly porated prokaryote and transform it. As I tried to emphasize in the last paragraph of Section 3.1 in my review article [1], the ranges of reversible and irreversible electroporation overlap even for prokaryotic organisms belonging to a single strain, because individual organisms vary in their size (due to being in different stages of the division cycle) and in their orientation with respect to the field direction, and also because pore formation is to some extent stochastic. But indeed, for two randomly sampled organisms belonging to different strains, there will – at least on average – be larger differences in their shape, size, as well as in composition of their wall and membrane, than if the two organisms being compared are of the same strain. Furthermore, the more distant the two strains are phylogenetically, the more pronounced – again, at least on average – most of these differences will be. With increasing differences between the donor and the acceptor, the availability of DNA released from the