Figure 4.

Regulation of energetically selfish proto-mitochondria by metabolic demand and stochastic processes. If the proto-eukaryote exerts strong metabolic demand because of rapid growth and replication (a), then normal proto-mitochondria (unfilled circles) will perceive a high ADP/ATP ratio and their rates of growth and division will match those of variant proto-mitochondria (filled circles). If metabolic demand of the proto-eukaryote falters and it undergoes whole-cell fusion and whole-genome recombination (b), stochastic processes may still produce a daughter cell with all normal proto-mitochondria.