Muller's ratchet can also be applied to plastids, as the organelles are excluded from any sexual recombination process of the host cell. Endosymbiotic ratchet accelerates divergence after organelle origin: The Paulinella model for plastid evolution: The Paulinella model for plastid evolution. The evolution of plastids from free-living cyanobacteria that first were taken up by a host cell and then converted to organelles is such a case.