(A) Trajectories of mean copy number and normalised heteroplasmy variance arising from the models described in the text, optimised with respect to data from experimental studies. Birth-death-partition (BDP) denotes the BDP model, encompassing Cree and Wai (A) mechanisms. Left plots show trajectories during development; right plots show behaviour in mature oocytes in the next generation. * denotes measurements in mature oocytes, modelled as 100 dpc (see ‘Materials and methods’). (B) Statistical support for different mechanisms from approximate Bayesian computation (ABC) model selection with thresholds ϵ1,2,3,4 = 75, 60, 50, 45. As the threshold decreases, forcing a stricter agreement with experiment (thinner, darker columns), support converges on the BDP model.