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Fig. 3 | BMC Biology

Fig. 3

From: Sexual conflict explains the extraordinary diversity of mechanisms regulating mitochondrial inheritance

Fig. 3

Changes in the variance of mutation number and fitness under maternal control. a Zygotic variance in mutation number is more constrained under biparental inheritance (BPI, π = 1) or higher values of π (red), as mixing mitochondria from two gametes increases the frequency of intermediate cytotypes compared to uniparental inheritance (UPI, π = 0) or lower values of π (blue). Note that the mode of inheritance does not alter the mean number of mutants (arbitrarily set at 20 mutants), only the variance in mutation frequency. The fitness function (black curve) is concave (epistasis ξ = 3), which assumes that a large number of mutants must accumulate before cell function is significantly undermined. Higher variance boosts the efficacy of purifying selection, allowing greater removal of mutant mitochondria in the long term. This favours lower values of π. b The distribution of zygote fitness given the frequency distributions in panel a. BPI has a short-term mean fitness advantage (dotted lines) because intermediate cytoplasmic states have higher fitness than the mean of the extreme states. Note that the variance in fitness is higher with UPI, as more individuals have higher as well as lower fitness

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