“Multilevel Selection Analysis Reveals Diversity in Selfish Mitochondrial Genome Dynamics”, 2022-04-10 (; similar):
Mutant copies of mitochondrial DNA (mtDNA) can behave as selfish entities, propagating within organisms at the expense of host fitness. We previously developed experiments to separately measure the within-host proliferation, and host fitness cost, of selfish mtDNA. By focusing on a single mutant genome, the uaDf5 variant, our previous work raises the question of generalizability: do selfish genomes uniformly overcome a heavy fitness cost by proliferating to high frequency, or do their population dynamics vary?
By applying a standardized multilevel selection analysis across a collection of mitochondrial mutants, we uncover variation in cheating strategies. Mutants that impose a heavy fitness cost nevertheless persist by outcompeting wildtype mtDNA within hosts. Conversely, some mutants fail to outcompete wildtype mtDNA but nevertheless persist, maintaining a frequency range at which host fitness cost is negligible.
These findings suggest that the population dynamics of mutant mtDNA depend on the loci affected.