The Mitochondrial Eve

Who will she be?

Screen reader users should click the D-link at the end of the description of this exercise. Then come back and read the Thought Questions towards the bottom of the page.
The mitochondrial genotype is inherited through the cytoplasm, and so follows the female line through the generations. Due to random sampling, mitochondrial genotypes get "lost", and so the number gradually decreases (irregularly) through the generations, and finally one mitochondrial genotype is "fixed". (New ones are generated by mutation, which is not considered in this exercise.) Mitochondrial Eve (last accessed 27 Aug. 2022) - a "retroactive" name for the most recent female ancestor of all of the species' cytoplasm. An essay by Krishna Kunchithapadam (last accessed 27 Aug. 2022) provides additional discussion and references on this topic. (Note that this exercise investigates the "prospective" inheritance of the mitochondrial genotype.)

Starting with 10 female parental mitochondrial genotypes (represented by different background colors - the males are gray since their mitochondrial genotypes are not passed on to the next generation) the offpring are produced by randomly sampling uniformly (with replacement) from the parental generation. The mitochondrial genotypes for all the offspring are visible, but only the females are counted. After the Offspring generation is produced, it can be "promoted" to be the new Parental generation, and the process repeated to form succeeding generations. The number of mitochondrial genotypes in each generation is recorded in the box at the bottom of the page.

It may take many generations, but eventually there will be only one mitochondrial genotype in the offspring generation. Did you guess right? [D]

Parents   maternal mitochondrial genotypes

Offspring   female mitochondrial genotypes

• Does it always take the same number of generations to reach a "uniform color"? (Initialize and run several times to see this.)
  • You can cut/paste the record box into your own records to compare different runs.
• Does the existence of The Mitochondrial Eve imply that there was only one original maternal parent?
• What would be the effects on the dynamics of this process if there were selective differences between the mitochondrial genomes?
• If the paternal line also is involved in transmitting mitochondrial DNA (mtDNA) to the offspring, what will be the effect on the time to "reach a uniform color"?
  • The commonly made assumption is that the mtDNA is inherited only from the maternal parent. For a discussion of this assumption and the possibility that the paternal mtDNA may also be involved see: "mtDNA Shows Signs of Paternal Influence" Science 24 Dec 1999, Vol 286 p 2436.
• What did you learn from this simulation? You can compare your ideas with what I thought you should learn - by reading the discussion I prepared for visually impaired students. It's provided in the "D-link" above the simulation display.