Loss of complementation and the logic of two‐step meiosis

Meiosis is usually a two‐step process: two divisions preceded by a duplication. One‐step meiosis, a single division without prior replication, is a more logical way to produce haploid gametes; moreover, one‐step meiosis leads to higher variabilty in the progeny than two‐step meiosis. Yet one‐step meiosis is very rare in nature, and may not even exist at all. I suggest that this is because one‐step meiosis, in contrast to two‐step meiosis, can be easily invaded and replaced by asexual reproduction. I discuss why other existing peculiar forms of division leading to the production of haploid gametes, but not one‐step meiosis, have the same effect as two‐step meiosis.