Standing Variation of Beneficial Mutations is Sufficient for Maintenance of Anisogamy

The advantages of sexual reproduction are well known. However, the benefits of having a population with anisogamous sexual reproduction (i.e., with males and females) is less clear. We propose that some of the benefits of anisogamous reproduction may come from the differences in the maximum number of offspring produced by anisogamous females, isogamous females, and anisogamous males. Only the anisogamous males are virtually unlimited in total number of potential offspring, which allows for a more rapid spread of beneficial alleles through the population. We show that in some parameter regimes this effect alone is sufficient to maintain anisogamy in computational experiments. We end with proposals for experimental verification of our theory.