Standing variation of beneficial mutations is sufficient for maintenance of anisogamy Open Access

Holmes, Caroline (2017)

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While the advantages of sexual reproduction for genetic recombination have been studied extensively, the question of emergence and maintenance of asymmetric sexual reproduction (anisogamy) has received much less attention. In the anisogamous case, females are limited in the maximum number of offspring that they can produce, so that the difference in number of offspring for a very fit or moderately fit female is minimal. In contrast, males are far less limited, and a single very fit male can have an enormous number of offspring. We propose that this asymmetry, and specifically the amount by which female fitness is curtailed by the maximum number of offspring she can produce, is what gives rise to evolutionary stability of anisogamy. We show that the variance in fitness for the males (which is related to how much the variance for females is limited) predicts the probability of success of an anisogamous population in competition with an isogamous one. This effect alone is sufficient to explain prevalence of anisogamy in rapidly changing environments, where mutations that had spread through the population as neutral mutations can quickly become beneficial. We end with proposals for experimental verifications of our theory.

Table of Contents

1. Introduction - pg. 1
2. The Model - pg. 3
2.1 Simulation Details - pg. 4
3. Results - pg. 4
Figure 1 - pg. 6

Figure 2 - pg. 7

Figure 3 - pg. 8
4. Discussion - pg. 5

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