Figure 1.

Frequency of sexual reproduction over time under different sexual strategies. (a) Uniform sex, where all the individuals have the same tendency for sexual reproduction, irrespective of condition or environment, and the variance is due to random effects only. (b) Condition-dependent sex, constant environment, where low- and high-quality individuals have high and low frequency of sexual reproduction, respectively (red for low-quality individuals, blue for high-quality ones). The mean frequency of sex (grey) is equal to that of the population with a uniform frequency in (a), but the variance in the frequency of sex is much higher. (c) Environment-dependent sex, where the frequency of sexual reproduction depends on environmental cues (red arrows). The variance in the frequency of sex is low at any given time point, but high over time. (d) Condition-dependent sex in a changing environment. Low- and high-quality individuals have high and low frequency of sexual reproduction, as in (b), but the fraction of low-quality individuals depends on environmental conditions. After an environmental change (red arrow) most of the population is maladapted, or low quality, and reproduces sexually at the high rate (red line). The variance in the frequency of sex is high at any given time point and high over time.