Figure 4.

Effects of fluctuations in growing season length among years (a) and the diapause timing of the early-diapausing genotype Jpn1A-C2T2 (b) on coexistence of the two genotypes in the theoretical model. (a) Larger variation in the length of the growing season promotes stable coexistence of the two genotypes. (b) Earlier production of diapausing eggs of JPN1 promotes stable coexistence, whereas late production makes coexistence difficult. Horizontal axes are the mean of the normal distribution that the length of the growing season follows. Lines indicate parameter conditions where invasion growth rates (the logarithm of equation (2.4)) are zero. The invasion growth rate of Jpn1A-C2T2 is positive on the left of the black line, and that of Jpn2C is positive on the right of the grey line. Coexistence occurs in the area where the invasion growth rates of both Jpn1A-C2T2 and Jpn2C are positive (i.e. mutually invasible). The black points represent the parameter values in both figure 1c and 1b. The horizontal line in figure 4b indicates the parameter value in figures 1c,b, and 4a. We randomly sampled 10 000 parameter combinations, evaluated invasibility, and drew contour plots for the phase diagrams.