Fig. 3
a An example of the coevolutionary dynamics observed between the male seminal gift size (V, blue) and the optimal number of matings for females (MO, red), together with changes in the realized number of matings by females (MR, orange) and female fitness (F, green). b Changes in the proportion of females with twin slots (2S), which started to invade the population at the 1000th generation (the black arrowhead), with schematics of 1S and 2S states. Solid lines and shaded areas of respective lighter colors show the mean ± SD for 40 runs under the FR (fair raffle) regime (R = 800, c = 55). c Spermathecal plate (delineated by red dashed line) of Neotrogla truncata with a spermatophore. A female can actively control the direction of seminal flow (blue arrow), either to slot A (green arrow) or to slot B (purple arrow). Scale bar: 50 µm