Fig. 1

Gametocytes are drawn from Poisson (left) or negative binomial (right) distributions, with a mean of 5 gametocytes/µl (the threshold of microscopic detection). Each capillary represents exactly 1 µL of blood and in addition to the male (yellow) and female (purple) gametocytes pictured, also contains 5 million RBCs (represented by the red background). Definite failures to infect are in the bottom capillaries, containing no or single sex gametocytes (2 failures for Poisson, 3 for negative binomial). The female mosquito takes her blood meal from the capillary with a relatively high number of males (7) and females (14), represented in her gut. The red cube zooms in on 1/10th of this meal (0.1 µl). As noted, this cube contains 500,000 RBCs but only 2 females and 1 male. The purple dots in the red cube are the approximate relative size of immotile females in 1/10th of a µL, and the two yellow cubes represent the volume explored by a single male swimming at 5 µm/s (slow) or 50 µm/s (fast). The male gametocyte present in this cube could produce up to 8 male gametes, but it would take 500 slow males or 50 fast males to fully explore this cube