Intra-host and population-level dynamics resulting from fitness components. A) Population-average dynamics of asexual parasitaemia as a function of time after the erythrocytic cycle’s onset. They dynamics are shown separately for the resistant and sensitive parasites following equation (2). The y-axes on the left and right side correspond to the P. falciparum and P. vivax respectively. The dynamics are identical up to a scaling constant. On day seven drugs are administered to eliminate parasites. Resistant parasites are eliminated slightly less efficiently. B) Population-average gametocytaemia derived from the parasitaemia dynamics in A). Whereas, gametocytes are produced readily in P. vivax, they appear much later in P. falciparum. The dynamics are according to Equations (3) and (4). Vertical lines in A) and B) mark important events in a clinical episode. C) Spread of a resistant mutation - according to equation (1) - in P. falciparum and P. vivax is determined by the ratio of the areas under the curve of the gametocytaemia dynamics of resistant over sensitive parasites derived from B). Shown is the frequency of the resistant mutation as a function of time measured in generations corresponding to transmission cycles. The horizontal lines show the fitness ratio of resistant over sensitive parasites with corresponding right-hand side y-axis. Parameters are as described in Methods.