P. gallinaceum gametocyte (sexual) parasite density (mean ± S.E.) following infection by either or both parasite clones using a fixed number of mosquitoes. Thai or SL clone alone, 8 infectious mosquitoes for either clone per bird; mixed infections were initiated using 8 infectious mosquitoes of each clone per bird (8+8) or 4 infectious mosquitoes of each clone per bird (4+4). 3 birds were thus infected for each treatment type and the experiment was performed twice using different batches of mosquitoes infectious for each clone. Thai clone (squares, thin line); SL clone (open circles, thick line); 8+8 mixed clones (triangles, long dotted line); 4+4 mixed clones (crosses, short dotted line).