Figure 1.

Experimental set up to select parasites for or against host manipulation. Only parasites were selected in different selection lines (presented in different colours) and the copepods harbouring these selected parasites fed to sticklebacks for the parasites to continue their life cycle (bottom left in the drawing) and bred in pairs in an in vitro system to produce eggs (top left in the drawing). The offspring that hatched from these eggs of selected parasites was then used to infect naive, unselected copepods from the stock population in every generation (top middle of the drawing).