Macroparasite population dynamics among geographical localities and host life cycle stages: eugregarines in Ischnura verticalis.

Populations of several species of gregarine parasites within a single host species, the damselfly Ischnura verticalis , were examined over the course of 1 season at 4 geographic localities separated by a maximum distance of 9.7 km. Gregarines, having a life cycle with both exogenous and endogenous stages, are subject to a wide variety of selective pressures that may drive adaptation.