Some exotic parasites have already been discovered as a result of their significant population effects, such as, for example, the European protozoan Glugea hertwigi, which caused high-rate die-offs of the rainbow smelt in Lake Erie and Lake Ontario during the 1960s and 1970s (Nepszy et al.
Mortality of young-of-the-year rainbow smelt (Osmerus mordax) in Lake Erie associated with the occurrence of Glugea hertwigi.
Until now, both of the EF phylogenies (EF-1 alpha tree is shown in [ILLUSTRATION FOR FIGURE 1 OMITTED]) clearly and consistently suggested (a) that three amitochondriate protists, Glugea
plecoglossi (microsporidian), Giardia lamblia (diplomonad), and Trichomonas tenax (trichomonad), represent an early-branching eukaryotic group; and that among them, the divergence of Glugea
seems to be the earliest (1-5); and (b) that another amitochondrial protist, Entamoeba histolytica, is likely to have diverged after the divergences of some mitochondrion-containing protists, but is not likely to have diverged later than euglenoids, as suggested by the SrRNA tree (6).