Flukes that parasitize amphibians The enemy of my enemy is my
friend—especially if I’m a frog and my enemies are competing
parasites. A recent study in PNAS found that frogs populations
exposed to a more diverse set of flukes actually had lower rates
of infection, with fewer frogs in the group afflicted with tiny
hitchhikers. Researchers at the University of Colorado-Boulder
bred Pacific chorus frogs in a lab and put their tadpoles in
different tanks with anywhere from one to six different types of
flukes. On average, 40% of the frogs that came into contact with
only a single fluke species developed infections, while 34% of
frogs exposed to four flukes and 23% of frogs exposed to six
flukes were infected (the numbers for two, three flukes followed
a roughly similar trend). Additionally, some of the fluke
species make frogs sicker than others, and oddly enough, the
frogs exposed to a greater variety of flukes had a lower
proportion of infections from these dangerous species. Most
research on host-parasite inte