MONTREAL, June 24 (UPI) — Canadian scientists say they have, for the first time, used DNA barcoding to show larval flukes parasitize only a few closely related fishes.
“Canada probably has the best studied freshwater fish parasites in the world, so we were amazed when we found four times more species of flukes in a few fishes from the St. Lawrence than were previously known in all fishes across the whole country,” said postdoctoral researcher Sean Locke of Concordia University, who led the research.
Locke and his colleagues said they discovered parasites found in most tissues — including muscle, gills, brains and internal organs — specialized on one or a few closely related fishes.
But they also found the lenses of fish eyes were home to five species of non-specialized flukes that thrive in many different fish species and even frogs.
“The lens seems to be the host’s Achilles’ heel,” Locke said. “An immune response there would blind the fish, so it appears evolution has favored immunological restraint … hence the same parasite species appear in all sorts of different fish.”
He said his team’s findings might have practical benefits for wildlife managers and fish farmers, since larval flukes are among the most common fish parasites in the world.
“Getting rid of wildlife parasites is very difficult even when you know what you’re dealing with,” Locke said. “But identifying a pathogen is the first step to controlling it.”
The study appears in the early online edition of the journal Molecular Ecology.
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