March 30, 2012
FOR IMMEDIATE RELEASE
Contact: B. Rose Huber
[412-624-4356 (office); 412-328-6008 (cell); rhu...@pitt.edu]
New Study Is First to Show That Pesticides Can Induce Morphological Changes
in Vertebrate Animals, Says Pitt Researcher
When exposed to the popular herbicide Roundup®, tadpoles change shape in
ways that are normally induced by predators
PITTSBURGH The worlds most popular weed killer, Roundup®, can cause
amphibians to change shape, according to research published today in
Ecological Applications.
Rick Relyea, University of Pittsburgh professor of biological sciences in
the Kenneth P. Dietrich School of Arts and Sciences and director of Pitt's
Pymatuning Laboratory of Ecology, demonstrated that sublethal and
environmentally relevant concentrations of Roundup® caused two species of
amphibians to alter their morphology. According to Relyea, this is the first
study to show that a pesticide can induce morphological changes in a
vertebrate animal.
Relyea set up large outdoor water tanks that contained many of the
components of natural wetlands. Some tanks contained caged predators, which
emit chemicals that naturally induce changes in tadpole morphology (such as
larger tails to better escape predators). After adding tadpoles to each
tank, he exposed them to a range of Roundup® concentrations. After 3 weeks,
the tadpoles were removed from the tanks.
It was not surprising to see that the smell of predators in the water
induced larger tadpole tails, says Relyea. That is a normal, adaptive
response. What shocked us was that the Roundup® induced the same changes.
Moreover, the combination of predators and Roundup® caused the tail changes
to be twice as large. Because tadpoles alter their body shape to match
their environment, having a body shape that does not fit the environment can
put the animals at a distinct disadvantage.
Predators cause tadpoles to change shape by altering the stress hormones of
tadpoles, says Relyea. The similar shape changes when exposed to Roundup®
suggest that Roundup® may interfere with the hormones of tadpoles and
potentially many other animals.
This discovery highlights the fact that pesticides, which are important for
crop production and human health, can have unintended consequences for
species that are not the pesticides target, says Relyea. Herbicides are
not designed to affect animals, but we are learning that they can have a
wide range of surprising effects by altering how hormones work in the bodies
of animals. This is important because amphibians not only serve as a
barometer of the ecosystems health, but also as an indicator of potential
dangers to other species in the food chain, including humans.
For two decades, Relyea has studied community ecology, evolution, disease
ecology, and ecotoxicology. He has authored more than 80 scientific articles
and book chapters and has presented research seminars around the world. For
more information about his laboratory, visit www.pitt.edu/~relyea/.
Relyea's research was funded by the U.S. National Science Foundation.
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