Nguyen told her boss, biologist Tyrone Hayes, of their unusual behavior. Hayes advised her to observe the frogs on a daily basis. Nguyen was perplexed because she knew that all of the frogs were male. Hayes was not as confused because he put a substance called atrazine in the water that the frogs were in.
30 percent of the male frogs changed gender, due to the atrazine. In fact, some of the transgender frogs sent out chemical signals to attract other males.
The laboratory is not the only place where this has happened. Atrazine is used as a weed killer, so it can pollute water near the crops it is used on. The concentration of atrazine in nearby water is 2.5 parts per billion, the same amount used in Hayes' experiments. This proves that frogs can be changing their gender in their natural habitats.
The Enviromental Protection Agency, or the EPA, is responsible for defining the concentration of certain chemicals in U.S. waterways. The EPA concluded that 3 parts of atrazine per billion is safe. The water that the frogs were tested in was 2.5 parts atrazine per billion parts. This means that even through the atrazine levels are safe to humans, the level is two high for frogs.
Its is not only the frogs' behavior that is altered by atrazine. Two frogs that behaved like females were dissected. To Hayes' surprise, they had female reproductive organs. Two other transgender frogs, that were introduced to male frogs, successfully mated.
Other scientist conducted similar experiments and came up with the same results, proving that Hayes' studies were accurate.
Knowing atrazine's affects on frogs is crucial because it can threaten a species reproduction. If there is an increase, or decrease, in an animal's reproduction, it can throw off the ecosystem's balance. With studies like these, we can be sure that our ecosystems will not be tampered with.
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| Dissection of female (transgender) frog. http://www.sciencenewsforkids.org/articles/20100324/Note2.asp |
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