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The golden frog is a small bright-yellow amphibian that lives in and around mountain streams in Panama. The species is severely endangered because of a fungus that infects the frog through its skin and inhibits the frog’s critical life functions, such as breathing. Conservationists have proposed a few solutions to the golden frog’s fungus problem.

Bacterial Protection

First, scientists have identified a natural enemy of the fungus: a type of bacterium. This bacterium produces a chemical that kills fungal cells. Scientists think that they may be able to introduce colonies of this bacterium to the skin of golden frogs. The bacterial colonies would then protect the frogs against the fungus infection.

Breeding Frogs in Captivity

Second, researchers are considering the possibility of breeding golden frogs in captivity and then releasing them in the wild to replenish wild populations. The golden frog can develop disease-free in captivity; where it is isolated from the fungus. When golden frogs bred in captivity are released in habitats where wild golden frogs have died out, the frogs bred in captivity will give rise to a healthy, fungus-free population.

A Natural Defense

Third, it is possible that golden frogs will overcome the threat posed by the fungus without human intervention. Some golden frogs have what seems to be a natural defense against the fungus. When infected, they increase their body temperature, which slows down the growth of the fungus. If this ability to resist the fungal infection spreads among the golden frog population as a whole, the frog population is likely to overcome the crisis and start increasing again.

Listening

听力原文

Unfortunately, none of the solutions you read about will be very effective in helping to save golden frog populations. 

First, using the protective bacterial will probably not work. Scientists introduce this bacterium to the skin of golden frogs. The bacterium did have a positive effect, but it did not last very long. The protection against the fungus was only temporary. You see, the bacterium produces a chemical that attacks the fungus. Unfortunately, the bacterium only produces this chemical early in its colonization of the frog’s skin. After this brief period, the bacteria stops producing this chemical and therefore, stop protecting the golden frogs from fungal infection.

Second, if we release healthy golden frogs bred in captivity to an area where the wild golden frogs died out, this new population is not going to stay healthy. That’s because some other animals living in that environment carry the same disease causing fungus. So, if we release golden frogs raised in captivity into that environment, they will soon get infected by the fungus, as they come into contact with the wild animals there that are already infected. So, this plan probably won’t work either. 

Third, what about the frogs that defend themselves against the fungus by heating up their bodies? Well, this type of natural defense seems to have a big drawback. Frogs that heat up their bodies have to use up a lot of energy. The expenditure of so much extra energy weakens the frogs, and frogs that are weak can easily get ill or even die from other causes. So, frogs that use this defense might be protected from the fungus, but they are not strong and healthy. It’s unlikely that using this defense would help the golden frog’s population to recover.

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