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Amphibian Structure and Function

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DNA From a Stream?
Teacher Contributed

I Didn't Know You Could Do That!


Environmental DNA

Student Exploration

Are these animals in a stream near you?

Rocky Mountain Tailed Frog

Idaho Giant Salamander

So what do you do when you are supposed to study an animal to see if it's threatened or endangered, but you can't find it? Does that mean the animal is extinct? Not necessarily. Scientists attempting to study rare animals face numerous difficulties, not the least of which is finding their study animals. This situation gets even more complicated for environmental managers as they often have to deal with conflicting needs of humans and numerous rare animals. Scientists faced with this challenge have turned to modern biomolecular techniques, specifically DNA to help them identify the presence of animals and determine their distributions among other things. An egg shell, a feather, hair, some poo scientists can extract DNA from all of these and use them to determine what species are using an area. But what if you have to deal with something like a stream, then it gets a bit trickier and that is when scientists turn to something called eDNA (environmental DNA). This is DNA they extract from the soil or water among other things. Yep, DNA from water. Watch this video to see how scientists prepare samples to test for the invasive Asian carp in the Great Lakes, USA.

But this technique is not used just to test for invasive species. Other scientists are using this technique to look for amphibians in streams. Go here to read about work being done by USGS scientists

Extension Investigation

If you need help scratching a mental itch, use the resources below:

  1. What is the first step in extracting eDNA from water samples? Why is contamination a concern?
  2. Why is it necessary to quickly process water samples if you want to retrieve DNA?
  3. What are some of the problems associated with finding amphibians in streams? How does eDNA help this process? Be as specific and complete as possible.
  4. How is eDNA useful in compiling biodiversity inventories?
  5. In what freshwater ecosystems besides streams has eDNA proved useful?
  6. Explain the PCR (Polymerase Chain Reaction) process as best as you can.
  7. When is the Giant Idaho Salamander most active? Why do you think this is the case? Be as specific as possible.
  8. What is one factor that determines how long it takes for a tadpole to become a Rocky Mountain Tailed Frog? Why do you think it is?

Resources Cited

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