Focus on Feces

Dung DNA from otters is now used to learn how this endangered species can affect the fish farming industry. A more accurate otter population estimate provides a better understanding of how many fish are eaten annually by otters.

An otter marks its territory up to 30 times a day, providing researchers with many specimens to study. "The practical thing about the otter is that it uses its droppings for the social communication and therefore leaves them exposed, making it very easy for us to find", explains Simone Lampa, who collected over 700 fecal samples in the Oberlausitz Biosphere Reserve during the last two years.

German researchers are now using these traces to estimate the number of animals in an area more accurately than was previously possible using the classical method of MRR – Mark Release Recapture.

The cells on the surface of the intestine are constantly regenerated in vertebrates and the old cells are discarded. So tiny DNA traces are found on each fecal sample, revealing their source.

But compared with blood or tissue samples, the DNA in fecal samples is only represented by a few cells, making it a very difficult procedure.

"In addition to this there is also still the problem that a high number of proteins, bacteria and enzymes in the feces disturb the analysis," reports Dr. Marion Hoehn, who is an expert in conservation genetics of vertebrates. "We have to extract the DNA and copy it several times in order to make it visible, which is prone to errors. The process therefore has to be repeated several times to obtain the true genotype."

-- LiveScience Staff

• Image Gallery: Endangered and Threatened Wildlife
• 10 Amazing Things You Didn’t Know About Animals
• Experts Tie Pigeon Poop, Bridge Collapse