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DNA Analysis Provides Dietary Clues

Scientists studying the diets of Steller sea lions have come up with an innovative use of DNA analysis to determine the relative proportions of prey in sea lion feces. A new study tests the accuracy of this novel technique, and assesses its potential use in sea lions and other animals.

Scientists are exploring a number of theories explaining the mysterious decline of Steller sea lion populations in Western Alaska. One possibility suggests that a long-term change in the distribution of fish stocks might be depriving sea lions of high-quality prey such as Pacific herring.

Testing this theory requires some gastric sleuthing, and the easiest way to determine a sea lion’s most recent meal is to examine its feces. By analyzing undigested bones and other “hard parts” in fecal samples, scientists can identify the types of prey that have been consumed, indicating possible dietary trends.

This method, while useful, may not accurately show how much of a particular prey has been eaten relative to other types of prey. Some scientists have suggested that analyzing the mitochondrial DNA (mtDNA) of soft tissue remains in feces may provide a more complete dietary picture.

A new study by Drs. Bruce Deagle (University of Tasmania) and Dominic Tollit (University of British Columbia) assesses whether a quantitative real-time PCR approach could be useful on a broad scale. The study was recently published in the journal Conservation Genetics.

[Read more at North Pacific Universities Marine Mammal Research Consortium]

| Posted 09.07.07 at 1:58 am

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