Scat = Scientific GOLD

Lab Note #2
Nov 06, 2014

To a molecular ecologist, wildlife scat holds a treasure trove of biological material!  When an animal poops, intestinal cells are sloughed off and excreted with the waste material.  We extract DNA from these shed cells and amplify (make many copies of) specific sections of the DNA.  Within each of our cells, there are two places that contain DNA - the mitochondria and the nucleus. 

Mitochondria, the power-houses our cells, have their own DNA (mtDNA).  There is a specific part of mtDNA (ATP6) that is particularly useful for telling one carnivore species apart from another, which is how we confirm whether our scat samples came from jaguar or puma. 

DNA contained in the nuclei of our cells has sections that are thought by some to be ‘junk’ DNA.  These sections, called microsatellites, do not code for proteins and they are made up of repeated sequences (e.g. a di-nucleotide repeat might look like AGAGAGAGAGAGAGAG).  Microsatellites are great for telling individuals apart, and also at looking at the genetic relatedness between individuals, or between groups of individuals. 

Besides DNA, scat also contains information on the stress levels experienced by animals.  When an animal faces a stress, the body releases hormones into the bloodstream, which are eventually excreted in feces.  T3 thyroid hormone is an excellent marker for tracking chronic nutritional stress - a jaguar that is consistently having difficulty finding prey will have lower T3 levels. Glucocorticoids are hormones that respond to all kinds of stress - they are the hormones responsible for mobilizing glucose when an animal has a 'fight-or-flight' response. Looking at the two hormones combined, we can tell if animals are nutritionally stressed (from not enough prey) and/or psychologically stressed (say from human activity). 

All in all, these molecular tools can tell us a lot about an animal – without ever laying eyes on them!  Completely noninvasive AND tons of data?  Holy sh#t! 

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