That is not true bc if the top level consumers were removed from the food chain, then the level below would become the top level of the food chain. If that happened then the level below the NEW top level of the food chain would still be getting eaten and the food chain still goes on, just with one missing level.
You would have to be very careful of cross-contamination. That means you would have to work very carefully and precisely with protective clothing, ensuring that none of your DNA (from skin or hair or even trace) gets into the sample you are working with
You would have to be very careful to check and record samples properly to ensure nothing got mixed up or mislabeled and this could be disastrous for criminal cases
All the material is very precious and sometimes only one sample exists, so you have to avoid making any mistakes. Experiments can't always be repeated.
